Matrix isolation FTIR spectroscopic and theoretical study of methyl lactate*1

Abstract

Methyl lactate [CH(CH 3 )OHC(¼O)OCH 3 ] conformational space was investigated by extensive DFT/B3LYP/6-311þþG(d,p) and MP2/6-31þþG(d,p) calculations and matrix-isolation FTIR spectroscopy in argon and xenon matrices. From the seven different conformers predicted by the calculations, two forms (the most stable conformers yielded by the calculations: SsC and GskC, where the letters refer to the conformations assumed by the HOCC, OCC¼O and O¼COC dihedrals, respectively) were observed and characterized spectroscopically. Conformer interconversion pathways were also theoretically investigated. The low calculated barrier associated with the) explains the absence of the third most stable form (G 0 sk 0 C) of methyl lactate in low-temperature matrices. Deposition of methyl lactate at different temperatures, together with the theoretical data, aided to the full assignment of the observed spectra. #