Selective hydrogenation of benzene to cyclohexadiene and cyclohexene by lanthanide precipitates obtained from Eu or Yb metal solutions in liquid ammonia

Lanthanide precipitates obtained by decomposition of Eu or Yb metal solutio ns in Liquid ammonia were active at 393 K for the partial liquid-phase hydr ogenation of benzene to cyclohexene with high selectivity (greater than or equal to 90%). When the reaction temperature decreased to 323 K, cyclohexad ienes were preferentially formed. The reducing behavior was markedly enhanc ed by the addition of ammonia to the reaction system.