Calculation Of ～1H NMR Of Pentanediol Aromatic Diester And The Mechanism Research Of Propene Bromination

2,4-Pentanediol diaromatic acid ester, as a new kind of internal electron donor, is the most important components of Ziegler-Natta catalyst. 2,4-pentanediol was prepared by the reduction of 2,4-pentanedione with NaBH4, and 2,4-pentanediol aromatic diester were synthesized by means of alcoholysis reaction using 2,4-Pentanediol and Aroly chloride as raw materials, and ~1H NMR spectrum was characterized .There are 3 groups of peak nearby chemical shift of 2 and it can not be explained.Stereochemistry model of 2,4-Pentanediol diaromatic acid ester have been established by means of parameter setting in this dissertation. The ~1H NMR spectra of 2,4-Pentanedioldiaromatic acid ester based on the model have been calculated using GIAO method.(1)Configurations of 2,4-pentanediol diaromatic acid ester are calculated using B3LYP method 3-21g, 6-31g, 6-31g(d) basis sets and ~1H NMR spectra are calculated using GIAO method 3-21 g, 6-31 g, 6-31 g(d) basis sets. As the size of the basis set increased, the calculated values become closer to those of experimental, the discrimination of experiment and theory calculation is less than 0.4ppm.(2) Theory calculation can assigned 2,4-pentanediol diaromatic acid ester compounds reasonably. The compound which is characterized is the mixture of racemate and mesomer. In the racemate 2,4-pentanediol diaromatic acid ester, the two hydrogen atoms of methylene are equivalent and in the mesomer 2,4-pentanediol diaromatic acid ester, the two hydrogen atoms of methylene are not equivalent. In the experimental spectrogram, the middle peak of the three which chemical shift nearby 2 is the chemical shift of two equivalent hydrogen atoms of methylene in the racemate 2,4-pentanediol diaromatic acid ester and the two other peaks are the chemical shifts of two nonequivalent hydrogen atoms of methylene in the mesomer 2,4-pentanediol diaromatic acid ester.Configurations of benzoyl peroxide and complexes of benzoyl peroxide and hydrobromide and transition state of peroxy bond fracturation are calculated using B3LYP method6-31g(d) basis set. Frequency of them is calculated to determine the optimized configuration is transition state or stable structure. Energy barrier of transition state is compared, and it is proved that when the complexes of benzoyl peroxide and hydrobromide formed, it can not cause the temperature of peroxy bond fracturation from40—100℃decreased to-30℃without thinking solvent effect.