Pyridine is an aromatic heterocyclic family of chemical compounds with a six-membered ring structure consisting of five carbon atoms and one nitrogen atom. Its molecular formula is C 5 H 5 N and it is the most basic member of the pyridine family. It is a highly flammable, mildly alkaline, water-miscible liquid with a fish-like odor. Before the invention of a synthesis based onacetaldehyde and ammonia, it was mostly obtained from coal tar. Chemicals of high purity that are best suited for analytical use are known as Analytical Reagent Grade. They are great for delivering consistent, reliable, and repetitive results in research applications. Lab Alley is selling online its premium quality products in the United States of America. Lab Alley highly recommends to use its Pyridine, Analytical Reagent Grade in industrial, commercial, and research applications.
- Pyridine CAS Registry Number: 110-86-1
- Pyridine Molar Mass: 79.1 g/mol
- Pyridine Formula: C5H5N
- Pyridine Boiling Point: 239.6°F (115.4°C)
- Pyridine Density: 982 kg/m³
- Pyridine pH: Between 7 to 14
- Pyridine ChemSpider ID: 1020
- Pyridine Properties, Searches, Spectra, Vendors, Articles, Patents, Reactions, Crystal CIFs, MeSH, Pharma Links, Data Sources, Curation
- Pyridine PubChem CID: 1049
- Pyridine Reactions PDF
- Pyridine For HPLC: ≥99.9%; CAS Number: 110-86-1; EC Number: 203-809-9; Linear Formula: C5H5N
- Systematic IUPAC Name For Pyridine: Azabenzene
- Other Names For Pyridine: Azine, Azinine, 1-Azacyclohexa-1,3,5-diene, trioxochromium, hydrochloride, 26299-14-9, A818366, tris(oxidanylidene)chromium, Pyridine hydrofluoride, Pyridinium poly(hydrogen fluoride)
- Pyridine Resonance: The 1H nuclear magnetic resonance (NMR) spectrum of pyridine contains three signals with the integral intensity ratio of 2:1:2 that correspond to the three chemically different protons in the molecule.
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. It is a highly flammable, weakly alkaline, water-miscible liquid with a distinctive, unpleasant fish-like smell. Pyridine is colorless, but older or impure samples can appear yellow. The pyridine ring occurs in many important compounds, including agrochemicals, pharmaceuticals, and vitamins. Historically, pyridine was produced from coal tar. Today it is synthesized on the scale of about 20,000 tonnes per year worldwide.
History Of Pyridine
Impure pyridine was undoubtedly prepared by early alchemists by heating animal bones and other organic matter, but the earliest documented reference is attributed to the Scottish scientist Thomas Anderson. In 1849, Anderson examined the contents of the oil obtained through high-temperature heating of animal bones. Among other substances, he separated from the oil a colorless liquid with unpleasant odor, from which he isolated pure pyridine two years later. He described it as highly soluble in water, readily soluble in concentrated acids and salts upon heating, and only slightly soluble in oils.
Pyridine For 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.
How Pyridine Is Used As A Solvent
Pyridine is used as a polar, basic, low-reactive solvent, for example in Knoevenagel condensations. It is especially suitable for the dehalogenation, where it 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. Even more active in these reactions are the pyridine derivatives 4-dimethylaminopyridine (DMAP) and 4-(1-pyrrolidinyl) pyridine. Pyridine is also used as a base in condensation reactions.
The optical absorption spectrum of pyridine in hexane contains three bands at the wavelengths of 195 nm (π → π* transition, molar absorptivity ε = 7500 L·mol−1·cm−1), 251 nm (π → π* transition, ε = 2000 L·mol−1·cm−1) and 270 nm (n → π* transition, ε = 450 L·mol−1·cm−1). The 1H nuclear magnetic resonance (NMR) spectrum of pyridine contains three signals with the integral intensity ratio of 2:1:2 that correspond to the three chemically different protons in the molecule. These signals originate from the α-protons (positions 2 and 6, chemical shift 8.5 ppm), γ-proton (position 4, 7.5 ppm) and β-protons (positions 3 and 5, 7.1 ppm). The carbon analog of pyridine, benzene, has only one proton signal at 7.27 ppm. The larger chemical shifts of the α- and γ-protons in comparison to benzene result from the lower electron density in the α- and γ-positions, which can be derived from the resonance structures. The situation is rather similar for the 13C NMR spectra of pyridine and benzene: pyridine shows a triplet at δ(α-C) = 150 ppm, δ(β-C) = 124 ppm and δ(γ-C) = 136 ppm, whereas benzene has a single line at 129 ppm. All shifts are quoted for the solvent-free substances. Pyridine is conventionally detected by the gas chromatography and mass spectrometry methods.
Pyridine is used to dissolve other substances. It is also used to make many different products such as vitamins, food flavorings, paints, dyes, rubber products, adhesives, insecticides, and herbicides.
It can be made from crude coal tar or from other chemicals. Pyridine is used as a solvent and to make many different products such as medicines, vitamins, food flavorings, pesticides, paints, dyes, rubber products, adhesives, and waterproofing for fabrics. The main use of pyridine is as a precursor to the herbicides paraquat and diquat.
This webcast contrasts two common heteroaromatic compounds, pyridine and pyrrole. In particular, we want to understand why pyridine is considered electron deficient, while pyrrole is considered electron rich.
Pyrimidine is an aromatic heterocyclic organic compound similar to pyridine. One of the three diazines (six-membered heterocyclics with two nitrogen atoms in the ring), it has the nitrogen atoms at positions 1 and 3 in the ring.
- Preparation Of Highly Reactive Pyridine- and Pyrimidine-Containing Diarylamine Antioxidants
- Synthesis of Pyridine, Pyrimidine and Pyridinone C-Nucleoside Phosphoramidites for Probing Cytosine Function in RNA
- Design, Synthesis and Screening of 4,6-Diaryl Pyridine and Pyrimidine Derivatives as Potential Cytotoxic Molecules
The Kröhnke pyridine synthesis is reaction in organic synthesis between α-pyridinium methyl ketone salts and α, β-unsaturated carbonyl compounds used to generate highly functionalized pyridines. Pyridines occur widely in natural and synthetic products, so there is wide interest in routes for their synthesis.
The determination of citric acid with pyridine and acetic anhydride has been investigated at reaction temperatures from 17 to 60° C. The optimum proportions of pyridine, acetic anhydride, water, and acetic acid for maximum color intensity and stability are given for each temperature. The procedure has been modified to eliminate the violent nature of the reaction, even when the analysis is done at a reaction temperature of 60° C. Details of a method for the determination of 25–200 μg. of citric acid, at a reaction temperature of 32° C., are presented. In comparison with previously published methods based on the reaction, the recommended technique results in improved sensitivity, stability, and reproducibility without requiring careful timing. The method has been successfully applied to the routine analysis of milk and milk products. Milk and serum can be analyzed directly, after suitable dilution. Corrections for the interference caused by fat in homogenized milk, and by trichloroacetic acid in T.C.A. serum, can be made easily. Results of direct analysis of milk were from 5 to 15% higher than those for the corresponding sera and are believed to represent the true values for the citric acid content of milk. Read more here.
Pyridine has a conjugated system of six π electrons that are delocalized over the ring. The molecule is planar and, thus, follows the Hückel criteria for aromatic systems. In contrast to benzene, the electron density is not evenly distributed over the ring, reflecting the negative inductive effect of the nitrogen atom.
Pyridine contains 6π electrons required for aromaticity and also it's planar and conjugated. Pyrrole has 4π electrons and the lonepair of electrons on the nitrogen participate in resonance with the ring to attain aromaticity. Therefore Pyridine is more aromatic than pyrrole.
The gas chromatography with the mass spectroscopy (GC-MS) analyses was used for the interpretation of high temperature region of the pyridine TPD spectra (T(MAX2)=620 degrees C). It was found that pyridine bonded on the strong acid centers is decomposed to N(2) and CO under very high temperature.
The mechanism of the Kröhnke pyridine synthesis begins with enolization of α-pyridinium methyl ketone 4 followed by 1,4-addition to the α, β-unsaturated ketone 5 to form the Michael adduct 6, which immediately tautomerizes to the 1,5-dicarbonyl 7. ... The pyridinium cation is then eliminated to form hydroxy-dienamine 12.
Trinseo announced the completion of its acquisition of the vinyl pyridine latex (VP latex) business from Synthomer plc. Trinseo funded the acquisition from cash on hand; the value of the transaction is not material to the company. VP latex is an essential ingredient in binders for coating tire cord fabrics, ensuring a strong bond between the tire cord and rubber during the tire manufacturing process. “Trinseo is a leader in latex binder chemistry and a long-standing supplier of synthetic rubber to the tire industry,” said Frank Bozich, president and CEO of Trinseo. “This acquisition aligns well with our strategy to grow our Latex Binders business in Coatings/CASE applications, and also reinforces our position as a solutions provider to the high-performance tire segment.” The transaction includes product recipes, customer lists and associated intellectual property related to the tire cord binders business; no physical assets or employees are transferring to Trinseo. As part of the transaction, Trinseo has established agreements with Synthomer for contract manufacturing the products at Synthomer’s production facility at Marl, Germany, where the products will continue to be produced.
Pyridine and Pyridine Derivatives Market With Impact Analysis: In-Depth Analysis, Global Market Share, Top Trends, Professional & Technical Industry Insights 2020 – 2026 [May 21, 2020]
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Pyridine, Analytical Reagent Grade Features:
|Water||0.003% - 0.005%|
|Residue after Evaporation||0.0005%|
|Boiling Point||239.6°F (115.4°C)|
|pH||Between 7 to 14|
- Artificial food flavoring
- Denaturing agent of alcohol
Pyridine AR Shipping Information:
DOT: Pyridine, 3, UN1282, PG II
Pyridine is added to ethanol to make it unsuitable for drinking. In low doses, pyridine is added to foods to give them a bitter flavor, and such usage was approved by the US Food and Drug Administration and is still considered safe by the agency even though external lobbying forced it to ban pyridine's use as a synthetic flavor in 2018. The detection threshold for pyridine in solutions is about 1–3 mmol·L−1 (79–237 mg·L−1).
Pyridine has a flash point of 17 °C and is, therefore, highly flammable. Its ignition temperature is 550 °C, and mixtures of 1.7–10.6 vol% of pyridine with air are explosive. The thermal modification of pyridine starts above 490 °C, resulting in bipyridine (mainly 2,2′-bipyridine and to a lesser extent 2,3′-bipyridine and 2,4′-bipyridine), nitrogen oxides, and carbon monoxide. Pyridine easily dissolves in water and harms both animals and plants in aquatic systems. The permitted maximum allowable concentration of pyridine was 15–30 parts per million (ppm, or 15–30 mg·m−3 in air) in most countries in the 1990s, but was reduced to 5 ppm in the 2000s. For comparison, indoor air contaminated with tobacco smoke may contain up to 16 µg·m−3 of pyridine, and one cigarette contains 21–32 µg.
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