Wen Hui Zhong,Ying Na Cui,Shen Min Li,Ying Ping Jia,Jing Mei Yin
The carbonylation of phenyl bromide catalyzed by Co(OAc) 2 has been investigated with PhCOPh as a sensitizer under visible light in the presence of basic additive. With strong base CH 3 ONa, PhCOOCH 3 is produced in 70% yield with 100% selectivity , the similar results are also obtained with a stronger base (CH 3 ) 3 CONa. However, with another strong base NaOH, the yield of the ester is only 40%. On the other hand, with weak base NaOAc or ( n -C 4 H 9 ) 3 N, phenyl bromide cannot be carbonylated. The results of carbonylation of the six substituted phenyl bromides suggest that the activities of o , m , p -BrC 6 H 4 CH 3 are similar to phenyl bromide, while the activities of o , m , p -BrC 6 H 4 Cl are higher with the high yields (≥93%) of the corresponding chloro-esters. In addition, the relative position of bromine and chlorine or methyl on phenyl ring has little effect on the activity of the carbonylation .
Tao Liu,Meng-Meng Liu,Xiao-Wen Zheng,Chong-Yang Du,Xiang-Yang Cui,Lu Wang,Ling-Li Han,Zhang-Yu Yu
The redox reactions of p -hydroquinone and pyrocatechol undergo a two-proton-two-electron process in aqueous solution. We calculated their redox potentials at the B3LYP/6-311+G(d,p) level, and verified the values by employing cyclic voltammetry experiments. Then we selected seven substituent groups (–F, –Cl, –OH, –COOH, –CN, –NH 2 , and –NO 2 groups) to systematically investigate the substituent effect , including the sort, position, and number of the substituent, on the redox potentials of p -hydroquinone and pyrocatechol. The calculated results show that –NH 2 and –OH groups can decrease the redox potentials, while –F, –Cl, –COOH, –CN, and –NO 2 groups increase the potential values of p -hydroquinone and pyrocatechol. The calculations can accurately predict the substituent effects on the redox potentials of pyrocatechol and p -hydroquinone. We would expect that the accurate calculation results for the model systems could be applied in the prediction of electrode potentials of other molecules.
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