Initiator diethylzinc- 3,3 dimethyl

We were able to isolate species of both types in the case of diethylzinc-(+) 3,3 dimethyl 2 butanol initiator system. The antisteric species has a composition close to Etf.Zn(0R)j, or Zn(0R) . (EtZnOR)g (-OR being the 3,3 dimethyl 2 butoxy group), while an homosteric initiator had a Zn(0R)j>. EtZnOR composition. Both species were soluble in benzene and were studied by H-NMR (18). It was possible to transform one specie into the other by ailing ZnEtp or by drying or heating (loss of ZnEt, and disproportionation . ... 

Up to now we have found that the best stereoelective initiator system for polymerization of oxiranes and thiiranes resulted from the reaction of diethylzinc and (-)3,3 dimethyl 1,2 butane diol (DMBD) taken in (1 1) proportion. 

In practice we have prepared the homosteric initiator by reacting at room temperature diethylzinc with (-) 3,3 dimethyl 1,2 butanediol and the antisteric initiator by reacting the latter diol with dimethylcadmium in the same conditions. 

When an optically active alcohol is used for the preparation of the initiator, the polymerizations become of the enantioa-symmetrical type. The system diethylzinc/(l )-(-)-3,3-dimethyl-1,2-butanediol (1 1) has a high stereoelective nature for the polymerization of MT. ... 

In Figure 3 experimental data are plotted obtained for methyl oxirane which was polymerized with a chiral initiator resulting from the reaction of diethylzinc with ( )-3,3-dimethyl-1, 2-butanediol in (1 1) ratio [13]. 

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