ABSTRACT

The sublimation process of aromatic amino acids, L-phenylalanine, L-tyrosine and L-tryptophan, were investigated by Knudsen s effusion method with mass spectrometric vapor composition measurement. Fragmentation of molecules under electron ionization was discussed. For these compounds, the molar enthalpies of sublimation were derived from the Clausius Clapeyron equation. Using values for the heat capacity differences between the gas and crystal phases of the compounds the molar standard enthalpies of sublimation at T = 298.15 K, were obtained. The molar enthalpies of solvation in water at infinite dilution (i.d.) were derived from the molar enthalpies of solution of amino acids in water at i.d. and the molar standard enthalpies of sublimation obtained. Correlations between the enthalpies of sublimation/solvation and some molecular descriptors of amino acids were discussed.

Compounds

#	Formula	Name
1	C7H6O2	benzoic acid
2	C9H11NO2	L-phenylalanine
3	C9H11NO3	3-(p-hydroxyphenyl)-L-alanine
4	C11H12N2O2	L-tryptophan

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 vaporization or sublimation, kJ/mol ; Crystal	Temperature, K; Crystal	Crystal Gas	Knudsen effusion method coupled with mass spectrometer, from logarithm of peak intensity	1
POMD	2	Molar enthalpy of vaporization or sublimation, kJ/mol ; Crystal	Temperature, K; Crystal	Crystal Gas	Knudsen effusion method coupled with mass spectrometer, from logarithm of peak intensity	1
POMD	3	Molar enthalpy of vaporization or sublimation, kJ/mol ; Crystal	Temperature, K; Crystal	Crystal Gas	Knudsen effusion method coupled with mass spectrometer, from logarithm of peak intensity	1
POMD	4	Molar enthalpy of vaporization or sublimation, kJ/mol ; Crystal	Temperature, K; Crystal	Crystal Gas	Knudsen effusion method coupled with mass spectrometer, from logarithm of peak intensity	1

Thermodynamics Research Center / ThermoML | Journal of Chemical Thermodynamics

Enthalpy of sublimation of natural aromatic amino acids determined by Knudsen's effusion mass spectrometric method

Tyunina, V. V.[Valeriya V.], Krasnov, A. V.[Alexandr V.], Tyunina, E. Y.[Elena Yu.], Badelin, V. G.[Valentin G.], Girichev, G. V.[Georgy V.]

ABSTRACT