Affinities of Poly basic Acids. ig 



On the Affinities of Polybasic Acids. By Bevan Lean, 

 D.Sc, B.A., Assistant Lecturer, and late Bishop 

 Berkeley Fellow of Owens College. Communicated 

 by W. H. Perkin,jun., F.R.S. 



Received October jotk, 1894.. 



Introduction. 



The author has described elsewhere 1 some tetracar- 

 boxylic acids which possess some very remarkable pro- 

 perties. They are derivatives of butane, of the general 

 formula 



HOOC COOH 



^> CR - CH 2 - CH 2 - CR <T 

 HOOC COOH 



in which R represents the alkyl group methyl, ethyl, cetyl 

 or benzyl, and, although they contain four carboxyl groups, 

 these acids do not in all cases behave as tetrabasic acids. 



On determining their basicity by titration with standard 

 solution of potassium hydrate, some of these acids show di- 

 basicity : notably is this the case with dibenzylbutanetetra- 

 carboxylic acid, the result being the same whether phenol 

 phthalei'n or litmus solution is used as the indicator. On 

 the other hand, dimethyl-, diethyl-, and dicetyl- butane- 

 tetracarboxylic acids, on being titrated with potassium 

 hydrate, give different results, according as phenol phthalei'n 

 or litmus is employed as an indicator. They behave as 

 tetrabasic acids when phenol phthalei'n is employed. If, 

 however, one or two drops of litmus solution be added to 



1 " On Ethyl Butanetetracarboxylate and its Derivatives," a Thesis accepted 

 for the degree of Doctor of Science of the University of London. 



B 



