Influence of a methyl substituent on the Raman spectrum of but-3-enyl methyl ether

The Raman spectrum of but-3-enyl methyl ether, CH2=CHCH2CH2OCH3 is reported and compared with those of its homologues in which a methyl group is substituted for a hydrogen atom on one of the carbon atoms of the alkenyl chain. Attention is focused on the influence of this methyl group on the bands in the spectrum associated with specific C-H, skeletal stretching and bending vibrations. The use of ab initio DFT quantum mechanical calculations to assist in making these assignments reveals a high degree of mode-mixing in the skeletal vibrations. The value of model studies of this kind in refining the correlations between the presence and absence of specific bands in a Raman spectrum with molecular structure is emphasised. (C) 2012 Elsevier B.V. All rights reserved.