| abstract |
A process for at least partially blocking the isocyanate groups of an organic polyisocyanate with 3,5-dimethylpyrazole, in which in a first reaction step an equimolar reaction mixture of acetylacetone and hydrazine hydrate in a water-immiscible solvent with cleavage and elimination of the introduced and the formed water of a condensation reaction and in a second reaction step, the organic phase obtained in this way is reacted with the polyisocyanate, which is optionally dissolved in a solvent, with at least partial blocking of its isocyanate groups, with the 3,5-dimethylpyrazole prepared in situ, without further working up. |