LV.—Researches on the alkyl-substituted succinic acids. Part II. s-Dipropyl, s-diisopropyl, and αα1-propylisopropyl-succinic acids

William A. Bone, Charles H. G. Sprankling
1900 Journal of the Chemical Society Transactions  
OF the acids which form the subject of this communication, only s-diisopropylsuccinic has been previously investigated, and our knowledge of it even has not only been incomplete, but in certain respects very unsatisfactory. I n 1889, Hell andeMayer (Ber., 1889,22,48) obtained two crystalline dibasic acids of the formula Cl0Hl8O4, melting at 168-169' and 199-200' respectively, by hydrolysing the oil obtained by the action of molecular silver upon ethyl a-bromoisovalerate at a temperature of
more » ... temperature of 150'. Both acids were sparingly soluble in cold water, and formed characteristic insoluble calcium, barium, and strontium salts ; they could be separated by distillation with steam, for the acid of lower melting point formed a volatile anhydride, whereas the other was nonvolatile, and moreover, did not give a n anhydride when heated to a temperature of 2 1 0 O . Hell and Mayer suggested that the acids might be the two stereoisomeric s-diisopropylsuccinic acids, formed from ethyl a-bromoisovalerate, as follows : 2(CH,),CH* CHBr*CO,Et + 2Ag = (CH,),CH* YH---VH*CH(CH,), + 2AgBr. C0,Et C0,Et Considering, however, that the action of molecular silver upon such a-bromo-esters was known to be a somewhat complex one (compare V. Meyer and Auwers, Ber., 1889, 22, 3005 ; 1890, 2 3 , 295), and does not merely consist in the elimination of bromine and the coupling up of two residues, as indicated by the foregoing equation, they admitted the possibility of structural difference between the two acids, and even suggested that, whereas one of them was probably a s-diisopropylsuccinic acid, the other might be aaalal-tetramethyladipic acid, I n 1896, Auwers re-investigated the products of the same reaction (Annalern, 1896, 292, 162) , but was quite unable to isolate more than one acid of the formula CloH,80,. It melted a t 178--182O, a temperature, i t will be observed, intermediate between the melting points of the two acids obtained by Hell and Mayer ; it was sparingly soluble in water, yielded a very stable and volatile liquid anhydride, and an rtnilic acid melting a t 179-180'. He had no hesitation in pronouncing it to be a s-diisopropylsuccinic acid. As s-diisopropylsuccinic acid contains two asymmetric carbon atoms, and should, t h e d o r e , like other
doi:10.1039/ct9007700654 fatcat:x47xvpomkvcshm6l5tiggzolw4