The enthalpies of formation of alkyl carbamates: Experimental and computational redetermination

In the present work, a redetermination of thermochemical data of methyl carbamate and ethyl carbamate was performed by both experimental and computational techniques. Their gas-phase standard (po = 0.1 MPa) molar enthalpies of formation, ΔfHmo(g), at T = 298.15 K, were derived from the standard molar enthalpies of formation, in the crystalline phase, ΔfHmo(cr), and from the standard molar enthalpies of sublimation, ΔcrgHmo at T = 298.15 K, measured, respectively, by static bomb combustion calorimetry and high temperature Calvet microcalorimetry. The experimental results were compared with computational data, calculated at the G3(MP2)//B3LYP level, as well as with values reported in the literature. At the B3LYP/6-31G(d) level of theory, the molecular structure of both carbamates was obtained.

► Combustion calorimetry was used to redetermine ΔfHmo(cr) of methyl and ethyl carbamates.
► ΔcrgHmo of methyl and ethyl carbamates were redetermined by Calvet Microcalorimetry.
► Gas-phase ΔfHmo of the studied compounds have been derived from the experimental values of ΔfHmo (cr) and ΔcrgHmo.
► Gas-phase ΔfHmo of the studied compounds have been calculated by computational thermochemistry.
► The obtained ΔfHmo(g) for the alkylcarbamates are discussed versus literature values for the same compounds.