Experimental and Theoretical Study of the Structures and Enthalpies of Formation of the Synthetic Reagents 1,3-Thiazolidine-2-thione and 1,3-Oxazolidine-2-thione

Abstract

This paper reports an experimental and a theoretical study of the structures and standard (p(o) = 0.1 MPa) molar enthalpies of formation of the synthetic reagents 1,3-thiazolidine-2-thione [CAS 96-53-7] and 1,3-oxazolidine-2-thione [CAS 5840-81-3]. The enthalpies of combustion and sublimation were measured by rotary bomb combustion calorimetry, and the Knudsen effusion technique and gas-phase enthalpies of formation values at T = 298.15 K of (97.1 +/- 4.0) and -(74.4 +/- 4.6) kJ.mol(-1) for 1,3-thiazolidine-2-thione and 1,3-oxazolidine-2-thione, respectively, were determined. G3-calculated enthalpies of formation are in reasonable agreement with the experimental values. In the solid state, 1,3-thiazolidine-2-thione exists in two polymorphic forms (monoclinic and triclinic) and 1,3-oxazolidine-2-thione exits in the triclinic form. The isostructural nature of these compounds and comparison of their molecular and crystal structures have been analyzed. The experimental X-ray powder diffractograms have been compared with the calculated patterns from their structures for identification of the polymorphic samples used in this study. A comparison of our results with literature thermochemical and structural data for related compounds is also reported.

Experimental and computational thermochemical studies of benzoxazole and two chlorobenzoxadole derivatives

“…Results of a typical experiment of each compound are presented in table 2; Dm(H 2 O) is the deviation of the mass of water added to the calorimeter from 2900.0 g or 5222.5 g, depending of the calorimeter used; DU P is the energy correction to the standard state; DU(IBP) is the internal energy for the isothermal bomb process calculated according to equation (12). The remaining terms have been previously described [41,42].…”

“…Hilal et al [10] have computed the proton affinities of benzoxazole and benzothiazole. More recently, several other experimental and computational studies have also been described in the literature for 2-benzoxazolinone and 2-benzimidazolinone [11], 1,3-oxazolidine-2-thione [12] and 3H-1,3-benzoxazole-2-thione [13]. Gomes et al [14] estimated the enthalpy of formation of benzoxazole from B3LYP calculations and presented a value more than 10 kJ Á mol À1 lower than that from the experiments [9].…”

Experimental and computational study of the energetics of hydantoin and 2-thiohydantoin

“…Experimental and computational studies for compounds with pentagonal ring cores, with two nitrogen atoms or a nitrogen and an oxygen or sulfur as heteroatoms, in the positions 1,3-, has been studied recently [5][6][7][8]. Other studies on the energetic of five-membered nitrogen heterocycles fused to a benzenic ring [9][10][11] have been also described in the recent literature.…”

Interplay of thermochemistry and Structural Chemistry, the journal (volume 16, 2005) and the discipline

“…There are surprisingly few thiazolidines for which enthalpies of formation have been determined. These include a penicillin derivative [28] and thiazolidine-2-thione [29]. Enthalpies of ring-chain isomerism of thiazolidines have been studied in [30].…”

“…There are surprisingly few species containing this group for which the enthalpy of formation is known. For a discussion of the enthalpy of formation of oxazolidinone and two of its sulfur-containing analogs, the reader is addressed to the recent calorimetric study [29].…”