Polymerization of conjugated diolefins with a lithium based catalyst and a hydrocarbon chain terminator

Claim 1

IN THE PROCESS OF PRODUCING AN ELASTOMER BY POLYMERIZATION OF ALIPHATIC HYDROCARBON MONOMERS OF THE CLASS CONSISTING OF CONJUGATED DIENES CONTAINING 4 TO 12 CARBON ATOMS AND MIXTURES OF SUCH CONJUGATED DIENES WITH OLEFINS, IN AN INERT SOLVENT IN A MONOMER-TO-SOLVENT RATIO RATIO OF 2 TO 100 PARTS BY WEIGHT OF MONOMER TO 98 TO 0 PARTS OF SOLVENT, WITH CATALYST OF THE CLASS CONSISTING OF LITHIUM AND ORGANOLITHIUM CATALYST AT A TEMPERATURE BETWEEN SUBSTANTIALLY -10*C. UP TO THE BOILING POINT OF THE CONSTITUENTS OF THE REACTION UNDER THE CONDITIONS EMPLOYED, THE IMPROVEMENT WHICH CONSISTS OF CARRYING OUT THE POLYMERIZATION IN THE PRESENCE OF A HYDROCARBON CHAIN TERMINATOR WHICH POSSESSES AT LEAST AS MUCH METALATION-REACTION ACTIVITY AS DIPHENYLMETHANE AND IS LESS REACTIVE THAN ACETYLENE AND THEREBY OBTAINING AN ELASTOMER WITH A HIGHER CIS-1,4 POLYMER CONTENT AND A LOWER MOLECULAR WEIGHT THAN OBTAINED UNDER IDENTICAL POLYMERIZATION CONDITIONS IN THE ABSENCE OF THE CHAIN TERMINATOR.