Fragmentation of the metastable molecular ion of methyl lactate: The formation of oxygen-protonated methanol [CH3OH 2] (+) involving double hydrogen atom transfers.
The spontaneous unimolecular dissociation reaction of methyl lactate (1) ionized by electron impact was investigated by a combination of mass-analyzed ion kinetic energy spectrometry and deuterium labeling. The metastable ions 1(+·) decompose in a variety of ways: four fragment peaks are observed at m/z 89, 76, 61, and 45, which correspond to the losses of ĊH3, CO, CH3ĊO, and ĊOOCH3, respectively. Double hydrogen atom transfer occurs in the third reaction.The source-generated m/z 61 ions decompose into oxygen-protonated methanols at m/z 33 ([CH3OH 2 (+) ]) by the loss of CO with double hydrogen atom migration. Both hydroxyl and methyne hydrogen atoms in 1 (+·) are present in the resultant protonated methanols.
Gunma College of Technology, 580 Toribamachi, 371, Maebashi, Gunma, Japan.
S
S
Tajima
Y
Y
Nagai
O
O
Sekiguchi
M
M
Fujishige
N
N
Uchida