The Fourier transform infrared spectra (FTIR) of 2-ethylhexyl acrylate have been measured in liquid phase. The molecular geometry, vibrational frequencies, and infrared intensities have been calculated by using density functional theory. We found two local minima representing s-cis and s-trans conformations for 2-ethylhexyl acrylate molecule. The optimized geometries at DFT//B3LYP/6-311+ are in good agreement with electron diffraction data of methyl acrylate for the acrylic group. The two conformers were used for the interpretation of the experimental infrared spectrum of title compound. PED calculations are represented for a more complete and concise assignment. There is one band in the infrared spectrum at 1646？cm？1 that definitely indicates the conformer with s-trans arrangement of acrylic moiety to be present or not in the liquid 2-ethylhexyl acrylate. 1. Introduction Alkyl acrylates are important monomers used in the manufacture of polymers and copolymers. Acrylates give polymers exhibiting outstanding transparency and aging proprieties which have made them of interest in a wide variety of applications [1–4]. The structural data and the preferred molecular conformation of these acrylates molecules would be important for basic understanding of these polymers [5]. 2-Ethylhexyl acrylate is used for production of paint, adhesive, and paper coating trade. This monomer imparts flexibility and water resistance to the polymers [1, 6]. It is also used for curing polymeric materials [7–15]. To our best knowledge no structural data or detailed interpretation of the vibrational spectra of 2-ethylhexyl acrylate is presented in the literature. This prompted us to look into the vibrational spectroscopy of 2-ethylhexyl acrylate more carefully. Many reports, experimental [16–21] and theoretical [20, 22], show that acrylates and related compounds exhibit rotational isomerism with the planar s-trans and s-cis heavy-atom structures being the energetically most stable conformations. However, uncertainty continues to exist regarding the relative stability of the two conformers. Gas electron diffraction studies on methyl methacrylate [20] suggested the cis/trans ratios to be equal to 2？:？1. On the other hand, the IR spectrum of methyl methacrylate in Ar low temperature matrix suggested an inverse ratio [23]. Many experimental and theoretical studies on methyl acrylate reported that the s-cis conformer is more stable than the s-trans conformer [24–29]. However, Bowles et al. [30] assumed that the s-trans conformer is more stable. 2. Experimental 2-Ethylhexyl acrylate
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