Question

Which of the following factors does not favour $S_{N}1$ mechanism?

• A. Strong nucleophile
• B. Polar solvent
• C. Low conc. of nucleophile
• D. $3^0$ halide

Answer 1

The correct option is A Strong nucleophile

$S{N}^1$ mechanism proceeds through carbocation formation, as stability of carbocation increases, reaction favours $S{N}^1$ mechanism.
$3^0$ carbocation are more stable than others and also polar solvent increases stability of carbocation so they both favours $S{N}^1$ mechanism.
Rate of $S{N}^1$ mechanism depends on nucleophile concentration only so as conc. of nucleophile increases, reaction favours $S{N}^1$ mechanism.