Malonic ester, carboxylic acids from

An important example of this reaction is the malonic ester synthesis, in which both Z groups are COOEt. The product can be hydrolyzed and decarboxylated (12-38) to give a carboxylic acid. An illustration is the preparation of 2-ethyl-pentanoic acid from malonic ester ... 

Sulfuric acid/sodium hydroxide Carboxylic acids from malonic acid esters s. 17, 132... 

Carboxylic acids from malonic acid esters via malonic acids. A suspension of ethyl a-carbethoxy-y-oxo-5-phthalimidovalerate in 48%-HBr allowed to stand at room temp, overnight, then heated on a steam bath until dissolved, allowed to cool, and evaporated to dryness in vacuo a-carboxy-y-oxo-<5-phthalimido-valeric acid (Y 83.0%) heated to 170 /3-4 mm until gas evolution ceases -phthalimidolevulinic acid (Y 90.7%). D. P. Tschudy and A. Collins, J. Org. Chem. 24, 556 (1959). 

Maleic acid, structure of, 753 Malic acid, structure of, 753 Walden inversion of, 359-360 Malonic ester, carboxylic acids from, 856-858... 

The malonic ester synthesis converts a primary or secondary alkyl halide into a carboxylic acid with two more carbons (a substituted acetic acid). Identify the component that originates from malonic ester (the acid component). The rest of the molecule comes from the alkyl halide, which should be primary or methyl. 

One of the oldest and best known carbonyl alkylation reactions is the malonic ester synthesis, a method for preparing a carboxylic acid from an alkyl halide while lengthening the carbon chain by two atoms. 

A combination of two of the reactions discussed in this chapter—alkylation of an a-carbon and decarboxylation of a j8-dicarboxylic acid—can be used to prepare carboxylic acids of any desired chain length. The procedure is called the malonic ester synthesis because the starting material for the synthesis is the diethyl ester of malonic acid. The first two carbons of the carboxylic acid come from malonic ester, and the rest of the carboxylic acid comes from the alkyl halide used in the second step of the reaction. 

Malonic ester synthesis Synthesis of 2,2-disubstituted carboxylic acids from diethyl propanedioate Imitlonic ester). 

Carboxylic from malonic esters s. 22, 84 ketones from -ketocarboxylic acid esters s. H. Hagiwara et al., Bull. Chem. Soc. Japan 48, 3723 (1975)... 

We have seen that when a carboxylic acid is synthesized by a malonic ester s5mthesis, the carbonyl carbon and the a-carbon come from malonic ester. Any substituent attached to the a-carbon comes from the alkyl halide used in the second step of the synthesis. If the a-carbon has two substituents, then two successive alkylations of the a-carbon will form the desired carboxylic acid. 

Loss of CO2 occurs readily only from the neutral carboxylic acid. If the ester is hydrolyzed with base, acid must be added to protonate the resulting carboxylate salt in order for decarboxylation to occur. Decarboxylation of substituted propanedioic (malonic) acids follows the same mechanism. 

Section 21 7 The malonic ester synthesis is related to the acetoacetic ester synthesis Alkyl halides (RX) are converted to carboxylic acids of the type RCH2COOH by reaction with the enolate ion derived from diethyl mal onate followed by saponification and decarboxylation... 

Strategy The malonic ester synthesis converts an alkyl halide into a carboxylic acid having two more carbons. Thus, a seven-carbon acid chain must be derived from the five-carbon alkyl halide 1-bromopentane. 

The alkylation of activated halogen compounds is one of several reactions of trialkylboranes developed by Brown (see also 15-16,15-25,18-31-18-40, etc.). These compounds are extremely versatile and can be used for the preparation of many types of compounds. In this reaction, for example, an alkene (through the BR3 prepared from it) can be coupled to a ketone, a nitrile, a carboxylic ester, or a sulfonyl derivative. Note that this is still another indirect way to alkylate a ketone (see 10-105) or a carboxylic acid (see 10-106), and provides an additional alternative to the malonic ester and acetoacetic ester syntheses (10-104). 

The synthesis of ethyl ester derivatives of imidazo[5,l-4][l,2,4]triazole-3-carboxylic acid 64 has been reported (Scheme 25) <1999CHE1349>. Starting from the known substituted 5-diazoimidazoles 276, their coupling with malonic acid derivatives afforded the azo compounds 277, which on treatment with triethylamine in DMF, upon prolonged heating time, gave products 64 in moderate yield. 

From the fact that malonic acid loses carbon dioxide on fusion and is converted into acetic acid, we conclude that a carbon atom has not the power of holding two carboxyl groups firmly. Now this also applies to all substituted malonic acids which can he readily obtained by hydrolysis from the esters. This constitutes a desirable simplification of the final product. 

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