91影视

For the conversion of an axial-substituted chair conformer to an equatorial-substituted chair conformer, we must identify the monosubstituted cyclohexanes with a negative 鈭咷掳.

The relationship between the equilibrium constant (K_eq) and the change in free energy (G) is well understood:

G^o = ^_RT ln K_eq

and, Keq=

The Keq value is greater than 1 for all -G^ovalues. The equilibrium constants for all monosubstituted cycloalkanes except H are larger than 1, as seen in the table.

As a result, for the conversion of an axial-substituted chair conformer to an equatorial-substituted chair conformer, all monosubstituted cyclohexanes in the table except H have a negative G^o.

b)Tert-butylcyclohexane has the most negative 鈭咷掳 for this conversion.

c)Tert-butylcyclohexane has the greatest preference for an equatorial position.

G^o = ^_RT ln K_eq

Keq= 18

-1.986 脳10^-3 kcal/mol 脳298 K 脳 ln 18 (T=藲C+273) = G^o

G^o = -0.59脳 ln 18 kcal/mol

G^o = -0.59脳2.89 kcal/mol

G^o = 1.79 kcal/mol