Ester sodium methoxide

The conditions for generating enolates from simple esters are similar to those used for aldehydes and ketones except that alkoxide bases are used instead of hydroxide. The alkoxide is chosen to match the ester (sodium ethoxide with ethyl esters, sodium methoxide with methyl esters) to avoid complications due to exchange of alkoxy groups by nucleophilic acyl substitution. An equilibrium is established in which the ester predominates and only a very small amount of enolate is present. 

In general the method is more satisfactory with esters of aromatic acids than with esters of aliphatic acids. Esters of alcohols other than methyl and ethyl are best treated by first converting them into methyl esters thus Heat together under reflux i ml. of the higher ester, 5 ml. of methanol and 0-2 g. of sodium methoxide. [In place of the sodium methoxide, it suffices to add o i g. of metallic sodium to the methanol.] After refluxing, distil off the excess of methanol (b.p, 65 ). The residue is then heated under reflux with benzylamine as described above. 

The reaction (which is essentially the direct aminolysis of esters with benzylamine) proceeds readily when R is methyl or ethyl. Esters of higher alcohols should preferably be subjected to a preliminary methano-lysis by treatment with sodium methoxide in methanol ... 

The hydrazides are often crystalline and then serve as useful derivatives. Esters of higher alcohols should be converted first to the methyl esters by boiling with sodium methoxide in methanol (see under AT-benzylamides). 

By increasing the molar proportion of the monocarboxylic acid, the yield of (II) is improved. Thus electrolysis of a mixture of decanoic acid (n-decoic acid capric acid) (V) (2 mols) and methyl hydrogen adipate (VI) (1 mol) in anhydrous methanol in the presence of a little sodium methoxide gives, after hydrolysis of the esters formed, n-octadecane (VII), tetradecanoic or myristic acid (VIH) and sebacic acid (IX) ... 

Alcoholysis (ester interchange) is performed at atmospheric pressure near the boiling point of methanol in carbon steel equipment. Sodium methoxide [124-41 -4] CH ONa, the catalyst, can be prepared in the same reactor by reaction of methanol and metallic sodium, or it can be purchased in methanol solution. Usage is approximately 0.3—1.0 wt % of the triglyceride. 

The alcoholysis reaction may be carried out either batchwise or continuously by treating the triglyceride with an excess of methanol for 30—60 min in a well-agitated reactor. The reactants are then allowed to settle and the glycerol [56-81-5] is recovered in methanol solution in the lower layer. The sodium methoxide and excess methanol are removed from the methyl ester, which then maybe fed directiy to the hydrogenolysis process. Alternatively, the ester may be distilled to remove unreacted material and other impurities, or fractionated into different cuts. Practionation of either the methyl ester or of the product following hydrogenolysis provides alcohols that have narrow carbon-chain distributions. 

On heating, an alkanolamine soap first dehydrates to the amide this is also obtained from the methyl ester of the fatty acid by heating with the alkanolamine at 60°C in the presence of a catalytic amount of sodium methoxide. Methanol is removed under partial vacuum. At higher temperature, the amide is dehydrated to an oxa2oline. 

Refluxing linoleic acid and a primary or secondary alkyl amine with -toluenesulfonic acid in toluene for 8—18 h also yields the substituted amides (32—34). The reaction of methyl esters with primary or secondary amines to make substituted amides is catalyzed with sodium methoxide. Reactions are rapid at 30°C under anhydrous conditions (35). Acid chlorides can also be used. Ai,A/-dibutyloleamide [5831-80-17 has been prepared from oleoyl chloride and dibutyl amine (36). 

Olestra is prepared by a solvenfless transesterification process in which sucrose is treated with methyl ester of fatty acids in the presence of sodium methoxide between 100—180°C for 14 hours (68). The manufacturing process involves removal of the unreacted fatty acid esters by enzymic hydrolysis... 

In an attempt to prepare an isothiazolobenzodiazepine, ethyl 5-o-aminoanilino-3-methyl-isothiazole-4-carboxylate was treated with sodium methoxide, but the only reaction was transesterification to the methyl ester 76UC(B)394). Only the 5-ester group of dimethyl 3-methylisothiazole-4,5-dicarboxylate reacts with iV,iV -diphenylguanidine, as with the corresponding isoxazole compound, but the product could not be cyclized, even under drastic conditions. This is in marked constrast to the isoxazole compound which cyclized at room temperature (80JCS(P1)1667). 

Perfluorohexamethylbenzene is converted to perfluoropentamethylbenzoic acid by sequential treatment with sodium methoxide, then concentrated sulfuric acid, and finally fuming sulfuric acid [37] (equation 38). The intermediate methyl ortho ester and methyl ester of the acid can be isolated... 

Perfluoro-2 (1 ethyl 1 methylpropyl)-3-methyl-l-pentene, the major hex-amer of tetrafluoroethylene, reacts with sodium methoxide to yield an ester, whereas a stable crowded ketene is formed by reaction with sodium hydroxide [2d] (equation 23)... 

The most widely used variant of the Gabriel-Colman is the conversion of saccharine derivatives to benzothiazine derivatives. The reaction has been extensively studied as benzothiazines are important pharmacophores, particularly in the oxicam class of antiinflammatories. The first reported instance of this transformation was in 1956 where 43 was treated with sodium methoxide to provide 44. The rearrangement also works with esters " and some amides " in addition to ketones. 

The preparation of the 6-propyl to 6-undecyl derivatives, however, was performed by boiling for 30 min with potassium carbonate. Sodium methoxide in a mixture of ethanol and benzene was used for the cyclization of the thiosemicarbazone of phenylglyoxylic acid ester. ... 

Hydrolysis of the acetate ester with alkali, e.g., sodium methoxide in methanol, affords the free alcohol, 16/3-methyl-1,4,9( 11 )-pregnatriene-17o, 21-diol-3,20-dione. To a suspension of 3 grams of 16/3-methyl-1,4,9(11)-pregnatriene-17o,21-diol-3,20-dione-21-acetate in 40 ml of acetone is added at 0°C with stirring 2 grams of N-chlorosuccinimide and then 7 ml of a perchloric acid solution prepared by dissolving 0.548 ml of 70% perchloric acid in 33 ml of water. The resulting reaction mixture is stirred at 0°C for about 4 hours 45 minutes. 

The 3-o-ch orophenvl-5-methvlisoxa2ole4-carboxylic acid, from which the acid chloride was prepared, was obtained by hydrolysis of the ester product of the reaction between o-chloro-benzohydroxamic chlorideand ethyl acetoacetate in methanolic sodium methoxide. Reaction with thionyl chloride gave the starting material. 

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