Cyclic silylureas and process of preparation

A cyclosilazane having the formula:

• ##STR14## wherein R is an alkyl group having 1 to 3 carbon atoms;
• R.sup.1 is selected from the group consisting of
• (i) hydrogen
• (ii) a linear or branched alkyl group having 1 to 6 carbon atoms, and
• (iii) an aryl group having 6 to 8 carbon atoms;
• and
• a is 0, 1, or 2.

A process for making a cyclosilazane having the formula:

• ##STR15## wherein R is an alkyl group having 1 to 3 carbon atoms;
• R.sup.1 is selected from the group consisting of
• (i) hydrogen;
• (ii) a linear or branched alkyl group having 1 to 6 carbon atoms;
• (iii) an aryl group having 6 to 8 carbon atoms;
• and
• a is is 0, 1, or 2;
• and
• which process comprises heating an aminoalkylalkoxysilane having the formula:
• H.sub.2 NCH.sub.2 C(R.sup.1).sub.2 CH.sub.2 CH.sub.2 SiR.sub.a (OR).sub.3-a
• wherein R, R.sup.1, and a are as defined above in the presence of a basic catalyst at subatmospheric pressure and at a temperature less than 100.degree. C.

A process for making an aminoalkylalkoxysilane having the formula:

• H.sub.2 NCH.sub.2 C(R.sup.1).sub.2 CH.sub.2 CH.sub.2 SiR.sub.a (OR).sub.3-a
• wherein
• R is an alkyl group having 1 to 3 carbon atoms;
• R.sup.1 is selected from the group consisting of
• (i) hydrogen;
• (ii) a linear or branched alkyl group having 1 to 6 carbon atoms;
• (iii) an aryl group having 6 to 8 carbon atoms;
• and
• a is 0, 1, or 2;
• and
• which process comprises:
• (1) reacting a nitrile having the formula:
• (R.sup.1).sub.2 HC-CN
• wherein R.sup.1 is as defined above with a vinyl silane having the formula:
• H.sub.2 C=CHSiR.sub.a (OR).sub.3-a, wherein a and R are as defined above while heating in the presence of a base selected from the group consisting of
• (i) an alkali metal,
• (ii) an alkali metal alkoxide,
• (iii) an alkali metal amide;
• and
• (iv) an alkali metal hydride;
• to form a nitrile-substituted alkylalkoxysilane reaction product having the formula:
• NCC(R.sup.1).sub.2 CH.sub.2 CH.sub.2 SiR.sub.a (OR).sub.3-a ;
• and
• (2) hydrogenating said reaction product.