title: Conformational equilibrium of phenylacetic acid and its halogenated analogues through theoretical studies, NMR and IR spectroscopy.
abstract: This paper presents a study on the conformational preferences of phenylacetic acid (PA) and its halogenated analogues (FPA, CPA, BPA). To clarify the effects that rule these molecules' behaviour, theoretical calculations were used, for both the isolated phase and solution, combined with nuclear magnetic resonance (NMR) and infrared (IR) spectroscopy. Most conformations of phenylacetic acid and its halogenated derivatives are stabilized through the hyperconjugative effect, which rules the conformational preference. NMR analyses showed that even with the variation in medium polarity, there was no significant change in the conformation population. Infrared spectroscopy showed similar results for all compounds under study. In most spectra, two bands were found through the carbonyl deconvolution, which is in accordance with the theoretical data. It was possible to prove that variation in the nature of the substituent in the ortho position had no significant influence on the conformational equilibrium.
authors.affiliation: Departamento de Química, Universidade Estadual de Ponta Grossa/UEPG, Av. General Carlos Cavalcanti 4748, 84030-900 - Ponta Grossa, PR, Brazil.
authors.forename: Mariana N
authors.initials: MN
authors.lastname: Levandowski
authors.affiliation: Departamento de Química, Universidade Estadual de Ponta Grossa/UEPG, Av. General Carlos Cavalcanti 4748, 84030-900 - Ponta Grossa, PR, Brazil.
authors.forename: Thiago C
authors.initials: TC
authors.lastname: Rozada
authors.affiliation: Departamento de Química, Universidade Estadual de Maringá/UEM, Av. Colombo 5790, 87020-900 - Maringá, PR, Brazil.
authors.forename: Ulisses Z
authors.initials: UZ
authors.lastname: Melo
authors.affiliation: Departamento de Química, Universidade Estadual de Maringá/UEM, Av. Colombo 5790, 87020-900 - Maringá, PR, Brazil.
authors.forename: Ernani A
authors.initials: EA
authors.lastname: Basso
authors.affiliation: Departamento de Química, Universidade Estadual de Ponta Grossa/UEPG, Av. General Carlos Cavalcanti 4748, 84030-900 - Ponta Grossa, PR, Brazil. Electronic address: bcfiorin@uepg.br.
authors.forename: Barbara C
authors.initials: BC
authors.lastname: Fiorin
keywords: Conformational analysis; Infrared spectroscopy; NMR spectroscopy; Phenylacetic acid; Theoretical calculations