A Picoline

Rcolinic acid Is readily prepared by the oxidation of a-picoline with potas-... 

Another example illustrating the greater reactivity of organolithium compounds is the preparation of the otherwise difficultly accessible esters of 2-pyridyl-acetlc acid by the following series of reactions from a-picoline ... 

Reactivity Acrolein is a highly reactive chemical, and contamination of all types must be avoided. Violent polymerization may occur by contamination with either alkaline materials or strong mineral acids. Contamination by low molecular weight amines and pyridines such as a-picoline is especially hazardous because there is an induction period that may conceal the onset of an incident and allow a contaminant to accumulate unnoticed. After the onset of polymeriza tion the temperature can rise precipitously within rninutes. 

Important commercial alkylpyridine compounds are a-picoline (2), Ppicoline (3), y-picoline (4), 2,6-lutidine (5), 3,5-lutidine (6), 5-ethyl-2-methylpyridine (7), and 2,4,6-coUidine (8). In general, the alkylpyridines serve as precursors of many other substituted pyridines used in commerce. These further substituted pyridine compounds derived from alkylpyridines are in turn often used as intermediates in the manufacture of commercially usehil final products. 

Ring Synthesis From Nonheterocyclic Compounds. These methods may be further classified based on the number of bonds formed during the pyridine ring formation. Synthesis of a-picoline (2) from 5-oxohexanenitrile is a one-bond formation reaction (eq. 16) (49). The nitrile is obtained by reaction between acetone and acrylonitrile (50). If both reaction steps are considered together, the synthesis must be considered a two-bond forming one, ie, formation of (2) from acetone and acrylonitrile in a single step comes under the category of two-bond formation reaction. 

Another of the few selective syntheses of aLkylpyridines is one for a-picoline (2) (76). This is a two-step process (eq. 24) where acrylonitrile is used to monocyanoethylate acetone in the Hquid phase at 180°C and at autogenous pressure, 2 MPa (300 psig). The monoadduct, 5-cyano-2-pentanone, is then passed over a palladium-containing catalyst to reduce, cyclize, and dehydrogenate, in sequence. 

The relative production volumes of pyridine compounds can be ranked in the following order pyridine (1) > P-picoline (3) > a-picoline (2)> niacin (27) or niacinamide (26)> 2-vinylpyridine (23)> piperidine (18). U.S. and Japanese production was consumed internally as well as being exported, mainly to Europe. European production is mosdy consumed internally. Growth in production of total pyridine bases is expected to be small through the year 2000. 

The primary use of a-picoline (2) is as a precursor of 2-vinylpyridine (23). It is also used in a variety of agrochemicals and pharmaceuticals, such as nitrapyrin [1929-82-4] (60) to prevent loss of ammonia from fertilizers picloram [1918-02-1] (61), a herbicide and amproHum [121 -25-5] (62), a coccidiostat. 

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. 

Similarly, 1-alkylpyrroles, indoles, furans, thiophenes [60], a-picoline [61], enols, malonates [76], and organometallic compounds [56, 62] react with acyl imines of trifluoropyruvates to give derivatives of a-trifluoromethyl a-amino acids... 

The reactivity of the 1-methyl group and of corresponding positions (i.e., a-carbon atoms) in other l-alkyl-j8-carbolines, analogous to that in a-picoline, quinaldine, and isoquinaldine, is due to the acidity of this center. Deprotonation yields a resonance-stabilized anion (288) which reacts readily with electrophilic reagents. Metallation with phenyl-lithium of the 1-methyl group of a l-methyl-j8-carboline derivative in which the indole nitrogen is protected, first described by Woodward... 

Several products other than 2,2 -biaryls have been isolated following reaction of pyridines with metal catalysts. From the reaction of a-picoline with nickel-alumina, Willink and Wibaut isolated three dimethylbipyridines in addition to the 6,6 -dimethyl-2,2 -bipyridine but their structures have not been elucidated. From the reaction of quinaldine with palladium-on-carbon, Rapoport and his co-workers " obtained a by-product which they regarded as l,2-di(2-quinolyl)-ethane. From the reactions of pyridines and quinolines with degassed Raney nickel several different types of by-product have been identified. The structures and modes of formation of these compounds are of interest as they lead to a better insight into the processes occurring when pyridines interact with metal catalysts. 

Benzoylation of 3-chloropropan-l-ol affords the haloester, 52. Condensation of this intermediate with the reduction product of a-picoline (S3) affords the local anesthetic, piperocaine (54)... 

Ethyl formate a-Picoline Sodium hydroxide Maleic acid... 

The 2D INADEQUATE spectrum of a-picoline (Fig. 5.57) provides carbon—carbon connectivity information. The pairs of coupled carbons... 

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