Journal of the American Chemical Society p. 3914 - 3921 (1996)
Update date:2022-08-03
Topics:
Pakarinen, Jaana M. H.
Smith, Rebecca L.
Vainiotalo, Pirjo
Pakkanen, Tapani A.
Kentt?maa, Hilkka I.
The long-lived radical cation of 2-methoxyethanol, CH3OCH2CH2OH.+, is stable toward isomerization in the gas phase. This radical cation reacts with neutral reagents via three main channels in a Fourier-transform ion cyclotron resonance mass spectrometer. CH3OCH2CH2OH.+ abstracts an electron from reagents with ionization energies less than that of CH3OCH2CH2OH. Neutral reagents with higher ionization energies replace CH3OCH2. or CH2O in the ion. Both replacement reactions are probably driven by the formation of a hydrogen bond between the entering nucleophile and the hydroxyl group in CH3OCH2CH2OH.+, which breaks the C-C bond in CH3OCH2CH2OH.+. For strong nucleophiles, this process is so exothermic that the resulting ion/molecule complex dissociates by loss of CH3OCH2.. However, weak nucleophiles yield a longer-lived ion-molecule complex. Within this complex, CH3OCH2. can react with the initially produced ion by replacement of CH2O (a weaker nucleophile) to yield the hydrogen-bridged complex of CH3OCH2. and the nucleophile. This reaction provides a general approach for the gas-phase synthesis of different hydrogen-bridged radical cations. Ab initio molecular orbital calculations suggest that the most stable geometry of CH3OCH2CH2OH.+ is characterized by an unusually long C-C bond (1.775 ? at the UMP2/6-31G** level of theory). This finding is in agreement with the observed facile cleavage of the C-C bond in CH3OCH2CH2OH.+. The isomeric ions .CH2O+(CH3)CH2OH, (CH3)2O+CH2O., .CH2OCH2CH2OH2+, .CH2O(CH3)-H+···O=CH2, and CH3OC(H)H···O(H)=CH2.+ were calculated to be less stable than CH3OCH2CH2OH.+ (at the UMP2/6-31G**//UHF/6-31G**+ZPE level of theory). Only the ion (CH3)2O-H···O=CH.+ was found to lie lower in energy than CH3OCH2CH2OH.+ (by 7.2 kcal/mol at the UMP2/6-31G**+ZPVE level of theory). However, experimental evidence does not support the formation of this hydrogen-bridged ion upon ionization of 2-methoxyethanol.
View MoreAnhui Biochem United Pharmaceutical Co., Ltd.
Contact:0086 551 5167062 / 5228268
Address:No. 30 Hongfeng Road, Hi-Tech Development Zone, Hefei (230088), China
Contact:+86-574-87065746
Address:10th Floor, No.787 Baizhang East Road,
Shanghai Taibao Pharmaceutical Technology Co., Ltd(expird)
Contact:021-52217366
Address:shanghai
Changzhou Jiana Chemical Co.,Ltd
website:http://www.jianachem.com
Contact:86-0519-88731808
Address:Zhenglu Town Wujin City, Jiangsu Province
SEA BRGIHT INDUSTRY CO.,LIMITED
Contact:0086 755 8622 3990
Address:Rm 17B3,GuangCaiXinTianDi Bldg,GuiMiao Rd,NanShan District,Shenzhen,China
Doi:10.1016/0040-4020(95)00306-S
(1995)Doi:10.1002/chem.201602719
(2016)Doi:10.1016/j.polymer.2010.08.066
(2010)Doi:10.1080/15257779408013225
(1994)Doi:10.1021/ja00115a003
(1995)Doi:10.1039/DT9950001933
(1995)