ABSTRACT

A static method was used to measure the vapor pressures of crystalline and liquid phases of benzamide, N-methylbenzamide, and N,N-dimethylbenzamide, in the temperature ranges (344.8 to 438.2) K, (322.9 to 388.4) K, and (297.0 to 361.7) K, respectively. The vapor pressures of the crystalline phase of benzamide were also measured using the Knudsen effusion method in the temperature range (324.1 to 344.2) K. From the experimental results, the standard molar Gibbs energies and enthalpies of sublimation and of vaporization, at T = 298.15 K, and the triple points coordinates (p,T) for the three compounds were derived. The temperatures and molar enthalpies of fusion were also determined using differential scanning calorimetry and were compared with the values derived from the vapor pressure measurements. The results enabled the determination of the hydrogen bond enthalpies in the studied compounds.

Compounds

#	Formula	Name
1	C7H7NO	benzamide
2	C8H9NO	N-methylbenzamide
3	C9H11NO	N,N-dimethylbenzamide

Datasets

The table above is generated from the ThermoML associated json file (link above). POMD and RXND refer to PureOrMixture and Reaction Datasets. The compound numbers are included in properties, variables, and phases, if specificied; the numbers refer to the table of compounds on the left.
Type	Compound-#	Property	Variable	Phase	Method	#Points
POMD	1	Molar enthalpy of transition or fusion, kJ/mol ; Crystal		Crystal Liquid Air at 1 atmosphere	DSC	1
POMD	1	Triple point temperature, K ; Crystal		Crystal Liquid Air at 1 atmosphere	DTA	1
POMD	1	Vapor or sublimation pressure, kPa ; Crystal	Temperature, K; Crystal	Crystal Gas	Calculated from knudsen effusion weight loss	12
POMD	1	Vapor or sublimation pressure, kPa ; Crystal	Temperature, K; Crystal	Crystal Gas	Closed cell (Static) method	26
POMD	1	Vapor or sublimation pressure, kPa ; Liquid	Temperature, K; Liquid	Liquid Gas	Closed cell (Static) method	30
POMD	2	Molar enthalpy of transition or fusion, kJ/mol ; Crystal		Crystal Liquid Air at 1 atmosphere	DSC	1
POMD	2	Triple point temperature, K ; Crystal		Crystal Liquid Air at 1 atmosphere	DTA	1
POMD	2	Vapor or sublimation pressure, kPa ; Crystal	Temperature, K; Crystal	Crystal Gas	CCELL:UFactor:0.5	15
POMD	2	Vapor or sublimation pressure, kPa ; Liquid	Temperature, K; Liquid	Liquid Gas	Closed cell (Static) method	34
POMD	3	Molar enthalpy of transition or fusion, kJ/mol ; Crystal		Crystal Liquid Air at 1 atmosphere	DSC	1
POMD	3	Triple point temperature, K ; Crystal		Crystal Liquid Air at 1 atmosphere	DTA	1
POMD	3	Vapor or sublimation pressure, kPa ; Crystal	Temperature, K; Crystal	Crystal Gas	CCELL:UFactor:0.5	10
POMD	3	Vapor or sublimation pressure, kPa ; Liquid	Temperature, K; Liquid	Liquid Gas	Closed cell (Static) method	31

Thermodynamics Research Center / ThermoML | Journal of Chemical and Engineering Data

Thermodynamic Study of Benzamide, N-Methylbenzamide, and N,N-Dimethylbenzamide: Vapor Pressures, Phase Diagrams, and Hydrogen Bond Enthalpy

Almeida, A. R. R. P.[Ana R.R.P.], Monte, M. J. S.[Manuel J. S.]

ABSTRACT