1,3-Bis(dichloromethyl)-1,1,3,3-tetramethyldisiloxane 2943-70-6 Bis(dichloromethyl)tetramethyldisiloxane Disiloxane, 1,3-bis(dichloromethyl)-1,1,3,3-tetramethyl- EINECS 220-939-1 NSC 139826