A Study of the Polymerization of Propylene Oxide Catalyzed by Anhydrous Potassium Hydroxide

Abstract

The polymerization of propylene oxide catalyzed by solid anhydrous KOH is shown to have essentially the same mechanism a s the well-known horriogeneous base-catalyzed polymerizations. The reaction is not surfacecatalyzed and the role of solid KOH is to convert hydroxylic groups almost quantitatively to alkoxide groups. Unsaturated end groups are shown to conie from rearrangement of propylene oxide to allyl alcohol, which initiates new polymer chains. Allyl ethers thus formed are converted t o &-propenyl ethers a t rates dependent upon their molecular weights. A kinetic analysis shows that the proposed reaction sequence accounts for all the characteristics of the polymerization including reaction rates, induction period, average molecular weight, and molecular weight distribution, and the arnount and type of unsaturation in the polymer. (51 C. C Price, lecture delivered a t Sorthwestern University, Dec. 8, 1959 I6J I ) M. Simons and J. J. I'erbanc, J. Polymer Sci , 44, 803 (1!>60) ( 7 ) G. Gee, Chem I n d . fI.ondonj, 678 (19.59).

Star polymers formed by MPEG reaction with diepoxides. The course of reaction

“…Calculated rate coefficients could now be compared with the rate constants reported in the literature for the anionic polymerization of propylene oxide: (14) Thus, in bulk, at 30 C k p ¼ 1.4 10 À5 L moL À1 s À1 [51], at 50 C k p ¼ 4.5 10 À5 L moL À1 s À1 [52], and at 70 C k p ¼ 1.1e1.4 10 À4 L moL À1 s À1 [51].…”

Application of Dipotassium Glycoxides–Activated 18-Crown-6 for the Synthesis of Poly(propylene oxide) with Increased Molar Mass

“…[1][2][3] They are mainly synthesized by anionic ring opening polymerization (AROP) of PO using typical initiators as alkali metal hydroxides [4,5] or alkoxides. [6][7][8][9] However, it is impossible to obtain high molar mass polymers by this method because of the side reaction, i.e., chain transfer to the monomer resulting in macromolecules with allyloxy starting groups and macromolecules with hydroxyl end groups.…”

“…[6][7][8][9] However, it is impossible to obtain high molar mass polymers by this method because of the side reaction, i.e., chain transfer to the monomer resulting in macromolecules with allyloxy starting groups and macromolecules with hydroxyl end groups. [10][11][12][13][14] In the Submitted presence of anhydrous potassium hydroxide [4] or potassium 1-methoxy-2-propoxide [6] the allyloxy groups isomerize to cis-propenyloxy groups. It is interesting that in the first system about 27% of the cis-propenyloxy groups were formed already at 30°C after complete conversion of the monomer, whereas in the second case a rearrangement did not occur even at 80°C.…”

Synthesis of biopolyols by mild oxypropylation of liquefied starch and its application to polyurethane rigid foams

“…However, it is known that under such severe conditions, monoalcoholic side products having unsaturated end groups can be formed. [8][9][10] The formation of these monoalcoholic products hinders the proceedings of crosslinking and polymerization during urethane resinification and results in a decrease in the physical properties of the urethane resins. The unsaturated end groups were shown to come from the isomerization of PO to allyl alcohol, which initiates new polymer chains.…”

“…The unsaturated end groups were shown to come from the isomerization of PO to allyl alcohol, which initiates new polymer chains. [8][9][10] Thus, the conditions of oxypropylation should be constrained to a much milder range.…”