Question

Verify the strain energy shown in Table 3.8 for cycloheptane.

Short answer

Strain energy of cycloheptane = actual heat of formation - strain less heat of formation

= 6.2 Kcal/mol

Step-by-step solution

Formula to find Strain energy

The difference between the actual heat of formation and strain less heat of formation is called the strain energy.

Strain energy of cycloheptane = actual heat of formation - strain less heat of formation

The strain energy of cycloheptane

From the table-

Actual heat of formation of cycloheptane = -28.2 Kcal/mol.

Strain less heat of formation value for one methyl = -4.29 Kcal/mol.

Cyclohexane contains 7 methyl groups so = 7 x (-4.92) = -34.4 Kcal/mol.

Therefore,

Strain energy of cycloheptane = actual heat of formation - strain less heat of formation

= 6.2 Kcal/mol