Preferred Label : axial (equatorial);
IUPAC definition : In the chair form of cyclohexane ring bonds to ring atoms (and molecular entities
attached to such bonds) are termed axial or equatorial according to whether the bonds
make a relatively large or small angle, respectively, with the plane containing or
passing closest to a majority of the ring atoms. Thus the axial bonds are approximately
parallel to the i C /i sub 3 /sub axis and the equatorial bonds approximately parallel
to two of the ring bonds. These terms are also used for the chair form of other saturated
six-membered rings. The corresponding bonds occurring at the allylic positions in
mono-unsaturated six-membered rings are termed pseudo-axial (or quasi-axial) and pseudo-equatorial
(or quasi-equatorial). The terms axial and equatorial have similarly been used in
relation to the puckered conformation of cyclobutane, crown conformer of cyclooctane,
etc. and the terms pseudo-axial and pseudo-equatorial in the context of the non-planar
structures of cyclopentane and cycloheptane. See apical (basal, equatorial) for an
alternative use of axial and equatorial with bipyramidal structures.;
Origin ID : A00546;
UMLS CUI : C0205131;
Automatic exact mappings (from CISMeF team)
Currated CISMeF NLP mapping
See also
Semantic type(s)
UMLS correspondences (same concept)
In the chair form of cyclohexane ring bonds to ring atoms (and molecular entities
attached to such bonds) are termed axial or equatorial according to whether the bonds
make a relatively large or small angle, respectively, with the plane containing or
passing closest to a majority of the ring atoms. Thus the axial bonds are approximately
parallel to the i C /i sub 3 /sub axis and the equatorial bonds approximately parallel
to two of the ring bonds. These terms are also used for the chair form of other saturated
six-membered rings. The corresponding bonds occurring at the allylic positions in
mono-unsaturated six-membered rings are termed pseudo-axial (or quasi-axial) and pseudo-equatorial
(or quasi-equatorial). The terms axial and equatorial have similarly been used in
relation to the puckered conformation of cyclobutane, crown conformer of cyclooctane,
etc. and the terms pseudo-axial and pseudo-equatorial in the context of the non-planar
structures of cyclopentane and cycloheptane. See apical (basal, equatorial) for an
alternative use of axial and equatorial with bipyramidal structures.