Encyclopedia / Pharmaceutical Intermediates / Others / Organic Intermediate

Pyridine

CAS：110-86-1
MW:79.09990
MF：C5H5N

Pyridine is a solvent for many organic compounds andanhydrous metallic salts chemicals. Contained in KarlFischer reagent, it induced contact dermatitis in alaboratory technician. View more+

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Names and ldentifier
Properties
Use and Manufacturing
Safety and Handling
Msds
NMR Spectrum
Other Information
Computational chemical data
Related Questions
Realated Product Infomation

1. Names and Identifiers

1.1 Name: Pyridine

1.2 Synonyms: azabenzene; FEMA 2932; FEMA 2966; FEMA NUMBER 2966; MFCD00002920; Pyridine,AcroSeal,Extra Dry; Pyridine,nonaqueous titration grade; pyridinecarboxylicacid,2-(4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1h-imidazol-2-yl)-5-methyl; pyridinecarboxylicacid,2-(4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1h-imidazol-2-yl)-5-methyl,monoammoniumsalt; Rcra waste number U196; rcrawastenumberu196;

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1.3 CAS No.: 110-86-1

1.4 CID: 1049

1.5 EINECS: 203-809-9; 230-720-2

1.6 Molecular Formula: C5H5N

1.7 Inchi: InChI=1S/C5H5N/c1-2-4-6-5-3-1/h1-5H

1.8 InChkey: JUJWROOIHBZHMG-UHFFFAOYSA-N

1.9 Canonical Smiles: C1=CC=NC=C1

1.10 Isomers Smiles: C1=CC=NC=C1

2. Properties

2.1 Vapour pressure: 2.72 (vs air)

2.2 Solubility: H2O: in accordance

2.3 VaporDensity: 2.72 (vs air)

2.4 AnalyticLaboratory Methods: Small concentrations /of pyridine;/ can be measured with UV spectrophotometry at 256 nm after collection in alcohol. Ultraviolet adsorption, gas chromatographic, liquid chromatographic techniques can also be used, as well as a portable infrared analyzer.

2.5 Appearance: colorless Liquid

2.6 AutoIgnition: 900° F (USCG, 1999)

2.7 Storage: Pyridine should be used only in areas free ofignition sources, and quantities greater than 1 liter should be stored in tightly sealedmetal containers in areas separate from oxidizers.

2.8 Carcinogenicity: Pyridine was not carcinogenic inseveral chronic subcutaneous studies.F344 rats were given pyridine orally in drinking water atdoses of 0, 7, 14, or 33 mg/kg for 2 years. The top doseproduced a decrease in body weights and water consumption.Increased renal tubular adenoma or carcinoma and tubularhyperplasia were observed in males at 33 mg/kg. Increasedmononuclear cell leukemia was observed in females at 14and 33 mg/kg, which was considered equivocal in terms ofthe relationship to pyridine exposure, since this is a commonfinding in this strain of rat. Concentration-related nonneoplasticchange in the liver was seen at 33 mg/kg. MaleWistar rats were similarly treated with doses of 0, 8, 17, or36 mg/kg for 2 years. Decreased survival and body weightswere seen at 17 and 36 mg/kg. Increased testicular celladenomas were seen at 36 mg/kg. No changes in survivalor neoplasm rates in other tissues, including the kidney, werereported although increased nephropathy and hepatic centrilobulardegeneration/necrosis was observed in some pyridine-treated rats.

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2.9 Chemical Properties: Pyridine is a colourless flammable liquid with a strong and unpleasant fish-like odour.

2.10 Physical Properties: Clear, colorless to pale yellow, flammable liquid with a sharp, penetrating, nauseating fish-likeodor. Odor threshold concentrations in water and air were 2 ppm (Buttery et al., 1988) and 21 ppbv(Leonardos et al., 1969), respectively. Detection odor threshold concentrations of 0.74 mg/m3 (2.3ppmv) and 6 mg/m3 (1.9 ppmv) were experimentally determined by Katz and Talbert (1930) andDravnieks (1974), respectively. Cometto-Mu?iz and Cain (1990) reported an average nasalpungency threshold concentration of 1,275 ppmv.

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2.11 Color/Form: Colorless to yellow liquid.

2.12 Contact Allergens: Pyridine (unsubstituted pyridine) and its derivative(substituted pyridines) are widely used in chemistry.Pyridine is a solvent used for many organic compoundsand anhydrous metallic salt chemicals. Contained inKarl Fischer reagent, it induced contact dermatitis in alaboratory technician. No cross-sensitivity is observedbetween those different substances.

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2.13 Corrosivity: Liquid pyridine; will attack some forms of plastics, rubber and coatings.

2.14 Decomposition: When pyridine; is heated to decomposition, cyanide; fumes are released.

2.15 Flammability and Explosibility: Pyridine is a highly flammable liquid (NFPA rating = 3), and its vapor can travel aconsiderable distance and "flash back." Pyridine vapor forms explosive mixtureswith air at concentrations of 1.8 to 12.4% (by volume). Carbon dioxide or drychemical extinguishers should be used for pyridine fires.

2.16 Heat of Combustion: -14.390 BTU/LB= -7992 CAL/G= -334.6X10+5 J/KG

2.17 Ionization Potential: 9.27 eV

2.18 Odor: Sharp, nauseating

2.19 Odor Threshold: Odor detection in water; is 8.20x10+1 ppm; chemically pure

2.20 PH: 8.5 (0.2 molar soln in water)

2.21 Physical: PYRIDINE; is a clear colorless to light yellow liquid with a penetrating nauseating odor. Density 0.978 g / cm3. Flash point 68°F. Vapors are heavier than air. Toxic by ingestion and inhalation. Combustion produces toxic oxides of nitrogen.

2.22 pKa: 5.25(at 25℃)

2.23 Water Solubility: Micible with water.

2.24 Spectral Properties: Index of refraction: 1.50920 @ 20 deg C/D
MAX ABSORPTION (CYCLOHEXANE): 251 NM (LOG E= 3.1); 256 NM (LOG E= 3.1); 279 NM (LOG E= 2.0) SHOULDER; 284 NM (LOG E= 1.8) SHOULDER; 288 NM (LOG E= 1.4) SHOULDER
IR: 4840 (Coblentz Society Spectral Collection)
UV: 9 (Sadtler Research Laboratories Spectral Collection)
NMR: 96 (Varian Associates NMR Spectra Catalogue)
MASS: 62073 (NIST/EPA/MSDC Mass Spectral Database, 1990 version)
Intense mass spectral peaks: 52 m/z, 79 m/z

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2.25 Stability: Stable. Flammable. Incompatible with strong oxidizing agents, strong acids.

2.26 StorageTemp: Store at +5°C to +30°C.

3. Use and Manufacturing

3.1 Definition: ChEBI: An azaarene comprising a benzene core in which one -CH group is replaced by a nitrogen atom. It is the parent compound of the class pyridines.

3.2 Description: Pyridine (CAS 110-86-1) is a colorless liquid with a distinct odor. It has a basic structure consisting of a six-membered aromatic ring with a nitrogen atom. Pyridine is highly soluble in water, forming a clear solution. It has a boiling point of 115.2 degrees Celsius and a density of 0.981 grams per milliliter. This chemical is flammable and should be handled with caution.

Applicable Fields
Pharmaceutical Industry: Pyridine is widely used in the pharmaceutical industry as a solvent and reagent. It is commonly used in the synthesis of various drugs and pharmaceutical intermediates. The mechanism of action involves its ability to dissolve and react with different compounds, facilitating the synthesis of desired pharmaceutical products.

Chemical Industry: In the chemical industry, pyridine is utilized as a versatile building block for the synthesis of various chemicals. It serves as a precursor for the production of agrochemicals, dyes, rubber chemicals, and other specialty chemicals. The mechanism of action involves its reactivity and ability to undergo various chemical reactions, enabling the synthesis of complex chemical compounds.

Storage Conditions
Store in a cool, dry place.

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3.3 GHS Classification: Signal: Danger
GHS Hazard Statements
H225: Highly Flammable liquid and vapor [Danger Flammable liquids]
H302: Harmful if swallowed [Warning Acute toxicity, oral]
H312: Harmful in contact with skin [Warning Acute toxicity, dermal]
H332: Harmful if inhaled [Warning Acute toxicity, inhalation]

Precautionary Statement Codes
P210, P233, P240, P241, P242, P243, P261, P264, P270, P271, P280, P301+P312, P302+P352, P303+P361+P353, P304+P312, P304+P340, P312, P322, P330, P363, P370+P378, P403+P235, and P501

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3.4 Methods of Manufacturing: Saturator mother liquor during high-temperature coking is used as raw material, crude pyridine is recovered and processed, slag is removed by heating to obtain aqueous pyridine, dehydrated with pure benzene, and anhydrous pyridine is obtained, and then 110-120°C fraction is distilled by distillation. From rectification.

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3.5 Potential Exposure: Pyridine is used as a solvent inthe chemical industry and as a denaturant for ethyl alco-hol; as an intermediate in the production of pesticides;in pharmaceuticals; in the manufacture of paints,explosives, dyestuffs, rubber, vitamins, sulfa drugs; anddisinfectants.

3.6 Shipping: UN1992 Flammable liquids, toxic, n.o.s., HazardClass: 3; Labels: 3-Flammable liquid, 6.1-Poisonous mate-rials, Technical Name Required.

3.7 Usage: 3.1 SolventPyridine is a polar, basic, low-reactive solvent, especially for dehydrochlorination reactions and extraction of antibiotics. In elimination reaction, pyridine acts as the base of the elimination reaction and bonds the resulting hydrogen halide to form a pyridinium salt. In esterifications and acylations, pyridine activates the carboxylic acid halides or anhydrides.3.2 MedicinesPyridine's chemical structure can be found in various medications that are synthesized thanks in part to pyridine. One example is a medication called esomeprazole, the generic name for Nexium. This is a medication that's used to treat GERD, or gastroesophageal reflux disease. Another example of a pyridine containing medication is loratadine, more commonly known by its brand name of Claritin. Loratadine helps in the treatment of allergies.3.3 PesticidesThe main use of pyridine is as a precursor to the herbicides paraquat and diquat. The first synthesis step of insecticide chlorpyrifos consists of the chlorination of pyridine. Pyridine is also the starting compound for the preparation of pyrithione-based fungicides. Cetylpyridinium and laurylpyridinium, which can be produced from pyridine with a Zincke reaction, are used as antiseptic in oral and dental care products. Pyridine is easily attacked by alkylating agents to give N-alkylpyridinium salts. One example is cetylpyridinium chloride.

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3.8 Waste Disposal: Controlled incinerationwhereby nitrogen oxides are removed from the effluent gasby scrubber, catalytic or thermal devices . Pyridine Preparation Products And Raw materials Preparation Products

4. Safety and Handling

4.1 Exposure Standards and Regulations: Pyridine is a food additive permitted for direct addition to food for human consumption as a synthetic flavoring substance and adjuvant in accordance with the following conditions: a) they are used in the minimum quantity required to produce their intended effect, and otherwise in accordance with all the principles of good manufacturing practice, and 2) they consist of one or more of the following, used alone or in combination with flavoring substances and adjuvants generally recognized as safe in food, prior-sanctioned for such use, or regulated by an appropriate section in this part.

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4.2 Octanol/Water Partition Coefficient: log Kow = 0.65

4.3 Other Preventative Measures: ... HANDLING OF PYRIDINE SHOULD BE CONDUCTED IN WELL-VENTILATED CONDITIONS ... .
Open lights and other /ignition sources/ capable of igniting pyridine and its vapor should be excluded from areas where pyridine is exposed in the course of manipulation.
Employees should wash immediately when skin is wet or contaminated. Remove clothing immediately if wet or contaminated to avoid flammability hazard. Provide emergency showers and eyewash.
Employees who handle liquid pyridine or solutions containing pyridine should wash their hands thoroughly before eating, smoking, or using toilet facilities.
If material not on fire and not involved in fire: Keep sparks, flames, and other sources of ignition away. Keep material out of water sources and sewers. Build dikes to contain flow as necessary. Attempt to stop leak if without hazard. Use water spray to disperse vapors and dilute standing pools of liquid.
Personnel protection: Avoid breathing vapors. Keep upwind. Avoid bodily contact with the material. Do not handle broken packages unless wearing appropriate personal protective equipment.
If the use of respirators is necessary, the only respirators permitted are those that have been approved by the Mine Safety and Health Administration (formerly Mining Enforcement and Safety Administration) or by the National Institute for Occupational Safety and Health. In addition to respirator selection, a complete respiratory protection program should be instituted which includes regular training, maintenance, inspection, cleaning, and evaluation.
Clothing contaminated with liquid pyridine should be placed in closed containers for storage until it can be discarded or until provision is made for the removal of pyridine from the clothing. If the clothing is to be laundered or otherwise cleaned to remove the pyridine, the person performing the operation should be informed of pyridine's hazardous properties. Non-impervious clothing which becomes contaminated with liquid pyridine should be removed immediately and not reworn until the pyridine is removed from the clothing.
... PROCESS PLANT SHOULD, BY PREFERENCE, BE ENCLOSED AND FITTED WITH LOCAL EXHAUST VENTILATION. DEPENDING ON THE EXTENT OF POSSIBLE CONTACT, WORKERS SHOULD BE PROVIDED WITH PERSONAL PROTECTIVE EQUIPMENT.
Skin that becomes wet with liquid pyridine should be promptly washed or showered. Eating and smoking should not be permitted in areas where liquid pyridine is handled, processed, or stored.
SRP: The scientific literature for the use of contact lenses in industry is conflicting. The benefit or detrimental effects of wearing contact lenses depend not only upon the substance, but also on factors including the form of the substance, characteristics and duration of the exposure, the uses of other eye protection equipment, and the hygiene of the lenses. However, there may be individual substances whose irritating or corrosive properties are such that the wearing of contact lenses would be harmful to the eye. In those specific cases, contact lenses should not be worn. In any event, the usual eye protection equipment should be worn even when contact lenses are in place.
The worker should immediately wash the skin when it becomes contaminated.
Work clothing that becomes wet should be immediately removed due to its flammability hazard.
Eyewash fountains should be provided in areas where there is any possbility that workers could be exposed to the substance; this is irrespective of the recommendation involving the wearing of eye protection.

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4.4 Cleanup Methods: 1. REMOVE ALL IGNITION SOURCES. 2. VENTILATE AREA OF SPILL OR LEAK. 3. FOR SMALL QUANTITIES, ABSORB ON PAPER TOWELS, EVAPORATE IN SAFE PLACE (SUCH AS FUME HOOD). ALLOW SUFFICIENT TIME FOR EVAPORATING VAPORS TO COMPLETELY CLEAR HOOD DUCTWORK. BURN PAPER IN SUITABLE LOCATION AWAY FROM COMBUSTIBLE MATERIAL. 3. LARGE QUANTITIES CAN BE COLLECTED & ATOMIZED IN SUITABLE COMBUSTION CHAMBER EQUIPPED WITH APPROPRIATE EFFLUENT GAS CLEANING DEVICE. PYRIDINE SHOULD NOT BE ALLOWED TO ENTER CONFINED SPACE, SUCH AS SEWER, BECAUSE OF POSSIBILITY OF EXPLOSION.
Biological treatment of wastewater for the removal of pyridine.
Removal of pyridine from waste gases by adsorption.
Eliminate all ignition sources. Stop or control the leak, if this can be done without undue risk. Use water spray to cool and disperse vapors, protect personnel, and dilute spills to form nonflammable mixtures. Control run-off and isolate discharged materials for proper disposal.

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4.5 DisposalMethods: Generators of waste (equal to or greater than 100 kg/mo) containing this contaminant, EPA hazardous waste number U196, F005, and D038 must conform with USEPA regulations in storage, transportation, treatment and disposal of waste.
A potential candidate for rotary kiln incineration at a temperature range of 820 to 1,600 deg C and residence times of seconds for liquids and gases, and hours for solids. A potential candidate for liquid injection incineration at a temperature range of 650 to 1,600 deg C and a residence time of 0.1 to 2 seconds. A potential candidate for fluidized bed incineration at a temperature range of 450 to 980 deg C and residence times of seconds for liquids and gases, and longer for solids.
The following wastewater treatment technologies have been investigated for Pyridine: Concentration process: Activated carbon.
Controlled incineration whereby nitrogen oxides are removed from the effluent gas by scrubber, catalytic or thermal devices. Recommendable method: Incineration. Not recommendable methods: Evaporation & landfill.
Photolysis: Treatment pyridine-containing effluents by uv-light irradiation is suggested. The photodegradation of pyridine by uv-light decreases in magnitude with increasing pH and is heavily inhibited in an alkaline medium (pH 10 to 12). Irradiation of pyridine water solutions with different pH values leads to production of intermediate photolytic products with mutually different light- absorption spectra. Photo-oxidation of pyridine and its primary degradation products occurs at the expense of the oxidant radicals that form during water photolysis. The presence of dissolved free oxygen adds intensity to the oxidative processes, thus increasing the yield of hydrogen peroxide. The latter's presence makes the photochemical breakdown of pyridine maximum effective and complete. In the process, the rate of pyridine photolysis increases, 3-3.5 times and its destruction, as well as of the products resulting from the photochemical reactions, is complete within 20-25 minutes of irradiation exposure, in the absence of FE(II) or FE(III) or their oxalate complexes. With the FE(II) or FE(III) oxalate complexes, the pyridine photolysis rate is much faster.
The limitations and feasibility of the land disposal of solid wastes containing organic solvents and refrigerants were investigated by evaluating the attenuation capacity of a hypothetical waste disposal site by numerical modeling. The basic theorem of this approach was that the land disposal of wastes would be environmentally acceptable if subsurface attenuation reduced groundwater concentrations of organic compounds to concentrations that were less than health based, water quality criteria. Computer simulations indicated that the predicted concentrations of 13 of 33 organic compounds in groundwater would be less than their health based criteria. Hence solid wastes containing these compounds could be safely disposed at the site. The attenuation capacity of the site was insufficient to reduce concentrations of 4 compounds to safe levels without limiting the amount of mass available to leach into groundwater. Threshold masses based on time dependent migration simulations were estimated for these compounds. Pyridine was one of 16 compounds that could not be safely landfilled without severe restrictions on the amounts disposed.
Pyridine is a waste chemical stream constituent which may be subjected to ultimate disposal by controlled incineration.
Spillage disposal: Wear butyl rubber gloves, laboratory coat and eye protection. Cover the spill with a 1:1:1 mixture by weight of sodium carbonate or calcium carbonate, clay cat litter (bentonite) and sand. Scoop into an appropriate labeled container for disposal by burning in a furnace equipped with an afterburner and scrubber.
Waste disposal: Compound should be burned. Dissolve in combustible solvent such as alcohol or benzene. Spray the solution into a furnace equipped with afterburner and scrubber.

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4.6 DOT Emergency Guidelines: /GUIDE 129: FLAMMABLE LIQUIDS (POLAR/WATER-MISCIBLE/NOXIOUS)/ Fire or Explosion: HIGHLY FLAMMABLE: Will be easily ignited by heat, sparks or flames. Vapors may form explosive mixtures with air. Vapors may travel to source of ignition and flash back. Most vapors are heavier than air. They will spread along ground and collect in low confined areas (sewers, basements, tanks). Vapor explosion hazard indoors, outdoors or in sewers. Runoff to sewer may create fire or explosion hazard. Containers may explode when heated. Many liquids are lighter than water.
/GUIDE 129: FLAMMABLE LIQUIDS (POLAR/WATER-MISCIBLE/NOXIOUS)/ Health: May cause toxic effects if inhaled or absorbed through skin. Inhalation or contact with material may irritate or burn skin and eyes. Fire will produce irritating, corrosive and/or toxic gases. Vapors may cause dizziness or suffocation. Runoff from fire control or dilution water may cause pollution.
/GUIDE 129: FLAMMABLE LIQUIDS (POLAR/WATER-MISCIBLE/NOXIOUS)/ Public Safety: CALL Emergency Response Telephone Number ... . As an immediate precautionary measure, isolate spill or leak area for at least 50 meters (150 feet) in all directions. Keep unauthorized personnel away. Stay upwind. Keep out of low areas. Ventilate closed spaces before entering.
/GUIDE 129: FLAMMABLE LIQUIDS (POLAR/WATER-MISCIBLE/NOXIOUS)/ Protective Clothing: Wear positive pressure self-contained breathing apparatus (SCBA). Structural firefighters' protective clothing will only provide limited protection.
/GUIDE 129: FLAMMABLE LIQUIDS (POLAR/WATER-MISCIBLE/NOXIOUS)/ Evacuation: Large spill: Consider initial downwind evacuation for at least 300 meters (1000 feet). Fire: If tank, rail car or tank truck is involved in a fire, ISOLATE for 800 meters (1/2 mile) in all directions; also, consider initial evacuation for 800 meters (1/2 mile) in all directions.
/GUIDE 129: FLAMMABLE LIQUIDS (POLAR/WATER-MISCIBLE/NOXIOUS)/ Fire: Caution: All these products have a very low flash point: Use of water spray when fighting fire may be inefficient. Small fires: Dry chemical, CO2, water spray or alcohol-resistant foam. Do not use dry chemical extinguishers to control fires involving nitromethane or nitroethane. Large fires: Water spray, fog or alcohol-resistant foam. Do not use straight streams. Move containers from fire area if you can do it without risk. Fire involving tanks or car/trailer loads: Fight fire from maximum distance or use unmanned hose holders or monitor nozzles. Cool containers with flooding quantities of water until well after fire is out. Withdraw immediately in case of rising sound from venting safety devices or discoloration of tank. ALWAYS stay away from tanks engulfed in fire. For massive fire, use unmanned hose holders or monitor nozzles; if this is impossible, withdraw from area and let fire burn.
/GUIDE 129: FLAMMABLE LIQUIDS (POLAR/WATER-MISCIBLE/NOXIOUS)/ Spill or Leak: ELIMINATE all ignition sources (no smoking, flares, sparks or flames in immediate area). All equipment used when handling the product must be grounded. Do not touch or walk through spilled material. Stop leak if you can do it without risk. Prevent entry into waterways, sewers, basements or confined areas. A vapor suppressing foam may be used to reduce vapors. Absorb or cover with dry earth, sand or other non-combustible material and transfer to containers. Use clean non-sparking tools to collect absorbed material. Large spills: Dike far ahead of liquid spill for later disposal. Water spray may reduce vapor; but may not prevent ignition in closed spaces.
/GUIDE 129: FLAMMABLE LIQUIDS (POLAR/WATER-MISCIBLE/NOXIOUS)/ First Aid: Move victim to fresh air. Call 911 or emergency medical service. Give artificial respiration if victim is not breathing. Administer oxygen if breathing is difficult. Remove and isolate contaminated clothing and shoes. In case of contact with substance, immediately flush skin or eyes with running water for at least 20 minutes. Wash skin with soap and water. Keep victim warm and quiet. In case of burns, immediately cool affected skin for as long as possible with cold water. Do not remove clothing if adhering to skin. Effects of exposure (inhalation, ingestion or skin contact) to substance may be delayed. Ensure that medical personnel are aware of the material(s) involved and take precautions to protect themselves.

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4.7 Fire Fighting Procedures: Use water spray, dry chemical, "alcohol resistant" foam, or carbon dioxide. Solid streams of water may be ineffective. Use water spray to keep fire-exposed containers cool.
If material is on fire or involved in fire: Do not extinguish fire unless flow can be stopped or safely confined. Use water in flooding quantities as fog. Solid streams may be ineffective. Cool all affected containers with flooding quantities of water. Apply water from as far a distance as possible. Use "alcohol" foam, carbon dioxide, or dry chemical.

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4.8 FirePotential: Pyridine is a flammable ... liquid.
Dangerous fire hazard when exposed to heat, flame, or oxidizers.

4.9 Formulations/Preparations: Grades: Technical at 20 deg C, 2 deg (meaning distillation range); Medicinal; CP; Spectrophotometric

4.10 Incompatibilities: Violent reaction with strong oxidizers;strong acids; chlorosulfonic acid; maleic anhydride; oleumiodine.

4.11 Protective Equipment and Clothing: WEAR SPECIAL PROTECTIVE CLOTHING AND POSITIVE PRESSURE SELF-CONTAINED BREATHING APPARATUS.
Employees should be provided with and required to use impervious clothing, gloves, face-shields (eight-inch minimum), and other appropriate protective clothing necessary to prevent skin contact with liquid pyridine or solutions containing pyridine, where skin contact may occur.
Depending on the extent of possible contact, workers should be provided with personal protective equipment. A charcoal gas mask canister respirator has been found to be effective against a 2% pyridine concentration at 30 l/min for 1 hr. Rubber and plastic gloves should not be relied upon to prevent skin contact because pyridine and many of its derivatives penetrate these materials ... . /Pyridine, homologues, and derivatives/
Wear appropriate personal protective clothing to prevent skin contact.
Wear appropriate eye protection to prevent eye contact.
Facilities for quickly drenching the body should be provided within the immediate work area for emergency use where there is a possibility of exposure. [Note: It is intended that these facilities provide a sufficient quantity or flow of water to quickly remove the substance from any body areas likely to be exposed. The actual determination of what constitutes an adequate quick drench facility depends on the specific circumstances. In certain instances, a deluge shower should be readily available, whereas in others, the availability of water from a sink or hose could be considered adequate.]
Recommendations for respirator selection. Max concn for use: 125 ppm. Respirator Class(es): Any supplied-air respirator operated in a continuous flow mode. Eye protection needed. Any powered, air-purifying respirator with organic vapor cartridge(s). Eye protection needed.
Recommendations for respirator selection. Max concn for use: 250 ppm. Respirator Class(es): Any chemical cartridge respirator with a full facepiece and organic vapor cartridge(s). Any air-purifying, full-facepiece respirator (gas mask) with a chin-style, front- or back-mounted organic vapor canister. Any powered, air-purifying respirator with a tight-fitting facepiece and organic vapor cartridge(s). Eye protection needed. Any self-contained breathing apparatus with a full facepiece. Any supplied-air respirator with a full facepiece.
Recommendations for respirator selection. Max concn for use: 1000 ppm. Respirator Class(es): Any supplied-air respirator that has a full facepiece and is operated in a pressure-demand or other positive-pressure mode.
Recommendations for respirator selection. Condition: Emergency or planned entry into unknown concn or IDLH conditions: Respirator Class(es): Any self-contained breathing apparatus that has a full facepiece and is operated in a pressure-demand or other positive pressure mode. Any supplied-air respirator that has a full face piece and is operated in pressure-demand or other positive pressure mode in combination with an auxiliary self-contained breathing apparatus operated in pressure-demand or other positive pressure mode.
Recommendations for respirator selection. Condition: Escape from suddenly occurring respiratory hazards: Respirator Class(es): Any air-purifying, full-facepiece respirator (gas mask) with a chin-style, front- or back-mounted organic vapor canister. Any appropriate escape-type, self-contained breathing apparatus.

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4.12 Reactivities and Incompatibilities: PYRIDINE REACTS VIOLENTLY WITH CHLOROSULFONIC ACID, CHROMIC ACID, MALEIC ANHYDRIDE, NITRIC ACID, FUMING SULFURIC ACID, PERCHROMATES, BETA-PROPIOLACTONE, SILVER PERCHLORATE, & SULFURIC ACID.
Incompatible with strong oxidizers.
... Contact with strong acids will cause violent spattering.
DANGEROUS ... WHEN EXPOSED TO HEAT, FLAME OR OXIDIZERS.
Reaction with bromine trifluoride gives solid which ignites when dry. Forms unstable complex with chromium trioxide. Reacts violently with liquid dinitrogen tetroxide. Incandesces on contact with fluorine.
Strong oxidizers, strong acids.
Reacts to form pyrophoric or explosive products with ... trifluoromethyl hypofluorite. Mixtures with formamide + iodine + sulfur trioxide are storage hazards, releasing carbon dioxide & sulfuric acid.

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4.13 Report: Community Right-To-Know List. Reported in EPA TSCA Inventory. EPA Genetic Toxicology Program.

4.14 Skin, Eye, and Respiratory Irritations: Irritating to eyes, nose, and throat. May cause smarting of the skin ...
... Pyridine & its derivatives cause local irritation on contact with the skin, mucous membranes & cornea.
It is a mild skin and severe eye irritant.

4.15 Safety: Hazard Codes of Pyridine (CAS NO.110-86-1): T,N,F,Xn
Risk Statements: 11-20/21/22-39-23/24/25
R11:Highly flammable.
R20/21/22: Harmful by inhalation, in contact with skin and if swallowed.
R39: Danger of very serious irreversible effects.
R23/24/25: Toxic by inhalation, in contact with skin and if swallowed.
Safety Statements: 36/37/39-38-45-61-26-28-24/25-22-16-7
S36/37/39: Wear suitable protective clothing, gloves and eye/face protection.
S38: In case of insufficient ventilation, wear suitable respiratory equipment.
S45: In case of accident or if you feel unwell, seek medical advice immediately (show the label whenever possible.)
S61: Avoid release to the environment. Refer to special instructions / safety data sheets.
S26: In case of contact with eyes, rinse immediately with plenty of water and seek medical advice.
S28: After contact with skin, wash immediately with plenty of soap-suds.
S24/25: Avoid contact with skin and eyes.
S22: Do not breathe dust.
S16: Keep away from sources of ignition.
S7: Keep container tightly closed.
RIDADR :UN 1282 3/PG 2
WGK Germany: 2
RTECS: UR8400000
F: 3-10
Hazard Note: Highly Flammable/Harmful
HazardClass: 3
PackingGroup: II
Irritates skin and eye. Can cause dizziness, headache, central nervous system depression, gastrointestinal upset, and liver and kidney damage.
Severe explosion hazard in the form of vapor when exposed to flame or spark.
When heated to decomposition it emits highly toxic fumes of NOx.
Currently, there is inadequate evidence that it's a possible carcinogenic agent in humans, though there is limited evidence of carcinogenic effects on animals.

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4.16 Specification: Degraded by bacteria to ammonia and carbon dioxide.

4.17 Toxicity: Oral-Rat? LD50: 891 mg/kg; Intravenous-Mouse LD50: 1500 mg/kg

5. MSDS

2.Hazard identification

2.1 Classification of the substance or mixture

Flammable liquids, Category 2

Acute toxicity - Oral, Category 4

Acute toxicity - Dermal, Category 4

Acute toxicity - Inhalation, Category 4

2.2 GHS label elements, including precautionary statements

Pictogram(s)
Signal word	Danger
Hazard statement(s)	H225 Highly flammable liquid and vapour H302 Harmful if swallowed H312 Harmful in contact with skin H332 Harmful if inhaled
Precautionary statement(s)
Prevention	P210 Keep away from heat, hot surfaces, sparks, open flames and other ignition sources. No smoking. P233 Keep container tightly closed. P240 Ground and bond container and receiving equipment. P241 Use explosion-proof [electrical/ventilating/lighting/...] equipment. P242 Use non-sparking tools. P243 Take action to prevent static discharges. P280 Wear protective gloves/protective clothing/eye protection/face protection. P264 Wash ... thoroughly after handling. P270 Do not eat, drink or smoke when using this product. P261 Avoid breathing dust/fume/gas/mist/vapours/spray. P271 Use only outdoors or in a well-ventilated area.
Response	P303+P361+P353 IF ON SKIN (or hair): Take off immediately all contaminated clothing. Rinse skin with water [or shower]. P370+P378 In case of fire: Use ... to extinguish. P301+P312 IF SWALLOWED: Call a POISON CENTER/doctor/\u2026if you feel unwell. P330 Rinse mouth. P302+P352 IF ON SKIN: Wash with plenty of water/... P312 Call a POISON CENTER/doctor/\u2026if you feel unwell. P321 Specific treatment (see ... on this label). P362+P364 Take off contaminated clothing and wash it before reuse. P304+P340 IF INHALED: Remove person to fresh air and keep comfortable for breathing.
Storage	P403+P235 Store in a well-ventilated place. Keep cool.
Disposal	P501 Dispose of contents/container to ...

2.3 Other hazards which do not result in classification

none

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6. NMR Spectrum

ESR : ANION RADICAL, ELECTROREDUCTION IN LIQ. NH3, -75C

ESR : COBALT COMPLEX, IN CHCL3

ESR : DIMER ANION RADICAL, REDUCTION WITH K IN DME

ESR : MN(II) COMPLEX IN TOLUENE

13C NMR : in CDCl3

13C NMR : Predict

1H NMR : 400 MHz in CDCl3

1H NMR : 90 MHz in CDCl3

1H NMR : parameter in CDCl3

1H NMR : parameter in DMSO-d6

1H NMR : Predict

Predict 1H proton NMR

IR : liquid film

Raman : 4880 A,100M,liquid

Mass

Mass spectrum (electron ionization)

UV/Visible spectrum

7. Synthesis Route

110-86-1Total: 239 Synthesis Route

96-54-8 132 Suppliers

110-86-1 80 Suppliers

636-41-9 28 Suppliers

59-67-6 656 Suppliers

110-86-1 80 Suppliers

100-54-9 239 Suppliers

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8. Precursor and Product

precursor:

64-17-5

59-67-6

75-07-0

96-54-8

535-83-1

75-56-9

109-06-8

product:

50-59-9

626-55-1

109-04-6

91-02-1

54-85-3

694-59-7

372-48-5

86-22-6

55-22-1

91-22-5

9. Computed Properties

Molecular Weight：79.09990g/mol
Molecular Formula：C₅H₅N
Compound Is Canonicalized：True
XLogP3-AA：79.042199164
Monoisotopic Mass：79.042199164
Complexity：30.9
Rotatable Bond Count：0
Hydrogen Bond Donor Count：0
Hydrogen Bond Acceptor Count：1
Topological Polar Surface Area：12.9
Heavy Atom Count：：6
Defined Atom Stereocenter Count：0
Undefined Atom Stereocenter Count：0
Defined Bond Stereocenter Count：0
Undefined Bond Stereocenter Count：0
Isotope Atom Count：0
Covalently-Bonded Unit Count：1
CACTVS Substructure Key Fingerprint：AAADcYBiAAAAAAAAAAAAAAAAAAAAAAAAAAAsAAAAAAAAAAABgAAAHAAAAAAACADBEgQ8gJIIEACgADBnRACCgCAxAiAI2CA4ZJgIIOLAkZGEIAhggADIyAYQAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA==

10.Other Information

Usage: Pyridine is used in spectrophotometry and environmental testing.

Usage: As polar, basic, low-reactive solvent, precursor, and reagent, pyridine finds wide range of applications in pharmaceuticals, agrochemicals and in the manufacture of dyes and rubber. Further it is used in the textile industry to improve network capacity of cotton. Pyridine finds applications in specialty chemical reagents like Cornforth reagent (pyridinium dichromate, PDC), pyridinium chlorochromate (PCC), the Collins reagent (complex of chromium(VI) oxide with pyridine) and the Sarret reagent (complex of chromium(VI) oxide with pyridine). Pyridine is a widely used ligand in coordination chemistry. Pyridine-base adducts like pyridine-borane and pyridine-sulfur trioxide are widely used owing to their superior characteristics in their reactivity and solubility characteristics.

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Usage: As polar, basic, low-reactive solvent, precursor, and reagent, pyridine finds wide range of applications in pharmaceuticals, agrochemicals and in the manufacture of dyes and rubber. Further it is used in the textile industry to improve network capacity of cotton. Pyridine finds applications in specialty chemical reagents like Cornforth reagent (pyridinium dichromate, PDC), pyridinium chlorochromate (PCC), the Collins reagent (complex of chromium(VI) oxide with pyridine) and the Sarret reagent (complex of chromium(VI) oxide with pyridine). Pyridine is a widely used ligand in coordination chemistry. Pyridine-base adducts like pyridine-borane (C5H5NBH3) and pyridine-sulfur trioxide (C5H5NSO3) are widely used owing to their superior characteristics in their reactivity and solubility characteristics.

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Usage: Pyridine is used in spectrophotometry and environmental testing.As polar, basic, low-reactive solvent, precursor, and reagent, pyridine finds wide range of applications in pharmaceuticals, agrochemicals and in the manufacture of dyes and rubber. Further, it is used in the textile industry to improve network capacity of cotton. Pyridine finds applications in specialty chemical reagents like Cornforth reagent (pyridinium dichromate, PDC), pyridinium chlorochromate (PCC), the Collins reagent (complex of chromium(VI) oxide with pyridine) and the Sarret reagent (complex of chromium(VI) oxide with pyridine). Pyridine is a widely used ligand in coordination chemistry. Pyridine-base adducts like pyridine-borane and pyridine-sulfur trioxide are widely used owing to their superior characteristics in their reactivity and solubility characteristics.

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Usage: Pyridine is used as a mobile phase in High Performance Liquid Chromatography and Liquid Chromatography coupled with Mass Spectrometry

Merck: 14,7970

BRN: 103233

Chemical Structure: Pyridine is a basic heterocyclic organic compound with the chemical formula C5H5N. It is structurally related to benzene, with one methine group (=CH?) replaced by a nitrogen atom. The pyridine ring occurs in many important compounds, including azines and the vitamins niacin and pyridoxine.

Pyridine Lewis structure

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Chemical properties: Pyridine is a colourless flammable liquid with a strong and unpleasant fish-like odour.

Pyridine

Productions: 2.1 Separation from Tar
Pyridine bases are a constituent of tars. They were isolated from coal tar or coal gas before synthetic manufacturing processes became established. The amounts contained in coal tar and coal gas is small, and the pyridine bases isolated from them are a mixture of many components. Thus, with a few exceptions, isolation of pure pyridine bases was expensive. Today, almost all pyridine bases are produced by synthesis. 2.2 Chichibabin synthesis

Fig. 2-1 Formation of acrolein from acetaldehyde and formaldehyde

Fig. 2-2 Condensation of pyridine from acrolein and acetaldehyde

The Chichibabin pyridine synthesis was reported in 1924 and is still in use in industry. Acetaldehyde and formaldehyde react with ammonia to give mainly pyridine. First, acrolein is formed in a Knoevenagel condensation from the acetaldehyde and formaldehyde. It is then condensed with acetaldehyde and ammonia into dihydropyridine, and then oxidized with a solid-state catalyst to pyridine. The reaction is usually carried out at 350-550°C and a space velocity of 500-1000 h ^-1 in the presence of a solid acid catalyst (e.g., silica-alumina). The product consists of a mixture of pyridine, simple methylated pyridines (picoline), and lutidine. The recovered pyridine is separated from byproducts in a multistage process.

Fig. 2-3 Flow sheet of pyridine and methylpyridine production from acetaldehyde and formaldehyde with ammonia. A) Reactor; b) Collector; c) Extraction; d) Solvent distillation; e) Distillation

2.3 Dealkylation of Alkylpyridines
Pyridine can be prepared by dealkylation of alkylated pyridines, which are obtained as byproducts in the syntheses of other pyridines. The oxidative dealkylation is carried out either using air over vanadium(V) oxide catalyst, by vapor-dealkylation on nickel-based catalyst, or hydrodealkylation with a silver- or platinum-based catalyst. Yields of pyridine up to be 93% can be achieved with the nickel-based catalyst.

2.4 Synthesis from Nitriles and Acetylene
Liquid-phase reaction of nitriles with acetylene is carried out at 120-180 ?C and 0.8-2.5 MPa in the presence of an organocobalt catalyst and gives 2-substituted pyridines:

Fig. 2-4 Synthesis of 2-methylpyridine from nitriles and acetylene
The trimerization of a part of a nitrile molecule and two parts of acetylene into pyridine is called B?nnemann cyclization. When using acetonitrile as the nitrile, 2-methylpyridine is obtained, which can be dealkylated to pyridine.

2.5 Synthesis from Acrylonitrile and Ketones

Fig. 2-5 Synthesis of 2-methylpyridine from acrylonitrile and acetone
Synthesis from acrylonitrile and acetone gives 2-methylpyridine selectively, which can be dealkylated to pyridine. First, the reaction of acrylonitrile and acetone, catalyzed by a primary aliphatic amine such as isopropylamine and a weak acid such as benzoic acid, occurs in the liquid phase at 180 ?C and 2.2 MPa to give 5-oxohexanenitrile, with 91% selectivity. The acrylonitrile conversion is 86%. Then cyclization and dehydration of the initial product are carried out in the gas phase in the presence of hydrogen over a palladium, nickel, or cobalt-containing catalyst at 240?C to give 2-methylpyridine in 84% yield.

2.6 Synthesis from Dinitriles
In a vapor-phase reaction over a nickel-containing catalyst in the presence of hydrogen, 2-methylglutaronitrile gives 3-methylpiperidine, which then undergoes dehydrogenation over palladium –alumina to give 3-methylpyridine. And 3-methylpyridine also can be dealkylated to pyridine.

Fig. 2-6 Synthesis of 2-methylpyridine from Dinitriles
A one-step gas-phase reaction over a palladium-containing catalyst is reported to give 3-methylpyridine in 50% yield.

2.7 Biosynthesis
Several pyridine derivatives play important roles in biological systems. While its biosynthesis is not fully understood, nicotinic acid (vitamin B3) occurs in some bacteria, fungi, and mammals. Mammals synthesize nicotinic acid through oxidation of the amino acid tryptophan, where an intermediate product, aniline, creates a pyridine derivative, kynurenine. On the contrary, the bacteria Mycobacterium tuberculosis and Escherichia coli produce nicotinic acid by condensation of glyceraldehyde 3-phosphate and aspartic acid.

2.8 Other methods
Ethylene and ammonia react in the presence of a palladium complex catalyst to give 2-methylpyridine and MEP. Pyridine can be prepared from cyclopentadiene by ammoxidation, or from 2-pentenenitrile by cyclization and dehydrogenation. Furfuryl alcohol or furfural reacts with ammonia in the gas phase to give pyridine. 2-Methylpyridine is also prepared from aniline.

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Uses: 3.1 Solvent
Pyridine is a polar, basic, low-reactive solvent, especially for dehydrochlorination reactions and extraction of antibiotics. In elimination reaction, pyridine acts as the base of the elimination reaction and bonds the resulting hydrogen halide to form a pyridinium salt. In esterifications and acylations, pyridine activates the carboxylic acid halides or anhydrides.

3.2 Medicines
Pyridine's chemical structure can be found in various medications that are synthesized thanks in part to pyridine. One example is a medication called esomeprazole, the generic name for Nexium. This is a medication that's used to treat GERD, or gastroesophageal reflux disease. Another example of a pyridine containing medication is loratadine, more commonly known by its brand name of Claritin. Loratadine helps in the treatment of allergies.

3.3 Pesticides
The main use of pyridine is as a precursor to the herbicides paraquat and diquat. The first synthesis step of insecticide chlorpyrifos consists of the chlorination of pyridine. Pyridine is also the starting compound for the preparation of pyrithione-based fungicides. Cetylpyridinium and laurylpyridinium, which can be produced from pyridine with a Zincke reaction, are used as antiseptic in oral and dental care products. Pyridine is easily attacked by alkylating agents to give N-alkylpyridinium salts. One example is cetylpyridinium chloride.

Fig 3-1 Synthesis of paraquat

3.4 Synthesis of piperidine
Piperidine, a fundamental nitrogen heterocycle, is important synthetic building-block. Piperidines are produced by hydrogenation of pyridine with a nickel-, cobalt-, or ruthenium-based catalyst at elevated temperatures.
C5H5N + 3 H2 → C5H10NH 3.5 Ligand and Lewis base
Pyridine is widely used as a ligand in coordination chemistry. As a ligand of metal complex, it can be easily replaced by a stronger Lewis base, which can be used in the catalysis of polymerization and hydrogenation reactions. After the completion of reaction, pyridine ligand replaced during the reaction can be restored again. Pyridine is also used as a base in condensation reactions. As a base, pyridine can be used as the Karl Fischer reagent, but it is usually replaced by alternatives with a more pleasant odor, such as imidazole.

3.6 Others
Except for above uses, Pyridine is also used to product polycarbonate resins, vitamins, food flavorings, paints, dyes, rubber products, adhesives, and waterproofing for fabrics. Pyridine is added to ethanol to make it unsuitable for drinking. It is also used in the in vitro synthesis of DNA.

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Toxicity information: 4.1 Toxicity Level
Low Toxicity

4.2 Acute Toxicity
LD501580mg/kg (Large mice, oral); 1121mg/kg (Rabbit, through skin); inhaled by human 25mg/m3×20 min, irritation of conjunctiva and upper respiratory tract mucosa. Subacute and chronic toxicity: inhaled by large mice 32.3mg/m3×7 hours/day x5 days/week x6 months, increase in liver weight; inhaled by humans 20～40mg/m3 (long term), nerve damage, unsteady walking, digital tremors, low blood pressure, over-sweating, occasional liver and kidney damage.

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Hazards: 5.1 Health hazards
Pyridine is extremely toxic by ingestion and inhalation. Vapors are heavier than air. its combustion produces toxic oxides of nitrogen. Pyridine is highly flammable (its flash point is just 17 oC). Pyridine also could have neurotoxic and genotoxic effects.

5.2 Fire Hazards
Behavior in Fire: Vapor is heavier than air and may travel considerable distance to source of ignition and flash back.

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References

https://en.wikipedia.org/wiki/Pyridine#Occurrence
http://www.zwbk.org/MyLemmaShow.aspx?zh=zh-tw&lid=169038
http://www.softschools.com/formulas/chemistry/pyridine_formula/378/
http://www.hmdb.ca/metabolites/HMDB0000926
https://study.com/academy/lesson/pyridine-in-medicine-uses-synthesis.html#partialRegFormModal
http://www.toxipedia.org/display/toxipedia/Pyridine
https://www..com/ProductChemicalPropertiesCB8852825_EN.htm
https://pubchem.ncbi.nlm.nih.gov/compound/pyridine#section=Top
http://www.ebi.ac.uk/chebi/searchId.do;jsessionid=E7088896622D62FC650863C2AD197CAA?chebiId=CHEBI:16227
https://www.britannica.com/science/pyridine
Shimizu, S.; Watanabe, N.; Kataoka, T.; Shoji, T.; Abe, N.; Morishita, S.; Ichimura, H. (2005), "Pyridine and Pyridine Derivatives", Ullmann's Encyclopedia of Industrial Chemistry, Weinheim: Wiley-VCH, doi:10.1002/14356007.a22_399

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Description: Pyridine is a solvent for many organic compounds and anhydrous metallic salts chemicals. Contained in Karl Fischer reagent, it induced contact dermatitis in a laboratory technician.

Chemical Properties: Pyridine, is a slightly yellow or colorless liquid; hygroscopic; unpleasant odor; burning taste; slightly alkaline in reaction; soluble in water, alcohol, ether, benzene, and fatty oils; specific gravity, 0.978; autoignition temperature, 482 °C. Pyridine, a tertiary amine, is a somewhat stronger base than aniline and readily forms quaternary ammonium salts.

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Chemical Properties: Pyridine is a weak base (pK_a= 5.25); a 0.2 M solution has a pH of 8.5 (HSDB 1988). Its carbon atoms are deactivated towards electrophilic substitution. This is especially true in acidic media, where salts form at the nitrogen. It does, however, readily undergo nucleophilic substitution, preferentially at the C-2 and also at the C-4 position (Jori et al 1983). Being a tertiary amine, pyridine reacts with alkylating agents to form quaternary salts (Santodonato et al 1985). Because of its reduced capacity to donate electrons, it is more resistant to oxidation than benzene. Oxidation with peroxy acids forms pyridine N-oxide which is then capable of undergoing electrophilic substitution (Jori et al 1983). Pyridine reacts violently with a number of compounds, including nitric acid, sulfuric acid, maleic anhydride, perchromate, beta-propiolactone and chlorosulfonic acid. Thermal decomposition can liberate cyanides (Gehring 1983). Both the pyridinium ion and pyridine itself are readily reduced to the commercially important compound, piperidine (Jori et al 1983).

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Physical properties: Clear, colorless to pale yellow, flammable liquid with a sharp, penetrating, nauseating fish-like odor. Odor threshold concentrations in water and air were 2 ppm (Buttery et al., 1988) and 21 ppb_v (Leonardos et al., 1969), respectively. Detection odor threshold concentrations of 0.74 mg/m³ (2.3 ppm_v) and 6 mg/m³ (1.9 ppm_v) were experimentally determined by Katz and Talbert (1930) and Dravnieks (1974), respectively. Cometto-Mu?iz and Cain (1990) reported an average nasal pungency threshold concentration of 1,275 ppm_v.

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Occurrence: Pyridine was discovered by Anderson in coal tar in 1846 (Windholz et al 1983). It is found in tobacco smoke (Vohl and Eulenberg 1871; Lehmann 1909) and roasted coffee (Bertrand and Weisweiller 1913). Pyridine is found in wood oil and in the leaves and roots of Atropa belladonna (HSDB 1988), and is also a component of creosote oil (Krone et al 1986).

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Uses: Pyridine is used as a solvent in paint andrubber industries; as an intermediate in dyesand pharmaceuticals; for denaturing alcohol;and as a reagent for cyanide analysis. Itoccurs in coal tar.

Uses: Pyridine is used directly in the denaturation of alcohol (ACGIH 1986; HSDB 1989; NSC 1978) and as a solvent in paint and rubber preparation (ACGIH 1986; HSDB 1989; NSC 1978) and in research laboratories for functions such as extracting plant hormones (Santodonato et al. 1985). Half of the pyridine produced today is used as an intermediate in making various insecticides and herbicides for agricultural applications (ACGIH 1986; Harper et al. 1985; Santodonato et al. 1985). Approximately 20% goes into the production of piperidine (Harper et al. 1985; Santodonato et al. 1985) which is commercially significant in the preparation of chemicals used in rubber vulcanization and agriculture (NSC 1978). Pyridine is also used as an intermediate in the preparation of drugs (antihistamines, steroids, sulfa-type and other antibacterial agents) dyes, water repellents, and polycarbonate resins (ACGIH 1986; Harper et al. 1985; NSC 1978; Santodonato et al. 1985). Pyridine is also approved by the Food and Drug Administration (FDA) for use as a flavoring agent in the preparation of foods (Harper et al. 1985; HSDB 1989) .

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Uses: Pyridine and derivatives of pyridine occur widely in nature as components of alkaloids, vitamins, and coenzymes. These compounds are of continuing interest to theoretical physical, organic, and biochemistry and to industrial chemistry. Pyridine and derivatives have many uses, e.g., herbicides and pesticides, pharmaceuticals, feed supplements, solvents and reagents, and chemicals for the polymer and textile industries.

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Definition: ChEBI: An azaarene comprising a benzene core in which one -CH group is replaced by a nitrogen atom. It is the parent compound of the class pyridines.

Production Methods: Pyridine is produced from the gases obtained by the coking of coal and by direct synthesis. The light-oil fraction of coal tar is treated with sulfuric acid to produce water-soluble pyridine salts and then the pyridine bases are recovered from the aqueous phase by sodium hydroxide or ammonia (Jori et al 1983). The majority of U.S. production is through synthetic means. This process uses a vapor-phase reaction of acetaldehyde, formaldehyde and ammonia, which yields a mixture of pyridine and 3-methylpyridine (Santodonato et al 1985). The product ratio depends on the relative amounts of acetaldehyde and formaldehyde. Added methanol increases the yield. The U.S. production of pyridine was estimated at 32 to 47 million pounds in 1975 (Reinhardt and Brittelli 1981). Pyridine is commercially available in technical, 2° and 1° grades, the latter two referring to their boiling ranges. Major impurities are higher boiling homologues, such as picolines, lutidines and collidines, which are mono-, di-, and trimethylpyridines (Santodonato et al 1985; Jori et al 1983).

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Preparation: Pyridine is produced either by isolation from natural sources such as coal, or through chemical synthesis (HSDB 1989). Pyridine is produced by the fractional distillation of coal-tar residues (HSDB 1989; NSC 1978; Santodonato et al. 1985) in which 1 ton of coal produces 0.07-0.21 pounds of pyridine bases of which 57% is pyridine (Santodonato et al, 1985). Synthetically produced pyridine is currently the more important source of pyridine for commercial uses (Santodonato et al. 1985). Small amounts of pyridine are synthesized from acetaldehyde, formaldehyde, and ammonia with a fluidized silica-alumina catalyst, followed by fractionation to isolate the pyridine (Harper et al. 1985; HSDB 1989; NSC 1978).
Pyridine is produced from natural sources by Crowley Tar Products of Stow, Ohio, and Oklahoma City, Oklahoma (Harper et al. 1985; HSDB 1989; SRI 1986, 1987, 1988). Pyridine is synthetically produced by two companies, the Nepera Chemical Co. of Harriman, New York and the Reilly Tar and Chemical Corporation of Indianapolis, Indiana (Harper et al. 1985; SRI 1986, 1987, 1988).

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Definition: An organic liquid of formula C₅H₅N. The molecules have a hexagonal planar ring and are isoelectronic with benzene. Pyridine is an example of an aromatic heterocyclic compound, with the electrons in the carbon–carbon pi bonds and the lone pair of the nitrogen delocalized over the ring of atoms. The compound is extracted from coal tar and used as a solvent and as a raw material for organic synthesis.

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Aroma threshold values: Detection: 0.079 to 790 ppb; recognition: 7.9 to 40 ppm

General Description: A clear colorless to light yellow liquid with a penetrating nauseating odor. Density 0.978 g / cm3. Flash point 68°F. Vapors are heavier than air. Toxic by ingestion and inhalation. Combustion produces toxic oxides of nitrogen.

Air & Water Reactions: Highly flammable. Soluble in water.

Reactivity Profile: Azabenzene is a base. Reacts exothermically with acids. During preparation of a complex of Azabenzene with chromium trioxide, an acid, the proportion of chromium trioxide was increased. Heating from this acid-base reaction led to an explosion and fire [MCA Case History 1284 1967]. A 0.1% solution of Azabenzene (or other tertiary amine) in maleic anhydride at 185°C gives an exothermic decomposition with rapid evolution of gas [Chem Eng. News 42(8); 41 1964]. Mixing Azabenzene in equal molar portions with any of the following substances in a closed container caused the temperature and pressure to increase: chlorosulfonic acid, nitric acid (70%), oleum, sulfuric acid (96%), or propiolactone [NFPA 1991]. The combination of iodine, Azabenzene, sulfur trioxide, and formamide developed a gas over pressurization after several months. This arose from the slow formation of sulfuric acid from external water, or from dehydration of the formamide to hydrogen cyanide. Ethylene oxide and SO2 can react violently in Azabenzene solution with pressurization if ethylene oxide is in excess (Nolan, 1983, Case History 51).

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Hazard: Flammable, dangerous fire risk, explosive limits in air 1.8–12.4%. Toxic by ingestion and inhalation. Skin irritant, liver and kidney damage. Questionable carcinogen.

Health Hazard: The acute toxicity of pyridine is low. Inhalation causes irritation of the respiratory system and may affect the central nervous system, causing headache, nausea, vomiting, dizziness, and nervousness. Pyridine irritates the eyes and skin and is readily absorbed, leading to systemic effects. Ingestion of pyridine can result in liver and kidney damage. Pyridine causes olfactory fatigue, and its odor does not provide adequate warning of the presence of harmful concentrations.
Pyridine has not been found to be carcinogenic or to show reproductive or developmental toxicity in humans. Chronic exposure to pyridine can result in damage to the liver, kidneys, and central nervous system.

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Health Hazard: The toxic effects of pyridine include headache,dizziness, nervousness, nausea, insomnia,frequent urination, and abdominal pain.The symptoms were transient, occurred inpeople from subacute exposure to pyridinevapors at about 125 ppm for 4 hours a dayfor 1–2 weeks (Reinhardt and Brittelli 1981).The target organs to pyridine toxicity are thecentral nervous system, liver, kidneys, gastrointestinaltract, and skin.
The routes ofexposure are inhalation of vapors, and ingestionand absorption of the liquid throughthe skin. Serious health hazards may arisefrom chronic inhalation, which may causekidney and liver damage, and stimulationof bone marrow to increase the productionof blood platelets. Low-level exposureto 10 ppm may produce chronic poisoningeffects on the central nervous system. Ingestionof the liquid may produce the samesymptoms as those stated above. Skin contactcan cause dermatitis. Vapor is an irritantto the eyes, nose, and lungs. Because of itsstrong disagreeable odor, there is always asufficient warning against any overexposure.A concentration of 10 ppm is objectionableto humans.
LCLO value, inhalation (rats): 4000 ppm/4 h
LD50 value, oral (mice): 1500 mg/kg.
Huh and coworkers (1986) have investigatedthe effect of glycyrrhetinic acid on pyridine toxicity in mice. Pretreatmentwith glycyrrhetinic acid decreaseddepression of the central nervous system andmortality in animals induced by pyridine.Such pretreatment markedly decreased theactivity of the enzyme serum transaminase, and increased the activity of hepaticmicrosomal aniline hydroxylase [9012-90-0], a pyridine- metabolizing enzyme.

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Flammability and Explosibility: Pyridine is a highly flammable liquid (NFPA rating = 3), and its vapor can travel a considerable distance and "flash back." Pyridine vapor forms explosive mixtures with air at concentrations of 1.8 to 12.4% (by volume). Carbon dioxide or dry chemical extinguishers should be used for pyridine fires.

Industrial uses: Pyridine is a good solvent for a large number of compounds, both organic and inorganic (Windholz et al 1983). About 50% of pyridine used in the U.S. is for the production of agricultural chemicals, such as the herbicides paraquat, diquat and triclopyr and the insecticide chlorpyrifos. Other uses are in the production of piperidine; the manufacture of pharmaceuticals, such as steroids, vitamins and antihistamines; and as a solvent. Solvent uses are found in both the pharmaceutical and polycarbonate resin industries. It is particularly useful as a solvent in processes where HC1 is evolved (Santodonato et al 1985). Minor uses for pyridine are for the denaturation of alcohol and antifreeze mixtures, as a dyeing assistant in textiles and as a flavoring agent (Jori et al 1983; Furia 1968; HSDB 1988).

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Contact allergens: Pyridine (unsubstituted pyridine) and its derivative (substituted pyridines) are widely used in chemistry. Pyridine is a solvent used for many organic compounds and anhydrous metallic salt chemicals. Contained in Karl Fischer reagent, it induced contact dermatitis in a laboratory technician. No cross-sensitivity is observed between those different substances.

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Safety Profile: Poison by intraperitoneal route. Moderately toxic by ingestion, skin contact, intravenous, and subcutaneous routes. Mildly toxic by inhalation. A skin and severe eye irritant. Mutation data reported. Can cause central nervous system depression, gastrointestinal upset, and liver and kidney damage. A flammable liquid and dangerous fire hazard when exposed to heat, flame, or oxidizers. Severe explosion hazard in the form of vapor when exposed to flame or spark. Reacts violently with chlorosulfonic acid, chromium trioxide, dinitrogen tetraoxide, HNO3, oleum, perchromates, ppropiolactone, AgClO4, H2SO4. Incandescent reaction with fluorine. Reacts to form pyrophoric or explosive products with bromine trifluoride, trifluoromethyl hypofluorite. Mixtures with formamide + iodine + sulfur trioxide are storage hazards, releasing carbon dioxide and sulfuric acid. Incompatible with oxidizing materials. Reacts with maleic anhydride (above 150°C) evolving carbon dioxide. To fight fire, use alcohol foam. When heated to decomposition it emits highly toxic fumes of NOx.

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Potential Exposure: Pyridine is used as a solvent in the chemical industry and as a denaturant for ethyl alco- hol; as an intermediate in the production of pesticides; in pharmaceuticals; in the manufacture of paints, explosives, dyestuffs, rubber, vitamins, sulfa drugs; and disinfectants.

Carcinogenicity: Pyridine was not carcinogenic in several chronic subcutaneous studies.
F344 rats were given pyridine orally in drinking water at doses of 0, 7, 14, or 33 mg/kg for 2 years. The top dose produced a decrease in body weights and water consumption. Increased renal tubular adenoma or carcinoma and tubular hyperplasia were observed in males at 33 mg/kg. Increased mononuclear cell leukemia was observed in females at 14 and 33 mg/kg, which was considered equivocal in terms of the relationship to pyridine exposure, since this is a common finding in this strain of rat. Concentration-related nonneoplastic change in the liver was seen at 33 mg/kg. Male Wistar rats were similarly treated with doses of 0, 8, 17, or 36 mg/kg for 2 years. Decreased survival and body weights were seen at 17 and 36 mg/kg. Increased testicular cell adenomas were seen at 36 mg/kg. No changes in survival or neoplasm rates in other tissues, including the kidney, were reported although increased nephropathy and hepatic centrilobular degeneration/necrosis was observed in some pyridine- treated rats.

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Source: Pyridine occurs naturally in potatoes, anabasis, henbane leaves, peppermint (0 to 1 ppb), tea leaves, and tobacco leaves (Duke, 1992). Identified as one of 140 volatile constituents in used soybean oils collected from a processing plant that fried various beef, chicken, and veal products (Takeoka et al., 1996).

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Environmental fate: Biological. Heukelekian and Rand (1955) reported a 5-d BOD value of 1.31 g/g which is 58.7% of the ThOD value of 2.23 g/g. A Nocardia sp. isolated from soil was capable of transforming pyridine, in the presence of semicarbazide, into an intermediate product identified as succinic acid semialdehyde (Shukla and Kaul, 1986). 1,4-Dihydropyridine, glutaric dialdehyde, glutaric acid semialdehyde, and glutaric acid were identified as intermediate products when pyridine was degraded by Nocardia strain Z1 (Watson and Cain, 1975).
Photolytic. Irradiation of an aqueous solution at 50 °C for 24 h resulted in a 23.06% yield of carbon dioxide (Knoevenagel and Himmelreich, 1976).
Chemical/Physical. The gas-phase reaction of ozone with pyridine in synthetic air at 23 °C yielded a nitrated salt having the formula: [C6H5NH]+NO3 - (Atkinson et al., 1987). Ozonation of pyridine in aqueous solutions at 25 °C was studied with and without the addition of tert-butyl alcohol (20 mM) as a radical scavenger. With tert-butyl alcohol, ozonation of pyridine yielded mainly pyridine N-oxide (80% yield), which was very stable towards ozone. Without tert-butyl alcohol, the heterocyclic ring is rapidly cleaved forming ammonia, nitrate, and the amidic compound N-formyl oxamic acid (Andreozzi et al., 1991).

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Metabolism: Pyridine is absorbed through the gastrointestinal tract, skin and lungs and is eliminated via the urine, feces, skin and lungs, both as metabolites and as the parent compound (Jori et al 1983). Uptake by tissues increases with dose and the elimination is biphasic in nature (Zharikov and Titov 1982; HSDB 1988). Elimination is rapid and there appears to be no tissue accumulation (Jori et al 1983). The observation by His (1887) of the urinary excretion of Af-methylpyridine by pyridine-dosed animals was the first example of Af-methylation. Known urinary metabolites of pyridine in mammals now include pyridine N-oxide, N-methyl pyridine, 4-pyridone, 2-pyridone and 3-hydroxypyridine. Some metabolites still remain to be identified (Damani et al 1982). The relative amounts of the metabolites are highly dependent on the species and dose (Gorrod and Damani 1980). For example, the rat has been shown to excrete 70% of a 1 mg/kg dose in the urine in the first 24 h after dosing, but that figure drops to only 5.8% for a 500 mg/kg dose (D'Souza et al 1980). Although urinary excretion of pyridine and its metabolites appears to be a major route for elimination, non-urinary excretion has not been extensively studied (Santodonato et al 1985). In rabbits, the pyridine N-methyltransferase activity has been shown to be highest in lung cytosol and it has been found to utilize 5-adenosyl methionine as the methyl donor (Damani et al 1986). This pathway is saturable in both the rat and the guinea pig (D'Souza et al 1980). The product of this reaction, N-methyl pyridine, is less chronically toxic but more acutely toxic than pyridine (Williams 1959). Pyridine N-oxide is produced by the cytochrome P-450 system and the activity is induced by phenobarbital or pyridine pretreatment but not by 3-methylcholanthrene (Gorrod and Damani 1979; Kaul and Novak 1987). In the rabbit, the alcohol-inducible (and pyridine inducible) P-450 LM_3A appears to be the low K_m isozyme which catalyzes pyridine Af-oxide production (Kim and Novak 1989). The N-oxidation of pyridine may represent a pathway for bioactivation (Santodonato et al 1985) and this pathway becomes more important as the pyridine dose is increased (Damani et al 1982).

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storage: Pyridine should be used only in areas free of ignition sources, and quantities greater than 1 liter should be stored in tightly sealed metal containers in areas separate from oxidizers.

Shipping: UN1992 Flammable liquids, toxic, n.o.s., Hazard Class: 3; Labels: 3-Flammable liquid, 6.1-Poisonous mate- rials, Technical Name Required.

Purification Methods: Likely impurities are H2O and amines such as the picolines and lutidines. Pyridine is hygroscopic and is miscible with H2O and organic solvents. It can be dried with solid KOH, NaOH, CaO, BaO or sodium, followed by fractional distillation. Other methods of drying include standing with Linde type 4A molecular sieves, CaH2 or LiAlH4, azeotropic distillation of the H2O with toluene or *benzene, or treated with phenylmagnesium bromide in ether, followed by evaporation of the ether and distillation of the pyridine. A recommended [Lindauer & Mukherjee Pure Appl Chem 27 267 1971] method dries pyridine over solid KOH (20g/Kg) for 2weeks and fractionally distils the supernatant over Linde type 5A molecular sieves and solid KOH. The product is stored under CO2-free nitrogen. Pyridine can be stored in contact with BaO, CaH2 or molecular sieves. Non-basic materials can be removed by steam distilling a solution containing 1.2 equivalents of 20% H2SO4 or 17% HCl until about 10% of the base has been carried over along with the non-basic impurities. The residue is then made alkaline, and the base is separated, dried with NaOH and fractionally distilled. Alternatively, pyridine can be treated with oxidising agents. Thus pyridine (800mL) has been stirred for 24hours with a mixture of ceric sulfate (20g) and anhydrous K2CO3 (15g), then filtered and fractionally distilled. Hurd and Simon [J Am Chem Soc 84 4519 1962] stirred pyridine (135mL), water (2.5L) and KMnO4 (90g) for 2hours at 100o, then stood for 15hours before filtering off the precipitated manganese oxides. Addition of solid KOH (ca 500g) caused pyridine to separate. It was decanted, refluxed with CaO for 3hours and distilled. Separation of pyridine from some of its homologues can be achieved by crystallisation of the oxalates. Pyridine is precipitated as its oxalate by adding it to the stirred solution of oxalic acid in acetone. The precipitate is filtered, washed with cold acetone, and pyridine is regenerated and isolated. Other methods are based on complex formation with ZnCl2 or HgCl2. Heap, Jones and Speakman [J Am Chem Soc 43 1936 1921] added crude pyridine (1L) to a solution of ZnCl2 (848g) in 730mL of water, 346mL of conc HCl and 690mL of 95% EtOH. The crystalline precipitate of ZnCl2.(pyridine)2 was filtered off, recrystallised twice from absolute EtOH, then treated with a conc NaOH solution, using 26.7g of solid NaOH to 100g of the complex. The precipitate was filtered off, and the pyridine was dried with NaOH pellets and distilled. Similarly, Kyte, Jeffery and Vogel [J Chem Soc 4454 1960] added pyridine (60mL) in 300mL of 10% (v/v) HCl to a solution of HgCl2 (405g) in hot water (2.3L). On cooling, crystals of pyridine-HgCl2 (1:1) complex separated and were filtered off, crystallised from 1% HCl (to m 178.5-179o), washed with a little EtOH and dried at 110o. The free base was liberated by addition of excess aqueous NaOH and separated by steam distillation. The distillate was saturated with solid KOH, and the upper layer was removed, dried further with KOH, then BaO and distilled. Another possible purification step is fractional crystallisation by partial freezing. Small amounts of pyridine have been purified by vapour-phase chromatography, using a 180-cm column of polyethyleneglycol-400 (Shell 5%) on Embacel at 100o, with argon as carrier gas. The Karl Fischer titration can be used for determining water content. A colour test for pyrrole as a contaminant is described by Biddiscombe et al. [J Chem Soc 1957 1954]. The 1:1-hydrochloride crystallises from EtOH with m 144o, b 218-219o/760mm (see below) and is hygroscopic. The 1:2-hydrochloride has m 46o [58888-58-7] and the picrate has m 165-166o [1152-90-5]. [Beilstein 20 H 181, 20 I 54, 20 II 96, 20 III/IV 2205, 20/5 V 160.] § Polystyrene-supported pyridine is commercially available.

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Incompatibilities: Violent reaction with strong oxidizers; strong acids; chlorosulfonic acid; maleic anhydride; oleum iodine.

Waste Disposal: Controlled incineration whereby nitrogen oxides are removed from the effluent gas by scrubber, catalytic or thermal devices .

Storage Conditions: Saturator mother liquor during high-temperature coking is used as raw material, crude pyridine is recovered and processed, slag is removed by heating to obtain aqueous pyridine, dehydrated with pure benzene, and anhydrous pyridine is obtained, and then 110-120°C fraction is distilled by distillation. From rectification.

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Storage features: The warehouse is ventilated, low temperature and dry; stored separately from oxidants and acids

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12. Related Questions

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