Cyclized Rubber May Be Polycyclic
Chemical & Engineering News · 1963
Additional evidence points to a polycyclic ring structure for cyclized rubber. The evidence stems from new unsaturation measurements and agrees with kinetic principles, say Dr. W. F. Watson and Dr. J. Scanlan of the Rubber and Plastics Research Association of Great Britain, Shawbury, Shrewsbury, England, and D. F. Lee of the Natural Rubber Producers Research Association, Herts, England. Results which the British group obtained with different reagents for measuring unsaturation compare favorably with each other. These results point to cyclized rubber's double bond content being well below the limits imposed by a predominantly mono- or bicyclic structure. This can only be explained by assuming that cyclization goes beyond the bicyclic stage, the three British scientists say. In addition, the results discount the presence of isolated isoprene units—frequently referred to as "widow" units—along the chain. The structure of cyclized rubber has posed a problem to chemists for a long time. One of the first definitive ...