Matrix Isolation FTIR Spectroscopic and Theoretical Study of Methyl Lactate

A. BORBA, A. GÓMEZ-ZAVAGLIA, L. LAPINSKI, R. FAUSTO

VIBRATIONAL SPECTROSCOPY

Elsevier

Lugar: Amsterdam; Año: 2004 vol. 36 p. 79 - 88

0924-2031

Methyl lactate [CH(CH3)OHC(O)OCH3] conformational space was investigated by extensive DFT/B3LYP/6-311++G(d,p) and MP2/6-31++G(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, OCCO and OCOC dihedrals, respectively) were observed and characterized spectroscopically. Conformer interconversion pathways were also theoretically investigated. The low calculated barrier associated with the G′sk′C→GskC conversion (∼1 kJ mol−1) explains the absence of the third most stable form (G′sk′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.