ABSTRACT

This paper reports experimental vapor pressures of condensed phases of methyl p-cyano, p-formyl, p-nitro, and p-(methylamino) benzoates measured over the temperature ranges (303.9 to 393.0) K, (303.1 to 388.2) K, (319.0 to 415.8) K, and (332.9 to 392.4) K, respectively, using a static method based on capacitance diaphragm manometers. The Knudsen mass-loss effusion technique was also used to measure the vapor pressures of crystalline methyl p-(methylamino)benzoate in the temperature range (317.1 to 339.2) K. These results enabled the calculation of the standard molar enthalpies and entropies of sublimation and of vaporization, at reference temperatures as well as the (p,T) values of the triple point of each compound. The temperatures and molar enthalpies of fusion were determined using differential scanning calorimetry and were compared with the values derived indirectly from the vapor pressure measurements. The enthalpies of the intermolecular hydrogen bonds O H***O in the crystalline phase of the parent benzoic acids were determined.

Compounds

#	Formula	Name
1	C9H7NO2	methyl p-cyanobenzoate
2	C9H8O3	methyl 4-formylbenzoate
3	C8H7NO4	methyl p-nitrobenzoate
4	C9H11NO2	methyl p-(methylamino)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	12
POMD	1	Vapor or sublimation pressure, kPa ; Liquid	Temperature, K; Liquid	Liquid Gas	Closed cell (Static) method	19
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	15
POMD	2	Vapor or sublimation pressure, kPa ; Metastable liquid	Temperature, K; Metastable liquid	Metastable liquid Gas	Closed cell (Static) method	32
POMD	3	Molar enthalpy of transition or fusion, kJ/mol ; Crystal		Crystal Liquid Air at 1 atmosphere	DSC	1
POMD	3	Normal melting temperature, K ; Crystal		Crystal Liquid Air at 1 atmosphere	DTA	1
POMD	3	Vapor or sublimation pressure, kPa ; Crystal	Temperature, K; Crystal	Crystal Gas	Closed cell (Static) method	24
POMD	3	Vapor or sublimation pressure, kPa ; Metastable liquid	Temperature, K; Metastable liquid	Metastable liquid Gas	Closed cell (Static) method	27
POMD	4	Molar enthalpy of transition or fusion, kJ/mol ; Crystal		Crystal Liquid Air at 1 atmosphere	DSC	1
POMD	4	Normal melting temperature, K ; Crystal		Crystal Liquid Air at 1 atmosphere	DTA	1
POMD	4	Vapor or sublimation pressure, kPa ; Crystal	Temperature, K; Crystal	Crystal Gas	Calculated from knudsen effusion weight loss	36
POMD	4	Vapor or sublimation pressure, kPa ; Crystal	Temperature, K; Crystal	Crystal Gas	Closed cell (Static) method	15
POMD	4	Vapor or sublimation pressure, kPa ; Metastable liquid	Temperature, K; Metastable liquid	Metastable liquid Gas	Closed cell (Static) method	23

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

Vapor Pressures of Four Methyl Esters of Substituted Benzoic Acids. The Intermolecular Hydrogen Bond OH...O

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

ABSTRACT