Tetrahedron p. 1795 - 1802 (1988)
Update date:2022-08-05
Topics:
Engbersen, J. F. J.
Geurtsen, G.
Bie, D. A. De
Plas, H. C. Van Der
Arylbenzoate esters with a quaternary pyridinium group ortho to the ester function exhibit enhanced reactivity towards basic hydrolysis relative to their para analogs in the order pyridinium < 4-aminocarbonylpyridinium < 3-aminocarbonylpyridinium < 3-aminocarbonylquinolium.In contrast, a trimethylammonium group in the ortho position shows a decelerating effect relative to the para analog.It is concluded that the catalytic effect of a neighboring pyridinium group is based upon interaction of the negatively charged transition state of ester hydrolysis with the electron deficient ?-system of the pyridinium ring.For the p-methoxyphenolate ester containing the 3-aminocarbonylpyridinium group in the ortho position this interaction leads to a change in mechanism from rate limiting hydroxide ion attack to hydroxide ion catalyzed expulsion of the leaving group as became apparent from deviation of the Hammett plot and second-order dependence on OH(1-) concentration.For the p-nitrophenolate ester it was observed that decrease of the solvent polarity by addition of dioxane results in an increase of the rate of hydrolysis and a marked increase of the neighboring group effect.
View MoreFujian Huitian Biological Pharmacy Co., Ltd.
Contact:0086-598-8300831; 8339920
Address:No.46,Taijiang Road,Sanming City,Fujian,China
Shandong Zhongcheng Barium Salt Co., Ltd
Contact:+86-15725732638
Address:No.29 baoxi road, hi-tech zone, zibo, shandong
Zhejiang Sanmei Chemical Industry Co., Ltd
Contact:86-579-87633213
Address:Huchu Industrial Zone, Qingnian Rd., Wuyi County, Zhejiang Prov., China.
Jinan Baozhao Pharmaceutical Co., Ltd
Contact:0086-531-86397156 82371858 82371868
Address:Huaneng Road, Jinan, Shandong ,China
Hengshui Bangsheng Environmental Protection and Technology Co., Ltd
Contact:+86-318-2275966
Address:1956 Renmin Road, Hengshui city, Hebei, China
Doi:10.1246/bcsj.65.97
(1992)Doi:10.1021/ol702122d
(2007)Doi:10.1246/cl.1988.1339
(1988)Doi:10.1016/j.bmc.2009.04.065
(2009)Doi:10.1080/00397910802663352
(2009)Doi:10.1007/BF00598590
(1988)