The Decomposition of Triphenylacetic Acid by Sulphuric Acid

Abstract

Triphenylacetic acid was observed by Bistrzycki and Reintke* 1 to decompose quantitatively into carbon monoxide and triphenyl-carbinol when dissolved in concentrated sulphuric acid. The sulphuric acid after the decomposition was orange-yellow in color, due to the triphenylcarbinol which remained dissolved and which was precipitated as a white solid upon diluting the acid with water. The reaction can be represented by the following equation:A study of this reaction was undertaken in order to compare this decomposition with others involving the action of sulphuric acid which had been investigated and explained by considering the sulphuric acid as a dehydrating agent only. Bredig and Lichty2•3 quantitatively studied the decomposition of oxalic acid by sulphuric acid, and concluded that the reaction was essentially one of dehydration. Schierz4, after investigating the action of sulphuric acid on formic acid, reached the same conclusion in regard to the mechanism of the reaction. The action of sulphuric acid on malic acid was studied by Whitford5 who concluded from his observations that the sulphuric acid did not function by merely extracting water from the malic acid and suggested a more complex reaction mechanism based upon the formation of a hypothetical intermediate compound between the two reactants.The decomposition of triphenylacetic acid by sulphuric acid although similar to the decomposition of oxalic, malic, and formic acids, could not possibly be connected with the dehydrating property of sulphuric acid because water is not a product of the reaction. A study of this reaction was undertaken with the object of discovering the mechanism of the decomposition, and from a comparison with the action of sulphuric acid on oxalic, formic, and malic acids, to show whether these latter reactions were dependent upon the dehydrating property of sulphuric acid or whether the sulphuric acid functioned in a different capacity. * This communication is an. abstract of the thesis submitted to the Graduate School of the University of Wisconsin by Harry R. Dittmar in partial fulfillment of the requirements for the degree of Doctor of Philosophy. This investigation was conducted under the supervision of Professor J. H. Walton.

Application Of The H0 Acidity Function To Kinetics And Mechanisms Of Acid Catalysis

“…The mechanisms of these acid-catalyzed decompositions in concentrated sulfuric acid have not been established, but an A-l type seems highly plausible (115b). Elliot and Hammick (86) point out that the mechanism for the decarboxylation of triphenylacetic acid (77,78) may be different from that for the others both because of the nonintegral slope of 2.6 in the log fci vs. -H0 relationship and because it is the only acid showing a slope much greater than unity which does not have a number of base centers equal to the presumed number of protons added. This reaction has also been considered by Deno and Taft (74), who note that log fci closely parallels the Jo acidity function rather than H0.…”

Kinetics in Acid Media

“…Schierz (51) studied the effects of various nitrogen compounds on the decomposition of formic acid, and in 1938 two Russians (47) noted the inhibitory effects of sulfur dioxide, hydrogen sulfide, phosphorus pentoxide, and arsenic pentoxide. Work on the decomposition of malic acid (15,16,68) showed the effects of fourteen inhibitors. 1 Present address, Colgate-Palmolive-Peet Company, Jersey City, N.…”