Pyridine anhydrous

Pyridine anhydrous - Names and Identifiers

Name	Pyridine
Synonyms	Pyr Pyridin Pyridine FEMA 2932 FEMA 2966 azabenzene Azabenzene FEMA NUMBER 2966 Pyridine anhydrous rcrawastenumberu196 Rcra waste number U196 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
CAS	110-86-1
EINECS	203-809-9
InChI	InChI=1/C5H5N/c1-2-4-6-5-3-1/h1-5H
InChIKey	JUJWROOIHBZHMG-UHFFFAOYSA-N

Pyridine anhydrous - Physico-chemical Properties

Molecular Formula	C5H5N
Molar Mass	79.1
Density	0.978 g/mL at 25 °C (lit.)
Melting Point	-42 °C (lit.)
Boling Point	115 °C (lit.)
Flash Point	68°F
Water Solubility	Miscible
Solubility	H2O: in accordance
Vapor Presure	23.8 mm Hg ( 25 °C)
Vapor Density	2.72 (vs air)
Appearance	Liquid
Color	colorless
Odor	Nauseating odor detectable at 0.23 to 1.9 ppm (mean = 0.66 ppm)
Exposure Limit	TLV-TWA 5 ppm (～15 mg/m3) (ACGIH,MSHA,and OSHA); STEL 10 ppm (ACGIH),IDLH 3600 ppm (NIOSH).
Maximum wavelength(λmax)	['λ: 305 nm Amax: 1.00', , 'λ: 315 nm Amax: 0.15', , 'λ: 335 nm Amax: 0.02', , 'λ: 35
Merck	14,7970
BRN	103233
pKa	5.25(at 25℃)
PH	8.81 (H2O, 20℃)
Storage Condition	Store at +5°C to +30°C.
Stability	Stable. Flammable. Incompatible with strong oxidizing agents, strong acids.
Explosive Limit	12.4%
Refractive Index	n20/D 1.509(lit.)
Physical and Chemical Properties	Characteristics of colorless or light yellow liquid. Has an unpleasant odor. boiling point 115.5 ℃ freezing point -42 ℃ relative density 0.9830g/cm3 refractive index 1.5095 flash point 20 ℃ solubility, ethanol, acetone, ether and benzene.
Use	Mainly used as raw materials for the pharmaceutical industry, used as solvents and alcohol denaturants, but also used in the production of rubber, paint, resin and corrosion inhibitors

Pyridine anhydrous - Risk and Safety

Risk Codes	R11 - Highly Flammable R20/21/22 - Harmful by inhalation, in contact with skin and if swallowed. R39/23/24/25 - R23/24/25 - Toxic by inhalation, in contact with skin and if swallowed. R52 - Harmful to aquatic organisms R36/38 - Irritating to eyes and skin.
Safety Description	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. S28A - 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. S36/37 - Wear suitable protective clothing and gloves. S16 - Keep away from sources of ignition. S7 - Keep container tightly closed.
UN IDs	UN 1282 3/PG 2
WGK Germany	2
RTECS	UR8400000
FLUKA BRAND F CODES	3-10
TSCA	Yes
HS Code	2933 31 00
Hazard Note	Highly Flammable/Harmful
Hazard Class	3
Packing Group	II
Toxicity	LD50 orally in rats: 1.58 g/kg (Smyth)

Pyridine anhydrous - Upstream Downstream Industry

Raw Materials	Benzene Ammonia Sulfuric acid
Downstream Products	2-Chloropyridine 2,6-Dichloropyridine 2-Aminopyridine 1,2,4-Triazolo[4,3-a]pyridin-3(2H)-one Larvin Pyridine Karl Fischer reagent Lomefloxacin hydrochloride Vitamin D2 Hydrocortisone acetate

Pyridine anhydrous - Nature

Open Data Verified Data

colorless transparent liquid. There is an unpleasant pungent odor. With water, ethanol, chloroform, petroleum ether, ether, oil and other organic solvents miscible, is a good solvent for many organic compounds. Its vapor and air to form an explosive mixture, fire, high heat caused by combustion explosion. A strong reaction with an oxidizing agent can occur. In case of high fever, the internal pressure of the container increases, and there is a risk of cracking and explosion. Strong acids can induce severe sputtering.

Last Update：2024-01-02 23:10:35

Pyridine anhydrous - Preparation Method

Open Data Verified Data

The pyridine base in the coke oven gas generated in the coking process was recovered and treated to obtain pyridine. Alternatively, pyridine can be obtained by reacting a mixture of acetaldehyde, formaldehyde and ammonia. It is also possible to heat the cyclization of 1,5-pentanediamine hydrochloride and dehydrogenate it in the presence of a platinum catalyst to obtain pyridine.

Last Update：2022-01-01 09:25:02

Pyridine anhydrous - Use

Open Data Verified Data

standard substance for chromatographic analysis. Analytical reagents for the determination of antimony, arsenic, aluminum, bismuth, cadmium, cerium, chromium, cobalt, copper, gold, lanthanum, lead, lithium, manganese, mercury, germanium, nickel, neodymium, platinum, phosphorus, rhenium, praseodymium, silicon, silver, sulfur, thallium, tellurium, thorium, titanium, uranium, vanadium, zinc, zirconium, chlorate, chromate, cyanide, dichromate, perchlorate, permanganate, persulfate, thiocyanate, thiosulfate. It is also a good solvent for organic and inorganic compounds.

Last Update：2022-01-01 09:25:03

Pyridine anhydrous - Safety

Open Data Verified Data

rat oral LD50:1580mg/kg; Rabbit percutaneous LDsa: 1121mg/kg. A drop of the original solution into the guinea pig eye, can cause corneal damage; 40% of the solution instilled into the rabbit eye, can cause corneal necrosis. Strong stimulation I can anesthetize the central nervous system. It can stimulate the eyes and upper respiratory tract. Long-term inhalation of liver and kidney damage can occur. Staff should be protected to avoid direct contact between pyridine and human body. The production site is well ventilated and the maximum allowable concentration in air is 15mg/m3.

Last Update：2022-01-01 09:25:03

Pyridine anhydrous - Reference Information

Open Data Unverified Data

update date:	2022/11/11 21:01:25
FEMA	2966 \| PYRIDINE
relative polarity	0.302
olfactory threshold (Odor Threshold)	0.063ppm
freezing point	-42 ℃
Henry's Law Constant	18.4 at 30 °C (headspace-GC, Chaintreau et al., 1995)
LogP	0.64 at 20℃
(IARC) carcinogen classification	2B (Vol. 77, 119) 2019
NIST chemical information	Information provided by: webbook.nist.gov (external link)
EPA chemical information	Information provided by: ofmpub.epa.gov (external link)
Overview	Pyridine (molecular formula C6H5N) contains a six-membered heterocyclic compound with a nitrogen heteroatom, that is, one of the benzene molecules-CH = is replaced by nitrogen The resulting compound is similar to benzene, has the same electronic structure, and is still aromatic, so it is also called nitrogen benzene and nitrogen benzene, at normal temperature, it is a colorless liquid with special smell, with a melting point of -41.6 ℃ and a boiling point of 115.2 ℃, forming an azeotropic mixture with water, with a boiling point of 92~93 ℃. (This property is used in industry to purify pyridine) with a density of 0.9819g/cm3. Easily soluble in water, ethanol, ether and other organic solvents, it can also be used as a solvent. Pyridine was initially separated from bone tar, and then it was found that coal tar, gas, shale oil, and petroleum also contained pyridine and its homologs, such as 2-methylpyridine and 2,6-dimethylpyridine. Pyridine and its derivatives are more stable than benzene, and their reactivity is similar to nitrobenzene. Due to the electron withdrawing effect of the nitrogen atom in the ring, the electron density at the 2,4, and 6 positions is lower than the 3,5 positions. The typical aromatic electrophilic substitution reaction occurs at the 3,5 positions, but the reactivity is higher than Benzene is low, and nitrification, halogenation, sulfonation and other reactions are generally not easy to occur. In addition, these substitution reactions are carried out in an acidic medium, and pyridine forms positively charged ions, making electrophiles difficult to access. The halogen of 2-or 4-halopyridine is active. Due to the low electron density at positions 2 and 6, nucleophilic substitution reactions can occur at this position, such as reaction with sodium amide or potassium hydroxide to obtain the corresponding 2-aminopyridine or 2-hydroxypyridine.
Structure	Pyridine is a typical electron-deficient aromatic heterocyclic compound. The pyridine ring is a planar ring with a closed conjugated system in the molecule. Since the electronegativity of the N atom is greater than that of the C atom, the density of the electron cloud on the pyridine ring is less than that of benzene; in addition, the density of the electron cloud around the nitrogen atom is high, while the density of the electron cloud in other parts of the ring is reduced, especially at the adjacent and para positions. Significant, so the aromaticity of pyridine is worse than benzene. In addition, the nitrogen atom in the pyridine molecule has a pair of unshared electron pairs that do not participate in the π system, so pyridine has a certain nucleophilic ability and can attack positively charged molecules. Pyridine is an important organic base. In the pyridine molecule, the role of the nitrogen atom is similar to the nitro group of nitrobenzene, so that the density of the electron cloud at the ortho and para positions is lower than that of the benzene ring, and the meta position is similar to the benzene ring. In this way, the electron cloud density of the carbon atom on the ring is far less than that of benzene, so the aromatic heterocyclic ring such as pyridine is also called "π-deficient" heterocyclic ring. This type of heterocycle is chemically difficult to be electrophilic and easy to be nucleophilic; difficult to oxidize and easy to reduce.
purification and water removal methods	analytically pure pyridine contains a small amount of water and can be used for general experiments. If you want to produce anhydrous pyridine, you can reflux the pyridine with granular potassium hydroxide (sodium), and then isolate the moisture and steam it out for later use. Dry pyridine has strong water absorption, and the container mouth should be sealed with paraffin wax during storage.
Source and synthesis method	Pyridine can be extracted from coking gas and tar. The coking gas is passed through sulfuric acid to absorb nitrogen-containing alkaline substances such as ammonia and pyridine, and the ammonium sulfate salt solution produced by the treatment of ammonia gas is separated into free nitrogen-containing organic alkalis, and then distilled to obtain pyridine A mixture of its alkyl substituents. It can also be made from acetaldehyde and ammonia. Pyridine and its derivatives can be synthesized by a variety of methods. Among them, the most widely used is the Hanchi pyridine synthesis method, which uses two molecules of β-carbonyl compounds, such as ethyl acetoacetate and one molecule of acetaldehyde, and the product is condensed with one molecule of ethyl acetoacetate and ammonia to form Dihydropyridine compounds are then dehydrogenated with oxidants (such as nitrous acid), and then hydrolyzed to lose carboxylation to obtain pyridine derivatives. Pyridine can also be prepared by catalysts at 500°C with acetylene, ammonia and methanol.
uses	pyridine, as one of the important nitrogen-containing heterocyclic compounds, has been widely used in fields including photocatalysis and photoelectric devices. In medicinal chemistry, pyridine is also commonly used as the mother core structure of drugs. At present, the deuteration reaction of pyridine mainly uses metal catalysts such as Pd, Rh, Ir, Ru and Ni to carry out hydrogen isotope exchange (HIE) at the α-position, while HIE at other positions is rarely involved. Among the many derivatives of pyridine, some are important drugs, and some are important components of vitamins or enzymes. For example, the amide of pyridine-3-carboxylic acid (I. e. nicotinamide) forms an important dinucleotide with adenine (see purine), ribose and phosphoric acid in Coenzyme I. Isoniazid, a derivative of pyridine, is an oral anti-tuberculosis drug. 2-Methyl-5-vinylpyridine is an important raw material for synthetic rubber. In addition to being used as a solvent, pyridine can also be used as a denaturing agent, dye aid, and the starting material for the synthesis of a series of products, including drugs, disinfectants, dyes, food seasonings, adhesives, explosives, etc. used as organic solvent, analytical reagent, also used in organic synthesis industry, chromatography analysis, etc. used as raw material for extraction and separation of pyridine and its homologs GB 2760-1996 regulations are allowed to use edible spices. Pyridine is a raw material for herbicides, pesticides, medicines, rubber auxiliaries, and textile auxiliaries. It is mainly used as a raw material in the pharmaceutical industry, as a solvent and alcohol denaturing agent, and also used in the production of rubber, paint, resin and corrosion inhibitors. It is used to make vitamins, sulfonamides, Insecticides and plastics, etc. It can be used as a solvent. Pyridine can also be used as a denaturing agent, a dye aid, and a starting material for synthesizing a series of products in industry, including medicines, disinfectants, dyes, food seasonings, adhesives, explosives, etc. Solvent, organic synthesis. Verification and determination of antimony, arsenic, aluminum, bismuth, cadmium, cerium, chlorate, chromate, cyanate, chromium, cobalt, copper, cyanide, gold, dichromate, halogen, lanthanum, lead, Lithium, manganese, mercury, germanium, nickel, perchlorate, persulfate, platinum, phosphorus, rhenium, praseodymium, silicon, silver, sulfur, thallium, tellurium, thiocyanate, thorium, thiosulfate, titanium, uranium, vanadium, zinc, zirconium. Moisture determination, strain mutagen. Solvent for acylation reaction. Catalyst.
Demand analysis in pesticides	In the field of agrochemical, a chemical structure can be seen almost everywhere, which is pyridine. From the structural point of view, pyridine is a six-membered heterocyclic compound containing a nitrogen heteroatom. In application, pyridine can be said to be an important intermediate of "sweeping" three drugs (pesticides, medicines, and veterinary drugs). It not only has a large market demand, but also has an extremely important role in promoting the green development of agrochemical and other industries. As the fourth generation of new pesticides in the world, pyridine pesticides have obvious advantages. Pyridine ring pesticides are not only high-efficiency, low-toxicity, and long-term, but also have good environmental compatibility with humans and organisms, which meets the development requirements and trends of pesticides. There are many kinds of pyridine special fine chemicals, among which chloropyridine is a high value-added product with great development potential. Among them, chlorpyrifos, a pesticide with huge market capacity, is an important intermediate in the production and manufacturing process of chloropyridine chemicals -2,3,5,6-tetrachloropyridine. The first-generation star product of neonicotinoid insecticides-an important intermediate of imidacloprid, is also a chloropyridine product 2-chloro-5-chloromethylpyridine. In the field of herbicides, chloropyridine can be seen everywhere. For example, the world's third largest killing herbicide after glyphosate and paraquat-diquat. The important intermediate of this kind of herbicide is the chloropyridine product 2-chloropyridine. The role of chloropyridine is far from limited to industry, and it can be seen everywhere in the field of daily use and medicine. Chloropyridine can be used to produce fungicide ZPT. This product is widely used in shampoo, including Haifei silk, Piao Rou and other familiar brands. In the field of medicine, chloropyridine is an important intermediate of antihistamine drugs such as feniramine, central excitant drug Ritalin, trazodone and antiarrhythmic drug imepiramide.
toxicity	GRAS(FEMA). It can be safely used in food as a spice (FDA,§ 172.515,2000).
usage limit	FEMA(mg/kg): soft drink 1.0; Mouth drink 0.02~0.12; Candy and baked goods 0.4.
harm	invasive routes: inhalation, ingestion, percutaneous absorption. Health hazards: strong irritation; can anaesthetize the central nervous system. It has a stimulating effect on the eyes and upper respiratory tract. After high concentration inhalation, the light has a sense of euphoria or suffocation, followed by depression, muscle weakness, vomiting; severe loss of consciousness, incontinence, tonic spasm, blood pressure drop. Mistakes can kill you. Chronic effects: long-term inhalation of dizziness, headache, insomnia, gait instability and digestive tract dysfunction. Liver and kidney damage can occur. Can cause dermatitis. Toxicity: low toxicity. Acute toxicity: LD501580mg/kg (rat oral);1121 mg/kg (rabbit percutaneous); Human inhalation of 25mg/m3 × 20 minutes has irritating effect on conjunctiva and upper respiratory tract mucosa. Subacute and chronic toxicity: rats inhaled 32.3mg/m3 × 7 hours/day × 5 days/week × 6 months, liver weight coefficient increased; Human inhalation of 20~40mg/m3 (long-term); Mental failure, gait instability, finger tremor, low blood pressure, hyperhidrosis, individual liver and kidney have influence.
production method	pyridine was previously extracted from coal tar. coke oven gas was washed with sulfuric acid and neutralized with ammonia to obtain crude light pyridine, and then purified by rectification. With the expansion of the use of pyridine, synthetic pyridine has developed greatly. Pyridine and pyridyl compounds obtained from coal tar abroad have accounted for 10%. The mixture of acetaldehyde (1.648mol), 37% formaldehyde (1.665mol) and ammonia (3.096mol) was reacted at 432 ℃. The catalyst was SiO2-Al2O3-Bi2O3 and the yield of pyridine was 48.4%. At the same time, β-methylpyridine is also generated, and the yield of pyridine, methylpyridine and methylpyridine can be adjusted by changing the operating conditions. In addition, 1, 5-pentanediamine hydrochloride can also be prepared by dehydrogenation in the presence of Pt catalyst after heating and cycliding. using the mother liquor of saturator during high-temperature coking as raw material, crude pyridine is recovered and processed, aqueous pyridine is obtained by heating and slag removal, and pure benzene is constant boiling dehydration. Anhydrous pyridine is obtained, and then 110~120 ℃ fraction is distilled by distillation, and finally obtained by rectification.
category	flammable liquid
toxicity classification	poisoning
acute toxicity	oral administration-rat LD50: 891 mg/kg; Intravenous-mouse LD50: 1500 mg/kg
stimulation data	eyes-rabbit 2 mg severe; Skin-rabbit 10 mg/24 hours mild
explosive hazard characteristics	blastable when mixed with air
flammability hazard characteristics	flammable in case of open flame, high temperature and oxidant; toxic nitrogen oxide smoke from combustion
storage and transportation characteristics	warehouse ventilation and low temperature drying; Store separately from oxidants and acids
fire extinguishing agent	dry powder, dry sand, carbon dioxide, foam, 1211 fire extinguishing agent
occupational standard	TWA 15 mg/m3; STEL 30 mg/m3
spontaneous combustion temperature	482°C
toxic substance data	information provided by: pubchem.ncbi.nlm.nih.gov (external link)
immediate life-threatening and health concentration	1,000 ppm