Vapour pressures, enthalpies and entropies of sublimation of trans-cinnamic acid and of nine methoxy and dimethoxycinnamic acids

• Type: Article in International Scientific Journal
• Date: 1999

Authors

Monte, MJS (Author) FCUP; Hillesheim, DM (Author) Other

Journal

Title: Journal of Chemical Thermodynamics

Vol. 31

Pages: 1443-1456

ISSN: 0021-9614

Publisher: Elsevier

Indexing

ISI Web of Knowledge - 28 Citations

Scopus - 27 Citations

Scientific classification

FOS: Engineering and technology > Mechanical engineering

Other information

Authenticus ID: P-001-2ZS

DOI: 10.1006/jcht.1999.0540

Abstract (EN): The Knudsen mass-loss effusion technique was used to measure the vapour pressure as a function of temperature for trans-cinnamic acid and nine substituted methoxy and dimethoxy cinnamic acids. From the temperature dependence of the vapour pressure the standard molar enthalpies and entropies of sublimation, at 298.15 K, were calculated for all the studied compounds using the estimated value Delta(cr)(g)c(p,m)(o) = -50 J.K-1.mol(-1). The results obtained for trans-cinnamic acid and for the trans-methoxy and trans-dimethoxy cinnamic acids together with literature results for benzoic acid and substituted methoxy and dimethoxy benzoic acids allowed us to derive the correlation: Delta(cr)(g)H(m)(o){T(p = 0.5 Pa)}/(kJ.mol(-1)) = (0.623 +/- 0.026).{T(p = 0.5 Pa)/K} + (-106.3 +/- 9.4) where T(p = 0.5 Pa) is the temperature at which the equilibrium vapour pressure of each crystalline compound is 0.5 Pa. (C) 1999 Academic Press.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 14