Dialkylmalonic esters

Where R and R are identical, the dialkylmalonic ester may be prepared in one operation by treating 1 mol of ethyl malonate with 2 mots each of sodium ethoxide and the alkyl halide (usually bromide or iodide). 

The results summarised in Table 4 show clearly that good yields of the 1 1 Michael adducts can be obtained in cathodically initiated reactions. It is not clear, however, why the reaction should fail for acrylonitrile even if dimerisation of the initially formed radical-anion is much faster thaq,protonation the resulting dimeric dianion should still be sufficiently basic to deprotonate dialkylmalonate esters. A feature of especial significance is the usefulness of esters of ethenetetracarboxylic acid. Apart from their use in EGB catalysed reactions they have been much used in stoichiometric amount. 

Certain dialkylmalonates may be partially saponified to the acid esters, which decarboxylate to esters upon heating, Decarbethoxylation of dialkylmalonic esters may also be effected by heating at 220-230° with sodium ethoxide,... 

The alkylmalonic ester still contains one ionizable hydrogen, and on treatment with sodium ethoxide it, too, can be converted into its salt this salt can react with an alkyl halide—which may be iKe same as, or different from, the first alkyl halide— to yield a dialkylmalonic ester ... 

The acidity of malonic ester thus permits the preparation of substituted malonic esters containing one or two alkyl groups. How can these substituted malonic esters be used to make carboxylic acids When heated above its melting point, malonic acid readily loses carbon dioxide to form acetic acid in a similar way substituted malonic acids readily lose carbon dioxide to form substituted acetic acids. The monoalkyl- and dialkylmalonic esters we have prepared are readily converted into monocarboxylic acids by hydrolysis, acidification, and heat ... 

Step 3 The mono- or dialkylmalonic ester can then be hydrolyzed to a mono- or dialkylmalonic acid, and substituted malonic acids decarboxylate readily. Decarboxylation gives a mono- or disubstituted acetic acid ... 

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