Struktur und Aggregation von Dimethylammonium‐dimethylcarbamat (Dimcarb) und analogen Dialkylammonium‐dialkylcarbamaten

Abstract

AbstractIn the wide range of carbamic acid derivatives, dialkylammonium‐dialkylcarbamates receive an exceptional position concerning their structure, molecular aggregation, and thermal behaviour. Among them the first member of this series, dimethylammonium‐dimethylcarbamate, briefly called dimcarb, represents a distillable liquid and claims additional interest in view of preparative utilizations. Its unusual properties have been investigated with regard to other ammonium‐carbamates, resulting in some remarkable conclusions by means of different physical methods. Thus, dimcarb is highly structured in dependence on temperature (viscosimetry, refractometry, cryoscopy). Dimethylamine and carbondioxide are bonded only weakly by binding energies in the order of non‐specific solvation energies (caloric measurements). The ionic species are predominantly involved in contact ion pairs (conductivity) and display a dynamic behaviour along with different prototropic interactions including dimethylcarbamic acid (N M R spectra). Informations about favoured structure combinations are given (quantum chemical calculations, I R and Raman spectra, mass spectra). Altogether, the unusual properties of dimcarb are based on a flexible structure behaviour, sensitively influenced by external factors (temperature, medium, reaction partners).