Question

Which of the following is the major product when 1-butanol is heated with concentrated ${\mathrm{H}}_2{\mathrm{SO}}_4$?

• A. 1-butene
• B. Cis-2-butene
• C. Trans-2-butene
• D. All of these

Answer 1

The correct option is C

Trans-2-butene

Explanation of correct options

(C) Trans-2-butene

Saytzeff Rule

• “In dehydrohalogenation reactions, the preferred product is that alkene which has the greater number of alkyl groups attached to the doubly bonded carbon atoms.”
• When 1-butanol is heated with concentrated${\mathrm{H}}_2{\mathrm{SO}}_4$, trans-2-butene is the leading product which can be shown as:

Hence, trans-2-butene is the major product.