Synthesis, characterization and thermochemical properties of N-acyl-N ',N '-diethylthioureas

Citation
Mavr. Da Silva et al., Synthesis, characterization and thermochemical properties of N-acyl-N ',N '-diethylthioureas, J CHEM S P2, (11), 2001, pp. 2174-2178
Citations number
39
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Physical Chemistry/Chemical Physics
Journal title
JOURNAL OF THE CHEMICAL SOCIETY-PERKIN TRANSACTIONS 2
ISSN journal
1472-779X → ACNP
Issue
11
Year of publication
2001
Pages
2174 - 2178
Database
ISI
SICI code
1472-779X(200111):11<2174:SCATPO>2.0.ZU;2-G
Abstract
Three N-acyl-N',N'-diethylthioureas, RCONHCSNEt2. R = Pr-1, Bu-1, Bu-1, hav e been prepared and characterised. The standard (p(o) = 0.1 MPa) molar enth alpies of combustion in oxygen of the three crystalline compounds, at T = 2 98.15 K. have been measured by rotating bomb-combustion calorimetry. and th e standard molar enthalpies of sublimation of the compounds by microcalorim etry. These values were used to derive the standard molar enthalpies of for mation of the compounds in their crystalline and gaseous phases, respective ly. The derived standard molar enthalpies of formation in the gaseous state are discussed comparatively. Acid constants and some complex stabilities h ave been measured pH-potentiometrically in dioxane-water mixture. The cryst al structure of N,N-diethyl-N'-isovaleroyl-thiourea is presented and shows a delocalization of the pi electrons of the C=S group over the carbon-amine nitrogen bond. CS-NEt2 stabilising the molecule, in accordance with the th ermochemical results.