FRAGMENTATION OF THE METASTABLE MOLECULAR ION OF METHYL LACTATE - THEFORMATION OF OXYGEN-PROTONATED METHANOL [CH3OH2](-ATOM TRANSFERS() INVOLVING DOUBLE HYDROGEN)

The spontaneous unimolecular dissociation reaction of methyl lactate ( 1) ionized by electron impact was investigated by a combination of mas s-analyzed ion kinetic energy spectrometry and deuterium labeling. The metastable ions 1(+.) decompose in a variety of ways: four fragment p eaks are observed at m / z 89, 76, 61, and 45, which correspond to the losses of CH3, CO, CH3CO, and COOCH3, respectively. Double hydrogen a tom 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 hydro xyl and methyne hydrogen atoms in 1(+.) are present in the resultant p rotonated methanols.