Document Type
Dissertation
Date of Award
Spring 6-30-1970
Degree Name
Doctor of Engineering Science in Chemical Engineering
Department
Chemical Engineering and Chemistry
First Advisor
William H. Snyder
Second Advisor
Deran Hanesian
Third Advisor
Ching-Rong Huang
Fourth Advisor
Saul I. Kreps
Fifth Advisor
Werner J. Wenisch
Abstract
Kinetic data for the anionic polymerization of bulk neopentylethylene oxide were determined. The initiator used for this study was potassium t-butoxide. Polymerization runs were made at temperatures of 39.9, 60.0 and 80.3°C using monomer to initiator ratios of 50/1 and 20/1.
The polymerization reaction was found to follow pseudo first order kinetics up to about 60% polymerization and second order after this. The energy of activation for the propagation reaction was found to be 17.4 ± 1.2 K cal/mole and 18.5 ± 1.5 K cal/mole, respectively, for the pseudo first order and second order portions of the polymerization. The value for the energy of activation should be constant at different degrees of polymerization and these two values are the same within experimental error. The highly negative entropy (-25.9 ± 3.6 cal/mole-deg @ 60.0°C) indicated that the transition state was very sterically hindered which is typical for SN2 type reactions.
There was evidence that chain transfer was taking place because of the difference in the experimentally determined and calculated number average molecular weights. The rate of chain transfer was found to decrease as the percent polymerization increased. The change in the reaction medium as the polymerization proceeded was thought to cause this change in chain transfer rate. The rate of chain transfer was found to be slower than the rate of polymerization therefore it had a higher energy of activation. The energy of activation for the chain transfer reaction was determined to be 21.5 ± 1.5 K cal/mole at about 75% conversion.
Neopentylethylene oxide was also polymerized using potassium hydroxide, cesium hydroxide, rubidium t-butoxide and zinc chloride as initiators. These runs were made to find out how fast the polymerization would proceed, what type of polymer would be obtained and what the molecular weight of the resulting polymer would be.
Attempts were made to prepare optically active neopentylethylene oxide. Methods that were tried for this preparation were; gas chromatography, distillation, crystallization and stereo selective reactions. However the optically active monomer could not be prepared by any of the methods tried.
Gas chromatographic columns with optically active packing were used to try and separate the enantiomers of neopentylethylene oxide and the enantiomers of the bromohydrin, 4,4-dimethyl-l-bromo-2-pentanol. Gas chromatography was also used to try and separate the diastereomers that resulted when 1-menthoxyacetic acid was reacted with the d,l-bromohydrin. In this reaction and in the following reactions only the purified secondary alcohol bromohydrin was used. Attempts were also made to try and separate these diastereomers by vacuum distillation. Optically active neopentylethylene oxide could then be prepared from the resolved bromohydrin or diastereomers by reacting with potassium hydroxide. Neither the enantiomers or the diastereomers could be resolved by any of the gas chromatograph or distillation methods that were tried.
Stereoselective reactions were also tried with the bromohydrin. The d,l-bromohydrin was reacted with 1-menthoxyacetic acid in one attempted separation and with cinchonine in another to try and obtain a partial resolution of the enantiomers. However the unreacted bromohydrin did not show any optical activity in either of these reactions.
Resolution by crystallization was to be tried by reacting the d,l-bromohydrin with phthalic anhydride. The resulting half esters would then be reacted with an alkaloid to form two diastereomers that might be separated by crystallization. However because of difficulty encountered with the reaction of bromohydrin with phthalic anhydride this method was not pursued very thoroughly and the actual crystallization was never tried.
Recommended Citation
Meisinger, Albert Edward, "A kinetic study of the anionic polymerization of neopentylethylene oxide" (1970). Dissertations. 1344.
https://digitalcommons.njit.edu/dissertations/1344
