Under mild conditions (348 K), carbon dioxide (PCO2 = 0.1 MPa) catalytically promotes the carbamation of the following industrially relevant aminofunctional silanes: H2N(CH2)3Si (OMe)3, H2N(CH2)3Si(OEt)3 and H2N(CH2)2NH (CH2)3Si(OMe)3. These, upon reaction with dimethylcarbonate, are selectively converted into the methyl carbamate esters MeO(O) CNH(CH2)3Si(OMe)3, MeO(O)CNH(CH2)3Si (OEt)3 and MeO(O)CNH(CH2)2NH(CH2)3Si (OMe)3 respectively. Carbamate MeO(O)CNH (CH2)3Si(OEt)3 is accompanied by MeO(O)CNH (CH2)3Si(OMe)x(OEt)3 ÿ x formed via transesterification of the triethoxysilyl group by the co-produced methanol. The carbamation process is very selective and N-methylated species are formed in trace amounts. Conversely, the ureidofunctional silane H2NC(O)NH (CH2)2NH(CH2)3Si(OMe)3 shows a poor reactivity towards carbamation, and, under the above conditions, N-methyl derivatives are preferably formed.
CO2-catalysed carbamation of aminofunctional silanes
DIBENEDETTO, Angela;QUARANTA, Eugenio;TOMMASI I.;
2000-01-01
Abstract
Under mild conditions (348 K), carbon dioxide (PCO2 = 0.1 MPa) catalytically promotes the carbamation of the following industrially relevant aminofunctional silanes: H2N(CH2)3Si (OMe)3, H2N(CH2)3Si(OEt)3 and H2N(CH2)2NH (CH2)3Si(OMe)3. These, upon reaction with dimethylcarbonate, are selectively converted into the methyl carbamate esters MeO(O) CNH(CH2)3Si(OMe)3, MeO(O)CNH(CH2)3Si (OEt)3 and MeO(O)CNH(CH2)2NH(CH2)3Si (OMe)3 respectively. Carbamate MeO(O)CNH (CH2)3Si(OEt)3 is accompanied by MeO(O)CNH (CH2)3Si(OMe)x(OEt)3 ÿ x formed via transesterification of the triethoxysilyl group by the co-produced methanol. The carbamation process is very selective and N-methylated species are formed in trace amounts. Conversely, the ureidofunctional silane H2NC(O)NH (CH2)2NH(CH2)3Si(OMe)3 shows a poor reactivity towards carbamation, and, under the above conditions, N-methyl derivatives are preferably formed.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
