ABSTRACT

The vapor pressures of condensed phases of methyl p-methylbenzoate and methyl p-(dimethylamino)benzoate were measured in the temperature ranges (269.3 to 357.0) K and (325.0 to 390.4) K, respectively, using a static method. The Knudsen mass-loss effusion technique was also used to study the vapor pressures as function of temperature of the crystals of methyl p-(dimethylamino)benzoate in the pressure range (0.1 to 1) Pa. The results obtained for each compound enabled the determination of the standard molar entropies and enthalpies of sublimation and of vaporization at T = 298.15 K as well as phase diagram representations of the (p,T) experimental data. The temperatures and molar enthalpies of fusion were determined using differential scanning calorimetry and were compared with the values derived from the vapor pressure measurements. The enthalpies of the intermolecular hydrogen bonds O H***O in the crystalline phase of the parent substituted benzoic acids were calculated.

Compounds

#	Formula	Name
1	C9H10O2	methyl 4-methylbenzoate
2	C10H13NO2	methyl 4-(dimethylamino)benzoate

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	Normal melting temperature, K ; Crystal		Crystal Liquid Air at 1 atmosphere	DTA	1
POMD	1	Vapor or sublimation pressure, kPa ; Crystal	Temperature, K; Crystal	Crystal Gas	Closed cell (Static) method	17
POMD	1	Vapor or sublimation pressure, kPa ; Liquid	Temperature, K; Liquid	Liquid Gas	Closed cell (Static) method	29
POMD	2	Molar enthalpy of transition or fusion, kJ/mol ; Crystal		Crystal Liquid Air at 1 atmosphere	DSC	1
POMD	2	Normal melting temperature, K ; Crystal		Crystal Liquid Air at 1 atmosphere	DTA	1
POMD	2	Vapor or sublimation pressure, kPa ; Crystal	Temperature, K; Crystal	Crystal Gas	Closed cell (Static) method	23
POMD	2	Vapor or sublimation pressure, kPa ; Liquid	Temperature, K; Liquid	Liquid Gas	Closed cell (Static) method	20
POMD	2	Vapor or sublimation pressure, kPa ; Crystal	Temperature, K; Crystal	Crystal Gas	Calculated from knudsen effusion weight loss	11

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

Vapor Pressures and Phase Diagrams of Two Methyl Esters of Substituted Benzoic Acids

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

ABSTRACT