The following were charged to a 1 L roundbottom flask equipped with stirrer, thermometer, and addition funnel and heated to 70° C: 375 g (3.15 mol) alpha-methylstyrene and 0.6 mL 1% isopropanolic chloroplatinic acid solution. 285 g (3.0 mol) dimethylchlorosilane was then dripped in from the addition funnel over 1 hour. The reaction was subsequently maintained at 80° C. for 1 hour and cooled. 424 g (2 mol) of the 2-methylphenethyldimethylchlorosilane product was dripped into a mixture of 300 g water and 100 g isopropyl alcohol. The resulting reaction mixture was washed with water 3 times, the water (lower) layer was removed, and the reaction mixture (upper layer) was heated in vacuo to give 350 g (95% of the theoretical yield) 1,3-di(2-methylphenethyl)tetramethyldisiloxane. This 1,3-di(2-methylphenethyl)tetramethyldisiloxane had a refractive index of 1.505. a viscosity of 9.3 centistokes, and a boiling point of 160° C./0.5 mmHg.
