Systematic evaluation of the conformational properties of aliphatic omega-methoxy methyl esters.
[structure: see text] A systematic conformational study of omega-methoxy methyl esters, CH(3)O-(CH2)n-COO-CH3 with n = 3 and 4, has been performed using quantum mechanical calculations at the MP2 level. Calculations have been carried out in both gas phase and chloroform solution, a polarizable continuum solvation model being used to represent the latter. Results have been compared with those recently obtained for the analogues omega-hydroxy acids, HO-(CH2)n-COOH with n = 3 and 4. The compounds with n = 3 clearly favor coiled conformations, the population expected for extended and semiextended conformations being very low. However, for compounds with n = 4 the minimum energy extended and semiextended structures become considerably more stable. The overall results indicate that the conformational preferences of the central aliphatic segment of omega-methoxy methyl esters and omega-hydroxy acids are not influenced by the formation of intramolecular O-H...O hydrogen bonds.
Alemán
Carlos
C
Departament d'Enginyeria Química, E.T.S. d'Enginyeria Industrial de Barcelona, Universitat Politècnica de Catalunya, Diagonal 647, Barcelona E-08028, Spain. carlos.aleman@upc.edu
Casanovas
Jordi
J
Hall
H K
HK