Which Grignard reagent gives 2-methylpropan-1 | vedclass

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Question

(A) The reaction of a Grignard reagent $(R-MgX)$ with methanal $(HCHO)$ followed by hydrolysis yields a primary alcohol with one more carbon atom than

Vedclass · Accepted Answer

$CH_3-CH(CH_3)-MgX$

Vedclass · Answer

(A) The reaction of a Grignard reagent $(R-MgX)$ with methanal $(HCHO)$ followed by hydrolysis yields a primary alcohol with one more carbon atom than the Grignard reagent.To obtain $2-$methylpropan$-1-$ol $(CH_3-CH(CH_3)-CH_2-OH)$,the Grignard reagent must be isobutylmagnesium halide $(CH_3-CH(CH_3)-CH_2-MgX)$.The reaction is:$CH_3-CH(CH_3)-CH_2-MgX + HCHO \rightarrow CH_3-CH(CH_3)-CH_2-CH_2-OMgX$$CH_3-CH(CH_3)-CH_2-CH_2-OMgX + H_2O \rightarrow CH_3-CH(CH_3)-CH_2-CH_2-OH + Mg(OH)X$Wait,the target product is $2-$methylpropan$-1-$ol $(C_4H_{10}O)$. The reaction of $R-MgX + HCHO$ adds one carbon. Thus,$R$ must be an isopropyl group $(CH_3-CH(CH_3)-)$.$CH_3-CH(CH_3)-MgX + HCHO$ $\rightarrow CH_3-CH(CH_3)-CH_2-OMgX$ $\xrightarrow{H_2O} CH_3-CH(CH_3)-CH_2-OH$.Therefore,the correct Grignard reagent is isopropylmagnesium halide,which is option $A$.

Which Grignard reagent gives $2-$methylpropan$-1-$ol upon reaction with methanal followed by hydrolysis?

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