The structure and thermochemistry of 3:4,5:6-dibenzo-2-hydroxymethylene-cyclohepta-3,5-dienenone (1) and some related compounds

Abstract

Condensed and gas phase enthalpies of formation of 3:4,5:6-dibenzo-2-hydroxymethylene-cyclohepta-3,5-dienenone (1, f H • m ( − 199.1 ± 16.4), ( − 70.5 ± 20.5) kJ mol −1 , respectively) and 3,4,6,7-dibenzobicyclo[3.2.1] nona-3,6-dien-2-one (2, ( − 79.7 ± 22.9), (20.1 ± 23.1) kJ mol −1 ) are reported. Sublimation enthalpies at T = 298.15 K for these compounds were evaluated by combining the fusion enthalpies at T = 298.15 K (1, (12.5 ± 1.8); 2, (5.3 ± 1.7) kJ mol −1 ) adjusted from DSC measurements at the melting temperature (1, (T fus , 357.7 K, 16.9 ± 1.3 kJ mol −1 )); 2, (T fus , 383.3 K, 10.9 ± 0.1) kJ mol −1 ) with the vaporization enthalpies at T = 298.15 K (1, (116.1 ± 12.1); 2, (94.5 ± 2.2) kJ mol −1 ) measured by correlation-gas chromatography. The vaporization enthalpies of benzoin ((98.5 ± 12.5) kJ mol −1 ) and 7-heptadecanone ((94.5 ± 1.8) kJ mol −1 ) at T = 298.15 K and the fusion enthalpy of phenyl salicylate (T fus , 312.7 K, 18.4 ± 0.5) kJ mol −1 ) were also determined for the correlations. The crystal structure of 1 was determined by X-ray crystallog-

Experimental and computational thermochemistry: how strong is the intramolecular hydrogen bond in alkyl 2-hydroxybenzoates (salicylates)

“…However, as discussed in Section 3.1, the reason for this discrepancy lies in the few incorrect pressures that Kahlbaum measured at the lower and upper temperatures. It should also be noted that the enthalpies of vaporisation derived for this compound by correlation with gas chromatography [29][30][31] are systematically somewhat higher than those determined by conventional methods. The reason for this discrepancy is that the correlations made in these papers are based on the data set of alkyl parabens by Perlovich et al 33 However, as shown in our earlier work, 22 this data set is in conflict with other data available for alkyl parabens.…”

Revision and Extension of a Generally Applicable Group-Additivity Method for the Calculation of the Standard Heat of Combustion and Formation of Organic Molecules

“…An especially extended amount of research has been done with hydrocarbons including alkanes, alkenes, alkynes, and aromatics , forming the core of the various carbon groups. In addition, many data have dealt specifically with alcohols and phenol derivatives [61][62][63][64][65][66][67][68][69][70][71][72][73][74], ethers [75][76][77][78][79][80][81][82][83][84], carbaldehydes [85][86][87][88][89][90][91][92][93][94], ketones [95][96][97][98][99][100][101][102][103][104][105][106][107][108][109]...…”

Interplay of thermochemistry and Structural Chemistry, the journal (volume 17, 2006) and the discipline

“…The next paper by Perişanu et al [357] is a continuation of the work on thermochemical properties of dibenzocycloalkane derivatives [358] and deals with the structure and thermochemistry of 3:4,5:6-dibenzo-2-hydroxymethylene-cyclohepta-3,5-dienenone and 3,4,6,7-dibenzobicyclo[3.2.1]nona-3,6-dien-2-one. Condensed and gas phase enthalpies of formation are reported as well as the finding that the former compound exists entirely in the enol form.…”