Journal of the Chemical Society. Perkin transactions II p. 579 - 591 (1980)
Update date:2022-08-03
Topics:
McCarthy, Daniel G.
Hegarty, Anthony F.
The rates of hydration of a series of ketenimines (9) have been examined in water (μ 1.0; 25 deg) over the pH range 2-13.Three mechanisms of hydration to the amides (8) were noted: (a) general acid catalysis by proton transfer from H3O(1+) in the pH range 2-7 (giving kH3O(1+)/kD3O(1+) 2.65); (b) general acid catalysis by H2O at pH > 7 (where kH2O/kD2O = 4.8); (c) rate determining HO(1-) attack.The last mechanism was only shown by N-arylketenimines, e.g. (9e); other N-alkylketenimines continue to react by rate-determining proton transfer from water even at pH 13.This result is confirmed by the incorporation of just one deuterium when (9a) reacted in acidic or basic D2O, while the deuteriated ketenimine (9f) does not loose the label on the reaction in water.Substituent effects are parallel for reactions involving H(1+) transfer from H3O(1+) or H2O; the major effects are obtained on changing substituents at carbon (the protonation site).For example, replacement of C-H by C-Me reduces the reactivity by 10-20-fold, while replacement of C-Me by C-Ph reduces the rate of hydration by >100-fold.Ammonium ions also generally react with ketenimines by rate-determining H(1+) transfer to the ketenimine followed by trapping of the nitrilium ion formed by the free amine.Only with the strongest amine base studied (piperidine) does direct nucleophilic attack on the ketenimine compete.
View MoreLeshan Kai Yada Photoelectric Technology Co., Ltd.,
website:http://www.kydmaterials.com
Contact:0833-5603116
Address:Airport road Jiajiang county, Sichuan province,China
Jiangsu Wanlong Chemical Co., Ltd.
website:http://www.wanlongchem.com
Contact:+86-511-86810993 0086-511-8681 0888;
Address:Quanzhou Town, Danyang City, Jiangsu
website:http://www.tbbmed.com
Contact:86--21-50498136
Address:Room 6002, Building 7-1, No.160 Basheng Road,Pudong Area,Shanghai China
Contact:+86-574-87065746
Address:10th Floor, No.787 Baizhang East Road,
Contact:+86-(0)21-3770 9035
Address:Room 301, Building 2, Meijiabang Road 1508, Shanghai China
Doi:10.1002/ejoc.201201210
(2013)Doi:10.1039/c3ob40745d
(2013)Doi:10.1055/s-0033-1338495
(2013)Doi:10.1039/c3cc42531b
(2013)Doi:10.1134/S1070363216060165
()Doi:10.1016/j.tetlet.2013.07.098
(2013)
