L. Bernander, G. Olofsson
1972
Citations
0
Influential Citations
5
Citations
Journal
Tetrahedron
Abstract
Abstract The interaction between HCl and dimethylacetamide (DMA), tetramethylurea (TMU) and dimethylsulphoxide (DMSO) in 1,2-dichloroethane solution has been studied. The enthalpies of formation of the 1:1 complexes have been determined and the equilibrium constants and enthalpy changes for the association of HCl to DMA·HCl and TMU·HCl to form the 1:2 complexes have been derived from calorimetric measurements. The acidic proton chemical shifts in the 1:1 complexes were observed at considerably lower field than those reported for the protonated compounds. The 1:1 complexes are described as strong, hydrogen bonded complexes in which HCl interacts at the O atom. In the 1:2 complexes the second HCl molecule is considered to associate at the N atom. Evidence of increased long range proton coupling and at the same time decreased rotational barrier about the NC(O) bond in DMA·2HCl give support to this interpretation.