Method for the synthesis of isocyanates

A method for the preparation of isocyanates, wherein

• (i) a first organosilicon compound having at least one silicon atom Si1 and a unit of formula G-I bound thereto
• is converted to a third organosilicon compound having a unit of formula G-II
• by silylation of the NH group of the unit of formula G-I with a second organosilicon compound having one silicon atom Si2;
• and
• (ii) the third organosilicon compound is reacted to an isocyanate by thermolysis, whereby the unit of formula G-II is converted to an isocyanate group.

A method for the preparation of an isocyanate compound of general formula I

• A3—N═C═O (formula I),
• wherein
• A3 is R1 or a group of formula G-V:
• R1 and Z have the meanings given in connection with the compound of general formula II,
• said method comprising silylating a compound of general formula II
• wherein
• A1 is R1 or a group of general formula G-III:
• R1 is a substituted or unsubstituted, aliphatic or aromatic group;
• R2 at each occurrence each independently is selected from the group consisting of hydrogen, a substituted or unsubstituted alkyl group with 1 to 12 carbon atoms and a substituted or unsubstituted aryl group, with the proviso that at least one residue R2 which is not hydrogen is bound to each silicon atom Si1;
• Z is a substituted or unsubstituted, aliphatic or aromatic group.