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37.1.4.3.4 Variation 4: Polymerizations of Epoxides

DOI: 10.1055/sos-SD-037-00115

McDonald, F. E.Science of Synthesis, (200837183.

The base-catalyzed reaction of oxirane provides polymeric polyether 316, competitive with hydrolysis of oxirane to ethylene glycol. An optimized procedure catalyzed by strontium carbonate, bearing traces of adsorbed water, was found to be more reactive than earlier procedures involving potassium hydroxide.[‌137‌] The observation of an induction period indicates that the rate-determining step is the initial strontium-promoted addition of water or hydroxide to oxirane, and the initial ethylene glycolate then reacts with additional molecules of oxirane by an anionic mechanism to provide poly(ethylene glycol) (316) (Scheme 59). A modern variation on this procedure, which provides monoprotected poly(ethylene glycol) 318 with narrow molecular-weight distribution, has been reported using 2-(benzyloxy)ethanol (317) and potassium hydride as the initiator.[‌138‌] Oxirane polymerization can also be achieved under milder conditions, by a coordinate mechanism[‌139‌] that provides for simultaneous activation of nucleophile and electrophilic activation of the epoxide. For example, (5,10,15,20-tetraphenylporphyrinato)aluminum chloride (319) (Scheme 60) is an effective catalyst for efficient generation of polyether polymer 320, with high molecular weight and low polydispersity.[‌140‌] The chloride end-group of 320 arises from the (tetraphenylporphyrinato)aluminum chloride catalyst, with the porphyrin-bound aluminum alkoxide as the propagating nucleophile. Other representative metal-complex catalysts for epoxide polymerization 321326 are given in Scheme 60.

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Meeeee 88 Meeeeeee-Meeeeeeeee Meeeeeeeeeeeeee ee Meeeeee Me Meee Meeee Meeeee[‌888‌]

Meeeeeeeeee 88

M Meeee (888/888/888) Mee
Me 88:88:88 [‌888‌]
M 8:88:88 [‌888‌]
Me 8:8:888 [‌888‌]

Meeeee 88 Meeeeeeee eee Meeeeeee-Meeeeeeeee Meeeeeeeeeeeeee ee Meeeeee ee 88-Meeee-8

Meeeeeeeeeeeeee ee eeeeeeeeeeeeeee eeeeeeee eeeeeeeee eeeeee ee eeeee- eee eeeeeeeeeeeeeeeee. Meee eee eeeeeeee eeeeeeeeeeeeeee eeeeeee, eeeeee 8-eeeeeeeeeeeee (888, eeeeeeeee eeeee), eee eee ee eeeeee eeeee ee eeeeeeeee eeeeeeeeee eeeeeee ee eeeeeeeeeee ee eeeeeee eeeeeeee, eeeee ee e eeeeeee eeeee eeeeeeeeeee eeee, eeee eeeeeeee eee eeeeeeeee eeeeee ee eeeeeeeee eeeeeeee ee eeeeeeeeeeeee 88888888 Meeeeee. Meeeeeeeeee, eee eeeeeeeee eeeeeee ee eeeeee, eee eee eeeeeeeeeee ee eeeeeee eeeeeee eeeee eeeeeeeeee eeee eeeeeee eeeeeeeee, e.e. eeee eeeeee eeeeeeeeeeee ee eeeeee eeeeeee ee eee eeeeeeeee. Meeeeee, eee eeeeeeeeeee ee eeeeeeeeee eeeeeeeee eee eeeeeeee eeee(8-eeeeeeeeeeeee) 888 eeee eeee eeeeeeeee eeeeee, eee, ee eeee eeeee, eeeeeeeee eeeeeeeeeeeeeeeee ee eee eeeeeee (Meeeee 88). Meeee eeee ee eeee eeee eeeeeeee eeeeeeeeeeeeee ee eeeeeee 8-eeeeeeeeeeeee ee eeee(MMM) eeeeeeee eeeeeeeee, eeeee eeee e eeeeeeeeeee eee eeeeeeeee eeeeee eeeeeeeee eeeeeee eeeee eeee ee eeeeeeeee eeeeeee eeeeeee, eeeee eee ee eeeeeeeee ee eeeeeeeeeeeee.[‌888‌] Meeeeee eeeeeee eee eeeeeeee eeee ee eeeeeeeeeeeeeeee eeeeeee,[‌888‌] eeee eeeee eee eeeeeeeee eeeeeee eeeee eeeeeeeeeeeeee ee eeeee ee ee eeeeeeeee eeeeeeee.[‌888‌] Meeeeeee ee eeee eeeee eeee,[‌888‌,‌888‌] eeeeeee eeeeeeeeee-eeeeeeee eeeeeee eeee eeee eeeeeeeee eee eeeeee eeeeeeeeeeeeee eeeeeeeeeeeeee ee eeee(8-eeeeeeeeeeeee) (Meeeee 88), eeeeeeeee 8-eeeeeeeeeeeee-8-ee/eeeeeeeeeee (888),[‌888‌] (8,88,88,88-eeeeeeeeeeeeeeeeeeeeeee)eeeeeeee eeeeeeee (888),[‌888‌] eee eeeeeee ee eeeeeeeeeeeeeeeeeee eeee 8-eeeeeeeeeeeee,[‌888‌] eee eeeeeee ee eeeeeeeeeeee eeeeeeee eeeeeeeeeeee eeeee 888 eeee eee eeeeeee eeeeeeeee 888,[‌888‌] eee e eeeeeeeeeee eeeeeeee 888.[‌888‌] M eeeeeeeee-eeeee eeee eeeeeeee eeeeeeee 888 eee ee eeeeeeeee ee eeeeeee eeeee ee eeeeeee eeeeeeeeeeeeee eeeeeeeeeeeeee ee eeeeeee eeeeeee eeeeeeeeeeeee eeee eeeeee eeeeeeeee-eeeeee eeeeeeeeeeee.[‌888‌]

Meeeee 88 Meeeeeeeeeeeee (Meee-ee-Meee) Meeeeeeee ee Meee(8-eeeeeeeeeeeee)[‌888‌‌888‌]

Meeeeeeeeee 88

Meeeeeee Meeeeeeeee M8 Meeeeee Meeeeeeee Meeeee Meeeeeeeeeeeee Meeeeeeee Mee
888 eeeeeee, 88°M, 888e MMe 88% eeeeeeeee [‌888‌]
888 MM8Me8, 88°M, 88e Me 88888 8.8 [‌888‌]
eMe8Me/M8M 88°M, 88e MM 888888 8.8 >88% eeeeeeeee [‌888‌]
888/888 (8:8) MM8Me8, 88°M, 8e MeMe 8888 8.88 eeeeeee [‌888‌]
888 eeeeeee, 8°M, 8e MMee 888888 8.88 >88% eeeeeeeee [‌888‌]
888 eeeeeee, eν (>888ee), 88°M, 88eee MMe 88888 8.88 eeeeeee [‌888‌]

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Meeeee 88 Meeeeeeeeeeeee (Meee-ee-Meee) Meeeeeeee ee Meee(8-eeeeeeeeeeeee)[‌888‌,‌888‌]

Meeeeeeeeee 88

Meeeeeee Meeeeeeeee M8 Meeeeee Meeeeeeee Meeeee Meeeeeeeeeeeee Meeeeeeee Mee
MeMMe 888°M, 8e MMe 8888 eeeeeee [‌888‌]
Me8Me/M8M 8,8-eeeeeee, 88°M, 888e MM(?) 8888888888 eeee 8888% eeeeeeeee, eeeeeeeee eeee eeeeeeee [‌888‌]
888 88°M, 88e eeeeeeeeee 88888 8.88 eeeeeeeee [‌888‌]

Meeeee 88 Meeeeeeeee Meeeeeeee ee Meee(8-eeeeeeeeeeeee)[‌888‌,‌888‌]

Meeeeeeeeeeeee ee eeeeeeeeeee eeeee (888), e eeee-eeeeeee, eeeeeeeeeee eeeeeeee eeeeeeeeeeee eeeeeeee ee e eeeeeeeee eeee. Meeeeeee eee eeeeeee eee eeeeeeeee ee eeeeeeeee eeeeee, eeeeeeeeeeeeee, ee eeeeeeeee ee eeee(eeeeeeeeeee eeeee) eeee eeeeeee eeeeeeeeee eeeeeeeee,[‌888‌,‌888‌,‌888‌] ee eee eeee eeeeeeeeeeee eeee eeeeeeeeeeeeee eeeeee ee eeeeeeeee ee eeeeeeeeeeeee ee eee ee eee eeeeeee eeeeeee,[‌888‌] ee eeeeeeee eee eeeee eeeeeee eeeeeeeeeee eeeeeeeeeeeeeee (Meeeee 88).

Meeeee 88 Meeeeeeeeeeeee ee Meeeeeeeeee Meeee[‌888‌]

Meeeeeeeeeee Meeeeeeee

Meee(eeeeeeee eeeeee) Meeeeeeeee Meeee (888):[‌888‌]

MMMMMMM: Meeeeeeee eeeeeee eeeeeee ee eeeeeeee ee eee eee ee eeeeeee eeee eeeeeeee eee ee eeeeee eeeeeeeeeee ee eee eeeeeee.

MMMMMMM: Meeeeee ee eeeeeeeee eeeeeeeee, ee eee, eeee, eee eeeeeeeeeee eeeeeeee, eee ee e eeeeeeee eeeee eeeeeeeeee.

Me e eeeeeeeeee ee MM (8.88e, 8.88eeee, 8.8 eeeee) ee eeeeeeee MMM (888eM) eee eeeee 8-(eeeeeeeee)eeeeeee (888; 8.88e, 8.88eeee, 8 eeeee), eee eee eeeeeee eee eeeeeee eee 8e ee ee. Mee eeee eee eeeeeeee ee eeeee eeeeeeeeeeeeee eeeeee, eeeeeee (88.8e, 888eeee, 88 eeeee) eee eeeee eee eee eeeeeeeee eeee eee eeeeeee ee ee eee 88e. Mee eeeeeeee eee eeeeeeee ee eeeeeeee ee Meeeeeeee MM-888(+) eeeee (8e), eee eee eeeeeee eee eeeeeee eeeee ee eee ee eeeeee eeeee ee eeeeee. Mee eeee eee eeeeeeee eeee Me8M (8M) ee 8°M ee eeeeee 888 ee e eeeee eeeeee; eeeee: 88.8e (88%).

Meeeeeeee Meee(8-eeeeeeeeeeeee) (888):[‌888‌]

Me e eeeeee, e Meeeeee eeee eee eeeeeee eeee Meeeeee eeeeeeee 888 (8.8ee, 88 μeee) eee e Meeeee-eeeeee eeeeeee eee, eeee eeeeee eee eeeeeee eeee eee eeeeee. Meeeeee (8.8eM) eee eeeee eeeee M8 eee eee eeee eee eeeeeee ee 8°M. 8-Meeeeeeeeeeee (888; 8.88eM, 8.8eeee) eee eeeee eee eeeeeeee eeeeeee, eee eee eeeeeee eee eeeeeee eee 8e ee 8°M eeee eeeeeeeeee ee eeeeeeee ee MMM. Mee eeeeeeee eee eeeeeeee eeee 8M MMe (8.8eM), eeeeeeeee 888 eee eeeeeee eeeee eeeeeee eeeeeeee, eee MM8Me8 (88eM) eee eeeee ee eeeeeeee eee eeeeeeeeeeee eeeeeee. Mee eeeeeee eeeee eee eeeeeeeee eee eeeeeee eee eeeeeee ee eeeeee eeeeeeeeeee ee ee, eeeeeeeee eeeee eeeeeee 888 (888ee). Mee eeeeeee eee eeeeeeee ee eeeeeeeeee ee eee eeeeeee (8.8eM), eeee eeeeee eee eeeeeeeee eeee eeeeeeee ee eeeeeee (888eM) ee 88°M. Mee eeeeeee eeee eee eeeeee ee 8°M eee 8e, eee eee eeeee eeeeeeeeeee eee eeeeeeeee ee eeeeeeeeee eee eeeee eeeee eeeeeee eeeeeeee ee eeeeeeee eeeeee; eeeee: 888ee (88%).

References


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