ABSTRACT

The standard molar enthalpy of the base catalysed hydrolysis of methyl paraben, DrHo m, was obtained at 298.02 K, 303.04 K and 310.01 K. The determination relied on isothermal microcalorimetry measurements and on a thermochemical scheme that, in contrast with previous strategies, does not require kinetic information. The results obtained were DrHo m = (50.99 +- 0.61) kJ mol 1 at 298.02 K, DrHo m = (50.60 +- 0.82) kJ mol 1 at 303.04 K, and DrHo m = (49.64 +- 0.90) kJ mol 1 at 310.01 K. The DrHo m value at 298 K is in very good agreement with the previously recommended benchmark at this temperature. The current procedure allowed, however, a 7-fold improvement in precision. It was also found that the DrHo m values show a linear variation with temperature. The fact that this variation is small lends support to the previous assumption of a negligible temperature dependency of DrHo m around 298 K. The present work resolves some important discrepancies in the reported standard molar enthalpies of the base catalysed hydrolysis of methyl paraben. Such inconsistencies can have a considerable impact on the determination of the effective volume of flow-through calorimetric apparatus. This parameter is essential to obtain kinetic and thermodynamic information on the growth, metabolism, and adaptation of living cells from flow calorimetry experiments.

Compounds

#	Formula	Name
1	CH4O	methanol
2	HNaO	sodium hydroxide
3	C7H4Na2O3	disodium 4-hydroxybenzoate
4	H2O	water
5	C8H8O3	methyl 4-hydroxybenzoate

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	5	Normal melting temperature, K ; Crystal		Crystal Liquid Air at 1 atmosphere	DTA	1
POMD	5	Molar enthalpy of transition or fusion, kJ/mol ; Crystal		Crystal Liquid Air at 1 atmosphere	DSC	1
POMD	5	Mass density, kg/m3 ; Crystal	Temperature, K; Crystal Pressure, kPa; Crystal	Crystal	X-ray diffraction	1
RXND	1 5 2 3 4	Molar enthalpy of reaction, kJ/mol			Solution calorimetry	1
RXND	1 5 2 3 4	Molar enthalpy of reaction, kJ/mol			Solution calorimetry	1
RXND	1 5 2 3 4	Molar enthalpy of reaction, kJ/mol			Solution calorimetry	1

Thermodynamics Research Center / ThermoML | Journal of Chemical Thermodynamics

The standard molar enthalpy of the base catalysed hydrolysis of methyl paraben revisited

Bento, R. N.[Rafael N.], Rendas, M. A.[Miguel A.], Semedo, V. A. R.[Valdir A. R.], Bernardes, C. E. S.[Carlos E. S.], Santos, M. S. C. S., Diogo, H. P.[Herminio P.], Antunes, F.[Fernando], Piedade, M. E. M. d.[Manuel E. Minas da]

ABSTRACT