'A' value

Also contains definition of: Winstein–Holness A value
The conformational preference of an @[email protected] compared to an axial substituent in a monosubstituted cyclohexane. This steric substituent parameter equals \(\Delta _{\text{r}}G^{\,\unicode{x26ac}}\) in \(\text{kcal mol}^{-1}\) for the @[email protected] to axial @[email protected] on cyclohexane. The values are also known as 'Winstein–Holness' A values.
PAC, 1994, 66, 1077. (Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994)) on page 1087 [Terms] [Paper]