Reaction of polymeric organolithium compounds with ethylene oxide in hydrocarbon solution: Determination of extent of oligomerization

The functionalization of poly(styryl)lithium with excess ethylene oxide in benzene solution has been reexamined to determine if oligomerization of ethylene oxide occurs under normal conditions. No ¹³C NMR peaks were observed at δ = 69-70 and 72-73 ppm as expected for a chain end with two ethylene oxide units. These peaks were not observed even when 3.3 equivalents of ¹³C-labeled ethylene oxide (98 atom % ¹³C) was utilized. No peak corresponding to two ethylene oxide units at the chain end (at m/z 104n + 210 + 44 Daltons) was observed in the MALDI-TOF mass spectrum of the functionalization product. The main series of peaks (Ag ⁺-cationized) appeared at m/z 104n + 210, corresponding to the expected C ₄H ₉ and CH ₂CH ₂OH end groups with a number average degree of polymerization of n. A small peak (ca. 3 %) corresponding to two ethylene oxide units at the chain end was observed in the mass spectrum of the functionalization product obtained using 10 equivalents of ethylene oxide.