ChemInform Abstract: UNTERSUCHUNG DER RK. VON P‐DIBROMDIMAGNESIUMBENZOL MIT FLUORALKYL(ARYL)CHLORSILANEN

Abstract

p‐Dibromdimagnesiumbenzol (III) wird in ca. 90% Ausbeute aus Magnesium und p‐Dibrombenzol (Molverhältnis: 6:1) in Tetrahydrofuran erhalten.

Grignard condensation routes to 1,3‐disilacyclobutane‐containing cyclolinear polycarbosilanes

“…There have been several reports of the preparation of poly(silylene‐ p ‐phenylene)s by polycondensation between di‐magnesium derivatives of p ‐dibromobenzene and dichloro‐organosilanes . However, considerable difficulties have been encountered in achieving a good yield and high purity of the polymers.…”

“…The low polycondensation efficiency has been explained by the incomplete formation of the Grignard reagent and the limited solubility of this polymer with increasing chain length. Odabashyan discovered that the yield of 1,4‐bis(bromomagnesio)benzene can reach 97% at room temperature by using a three times excess of magnesium powder, even without the addition of an alkali metal such as potassium, which can cause side reactions such as Wurtz coupling . The polymer, poly[ cyclo‐ (1,3‐dimethyl‐1,3‐disilacyclobutane)−1,4‐phenylene], 3(6) obtained from polycondensation of the di‐Grignard reagent and the dichloro‐DSCB has a number average molecular weight of 3100 and a DP of 16, as determined by GPC.…”