Gas-phase reactivity of the OP(OCH3)2+ phosphonium ion towards α,β-unsaturated esters in a quadrupole ion trap

✍ Scribed by Eric Leclerc; Emmanuelle Leon; Marie-Hélène Taphanel; Jean-Pierre Morizur

• Publisher: John Wiley and Sons
• Year: 2005
• Tongue: English
• Weight: 345 KB
• Volume: 40
• Category: Article
• ISSN: 1076-5174
• DOI: 10.1002/jms.815

✦ Synopsis

Abstract

Ion–molecule reactions between the OP(OCH~3~)~2~^+^ phosphonium ions and eight α,β‐unsaturated esters (methyl acrylate, ethyl acrylate, methyl crotonate, ethyl crotonate, methyl 3,3‐dimethylacrylate, ethyl 3,3‐dimethylacrylate, methyl methacrylate and ethyl methacrylate) were performed in a quadrupole ion trap mass spectrometer. The OP(OCH~3~)~2~^+^ phosphonium ions, formed by electron ionization from neutral trimethyl phosphite, were found to react with α,β‐unsaturated esters to give an adduct [RR′CCR″COOR″′, OP(OCH~3~)~2~]^+^, which lose spontaneously a molecule of trimethyl phosphate (R″′CH~3~) or dimethyl ethyl phosphate (R″′C~2~H~5~). An ion corresponding to a protonated trialkyl phosphate is also observed when substituent R″H. To confirm the experimental results, and to elucidate the mechanism for the formation of the ionic species, a theoretical study using the density functional theory (DFT) approach was carried out. The potential energy surface obtained from B3LYP/6–31G(d,p) calculations for the reaction between OP(OCH~3~)~2~^+^ and methyl acrylate is described. Copyright © 2005 John Wiley & Sons, Ltd.