Application of Green Chemistry for the One-pot Preparation of Tris (4-bromophenyl) Chlorosilane

Among the twelve principles of green chemistry are the avoidance of waste, the use of benign chemicals, and the incorporation of the starting materials into the final product. To this end, a one-pot facile, more benign, less expensive and higher yield method has been used for the preparation of tris(4-bromophenyl)chlorosilane, which is a highly used precursor for the making of a rigid core carbosilane dendrimers. The reaction pathway for the synthesis of tris(4bromophenyl)chlorosilane is similar to the procedure followed for synthesising similar compounds in the literature but with differences in starting materials and modifications in the workup processes. The tris(4-bromophenyl)chlorosilane in this work was prepared by the dissolution of 1,4-dibromobenzene in dry ether at -76 °C, followed by the slow addition/stirring of n-BuLi. After 1 h of stirring, tetrachlorosilane was slowly added at temperature range of -70 to -75 °C. The reaction setup was allowed to stir further to room temperature for 24 h. The reaction was stopped, followed by a workup to obtain a colourless powder product with an 82% yield. The colourless powder was characterised by melting point (123.4 °C) and elemental analysis (Anal. Calc for C18H12ClBr3Si: C, 40.67; H, 2.28; found: C, 40.80; H, 2.26; as well as H NMR: δ (CDCl3 400 MHz) 7.44 (d, J = 8.4 Hz, 6H, Ar-H), 7.58 (d, J = 8.4 Hz, 6H, Ar-H); C{H}, NMR: δ (CDCl3, 101 MHz) 126.46, 130.66, 131.61, 136.53 ppm; Si{H}, NMR: δ (CDCl3, 79.5 MHz) 1.47 ppm. The results obtained from this one-pot synthetic method are in agreement with that reported in the literature for the multi-step pathway and more expensive starting materials.