Purification of d,d'-2,2'(ethylenediimino)di-1-butanol dihydrochloride

Claim 1

In a process for preparing d,d'-2,2'-(ethylenediimino)di-1-butanol dihydrochloride comprising the steps of reacting excess d-2-amino-1-butanol with ethylene dichloride, adding to the reaction mixture thus formed sufficient finely divided sodium hydroxide to neutralize hydrogen chloride formed therein, distilling off unreacted d-2-amino-1-butanol, adding sufficient of a 2 to 4 carbon alkanol to the residue to dissolve the thus formed d,d'-2,2'-(ethylenediimino)di-1-butanol, separating sodium chloride therefrom, adding hydrogen chloride to the resulting solution to form d,d'-2,2'-(ethylenediimino)di-1-butanol dihydrochloride, and separating the same from said alkanol, the improvement which comprises: reacting a 2 carbon alkanol solution of d,d'-2,2'-(ethylenediimino)di-1-butanol with an essentially stoichiometric amount of hydrogen chloride at 40°-60°C. in the presence of about 7% to 10% by weight water, based on the total weight of the reaction mixture to form d,d'-2,2'-(ethylenediimino)di-1-butanol dihydrochloride, slowly cooling the resulting aqueous alkanol solution to 0 to -10°C. to precipitate said dihydrochloride, separating said dihydrochloride from said aqueous alkanol solution, washing said dihydrochloride with a 2 to 4 carbon alkanol, and drying the same.