Catalytic chlorination of methylphenyldichlorosilane with gaseous chlorine to chlorinated methylphenyldichlorosilanes over Lewis acids

Methylchlorophenyldichlorosilane (MeClPhSiCl2) and methyldichlorophenyldichlorosilane (MeCl2PhSiCl2) were synthesized by the catalytic chlorination of methylphenyldichlorosilane (MePhSiCl2) with Cl2 over Lewis acid catalysts. The catalytic activities of Lewis acid catalysts were in an order of FeCl3 > SbCl5 > AlCl3 > SnCl4. However, FeCl3 also highly catalyzed the cleavage of chlorophenyl–silicon bond to form chlorobenzene. At a low mole ratio of SbCl5 to MePhSiCl2 of 1.4 × 10−5:0.45, the yield of MeClPhSiCl2 was around 60% after reacting at 25–100 °C for 15–20 h. At a high mole ratio of 1.4 × 10−4:0.45, the yield of MeCl2PhSiCl2 reached 44% after reacting at 80–100 °C for 20 h.