Question:

Consider the following reaction :

\( {\left( {C{H_3}} \right)_3}CCH\left( {OH} \right)C{H_3}\buildrel {conc.\,\,\,{H_2}S{O_4}} \over \longrightarrow \)

\( {\left( {C{H_3}} \right)_2}CHCH\left( {Br} \right)C{H_3}\buildrel {alc.\,\,KOH} \over \longrightarrow \)

\( {\left( {C{H_3}} \right)_2}{\rm{ }}CHCH\left( {Br} \right)C{H_3}\buildrel {{{(C{H_3})}_3}{O^\Theta }{K^ \oplus }} \over \longrightarrow \)

\( {\left( {C{H_3}} \right)_2}\mathop C\limits_{\mathop |\limits_{OH} } - C{H_2} - CHO\buildrel \Delta \over \longrightarrow \)

Which of these reaction(s) will not produce Saytzeff product ?

Show Hint

Saytzeff's rule: the more substituted (more stable) alkene is the major elimination product; bulky bases such as t-BuOK give the less substituted Hofmann product.
Updated On: Oct 31, 2026
  • (d) only
  • (b) and (d)
  • (a), (c) and (d)
  • (c) only
Show Solution
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The Correct Option is D

Solution and Explanation

(a) (CH3)3CCH(OH)CH3 with conc. H2SO4: a secondary carbocation forms and rearranges by methyl shift to the tertiary cation, which loses H+ to give the tetrasubstituted alkene (CH3)2C=C(CH3)2: Saytzeff product.
(b) (CH3)2CHCH(Br)CH3 with alc. KOH: small base, gives the more substituted 2-methylbut-2-ene: Saytzeff product.
(c) The same bromide with bulky (CH3)3CO-K+: removes the less hindered H and gives 3-methylbut-1-ene: Hofmann product, not Saytzeff.
(d) (CH3)2C(OH)CH2CHO on heating: dehydration gives the more substituted conjugated alkene (CH3)2C=CH-CHO: Saytzeff product.
Only (c) does not give the Saytzeff product.
Answer: Option 4 (c) only
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