Answer :
a) CH₃CH₂MgBr + BrCH₂CH₂CH₂CH₃ → (CH₃CH₂CH₂CH₂)₂CBr + MgBr₂
b) (CH₃CH₂CH₂CH₂)₂CBr + MgBr₂ → 2(CH₃CH₂CH₂CH₂)₂CMgBr + Br₂
c) 2(CH₃CH₂CH₂CH₂)₂CMgBr + 2CH₃CH₂CH₂CHO → 2(CH₃CH₂CH₂CH₂)₂COH + 2CH₃CH₂CH₂CH₂MgBr
a) In the first step, the n-butyl bromide Grignard reagent is formed by the reaction between bromobutane (CH₃CH₂Br) and magnesium (Mg), yielding butyl magnesium bromide (CH₃CH₂MgBr). This reacts with another molecule of bromobutane to form a di-n-butyl Grignard reagent [(CH₃CH₂CH₂CH₂)₂CMgBr] and magnesium bromide (MgBr₂).
b) Transmetallation occurs when the di-n-butyl Grignard reagent reacts with additional magnesium bromide, producing two molecules of n-butyl magnesium bromide [(CH₃CH₂CH₂CH₂)₂CMgBr] and elemental bromine (Br₂).
c) Finally, the n-butyl magnesium bromide reacts with two molecules of the given aldehyde (CH₃CH₂CH₂CHO) to yield two molecules of the corresponding alcohol (CH₃CH₂CH₂CH₂OH) and regenerate two molecules of the n-butyl Grignard reagent (CH₃CH₂CH₂CH₂MgBr).
