2- Picoline 6-methyl

Methylpyridine. See y-Picoline a-Methylpyridine. See a-Picoline Methyl 3-pyridinecarboxylate. See Methyl... 

LIGHT OIL up to 180 benzene, toluene, xylenes (dimethyl benzenes), pyridine, picolines (methyl-pyridines)... 

Amino-4-bromo-3-phenylisothiazole (96), obtained by bromination of (95) or directly from 3-phenyl-3-iminothiopropionamide (94), was deaminated to 3-phenyl-4-bromoisothiazole (97) and converted into the 4-cyano-analogue (98) by the action of cuprous cyanide in boiling picoline. Methylation of 3-phenyl-4-cyanoisothiazole (98) with butyl-lithium and methyl iodide gave low yields of the 5-methyl homologue (101) the alternative route (97) (102) (101) proved to be more advantageous. 

Chapter V. Quinaldine (V,2) 2-methyl-, 2 5-dimethyl- and 2-acetyl-thiophene (V,8-V,10) 2 5-dimethyl and 2 4-dimethyl-dicarbethoxy-p3nrole (V,12-V,13) 2-amino- and 2 4 dimethyl-thiazole (V,15-V,16) 3 5-dimethyl-pyrazole (V,17) 4-ethylp3rridine (from pyridine) (V,19) n-amyl-pyridines from picolines) (V,28) picolinic, nicotinic and isonicotinic acid (V,21-V,22) (ethyl nicotinate and p-cyanop3n idine (V,23-V,24) uramil (V,25) 4-methyl-(coumarin (V,28) 2-hyi-oxylepidine (V,29). 

The easier elimination of pyridine compared to quinoline-4 may be related to the pK value of 4-methylthiazole, which is between those of lepidine and 2-picoline (25. 55). This reaction explains also why a neutrodimethine cyanine is obtained with such good yields when reacting together a quaternary salt, ketomethylene, and o-ester in a basic medium. As the reaction proceeds, the trimethine cyanine is attacked by the ketomethylene. The resulting 2-methyl quaternary salt is transformed into trimethine cyanine, consuming the totality of the ketomethylene (1, p. 512 661). The mesosubstituted neutrodimethine cyanine is practically pure. 

Picoline 129 2-Methyl-thiazole 128 2-Methvl-selen azole 149... 

For the methyl-substituted compounds (322) the increase in AG and AHf values relative to the unsubstituted thiazole is interpreted as being mainly due to polar effects. Electron-donating methyl groups are expected to stabilize the thiazolium ion, that is to decrease its acid strength. From Table 1-51 it may be seen that there is an increase in AG and AH by about 1 kcal mole for each methyl group. Similar effects have been observed for picolines and lutidines (325). 

These results show that the measured values of H° are close to those calculated from the thiazole value and the increments. That compounds substituted ortho-ortho to nitrogen (2,4-dimethyI and 2,4,5-trimethyl-thiazole) also obey this rule shows that the methyl groups do not interact sterically (150). The same conclusion had been reached in the case of the picolines and lutidines (151). 

Other auxin-like herbicides (2,48) include the chlorobenzoic acids, eg, dicamba and chloramben, and miscellaneous compounds such as picloram, a substituted picolinic acid, and naptalam (see Table 1). Naptalam is not halogenated and is reported to function as an antiauxin, competitively blocking lAA action (199). TIBA is an antiauxin used in receptor site and other plant growth studies at the molecular level (201). Diclofop-methyl and diclofop are also potent, rapid inhibitors of auxin-stimulated response in monocots (93,94). Diclofop is reported to act as a proton ionophore, dissipating cell membrane potential and perturbing membrane functions. 

The N-oxide function has proved useful for the activation of the pyridine ring, directed toward both nucleophilic and electrophilic attack (see Amine oxides). However, pyridine N-oxides have not been used widely ia iadustrial practice, because reactions involving them almost iavariably produce at least some isomeric by-products, a dding to the cost of purification of the desired isomer. Frequently, attack takes place first at the O-substituent, with subsequent rearrangement iato the ring. For example, 3-picoline N-oxide [1003-73-2] (40) reacts with acetic anhydride to give a mixture of pyridone products ia equal amounts, 5-methyl-2-pyridone [1003-68-5] and 3-methyl-2-pyridone [1003-56-1] (11). 

Although an inherently more efficient process, the direct chemical oxidation of 3-methylpyridine does not have the same commercial significance as the oxidation of 2-methyl-5-ethylpyridine. Liquid-phase oxidation procedures are typically used (5). A Japanese patent describes a procedure that uses no solvent and avoids the use of acetic acid (6). In this procedure, 3-methylpyridine is combined with cobalt acetate, manganese acetate and aqueous hydrobromic acid in an autoclave. The mixture is pressurized to 101.3 kPa (100 atm) with air and allowed to react at 210°C. At a 32% conversion of the picoline, 19% of the acid was obtained. Electrochemical methods have also been described (7). 

METHYL-4-NITROPYRIDINE-1-OXIDE (3-Picoline, 4-nitro-, 1-oxide)... 

Jacobs and Craig have made an extended study of the selenium dehydrogenation products of cevine and in addition to cevanthrol and eevanthridine have obtained the following thirteen substances Bases, j3-picoline, 5-methyl-2-ethylpyridinc, 5-methyl-2-hydroxyethylpyridine, base, CgHgON (pierate, m.p. 151-2°), base, CgHjgN (pierate, m.p. 150-1°), base, CggHigN, m.p. 233-5° (methiodide, m.p. 285-290°), base, m.p. 229-230° (methiodide, m.p. 295° (dec.) )... 

The separation of mixtures involving N-methyl-JLtetrahydropyridines into their pure components by means of gas-liquid chromatography was discussed in a report by Holik et al. (87). They found that, using tris(/3-cyanoethoxymethyl)-y-picoline as the stationary phase, the primary factors involved in the specific retention volumes of these enamines is the electronic effect of a methyl substituent and the nitrogen atom on the carbon-carbon double bond. It was observed that 1,3-dimethyl-Zl -tetrahydropyridine (141) has a smaller specific retention volume and, hence, is eluted before... 

The most thoroughly investigated compounds are the alkyl-pyridines. Coleman and Fuoss compared the reactions of pyridine, 4-picoline, and 4-isopropylpyridine with n-butyl bromide and found a steady increase in the rate in the order given the activation energies are 16.0,15.95, and 15.6 kcal per mole, respectively. Brown and Cahn carried out a detailed study of the reactions of 2-, 3-, and 4-alkyl-pyridines with methyl, ethyl, and isopropyl iodides in nitrobenzene the results are given in Table II. These data show the higher activation... 

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... 

A characteristic feature of picolines and many azoles is the well-known ability of methyl (and corresponding methylene) groups to undergo condensation of the aldol, crotonic, and Michael type. This is especially pronounced in the quaternary salts of these heterocycles where it occurs under comparatively mild conditions. Such condensations are not unknown for alkylisoxazoles. Lampe and Smolinska were the first to describe the condensation of the quaternary alkyl iodides of 3,5-dimethyl- (96) and 3-methyl-5-phenylisoxazole with... 

A) Preparation of 1-Methyl-2-Picolinium Chloride 98 ml of cx-picoline is dissolved in 200 ml of methanol, cooled and 85 ml (at -68°C) of methyl chloride is added. The solution is charged to an autoclave, sealed and the nitrogen pressure of 300 psig is established. The mixture is heated at 120° to 130°C for 2 hours, cooled and opened. The resulting solution is then evaporated to dryness in vacuo, yielding a residue of 110 g. This residue is then dissolved in 50 ml of water and extracted with two 50 ml portions of ether. The aqueous phase is then diluted to 150 ml with water and an assay for ionic chloride is performed which indicates the presence of chloride ion equivalent to 721 mg/ml of 1-methyl-2-picolinium chloride. 

Table 4-2. Computed and experimental primary 12C/13C and secondary 14N/15N kinetic isotope effects for the decarboxylation of N-methyl picolinate at 25 °C in water...

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