Question

2,3-Dimethyl-2-butene can be prepared by heating which of the following compounds with a strong acid ?

• A. ${\left(C{H}_3\right)}_{2}CH-C{H}_2-CH=C{H}_2$
• B. ${\left(C{H}_3\right)}_{3}C-CH=C{H}_2$
• C.
• D. ${\left(C{H}_3\right)}_{2}C=CH-C{H}_2-C{H}_3$

Answer 1

The correct option is B ${\left(C{H}_3\right)}_{3}C-CH=C{H}_2$


It is an example of isomerisation of alkene reaction.
Here, the alkene attacks the $H^{+}$ to form a carbocation and it undergoes 1, 2 -methyl shift to form stable carbocation followed by elimination of $H^{+}$ to give stable alkene product ( more substituted alkene).

All other options (a), (b) and (c) does not give the desired product.

Hence, option (d) is the correct answer.