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Chemical Structure History Chemical properties Productions Uses Toxicity information Hazards References
Chemical Name:
AA;PY;PYR;cp32;Azine;Pirydyna;Piridina;PYRIDINE;ai3-01240;FEMA 2932
Molecular Formula:
Formula Weight:
MOL File:

Pyridine Properties

Melting point:
-42 °C
Boiling point:
96-98 °C(lit.)
0.983 g/mL at 20 °C
vapor density 
2.72 (vs air)
vapor pressure 
23.8 mm Hg ( 25 °C)
refractive index 
n20/D 1.509(lit.)
Flash point:
68 °F
storage temp. 
Store at RT.
H2O: in accordance
5.25(at 25℃)
Relative polarity
8.81 (H2O, 20℃)
explosive limit
Water Solubility 
Stable. Flammable. Incompatible with strong oxidizing agents, strong acids.
CAS DataBase Reference
110-86-1(CAS DataBase Reference)
NIST Chemistry Reference
EPA Substance Registry System
  • Risk and Safety Statements
  • Hazard and Precautionary Statements (GHS)
Hazard Codes  T,N,F,Xn
Risk Statements  11-20/21/22-39/23/24/25-23/24/25-52-36/38
Safety Statements  36/37/39-38-45-61-28A-26-28-24/25-22-36/37-16-7
RIDADR  UN 1282 3/PG 2
WGK Germany  2
RTECS  UR8400000
Hazard Note  Highly Flammable/Harmful
HazardClass  3
PackingGroup  II
Hazardous Substances Data 110-86-1(Hazardous Substances Data)
Toxicity LD50 orally in rats: 1.58 g/kg (Smyth)
Signal word: Danger
Hazard statements:
Code Hazard statements Hazard class Category Signal word Pictogram P-Codes
H225 Highly Flammable liquid and vapour Flammable liquids Category 2 Danger P210,P233, P240, P241, P242, P243,P280, P303+ P361+P353, P370+P378,P403+P235, P501
H301 Toxic if swalloed Acute toxicity,oral Category 3 Danger P264, P270, P301+P310, P321, P330,P405, P501
H302 Harmful if swallowed Acute toxicity,oral Category 4 Warning P264, P270, P301+P312, P330, P501
H311 Toxic in contact with skin Acute toxicity,dermal Category 3 Danger P280, P302+P352, P312, P322, P361,P363, P405, P501
H312 Harmful in contact with skin Acute toxicity,dermal Category 4 Warning P280,P302+P352, P312, P322, P363,P501
H315 Causes skin irritation Skin corrosion/irritation Category 2 Warning P264, P280, P302+P352, P321,P332+P313, P362
H319 Causes serious eye irritation Serious eye damage/eye irritation Category 2A Warning P264, P280, P305+P351+P338,P337+P313P
H331 Toxic if inhaled Acute toxicity,inhalation Category 3 Danger P261, P271, P304+P340, P311, P321,P403+P233, P405, P501
H332 Harmful if inhaled Acute toxicity,inhalation Category 4 Warning P261, P271, P304+P340, P312
H370 Causes damage to organs Specific target organ toxicity, single exposure Category 1 Danger P260, P264, P270, P307+P311, P321,P405, P501
Precautionary statements:
P210 Keep away from heat/sparks/open flames/hot surfaces. — No smoking.
P260 Do not breathe dust/fume/gas/mist/vapours/spray.
P261 Avoid breathing dust/fume/gas/mist/vapours/spray.
P280 Wear protective gloves/protective clothing/eye protection/face protection.
P311 Call a POISON CENTER or doctor/physician.
P301+P310 IF SWALLOWED: Immediately call a POISON CENTER or doctor/physician.
P303+P361+P353 IF ON SKIN (or hair): Remove/Take off Immediately all contaminated clothing. Rinse SKIN with water/shower.
P304+P340 IF INHALED: Remove victim to fresh air and Keep at rest in a position comfortable for breathing.
P305+P351+P338 IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continuerinsing.
P337+P313 IF eye irritation persists: Get medical advice/attention.
P370+P378 In case of fire: Use … for extinction.
P403+P235 Store in a well-ventilated place. Keep cool.

Pyridine price More Price(69)

Manufacturer Product number Product description CAS number Packaging Price Updated Buy
Sigma-Aldrich 02486 Pyridine analytical standard 110-86-1 1ml $29.1 2018-11-13 Buy
Sigma-Aldrich 1601747 Pyridine United States Pharmacopeia (USP) Reference Standard 110-86-1 3x1.2ml $348 2018-11-13 Buy
Alfa Aesar 019378 Pyridine, ACS, 99.0% min 110-86-1 *4x1L $307 2018-11-16 Buy
Alfa Aesar 019378 Pyridine, ACS, 99.0% min 110-86-1 1L $100 2018-11-16 Buy
Sigma-Aldrich 270970 Pyridine anhydrous, 99.8% 110-86-1 100ml $101 2018-11-13 Buy

Pyridine Chemical Properties,Uses,Production

Chemical Structure

Lewis structureSkeletal formula
Ball-and-stick diagramSpace-filling model
Molecular model kit
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.


Thomas Anderson
Pyridine was discovered in 1849 by the Scottish chemist Thomas Anderson as one of the constituents of bone oil. Two years later, Anderson isolated pure pyridine through fractional distillation of the oil.

Chemical properties

It is a colorless or light yellow, highly flammable, weakly alkaline, water-soluble liquid with a distinctive, unpleasant fish-like smell. Its melting point is -41.6 ℃, and boiling point is 115.2 ?C. It will form azeotropic mixture with water, and boiling point of the mixture is 92~93 ?C. The property is used to purify pyridine in industry.) Its density is 0.9819g / cm3. Pyridine is soluble in water, ethanol, ether and other organic solvents, and itself can also be used as solvent.


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 Bönnemann 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.


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.

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.


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.


  11. 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

Chemical Properties

Pyridine, C5H5N, is a yellowish, flammable, poisonous organic solvent with a very distinctive and penetrating odor. Pyridine is soluble in water, alcohol, benzene, and ether.It has a boiling point of 116°C (240 OF). Pyridine is used in paints,medicine,and textile dyeing.


Used as solvent; complexing agent.


As solvent for Anhydrous mineral salts. Synthetic intermediate in laboratory and industry.


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.

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).


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

Vapor irritates eyes and nose. Liquid irritates skin and is absorbed through the skin. Overexposure causes nausea, headache, nervous symptoms, increased urinary frequency.

Fire Hazard

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

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.

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.

Pyridine Preparation Products And Raw materials

Raw materials

Preparation Products

Pyridine Suppliers

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View Lastest Price from Pyridine manufacturers

Image Release date Product Price Min. Order Purity Supply Ability Manufacturer
2018-10-19 py
US $1500.00-1700.00 / KG 10UG 99% 10TON Research Chemical Lab Co,.Let

Pyridine Spectrum

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