2-Methylpentan-3-ol is dehydrated with conc. $H X_{2} SO X_{4}$ via the secondary carbocation at C3 and the tertiary carbocation formed from it by a 1,2-hydride shift. Count all distinct alkenes of formula $C X_{6} H X_{12}$ that can form from these two cations, counting (E) and (Z) isomers separately. Give the total number.

Numerical answer type, tolerance 0.5.

Answer: 4

The secondary cation

(CH X_{3}) X_{2} CH - CH X^{+} - CH X_{2} CH X_{3}

gives 2-methylpent-2-ene (H from C2) and (E)- and (Z)-4-methylpent-2-ene (H from C4). The hydride shift gives

(CH X_{3}) X_{2} C X^{+} - CH X_{2} CH X_{2} CH X_{3}

, which gives 2-methylpent-1-ene and 2-methylpent-2-ene (already counted). Distinct alkenes: 4.