Consider the following reactions, which of these reaction(s) will not produce Saytzeff product? Which of these…

Step 1: Understand Saytzeff (Zaitsev) product

Saytzeff's rule: In elimination, the more substituted alkene is the major product.

Exceptions (Hofmann product):

• Bulky bases
• Poor leaving groups
• Quaternary ammonium salts

Step 2: Analyze each reaction

From the image:

(A) $\ce{(CH3)3CCH(OH)CH3}$ with conc. $\ce{H2SO4}$:

• Dehydration of alcohol
• Acid-catalyzed E1 mechanism
• Gives Saytzeff product (more substituted alkene) ✓

(B) $\ce{(CH3)2CHCH(Br)CH3}$ with $\ce{KOH/C2H5OH}$:

• E2 elimination
• Small base (OH⁻)
• Gives Saytzeff product ✓

(C) $\ce{(CH3)3CHCH(Br)CH3}$ with $\ce{(CH3)3CO-K+/Δ}$:

• E2 elimination
• Bulky base (tert-butoxide)
• Gives Hofmann product (less substituted) ✗

(D) $\ce{(CH3)2C-CH-CHO}$ with Δ:

• Aldol condensation or dehydration
• Heat-induced elimination
• Gives Saytzeff product ✓

Step 3: Identify non-Saytzeff reactions

Only (C) gives Hofmann product (not Saytzeff)

Answer: (b) (C) only

Key Concepts:

Saytzeff vs Hofmann:

| Conditions | Base | Product | Rule | |------------|------|---------|------| | Saytzeff | Small (OH⁻, OEt⁻) | More substituted | Thermodynamic | | Hofmann | Bulky (t-BuO⁻) | Less substituted | Kinetic |

Why bulky bases give Hofmann:

• Steric hindrance at more substituted β-carbon
• Base attacks less hindered β-hydrogen
• Faster reaction (kinetic product)
• Less stable alkene formed

Bulky bases:

• t-BuO⁻ (tert-butoxide)
• LDA (lithium diisopropylamide)
• DBU, DBN (bicyclic bases)