Butane tetra carboxylic acids

Yakubchik and his co-workers (1956, 1959 and 1962) have preferred to separate the acid derivatives by means of partition chromatography and compared the results with those obtained from an artificial mixture of those acids expected to be present. In the case of Ziegler-Natta catalyzed polybutadienes with less than 1% 1,2- units the presence of 1,4-1,2-1,4 sequences was indicated by the identification of some 1,2,4-butane tricarboxylic acid. Examination of their chromatograms suggests, at most, just a trace of any hexane tetra-carboxylic acid so that only a very small amount, if any, of 1,4-1,2-1,2-1,4 structures were present. Furthermore, no trace of any 1,2,3-propane tricarboxylic acid was found so there was no positive sign of any branching at the a-methylene position. On the other hand in the case of rubidium-catalyzed poly butadienes, which, like other polybutadienes prepared by the use of alkali metal catalyst systems, have a high 1,2- content, both hexane tetracarboxylic acid and 1,2,3-propane tricarboxylic acid were present in the ultimate products of ozonolysis. 

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