Conformational analysis of alkoxyalcohols A combined IR and molecular mechanics study

Abstract

The conformational behaviour of one branched and three linear alkoxyalcohols has been investigated by IR spectroscopy and molecular mechanics (MM). The OH-stretching region (3750–3150 cm^-1) has been studied in dilute apolar solution. In the MM calculations, for each compound all unique staggered conformations have been analysed, both with and without contributions to the steric energy from rotational and vibrational energy and entropy. The corrections enhance the amount of non-bonded conformers and significantly improve the agreement between theoretical and experimental populations. Calculated H-bond geometries are seen to be related with observed OH-stretching vibrations. The agreement between theoretical and experimental frequency shifts (Δ[small nu, Greek, tilde]_OH, i.e. the difference between free and bonded) is poor, especially for short H-bond contacts, thus making calculated OH-stretching frequencies unsuitable for assignment purposes.

References

1. M. H. Langoor and J. H. van der Maas, J. Mol. Struct., 1997, 403, 213.
2. M. H. Langoor and J. H. van der Maas, Vib. Spectrosc., 1997, 14, 261.
3. H. Yoshida, K. Takikawa, K. Ohno and H. Matsuura, J. Mol. Struct., 1993, 299, 141.
4. B. T. Luke, J. Comput. Chem., 1994, 15, 1176.
5. F. P. S. C. Gil, R. Fausto, A. M. A. Dacosta and J. J. C. Teixeira-Dias, J. Chem. Soc., Faraday Trans., 1994, 90, 689.
6. S. Reiling, J. Brickmann, M. Schlenkrich and P. A. Bopp, J. Comput. Chem., 1996, 17, 133.
7. C. J. Cramer and D. G. Truhlar, J. Am. Chem. Soc., 1994, 116, 3892.
8. B. J. Teppen, M. Cao, R. F. Frey, C. van Alsenoy, D. M. Miller and L. Schafer, J. Mol. Struct. (THEOCHEM), 1994, 120, 169.
9. M. Traetteberg and K. Hedberg, J. Am. Chem. Soc., 1994, 116, 1382.
10. L. Pichat, C. Baret and M. Audinot, Bull. Soc. Chim. Fr., 1956, 151.
11. F. A. J. Singelenberg, E. T. G. Lutz and J. H. van der Maas, Appl. Spectrosc., 1986, 40, 1093.
12. MacProlog 4.0, Logic Programming Associates Ltd, London, 1991.
13. N. L. Allinger, Y. H. Yuh and J.-H. Lii, J. Am. Chem. Soc., 1989, 111, 8551.
14. N. L. Allinger, M. Rahman and J.-H. Lii, J. Am. Chem. Soc., 1990, 112, 8293.
15. J.-H. Lii and N. L. Allinger, J. Am. Chem. Soc., 1989, 111, 8566.
16. D. McQuarrie, Statistical Mechanics, Harper and Row, New York, 1976.
17. L. S. Prabhumirashi and C. I. Jose, J. Chem. Soc., Faraday Trans. 2, 1975, 71, 1545.
18. F. A. J. Singelenberg and J. H. van der Maas, J. Mol. Struct., 1991, 243, 111.
19. A. B. Foster, A. H. Haines and M. Stacey, Tetrahedron, 1961, 16, 177.
20. L. P. Kuhn and R. A. Wires, J. Am. Chem. Soc., 1964, 86, 2161.
21. P. J. Krueger and H. D. Mettee, J. Mol. Spectrosc., 1965, 18, 131.
22. S. Vazquez, R. A. Mosquera, M. A. Rios and C. van Alsenoy, J. Mol. Struct. (THEOCHEM), 1989, 188, 95.
23. F. A. J. Singelenberg, J. H. van der Maas and L. M. J. Kroon-Batenburg, J. Mol. Struct., 1991, 245, 183.
24. J.-H. Lii and N. L. Allinger, J. Phys. Org. Chem., 1994, 7, 591.
25. L. S. Prabhumirashi and C. I. Jose, J. Chem. Soc., Faraday Trans. 2, 1978, 74, 255.
26. F. A. J. Singelenberg and J. H. van der Maas, J. Mol. Struct., 1990, 240, 213.
27. J. P. Hawranek and M. A. Broda, Chem. Phys. Lett., 1983, 98, 373.
28. J. H. van der Maas and E. T. G. Lutz, Spectrochim. Acta, Part A, 1982, 38, 927.
29. F. G. Dijkman, Mol. Phys., 1978, 36, 705.
30. W. J. Hehre, L. Radom, P. von Ragué Schleyer and J. A. Pople, Ab Initio Molecular Orbital Theory, John Wiley & Sons, New York, 1986.
31. L. S. Prabhumirashi, J. Chem. Soc., Faraday Trans. 2, 1978, 74, 1567.
32. L. P. Kuhn, J. Am. Chem. Soc., 1952, 74, 2492.
33. J. C. Caballero, C. Bruynes and J. H. van der Maas, J. Mol. Struct., 1986, 147, 243.
34. J. C. Caballero and J. H. van der Maas, J. Mol. Struct., 1985, 127, 57.
35. I. A. Koppel and A. I. Paju, Org. React. (Tartu), 1974, 11, 121.
36. J. G. C. M. van Duijneveldt-van de Rijdt, F. B. van Duijneveldt, J. A. Kanters and D. R. Williams, J. Mol. Struct. (THEOCHEM), 1984, 109, 351.