Search

A conformational search of the flexible 2-hedroxyethyl methacrylate molecule by semi-empirical AM1 and B3LYP formalisms leads to six stable conformations. Four of them are in the s-trans conformation. The optimized geometries at DFT using 6-311+G(∗∗) basis set are in good agreement with experimental electron diffraction data of the methyl methacrylate molecule, thereby the s-trans is the most stable form. The harmonic frequencies at the fully optimized geometries of all conformers have been performed at the DFT//B3LYP/6-311+G(∗∗) level of theory. Infrared and Raman intensities and potential energy distributions of the scaled harmonic frequencies are used for the assignment of the observed IR and Raman bands. We noticed a good agreement between the experimental and the computed spectra. The strong band at 1081 cm(-1), in the infrared spectrum, maybe used as a characteristic band of the s-trans conformation. Henceforth, the less stable structure contribute alone for reproducing the Raman bands located at 276 (sh) and 3020 (vw) cm(-1).

2-Hydroxyethyl acrylate is generally used with other acrylic and methacrylic products in order to get the desired characteristics of the final product. In this work we are about to make an assignment of experimental infrared bands with the help of a theoretical quantum chemistry calculations. The exact knowledge of some bands which are not characteristics of acrylic materials will enable us to make a quick analysis with available techniques of low costs for mixtures of polymers based on acrylate and methacrylate molecules. In the experimental part, the infrared spectrum of 2-hydroxyethyl acrylate is obtained by using a FTIR Perkin Elmer model 2000. In the computational part and as first step, the theoretical calculations are performed by the semi-empirical AM1 method for excluding similar structures of 2-hydroxyethyl acrylate molecule by a meticulous conformational analysis. As a second step the obtained structures are optimized using DFT. The simulated frequencies are then scaled and a tentative assignment is made based on band intensities and PED percentages. The theoretical calculations predict the existence of thirteen conformations two of them represent the majority of experimental bands in the infrared spectrum. Two neighbor experimental bands located at 1301 and 1207 cm−1 maybe used as characteristic bands to locate and distinguish the existence of one or both conformations.