Morton A. Golub

Photo‐ and Radiation‐Induced cis—trans Isomerization of Several 2‐Olefins

Benzene photo‐ and radiation‐sensitized cis‐trans isomerization of 2‐pentene, 2‐hexene, 2‐heptene, and 2‐octene all yield the same photo‐ and radiostationary trans/cis ratio, viz., 1.0. The G value for benzene triplet formation is estimated at 5.0. G values for the radiation‐induced unsensitized isomerization of the above olefins are 2.50, 2.13, 1.85, and 1.67, respectively.

Tetracyclosqualene and its bearing on the structure of cyclized rubber

Abstract Recently we reported that cyclized rubber consists of six-membered rings fused into predominantly bicyclic structures which are connected by methylene groups and/or uncyclized isoprene units. Each of the fused ring structures is presumed to contain a single tetra-, tri- or di-substituted double bond, the relative amounts of which are in the order, tetra- > tri- > di-substituted. The predominantly bicyclic structure was not rigorously established, but it was considered reasonable on the basis of a comparison of the nmr spectra of cyclized cis-polyisoprene and cyclized cis-poly (2-methyl-d3-1,3-butadiene-1,1-d2). However, although a predominantly monocyclic structure was clearly excluded, it was not possible to rule out a structure in which the average number of rings per fused segment (“cyclicity”) exceeds two and may even be as high as three. In an effort to determine this cyclicity more accurately, we now compare the nmr and ir spectra of cyclized cis- and trans-polyisoprenes with the correspond...