Abstract
Stereospecific polymerization of acetaldehyde by triethylaluminum was studied. It was found that some catalyst was made at room temperature or at a low temperature and that the effective catalyst of the polymerization was the reaction product of organometallic compound and water contained in aldehyde. When addition is made at room temperature, Polymerization proceeds more rapidly than when at low temperature. and there is a miximal conversion at a certain concentration of catalyst. Because the maximal catalytic activity occurred at a molar ratio of H~2~O/ALEt~3~ of about 0.5, the effective catalyst is considered to be tetraethyl dialumoxane not but triethylaluminum itself. It is considered that the dialumoxane produced the stereogularity in the present case. Crystalline polyacetaldhyde was formed even in a homogeneous solution. The polarity of solvent did not completely destroy the stereospecificity but reduced the yield of polymer in spite of the ionic nature of the polymerization. Clear relationships were obtained between the dipole moment, or the logarithm of dielectric constant of the solvent used, and the conversion. It was found that there is a critical temperature near β40Β°C., above which polymer could not be obtained, and that as the temperature was lowered below β40Β°C. the rate of reaction was increased, showing negative temperature coefficient. The critical temperature β40Β°C., may be regarded as a ceiling temperature for the polymerization of acetaldehyde.