Journal of the Chemical Society - Faraday Transactions p. 1923 - 1930 (1995)
Update date:2022-08-05
Topics:
Schoeneich, Christian
Asmus, Klaus-Dieter
Bonifacic, Marija
Absolute rate constants have been determined for the reversible hydrogen-transfer process R. + RSH ->/<- RH + RS. by pulse radiolysis, mainly through direct observation of the RS. radical formation kinetics in water-RH (1:1, v/v) mixtures.The thiols investigated were penicillamine and glutathione; the RH hydrogen donors were methanol, ethanol, propan-1-ol, propan-2-ol, ethylene glycol, tetrahydrofuran and 1,4-dioxane with the abstracted hydrogen being located α to the hydroxy or alkoxy function.Rate constants for the forward reaction of the above equilibrium (in radiation biology referred to as 'repair' reaction) were typically of the order of 1E7-1E8 dm3 mol-1 s-1 while hydrogen abstraction from RH by thiyl radicals (reverse process) occurred with rate constants of the order of 1E3-1E4 dm3 mol-1 s-1.This yields equilibrium constants of the order of 1E4.Based on these data, standard reduction potentials could be evaluated for the R'R''C.OH/H(1+)//R'R''CHOH, R'R''CO/H(1+)//R'R''C.(OH) and R'R''CO//R'R''C.O(1-) couples from methanol, ethanol and propan-2-ol.Effective hydrogen-atom abstraction by RS. required activation by neighbouring groups of the C-H bond to be cleaved in RH.No such process was observed for the RS. reaction with -CH3 groups, e.g. in 2-methylpropan-2-ol.Several halogenated hydrocarbons, including some anaesthetics (e.g. halothane) and Fe(CN)6(3-) have been tested with respect to their ability to disturb the (CH3)2C.OH + RSH ->/<- (CH3)2CHOH + RS. equilibrium through an irreversible electron-transfer reaction with the reducing α-hydroxyl radical, thereby drawing the equilibrium to the left-hand side.The respective efficiencies are found to be related to the electronegativities of the electron acceptors.The results are briefly discussed in terms of their biological relevance.
View MoreTai zhou world Pharm & Chem Co., Ltd
Contact:+86-576-85301198
Address:Rome 1001,wangjiang plaza,unti 2,jinshan east Road linhai,zhejiang,china
zhejiang huangyan wanfeng pharm chem co.ltd
Contact:+86-576- 84160728
Address:No. 5 Dazha Road, Economic,Development Zone(JiangKou), Zhejiang, China
Contact:+86-21-61318535
Address:Building 29,No.2139 Xizha Road, Fengxian District, Shanghai
website:http://www.cartoonchem.com/
Contact:+86-25-58074918
Address:Room 2109, RuiHua Business Center,315 South ZhongShan Road, Nanjing 210001, China
Hangzhou GreenCo Science & Technology Co., Ltd.
Contact:86-571-88257303
Address:1713 Room,Jingui Building,Gudun Road,Xihu District,Hangzhou,China
Doi:10.1080/09168451.2015.1010479
(2015)Doi:10.1021/om00114a003
(1989)Doi:10.1021/jo00284a035
(1989)Doi:10.1016/j.bmcl.2008.10.066
(2008)Doi:10.1016/j.tetlet.2010.03.039
(2010)Doi:10.1021/ol1010246
(2010)
