TY - JOUR
AU1 - Cooper, Glenn D.
AU2 - Elliott, John R.
AB - The effect of small amounts (0.01%–1%) of dimethyl sulfoxide on base‐catalyzed polymerization and equilibration of methylsiloxanes has been examined. The addition of 0.5% of the sulfoxide increases the rate of potassium hydroxide‐catalyzed polymerization of octamethylcyclotetrasiloxane by factors of 100–1000 and amounts as low as 0.01% have a large effect when low (12 ppm) catalyst concentrations are used. The rate of basecatalyzed equilibration of hexamethyl disiloxane with octamethylcyclotetrasiloxane is similarly enhanced by dimethyl sulfoxide. The equilibration occurs rapidly at 80°C. with 0.01% of potassium hydroxide and 1% of dimethyl sulfoxide, but does not proceed at a measurable rate with potassium hydroxide alone. The combination of 0.01% potassium hydroxide and 1% dimethyl sulfoxide is more effective than 0.1% of tetramethylammonium hydroxide. The large accelerating effect of the sulfoxide is believed to be due to solvation of the cation, which promotes ionization of the metal silanolate, increasing the concentration of silanolate anions.
TI - Promotion of base‐catalyzed siloxane rearrangements by dimethyl sulfoxide
JF - Journal of Polymer Science Part A Polymer Chemistry
DO - 10.1002/pol.1966.150040314
DA - 1966-03-01
UR - https://www.deepdyve.com/lp/wiley/promotion-of-base-catalyzed-siloxane-rearrangements-by-dimethyl-D0dUQAWXmc
SP - 603
EP - 611
VL - 4
IS - 3
DP - DeepDyve
ER -