Production of isocyanate functional organosilanes
AssigneeWacker Chemie AG
InventorsVolker STANJEK, Lars ZANDER
Life of this patent
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Abstract
Isocyanate-functional silanes are prepared in high yield by pyrolysis of an O-carbamate prepared by reaction of a dialkylcarbonate with an aminoalkyl-functional silane in the presence of a basic catalyst, where the catalyst is neutralized by an acid which has a pKa of all protolysis stages of not more than 4. The neutralized or partially neutralized catalyst need not be removed prior to pyrolysis. The isocyanato-functional silanes exhibit higher storage stability as compared to those prepared from O-carbamates where catalyst neutralization is effected by weak acids.
Claims13
-9. (canceled)
A process for preparing isocyanatoorganosilanes of the formula (4)
- OCN—R2—SiR(3−x)(OR4)x (4),
- from carbamatoorganosilanes of the formula (5)
- wherein carbamatoorganosilanes which have been prepared by reaction of at least one aminoorganosilane of the formula (6),
- NH2—R2—SiR3(3−x)(OR4)x (6),
- with at least one dialkyl carbonate of the formula (7),
- in the presence of a basic catalyst having basic functions which is a metal alkoxide, comprising:
- completely or partially neutralizing the basic catalyst with an acid, all of whose protolysis stages have pKa values of not more than 4.0 before preparation of the isocyanatoorganosilanes,
- where
- R1, R3, R4 and R5 are identical or different and are each a monovalent, unsubstituted or substituted hydrocarbon radical,
- R2 is a divalent, unsubstituted or substituted hydrocarbon radical and
- x is 1, 2 or 3.
Dependencies are inferred from the claim text.