Method of producing N,N'-(dimethyl) piperazine compounds

An improved process for producing an N,N'-(dimethyl) piperazine compound of the formula:

• ##STR5## wherein each R is, independently, hydrogen or a C.sub.1-4 lower alkyl radical comprising the step of:
• contacting a monoethanol amine having the formula:
• ##STR6## wherein each R, independently, is hydrogen or a C.sub.1-4 lower alkyl radical with methyl alcohol in the presence of a catalytically effective amount of a phosphorus-containing substance selected from the group consisting of acidic metal phosphates, orthophosphoric acid, metaphosphoric acid, polyphosphoric acid, orthophosphorous acid, alkyl or aryl phosphate esters, alkyl or aryl phosphite esters, alkyl or aryl substituted phosphorus and phosphoric acids wherein said alkyl groups have from 1 to 8 carbon atoms and said aryl groups have from 6 to 20 carbon atoms, alkali metal monosalts of phosphoric acid and mixtures of the above at a temperature of from 150.degree. C to about 350.degree. C. under pressure sufficient to maintain the mixture essentially in liquid phase;
• and
• recovering from the resultant reaction mixture said N,N'-(dimethyl) piperazine compound.