J O U R N A L OF T H E AMERICAN CHEMICAL SOCIETY JUNE 5 , 1936
VOLUME58
[CONTRIBUTION FROM THE CHEMICAL
NUMBER 6
LABORATORY OF THE
UNIVERSITY O F ILLINOIS]
Rearrangement of Polyynes. IX.’ Dimers of Tri-t-butylethynylmethyl Halides BY WILLIAM J. SPARKSAND C. S. MARVEL In an early attempt to prepare hexaacetylenic it decomposes with the evolution of hydrogen ethanes, Gray and Marvel2 treated tri-t-butyl- bromide and the formation of tar. When small ethynylcarbinol (I) with phosphorus trichloride amounts of the chloride are melted, a further and obtained a halogen compound which, although rearrangement occurs, giving a new dimeric having the expected composition, did not show chloride in which both chlorine atoms are inert reactions which would be given by tri-t-butyl- toward molecular silver. In seeking an explanation for the ready diethynylmethyl chloride (11). Later Salzberg and merization of the tri-t-butylethynylmethylhalides [(CHs),CCsC]sC-OH [(cHs)scc~c]ac-cI I I1 (I1and 111)it occurred to us that a rearrangement [(CHs)aCC=C IaC-Br of the acetylenic halide to an allenic halide (IV) I11
Marvela were able to prepare the bromide (111) and show that it had the structure indicated. They observed that this bromide readily rearranged to a higher melting compound of the same composition, but they did not report further on the properties of this rearrangement product. In the present investigation it has been found that the chloride of Gray and Marvel and the higher melting bromide of Salzberg and Marvel are produced by the rearrangement and dimerization of the simple halides (I1 and 111). Each dimer contains one halogen atom which reacts with molecular silver and one halogen atom which does not react with this reagent. The product of the reaction of the dimeric halide and silver is a molecule of four times the original molecular weight minus the weight of the two halogen atoms removed by the action of silver. When the dimeric bromide is heated to its melting point,
(CH3)aCkC-C
< c1 I
[C=C-C(CHs)a]2
(CHa)C-C=C=C
I
