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Heats of combustion of normal saturated fatty acids and their methyl esters

Heats of combustion of normal saturated fatty acids and their methyl esters

Authors :
H. Dekker
N. Adriaanse
J. Coops
Source :
Recueil des Travaux Chimiques des Pays-Bas. 84:393-407
Publication Year :
2010
Publisher :
Wiley, 2010.

Abstract

Accurate heats of combustion of the title compounds were measured in an electrically calibrated calorimeter; the liquid samples were burned in Pyrex ampoules; the water content in the samples was titrated by the Karl Fischer method. The increment of the standard enthalpy of combustion, -ΔHR25liq. (=-ΔHC0liq.) for one CH2 group in the chain proved to be 653.8 kj/mole for both the acids and the methyl esters studied, which is the same value as determined for the liquid paraffins. The following formulae, in which c = the number of carbon chain atoms (c > 5) can be used to calculate the standard enthalpies of combustion (based on the 1951 atomic weights): -ΔHliq. = 653.8 c − 430.2 kj/mole for the acids, accurate to 0.03 − 0.04%, -ΔHliq. = 653.8 c + 292.6 kj/mole for the methyl esters, accurate to 0.02%. The theoretical heat of esterification of a fatty acid with methanol at 25 °C, disregarding heats of solution and dilution, was calculated to be 3.8 ° 0.6 kj/mole, which can be compared with the value of 4.2 ° 0.3 kj/mole for the theoretical heat of esterification of acetic acid with ethanol at about 20 °C, determined directly by Mme Berenger-Calvet.

Details

ISSN :
01650513
Volume :
84
Database :
OpenAIRE
Journal :
Recueil des Travaux Chimiques des Pays-Bas
Accession number :
edsair.doi...........250987a406dd60fa5ea207da5cd49424
Full Text :
https://doi.org/10.1002/recl.19650840316