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The kinetics of the base-catalysed solvolyses of ethylene oxide in a series of alcohols have been studied and comparisons made between reactions catalysed by sodium alkoxides and reactions catalysed by tertiary amines. In the former case the reactions take place in a single step and the effects of substituent groups on reactivity tend to cancel, so that in the temperature range 60-70" the rates in nine alcohol-alkoxide combinations are all very si m i I a r.The amine-catalysed reactions take place in several stages, the active catalyst in the case of triethylamine a t temperatures below 50" being triethyl-2-hydroxyethylammonium alkoxide. formed by an initial relatively slow reaction between triethylamine and ethylene oxide and subsequent rapid equilibration of the resulting zwitterion with solvent. With a series of nuclear-substituted NN-dimethylanilines nucleophilic catalysis was also demonstrated and a t higher temperatures this probably constitutes the major reaction route for reactions catalysed by tertiary amines. General base catalysis by tertiary amines was shown to be negligible in all the solvents studied. THE solvolysis2 of ethylene oxide in an alcohol ROH in the presence of the alkoxide ion ROmay be thought of as a special case of the base-catalysed polymerisation of ethylene oxide (equation l ) , 3 in which the composition of the reaction medium remains constant and in which only the first addition step (n = 1) takes place. A similar mechanism has been suggested for the curing /*\ CH,-CH, + RIO(CH,*CH,*O)-, -R1O (CH,*CH,*O) -n (1)

of the Reactions of oand p-Halogenonitrobenzenes with Piperidine and with Morpholine.