Semi-continuous process for preparing bis-silyl carboxamides

Semi-continuous process for preparing bis-silyl carboxamides of formula (I):

• 5
• in which R represents a linear or branched alkyl radical containing a number of carbon atoms ranging from 1 to 4;
• —CH═CH2, —C(CH3)═CH2, —CH2F, —CHF2, —CF3 by reacting an amide RCONH2 (2) or the N-monotrimethylsilyl derivative thereof RCONHSi(CH3)3 (3) with a silylating agent R1Si(CH3)3 (4) according to the reactions:
• 6
• in which R1 is chosen from pyrazolyl, imidazolyl, 1,2,4-triazolyl, pyrrolidinyl, morpholinyl and benzotriazolyl radicals, optionally substituted with one or more linear or branched alkyl residues containing a number of carbon atoms ranging from 1 to 4;
• characterized in that the following are simultaneously carried out:
• firstly, the introduction of the amide (2) or the N-trimethylsilyl derivative thereof RCONHSi (CH3)3 (3), or alternatively the amide (2) or the N-trimethylsilyl derivative thereof and some of the silylating agent R1Si(CH3)3 (4) as a mixture or separately into a reactor containing a stirred distillation residue, consisting of all or some of the silylating agent R1Si(CH3)3 (4) brought to a temperature ranging from 130° C. to 190° C. and preferably between 150° C. and 183° C.,
• secondly, the extraction of the bis-silyl carboxamide (1) gradually as it is formed by distillation at a pressure below atmospheric pressure and preferably at a pressure of between 1×103 Pa and 2×104 Pa.