Question

3, 3-dimethyl butane-2-ol on treatment with conc. H₂SO₄ to give tetramethyl ethylene as a major product. Suggest a suitable mechanism.

Answer 1

According to Saytzeff’s rule the dehydration of 3, 3-dimethyl butane-2-ol gives a mixture of alkenes. But the secondary carbocation formed in this reaction undergoes rearrangement to form a more stable tertiary carbocation which further, undergoes 13 elimination leads more stable product, that is 2, 3-dimethyl but-2-ene (more yield). According to Saytzeff’s rule, 2, 3-dimethyl pent-2-ene is the major product.