Vapor Pressure and Thermodynamics of L-Tryptophan Sublimation

Моталов, В. Б.; Korobov, Mikhail A.; Dunaev, A.M.; Dunaeva, V. V.; Кудин, Л. С.

doi:10.1134/s1070363221100030

Cited by 7 publications

(15 citation statements)

References 31 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Based on the energies of conformers, the theoretical conformational composition of l -methionine vapor in the temperature range of 298.15–500 K was calculated (for details, see ref ). TFs were calculated in the StatThermo program in the “rigid rotator–harmonic oscillator” approximation based on molecular constants obtained for each conformer structure, taking into account the conformational contribution to entropy.…”

Section: Resultsmentioning

confidence: 99%

“…The saturated vapor pressure was determined by the classical effusion method according to the Hertz–Knudsen equation Here Δ m is the weight loss due to substance effusion in the evaporation time Δ t , s is the geometric area of the effusion hole, C is the Clausing factor, R is the universal gas constant, T is the temperature, and M is the molar mass. The effective effusion area sC = (3.40 ± 0.66) × 10 –8 m 2 was determined in experiments with zinc (reference pressure, see ref for details).…”

Section: Resultsmentioning

confidence: 99%

“…The sublimation enthalpy of the compounds under study was determined according to the methods of the second and third laws of thermodynamics (for details see ref ) using the TFs defined in this paper (Tables , ). Our TFs were also used to recalculate the literature values − obtained at experimental temperatures to 298.15 K.…”

Section: Resultsmentioning

confidence: 99%

“…In our recent publication, 1 a problem of the lack of reliable data on the saturated vapor pressure and the sublimation thermodynamics of amino acids was outlined, and the relevance of research of representatives of this class of compounds was justified. In addition, the advantage of the Knudsen effusion mass spectrometry (KEMS) technique was underlined and the results on the sublimation thermodynamics of L-tryptophan were presented.…”

Section: ■ Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Refined Data on the Sublimation Enthalpy and Thermodynamic Functions of l- and dl-Methionine

et al. 2022

Self Cite

View full text Add to dashboard Cite

In this work, comprehensive investigations of l- and dl-methionine have been conducted by the methods of differential scanning calorimetry (DSC), Knudsen effusion mass spectrometry (KEMS), and quantum chemistry. Heat capacities of crystalline l- and dl-methionine were measured by DSC in the temperature range of 209–473 K and their thermodynamic functions (TFs) have been determined. The structures and molecular parameters of 29 gaseous conformers were computed in the framework of DFT theory (B3LYP/cc-pVTZ) and TFs of methionine in the ideal gas state have been obtained. Sublimation of l- and dl-methionine was investigated by KEMS in the temperature range 369–431 K. Both compounds were found to sublime congruently in the form of monomers. The saturated vapor pressure in the studied temperature range has been obtained as ln (p/Pa) = −(16905 ± 166)/(T/K) + (38.145 ± 0.411) (l-methionine) and ln(p/Pa) = −(16969 ± 140)/(T/K) + (38.473 ± 0.350) (dl-methionine). Sublimation enthalpies Δsub H°(298.15 K) equal to 147.9 ± 1.2 kJ·mol–1 (l-methionine) and 148.7 ± 2.6 kJ·mol–1 (dl-methionine) have been determined by the second and third law techniques.

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Refined Data on the Sublimation Enthalpy and Thermodynamic Functions of l- and dl-Methionine

et al. 2022

Self Cite

View full text Add to dashboard Cite

show abstract

“…The new data 1,2 made it possible to eliminate contradictions in the literature data and to recommend the most reliable values of the sublimation enthalpy based on independent approaches to data processing (through the methods of the second and third laws of thermodynamics). This work continues studies 1,2 and reports the data for Lserine and L-cysteine. These two compounds are thermally less stable than other proteinogenic amino acids.…”

Section: ■ Introductionmentioning

confidence: 99%

Saturated Vapor Pressure and Sublimation Enthalpy of l-serine and l-cysteine

Motalov,

Korobov,

Dunaev

et al. 2023

J. Chem. Eng. Data

Self Cite

View full text Add to dashboard Cite

The crystal–vapor equilibrium for the standard amino acids l-serine and l-cysteine was studied by Knudsen effusion mass spectrometry in the temperature ranges of 387–442 and 361–429 K, respectively. At these relatively low temperatures, the surface degradation of the samples was shown to be minor. The vapor pressure obtained by the Knudsen effusion method was used to calibrate the mass spectrometer. The temperature dependence of the vapor pressure in the investigated temperature range is described by a linear equation ln(p/Pa) = −(18.227 ± 289)/T + (39.828 ± 0.593) for l-serine and ln(p/Pa) = −(16.658 ± 270)/T + (38.295 ± 0.806) for l-cysteine. The set of thermodynamic functions for l-serine and l-cysteine in the ideal gas state was developed. The sublimation enthalpy was obtained by the methods of the second and third laws of thermodynamics. The values Δsub H°(298.15 K) recommended from the analysis of all available data are 151.4 ± 2.3 and 142.5 ± 1.9 kJ mol–1 for l-serine and l-cysteine, respectively.

show abstract