Question

Arrange the following functional groups in the decreasing order of reactivity with $PrMgBr$.
$\left(i\right)$ Alcohol $\left(ii\right)$ Aldehyde $\left(iii\right)$ Ketone $\left(iv\right)$ Ester

• A. $\left(iv\right)>\left(iii\right)>\left(ii\right)>\left(i\right)$
• B. $\left(i\right)>\left(ii\right)>\left(iii\right)>\left(iv\right)$
• C. $\left(ii\right)>\left(iii\right)>\left(i\right)>\left(iv\right)$
• D. $\left(iv\right)>\left(i\right)>\left(iii\right)>\left(ii\right)$

Answer 1

The correct option is B $\left(i\right)>\left(ii\right)>\left(iii\right)>\left(iv\right)$

Reactivity of PrMgBr or propyl magnesium bromide with (i) alcohol (ii) aldehyde (iii) ketone (iv) ester in the decreasing order is (i)>(ii)>(iii)>(iv). This is due to combination of steric and electronic effects.