Studies On The Synthesis Of Para-Substitued Phenylboronic Acid

There are various kinds of substituent phenylboronic acids which smell sweet, are being developed rapidly and have been widely used in the fields of electronics, chemistry, medicine and biology, especially in glucose sensors. In this thesis, the synthesis, the application and the prospect of substituent phenylboronic acids were summarized, and the synthesises of 4-tert-Butylphenylboronic acid, 4-iso-propylphenyl boronic acid and 4-chlorophenylboronic acid and their improvement were studied in detail. The influencing factors such as temperature, reaction time, reactants molar ratio were analyzed with the orthogonal experiment and the Grey Correlation Degree method, an optimized process for the preparation of 4-tert-Butylphenylboronic acid was thus obtained as follows: the reactant molar ratio of 1-bromo-4-tert-butylbenzene to the trimethyl borate was 1/1.4, the temperature was -20℃, and the reaction time was 160 min. The final yield was 69.5%. An optimized process was obtained by investigating the influence of the temperature, reactant proportion on the yield of 4-iso-propylphenyl boronic acid: The molar ratio of reactants is n(C8H9Br): n(B(OC4H9)3)=1/1.5, the temperature is -10℃,and the isolated total yield is 56.6%. An optimized process for the synthesis of 4-chlorophenylboronic acid was also obtained as follows: the reactant molar ratio of p-chlorobromobenzene to the tributylborate was 1/2, the temperature was -40℃, and the reaction time was 160 min. The final yield was 87.77%. Meanwhile, the preliminary synthesis of 4-bromophenylboronic acid was investigated too. Each of the above products was identified by mass spectrum, 1HNMR, IR and HPLC.