摘要:

AbstractStereospecific 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 H2O/ALEt3of 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 −40°C., above which polymer could not be obtained, and that as the temperature was lowered below −40°C. the rate of reaction was increased, showing negative temperature coefficient. The critical temperature −40°C., may be regarded as a ceiling temperature for the polymerization of acet

ISSN:0022-3832    

DOI:10.1002/pol.1962.1206217301

出版商:Interscience Publishers, Inc.    

年代:1962

数据来源: WILEY

ISSN:0022-3832    

DOI:10.1002/pol.1962.1206217321

出版商:Interscience Publishers, Inc.    

年代:1962

数据来源: WILEY

ISSN:0022-3832    

DOI:10.1002/pol.1962.1206217322

出版商:Interscience Publishers, Inc.    

年代:1962

数据来源: WILEY

ISSN:0022-3832    

DOI:10.1002/pol.1962.1206217324

出版商:Interscience Publishers, Inc.    

年代:1962

数据来源: WILEY

ISSN:0022-3832    

DOI:10.1002/pol.1962.1206217325

出版商:Interscience Publishers, Inc.    

年代:1962

数据来源: WILEY

ISSN:0022-3832    

DOI:10.1002/pol.1962.1206217326

出版商:Interscience Publishers, Inc.    

年代:1962

数据来源: WILEY

ISSN:0022-3832    

DOI:10.1002/pol.1962.1206217327

出版商:Interscience Publishers, Inc.    

年代:1962

数据来源: WILEY

ISSN:0022-3832    

DOI:10.1002/pol.1962.1206217328

出版商:Interscience Publishers, Inc.    

年代:1962

数据来源: WILEY

摘要:

AbstractThe preparation of trallyloxypyrimidine is described, together with the polymerization characteristics of this compound under differential thermal analysis conditions. The DTA curves show a doublet first exotherm near 100°C, and a singlet exotherm at 225°C. Combining the heat values obtained from the DTA curves with infrared spectral data indicates that the complex first exotherm represents a total polymerization of two allyl groups, while the second exotherm involves rearrangment to the barbiturate structure. The fact that the last allyl group does not polymerize during the second exotherm is due to the presence of a hydroxyl group in the rearranged structure. The results are compared to a previous study of the reaction mechanism of triallyl cyanurate polymerizatio

ISSN:0022-3832    

DOI:10.1002/pol.1962.1206217302

出版商:Interscience Publishers, Inc.    

年代:1962

数据来源: WILEY

ISSN:0022-3832    

DOI:10.1002/pol.1962.1206217331

出版商:Interscience Publishers, Inc.    

年代:1962

数据来源: WILEY