The carbocation $CH X_{3} - CH X_{2} - C X^{+} (CH X_{3}) X_{2}$ (2-methylbutan-2-yl cation) can be stabilised by hyperconjugation. The number of hyperconjugative (no-bond resonance) structures equals the number of alpha C-H bonds (alpha hydrogens on the sp3 carbons directly attached to the cationic carbon). Find this number.

Numerical answer type, tolerance 0.5.

Answer: 8

The cationic carbon carries two

CH X_{3}

groups (

2 \times 3 = 6

alpha H) and one

CH X_{2}

of the ethyl group (2 alpha H). Total

6 + 2 = 8

alpha C-H bonds, hence 8 hyperconjugative structures.