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

• MeClPhSiCl2 was mainly formed by chlorination of MePhSiCl2 with Cl2 on Lewis acids.
• High catalyst loading favored further chlorination of MeClPhSiCl2 to MeCl2PhSiCl2.
• Lewis acid catalysts suppressed chlorination of MePhSiCl2 with Cl2 to ClMePhSiCl2.
• Catalytic activities of Lewis acids were in an order of FeCl3 > SbCl5 > AlCl3 > SnCl4.
• FeCl3 caused rapid cleavage of chlorophenyl–silicon bond to form chlorobenzene.

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.

Methylchlorophenyldichlorosilane and methyldichlorophenyldichlorosilane were synthesized by catalytic chlorination of methylphenyldichlorosilane with gaseous chlorine over Lewis acid catalysts. Among the Lewis acid catalysts, antimony (V) chloride showed high catalytic activity in the chlorination reaction toward the formation of methylchlorophenyldichlorosilane and methyldichlorophenyldichlorosilane which containing one or two chlorine atoms directly attached to the phenyl radical.Figure optionsDownload as PowerPoint slide