Theoretical study of structure, vibrational and electronic spectra of isomers of methyl-3-methoxy-2-propenoate
A systematic quantum mechanical study of the possible conformations, their relative stabilities, vibrational and electronic spectra and thermodynamic parameters of methyl-3-methoxy-2-propenoate has been reported for the electronic ground (S0) and first excited (S1) states using time-dependent and time-independent Density Functional Theory (DFT) and RHF methods in extended basis sets. Detailed studies have been restricted to the E-isomer, which is found to be substantially more stable than the Z-isomer. Four possible conformers c′Cc, c′Tc, t′Cc, t′Tc, of which the first two are most stable, have been identified in the S0 and S1 states. Electronic excitation to S1 state is accompanied with a reversal in the relative stability of the c′Cc and c′Tc conformers and a substantial reduction in the rotational barrier between them, as compared with the S0 state. Optimized geometries of these conformers in the S0 and S1 states are being reported. Based on suitably scaled RHF/6-31G** and DFT/6-311G** calculations, assignments have been provided to the fundamental vibrational bands of both these conformers in terms of frequency, form and intensity of vibrations and potential energy distribution across the symmetry coordinates in the S0 state. A complete interpretation of the electronic spectra of the conformers has been provided.
-  W.O. George, D.V. Hassid and W.F. Maddams: “Conformationals of some αβ-unsaturated carbonyl compounds. Part III. Infrared solution spectra of methyl, [2H3] methyl, ethyl, and [2H5] ethyl acrylates and trans-crotonates”, J. Chem. Soc. Perkin II, (1972), pp. 400–404.
-  A.J. Bowles, W.O. George and D.B. Cunliffe-Jones: “Conformations of some αβ-unsaturated carbonyl compounds. Part II. Infrared and Raman Spectra of methyl and ethyl acrylate and trans-crotonate”, J. Chem. Soc (B), (1970), pp. 1070–1075. [Crossref]
-  V. Santhanam, S. Singh and J. Sobhanadri: “Conformational analysis of some acrylates using dipole moment calculations by CNDO/Force method”, Tetrahedron, Vol. 39, No. 24, (1983), pp. 4183–4187. http://dx.doi.org/10.1016/S0040-4020(01)88638-5[Crossref]
-  T. Egawa, S. Maekawa, H. Fujiwara, H. Takeuchi and S. Konaka: “Molecular structure and conformation of methyl acrylate. A gas electron diffraction study augmented by ab initio calculation and rotational constants”, J. Mol. Struct. (Theochem), Vol. 352/353, (1995), pp. 193–201.
-  M.L.M. Rocco, M.C.A. Lopes, C.A. Lucas, E. Hollauer, E.E. Monteiro and G.G.B. de Souza: “Excitation of the methyl methacrylate molecule in the VUV range by angle-resolved EELS”, Chem. Phys., Vol. 223, (1997), pp. 15–21. http://dx.doi.org/10.1016/S0301-0104(97)00227-9[Crossref]
-  E. Hollauer, M.L.M. Rocco, M.C.A. Lopes and G.G.B. de Souza: “An ab initio study of the valence excitation of methyl methacrylate as observed by EELS”, J. Electron Spectrosc. Relat. Phenom., Vol. 104, (1999), pp. 31–39. http://dx.doi.org/10.1016/S0368-2048(99)00011-0[Crossref]
-  A. Virdi, A. Sharma and V.P. Gupta: “Molecular orbital study of torsional potentials, physicochemical properties and electronic spectra of methyl acrylate in different electronic states”, Indian J. Phys., Vol. 75B, No. 6, (2001), pp. 509–514.
-  A. Virdi, V.P. Gupta and A. Sharma: “Ab initio studies on conformation, vibrational and electronic spectra of methyl methacrylate”, J. Mol. Struct. (Theochem), Vol. 634, (2003), pp. 53–65. http://dx.doi.org/10.1016/S0166-1280(03)00244-6[Crossref]
-  A. Virdi, V.P. Gupta and A. Sharma: “Molecular structure, conformation, vibrational and electronic spectra of methyl trans crotonate”, J. Mol. Struct. (Theochem), Vol. 678, (2004), pp. 239–247. http://dx.doi.org/10.1016/j.theochem.2004.02.046[Crossref]
-  K. Topek, V. Vsetecka and M. Prochazka: “(E-Z)-isomerization of 3-substituted methyl 2-propenoates”, Collect. Czech. Chem. Commun., Vol. 43, (1978), pp. 2395–2402.
-  V. Vsetecka, J. Pecka and M. Prochazka: “(E-Z)-isomerization of unsaturated esters X−CH=CH−COOCH3”, Collect. Czech. Chem. Commun., Vol. 47, (1982), pp. 277–285.
-  P. Pulay, G. Fogarasi, G. Pongor, J.E. Boggs and A. Vargha: “Combination of theoretical ab initio and experimental information to obtain reliable harmonic force constants. Scaled quantum mechanical (SQM) force fields for glyoxal, acrolein, butadiene, formaldehyde and ethylene”, J. Am. Chem. Soc., Vol. 105, (1983), pp. 7037–7047. http://dx.doi.org/10.1021/ja00362a005[Crossref]
-  J. Baker, A.A. Jarzecki and P. Pulay: “Direct scaling of primitives valence force constants: An alternative approach to scaled quantum mechanical force fields”, J. Phys. Chem. A, Vol. 102, (1998), pp. 1412–1424. http://dx.doi.org/10.1021/jp980038m[Crossref]
-  R.E. Stratmann and G.E. Scuseria: “An efficient implementation of time-dependent density-functional theory for the calculation of excitation energies of large molecules”, J. Chem. Phys., Vol. 109, (1998), pp. 8218–8224. http://dx.doi.org/10.1063/1.477483[Crossref]
-  M.J. Frisch, G.W. Trucks, H.B. Schlegel, G.E. Scuseria, M.A. Robb, J.R. Cheeseman, V.G. Zakrzewski, J.A. Montgomery, Jr., R.E. Stratmann, J.C. Burant, S. Dapprich, J.M. Millam, A.D. Daniels, K.N. Kudin, M.C. Strain, O. Farkas, J. Tomasi, V. Barone, M. Cossi, R. Cammi, B. Mennucci, C. Pomelli, C. Adamo, S. Clifford, J. Ochterski, G.A. Petersson, P.Y. Ayala, Q. Cui, K. Morokuma, P. Salvador, J.J. Dannenberg, D.K. Malick, A.D. Rabuck, K. Raghavachari, J.B. Foresman, J. Cioslowski, J.V. Ortiz, A.G. Baboul, B.B. Stefanov, G. Liu, A. Liashenko, P. Piskorz, I. Komaromi, R. Gomperts, R.L. Martin, D.J. Fox, T. Keith, M.A. Al-Laham, C.Y. Peng, A. Nanayakkara, M. Challacombe, P.M.W. Gill, B. Johnson, W. Chen, M.W. Wong, J.L. Andres, C. Gonzalez, M. Head-Gordon, E.S. Replogle and J.A. Pople: Computer Program Gaussian98, Gaussian, Inc., Pittsburgh PA, 2001.
-  M.W. Schmidt, K.K. Baldridge, J.A. Boatz, S.T. Elbert, M.S. Gordon, J.H. Jensen, S. Koseki, N. Matsunaga, K.A. Nguyen, S.J. Su, T.L. Windus, M. Dupuis and J.A. Montgomery: “Computer Program GAMESS”, J. Comput. Chem., Vol. 14, (1993), pp. 1347–1369. http://dx.doi.org/10.1002/jcc.540141112[Crossref]
-  S. Thakur, V.P. Gupta and B. Ram: “Semi-empirical calculation and normal coordinate study of the conformation and electronic and vibrational spectra of acrolein”, Spectrochimica Acta A, Vol. 53, (1997), pp. 749–759. http://dx.doi.org/10.1016/S1386-1425(96)01733-7[Crossref]
-  S. Thakur and V.P. Gupta: “Quantum mechanical study of the electronic spectra, torsional potential and physico-chemical properties of rotational conformers of methyl vinyl ketone in different electronic states”, Indian J. Phys., Vol. 73B, No. 4, (1999), pp. 651–659.
-  G. Buemi and F. Zuccarello: “Molecular orbitals and ionization potentials of α,β-unsaturated carbonyl compounds”, Gazzetta Chimica Italian, Vol. 113, (1983), pp. 865–868.
-  H. Yoshida, K. Takeda, J. Okamura, A. Ehara and H. Matsuura: “A new approach to vibrational analysis of large molecules by Density Functional Theory: Wavenumber-Linear scaling method”, J. Phys. Chem. A, Vol. 106, (2002), pp. 3580–3586. http://dx.doi.org/10.1021/jp013084m[Crossref]
-  H. Yoshida, A. Ehara and H. Matsuura: “Density functional vibrational analysis using wavenumber-linear scale factors”, Chem. Phys. Lett., Vol. 325, (2000), pp. 477–483. http://dx.doi.org/10.1016/S0009-2614(00)00680-1[Crossref]
-  M. Dulce, G. Faria, J.J.C. Teixeira-Dias and R. Fausto: “Vibrational spectra and structure of methyl trans-crotonate”, Vibrational Spectr., Vol. 2, (1991), pp. 107–123. http://dx.doi.org/10.1016/0924-2031(91)85017-H[Crossref]
-  E. Winterfeldt and H. Preuss: “Addition to the triple bond V. Steric course of additions to the triple bond”, Chem. Ber., Vol. 99, No. 2, (1966), pp. 450–458.
-  H.O. House, W.L. Roelofo and B.M. Trost: “The chemistry of carbanions. XI. Michael reactions with 2-methylcyclopentanone and 2-methylcyclohexanone”, J. Org. Chem., Vol. 31, (1966), pp. 646–655.