Patent ID: 7576235

Claim:
A process for preparing bis[urea-urethane] compounds of the formula wherein R 1 is an alkyl group, an aryl group, an arylalkyl group, or an alkylaryl group, R 2 is an alkylene group, an arylene group, an arylalkylene group, or an alkylarylene group, R 3 is an alkylene group, an arylene group, an arylalkylene group, or an alkylarylene group, and R 4 is a hydrogen atom or an alkyl group, said process comprising: (1) first bring to a reaction temperature of from about 20 to about 125° C. a reaction mixture comprising a monoalcohol reactant of the formula R 1 —OH, a diisocyanate reactant of the formula OCN—R 2 —NCO and a Lewis acid catalyst, said monoalcohol being present in an amount of from about 0.8 to about 1.2 moles of monoalcohol per every one mole of diisocyanate, said monoalcohol and said diisocyanate reactants being admixed in a solvent, said reactants and said solvent being present in relative amounts of about 1 milliliter or more of solvent per every 1 millimole of diisocyanate, said reaction temperature continuing until reaction between the monoalcohol and the diisocyanate is complete; and (2) subsequent to step (1), adding to the reaction mixture a diamine of the formula without isolating the reaction product of step (1), thereby forming a compound of the formula in desirably high yield and high purity.