Health & Environmental Research Online (HERO)


Print Feedback Export to File
7737049 
Journal Article 
NH2 STRETCHING VIBRATION ABSORPTION AND ASSOCIATION MECHANISM OF METHYLAMINE IN N-HEXANE AND CARBON-TETRACHLORIDE 
Wolff, H; Schmidt, U; Wolff, E 
1990 
1 
Spectrochimica Acta. Part A: Molecular Spectroscopy
ISSN: 0584-8539 
46 
1 
85-89 
English 
WOS:A1990CU06400013 
Hydrogen bonding of methylamine in n-hexane is studied by recording the NH2 stretching vibration absorption as a function of temperature and concentration and comparing it to the absorption in carbon tetrachloride. A continuous or quasi-continuous shift of the symmetric NH2 stretching vibration on association in hexane and a discontinuous shift by about the same total amount together with an intensity change between a monomeric and an associated band in carbon tetrachloride suggest different association mechanisms in the two solvents. These are related to the enhancement of the proton donor or acceptor ability of the amine resulting from complexation with the solvent in carbon tetrachloride and to a similar influence of the added amine molecules, corresponding to the concept of hydrogen bond cooperativity, in hexane. Differences of 3-5 kJ mol-1 between the mean association energy of methylamine in hexane and of methylamine or its homologues in carbon tetrachloride can be attributed to the energy needed for disruption of the complexes with the chlorine solvent and therefore support the assumption of the complex formation. Further results concern the chain-length dependence of the amine association, the association degrees in the two solvents and the intensity behaviour of the symmetric vibration of the neat compound in i.r. and Raman spectra. © 1990.