Matrix Isolation Low Temperature Solid State FTIR Spectroscopy Study of Methyl 4-Chloro-5-Phenylisoxazole-3-Carboxylate

SUSY LOPES, ANDREA GÓMEZ-ZAVAGLIA, RUI FAUSTO.

Luso, Portugal

Congreso; 8º Encontro Nacional da Sociedade Portuguesa de Química.; 2007

Sociedade Portuguesa de Quimica

Isoxazoles are a class of heterocyclic compounds which have a number of important pharmaceutical applications that vary from antiallergic, anti-inflammatory, analgesic to antitumor activity. On the other hand, the agricultural uses of isoxazole derivatives include herbicidal, insecticidal and soil fungicidal activity. Isoxazoles have also been used as semiconductors, as corrosion inhibitors in fules and lubricants and in the production of photographic and liquid crystalline materials [1]. In this study, methyl 4-chloro-5-phenylisoxazole-3-carboxylate (MCPIC) has been synthesized and its monomeric structure has been studied by Matrix Isolation FTIR spectroscopy (argon, xenon matrices) and for the compound in the condensed phases: neat amorphous and crystalline solid states, supported by DFT(B3LYP)/6-311++G(d,p) calculations. Matrices were irradiated using a standard Hg(Xe) lamp as UV-light (l > 235 nm) and annealing of the matrices was also carried out. Theoretical calculations were undertaken using the Gaussian 98 (Revision A.9) program. High-level theoretical DFT calculations predicted the existence of three different conformations with energy differences smaller than 5 kJ mol-1 in the ground state potential energy surface. The theoretical calculations predicted the two higher energy forms being 3.87 and 4.22 kJ mol-1 higher in energy than the most stable form, respectively.