Cellulose Conformation

Abstract

Like cyclohexane derivatives, the glucopyranose ring may have the chair or boat conformation [2]. It is generally accepted that the more stable conformation of cyclohexane is the chair one with D_3d-symmetry (Fig. II.15). The bonds parallel to the C₃-axis are usually called axial (a), those forming a tetrahedral angle with this axis—equatorial (e). The cyclohexane ring actually is not tetrahedral and the endocyclic angle C-C-C seems to be 111.5° (Fig. II.16). With regard to this value the torsion angle C-C-C (ϕ) happens to be 54.5°. The torsion angle between the adjacent axial and equatorial bonds is also 54.5°. Taking into account that the H-C-H angles in cyclohexane are less than tetrahedral the value of the projection angle H-C-H (ω) is accepted as being 118°.