Wacker-chemie Gmbh

Hartmut Menzel

Herbert Eck

Reinhard Jira

Alfred Prasse

Tassilo Lindner

Manfred Riederer

Rudolf Reitmeier

Martin Piehler

Hermann Braunling

Process for preparing alkylsilanes having bulky alkyl radicals

Organosilicon compounds containing SiC-bonded biuret groups are prepared by (I) adding a silane containing 1 or 2 silicon atoms per molecule and an SiC-bonded organic radical having at least one basic ##STR1## group and at least one SiOC-bonded aliphatic radical per molecule to a monoisocyanate or a diisocycanate at a temperature up to 125.degree. C. and (II) maintaining the temperature at 110.degree. C. to 125.degree. C. for at least two minutes. In an alternate procedure the silane and mono- or diisocyanate may be heated to a temperature in the range of from 110.degree. C. up to 200.degree. C. for at least two minutes, after or while adding additional monoisocyanate or diisocyanate. The resultant silicon compounds are used in the preparation of polyurethanes and as additives to lacquers.

Silicon compounds containing SiC-bonded biuret groups and a method for

Diorganopolysiloxanes may be polymerized to increase their molecular weight by heating the siloxane in the presence of a quaternary phosphonium hydroxide, in which one of the substituents on the phosphorus atom of the phosphonium cation is a monovalent radical containing carbon, hydrogen and silicon atom(s) and possibly siloxane oxygen atoms(s) and the three remaining substituents on the phosphorus atom are the same or different hydrocarbon radicals that are free of aliphatic carbon-carbon multiple bonds.

Method for increasing the molecular weight of diorganopolysiloxanes

Organosilicon compounds containing SiC-bonded biuret groups are prepared by (I) adding a silane containing 1 or 2 silicon atoms per molecule and an SiC-bonded organic radical having at least one basic ##STR1## group and at least one SiOC-bonded aliphatic radical per molecule to a monoisocyanate or a diisocyanate at a temperature up to 125.degree. C. and (II) maintaining the temperature at 110.degree. C. to 125.degree. C. for at least two minutes. In an alternate procedure the silane and mono- or diisocyanate may be heated to a temperature in the range of from 110.degree. C. up to 200.degree. C. for at least two minutes, after or while adding additional monoisocyanate or diisocyanate. The resultant silicon compounds are used in the preparation of polyurethanes and as additives to lacquers.

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Burghausen, Germany

Hartmut Menzel