Application of Conformational Analysis to Cycloalkanes

Stereochemistry of Carbon Compounds McGraw-Hill New York, 1%2 p. 189. 

Electron diffraction measurements suggest that the preferred conformation of cyclohexane is a somewhat flattened chair, with C—C—C bond angles of 111° and torsional angles of 55.9°. For a review of cyclohexane data, see Osawa, E. Collins J. B. Schleyer, P. v. R. Tetrahedron 1977,33,2667. See also Dommen, J. Brupbacher, T. Grassi, G. Bauder, A. /. Am. Chem. Soc. 1990,112,953. For a theoretical analysis, see reference 38. 

Sauers, R. R. /. Chem. Educ. 2000,77,332 reported a density functional calculation indicating that those hydrogens are about 2.5 A apart and thus contribute only minimally to the twist boat— boat-twist boat barrier. 

Kekul Baeyer model of cyclohexane. (Adapted from reference 57.) 

Bassindale, A. The Third Dimension in Organic Chemistry John Wiley Sons Chichester, 

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