Abstract: A process for epoxidizing olefins with hydrogen peroxide in the presence of a catalyst composition comprising a Group V element containing Co-catalyst I, such as diphenylarsinic acid, and a phenol containing compound having a pK.sub.a of from about 5 to about 13 as Co-catalyst II such as p-chlorophenol is disclosed.

Abstract: A process for making alkylene carbonate by the reaction of carbon dioxide and an alkylene oxide of the formula ##STR1## wherein R, R.sub.1, R.sub.2 and R.sub.3 are one or more of hydrogen, alkyl, aryl, alkaryl, aralkyl, cycloalkyl, allyloxy, chloroalkyl, and aryloxy to produce the corresponding carbonate, which comprises:(a) providing a homogeneous liquid phase reaction zone in which the predominant material therein is the alkylene carbonate;(b) providing a catalytic amount of an alkylene oxide carbonation catalyst to said liquid phase;(c) having dissolved in said liquid phase sufficient CO.sub.2 to provide a molal amount therein which exceeds the molal amount of the catalyst;(d) providing a CO.sub.2 pressure in the reaction zone of between about 150 psig and about 750 psig;(e) maintaining a sufficient amount of the alkylene oxide in the reaction to maintain the pressure and temperature thereof;(f) maintaining the reaction zone at a temperature at which the alkylene oxide and CO.sub.