Tetramethylsuccinic acid

SYNONYMS tetramethylbutanedinitrile, tetramethylsuccinic acid dinitrile, tetramethyl succinodinitrile, TMSN. 

Azobisisobutyronitrile. Azobisisobutyronitrile is now scarcely used and only to foeim PVC and PS. This limitation in its application comes from the high toxicity of the dinitrile of tetramethylsuccinic acid, a major product of its decomposition. 

This synthesis has one rather anomalous application, when a-bromo-isobutyric acid (or its ethyl ester) is heated with silver, some tetramethyl-succinic acid is produced in the ordinary way (B., 23, 297 26, 1458). But there also appears trimethylglutaric acid (A., 292, 220). To explain the unexpected formation of this acid, it has been assumed that a portion of the a-bromoisobutyric acid gives up HBr to form methylacrylic acid. This latter then forms j3-bromoisobutyric acid, and the silver withdraws bromine from the a- and /3 acids, whereby the residues unite to tri-methyl-glutaric acid (B., 22, 48, 60). A similar explanation applies to some other syntheses in which tetramethylsuccinic and trimethylglutaric acids appear together. 

Alkylation of disubstituted acetic esters has become an important new route to trisubstituted acetic acids and their derivatives. Sodium tri-phenylmethide or potassium triphenylmethide is used to convert the ester to its enolate ion, which, in turn, is allowed to react with an alkyl iodide to form the trialkylated ester. The yields are in the range of 42-61%. Potassium hydroxide in acetal solvents serves as basic reagent in the alkylation of certain esters by reactive halides. An interesting preparation of diethyl tetramethylsuccinate involves alkylation of ethyl isobutyrate with ethyl a-bromoisobutyrate. The yield is 30%. ... 

Hydrolysis by acid Acid hydrolysis is less often used for esters in laboratory practice. It is, however, useful for alkali-sensitive compounds and in cases, such as for tetramethylsuccinic esters,73 when alkaline hydrolysis is ineffective. To carry out the hydrolysis, the ester is boiled with aqueous mineral acid, but acetone, dioxan, or glacial acetic acid is added if the ester is insoluble in water. 

C8H12CI2O4, Dimethyl meso-j3,/3 -dichloroadipate, 40B, 7 C8H12O3, Tetramethylsuccinic anhydride (gas-ed), 42B, 1027 C8H12O4, a-Methylacrylic acid dimer (gas-ed), 23, 539 C8H13NO4, Dimethyl (dimethylaminomethylene)malonate, 39B, 9 C8H14O2, 2-Propyl-2-pentenoic acid, 43B, 11 C8H14O4, Suberic acid, 29, 470 30B, 6... 

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