Organoaluminum catalyst for polymerization reaction. Synthesis of isotactic polyacetaldehyde by AIR3–alkali metal hydroxide catalysts in situ

The catalytic behavior of binary systems derived from AIR₃ and alkali metal hydroxide in a molar ratio of 1 to 0.5 in situ for stereospecific polymerization of acetaldehyde was studied for the purpose of preparation of isotactic polyacetal. The polymer obtained can be readily stretched to a film. The polymerization proceeds slowly (in ～20 hr). The polymer yield and stereospecificity of the polymerization by AlEt₃–LiOH (1:0.5) catalyst were not significantly changed by the nature of solvent or dilution as far as studied. AlEt₃–NaOH, AlEt₃–KOH, AlEt₃–CsOH, AliBu₃–LiOH and AlMe₃–LiOH in molar ratios of 1 to 0.5 behaved similarly. AlMe₃–NaOH, AlMe₃–KOH and AliBu₃–NaOH also gave isotactic polymer of high stereoregularity but in lower yields.