Asymmetrically substd. urea(s) prodn. - by passing prim. or sec. amine into hot gaseous mixt. of isocyanic acid and ammonia and cooling reaction mixt. to condense prod.

摘要

Asymmetrically substd. ureas (I) are prepd. by introducing a prim. or sec. amine into a gaseous mixt. of isocyanic acid and ammonia at 250-600 deg.C and cooling the reaction mixt. by which the (I) condenses out. Pref the amine is introduced at a temp. of 320-380 deg.C and 1-7 equivs. esp. 1.1-3 equivs. prim. or sec. amine is introduced per mol. isocyanic acid. Pref. the reaction mixt. is cooled in an inert diluent such as water or an organic solvent such as a low aliphatic alcohol. USE/ADVANTAGE - Allows prodn. of (I) from isocyanic acid/ammonia mixts. pbtd. by thermal decomposition of urea e.g. as described in EP-124704, without first isolating the isocyanic acid. The prim. or sec. amine reacts with the isocyanic acid despite the presence of the ammonia to yield the assymetrically substd. urea prod. which is then condensed out and is thus sepd. from the ammonia.