Pyridines 4-methylpyridine

First, the tar acids were removed from the naphtha fractions of light oils and, in the case of CVR tars, carboHc oil. The oils were then mixed with 25—35% sulfuric acid. After separation of the sulfates, the aqueous solution was diluted with water and the resinous material skimmed off. The diluted sulfate solution was boiled to expel any neutral oils, dried by the addition of soHd caustic soda or a2eotropically with ben2ene, and fractionated to yield pyridine, 2-methylpyridine (a-picoline), and a fraction referred to as 90/140 bases, which consisted mainly of 3- and 4-methylpyridines and 2,6-dimethylpyridine (2,6-lutidine). Higher boiling fractions were termed 90/160 and 90/180 bases because 90% of the product distilled at 160 and 180°C, respectively. 

Commercial development of a range of cycloalkene-cobalt homogeneous catalysts has prompted their application in the synthesis of pyridine and 2-substituted pyridines. Thus, bis(cyclopentadienyl)cobalt catalyzes the reaction of acetylene with hydrogen cyanide, acetonitrile or acrylonitrile to yield pyridine, 2-methylpyridine and 2-vinylpyridine respectively (Scheme 4 R = H, Me or CH=CH2) (76S26, 78AG(E)505, 75BEP846350). The high cost of the catalyst has so far limited full commercial realization of this route. Acrylonitrile... 

Pyridine readily forms stable coordination compounds. Thus, boron, aluminum and gallium trihalides react at 0°C in an inert solvent to give 1 1 adducts (cf. 85). Steric factors are important, and a-substituents decrease the ease of reaction. This is illustrated by the heats of reaction of pyridine, 2-methylpyridine and 2,6-dimethylpyridine with boron trifluoride which are 101.3, 94.1 and 73.2 kJ mol-1, respectively. The marked decrease in exothermicity here should be contrasted with the small steric requirement of the proton as shown by the pA., values of substituted pyridines (see Section 3.2.1.3.4). 

Pyridines - The industrially significant pyridine bases are pyridine, 2-methylpyridine (2-picoline) and 2-methyl-5-ethylpyridine (MEP)46. 

Pyridine and its derivatives. The most unique pyridine derivative isolated from processed food is l,lt,5,6-tetrahydro-2-ace-topyridine. This compound was prepared by roasting proline and dihydroxyacetone at 92°C in presence of sodium bisulfate, and exhibited a strong odor reminiscent of freshly backed soda crackers (82). 2-Ethylpyridine and 2-pentylpyridine were reported in volatile flavor components of shallow fried (83). Pyridine, 2-methylpyridine, 3-methylpyridine, 2-ethylpyridine, 3-ethylpyri-dine, 5-ethyl-2-methylpyridine, 2-butylpyridine, 2-acetylpyridine, 2-pentylpyridine, 2-hexylpyridine, 3-pentylpyridine, 5-methyl-2-pentylpyridine, and 5-ethyl-2-pentylpyridine were identified in the volatiles of roasted lamb fat (8H). 2,5-Dimethylpyridine and... 

Pyridine, 2-methylpyridine, pyrimidine, pyrrole, imidazole, indole, and purine are aromatic. 19.3. (a) pentan-2-amine (b) A-methylbutan-2-amine (c) m-aminophenol (d) 3-methylpyrrole (e) /ram-cyclopentane -1,2-diamine (f) c -3-aminocyclohexanecarbaldehyde. 19.4. (a) resolvable (chiral carbons) (b) not resolvable (N inverts) (c) symmetric ... 

Pyridine, 2-methylpyridine, and 2,4,6-collidinehave been added to avoid acidic conditions (to prevent secondary isomerizations) without deactivation of the silver salt by complexation or precipitation. In the absence of a nucleophile, pyridine forms allylic pyridinium salts and acetonitrile forms allylic amides. For example, formation of 5 and 6. ... 

These compounds satisfy the criteria for aromaticity (planar, cyclic n system, and the Huckel number of 4n -I- 2 71 electrons) pyrrole, imidazole, indole, pyridine, 2-methylpyridine, pyrimidine, and purine. The systems with 6 7i electrons are pyrrole, imidazole, pyridine, 2-methylpyridine, and pyrimidine. The systems with 10 7i electrons are indole and purine. The other nitrogen heterocycles shown are not aromatic because they do not have cyclic 7i systems. 

Pyridine, 2-methylpyridine, and 2-chloropyridine can all be oxidised to the corresponding N-oxides using MMPP in acetic acid [5]. In our more recent work we have also shown that quinoxaline can be oxidised to the di-N-oxide using the UHP-trifluoroacetic anhydride procedure in moderate yield [11]. It is likely that isolation difficulties were a major problem in the latter case. The oxidation of quinoxaline using MMPP to the di-N-oxide in 1,2-dichloroethane proceeds in high yield (Eq. 43) and there are then no difficulties in isolating the product. The oxidation of the pyrimidine shown in Eq. (44) has been reported [50] using MMPP and a yield of 91% obtained in the oxidation shown in Eq. (45) [51]. 

One study by Dubinin and Chelintsev (1075a) reported on the pyrolytic products of anabasine heated at 580 to 650°C in a charcoal-filled reactor. Exclnsive of gases, the major prodncts were reported to be pyridine, 2-methylpyridine,... 

Rate constants and activation parameters for the axial ligation of zinc(II) meso -tetraphenylporphyrin by pyridine, 2-methylpyridine, and imidazole in aprotic solvents are close to, but significantly different from, the diffusion-controlled values, and it appears that desolvation (either of the base or the metalloporphyrin) is an important step in these reactions. 

Nakanishi, K. Ashitani, K. Touhara, H. Excess Gibbs free energy and excess volume of methanol + pyridine, + 2-methylpyridine, and + 2,6-dimethylpyridine. J. Chem. Thermodyn. 1976, 8, 121-126. 

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