Write chemical equations for the following reactions: (a) Hydroboration – Oxidation reaction: (b) Williamson Synthesis: (c) Friedel-Crafts Alkylation of Anisole: (d) Reimer-Tiemann Reaction:
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These reactions are classic organic transformations. Hydroboration-oxidation adds alcohol across alkenes, Williamson synthesis forms ethers, Friedel-Crafts alkylation alkylates aromatic rings, and Reimer-Tiemann introduces a formyl group to phenol.
(a) Hydroboration – Oxidation reaction:
The hydroboration-oxidation of an alkene results in an alcohol. In this reaction, alkene (CH$_3$CH=CH$_2$) undergoes hydroboration with diborane (B$_2$H$_6$), followed by oxidation with hydrogen peroxide to form an alcohol. The reaction is as follows:
\[
\text{CH}_3\text{CH}= \text{CH}_2 + B_2H_6 \xrightarrow{\text{H}_2O_2} \text{CH}_3\text{CH}_2\text{OH}
\]
Here, the alkene is converted to the alcohol with anti-Markovnikov addition.
(b) Williamson Synthesis:
The Williamson synthesis involves the reaction of an alkoxide ion with an alkyl halide to form an ether. The general reaction is:
\[
R\text{-}X + \text{R'}\text{O}^- \rightarrow R\text{-}R' + \text{Na}X
\]
Where \( R \)-X is the alkyl halide, \( R' \)-O$^-$ is the alkoxide ion, and \( R \)-R' is the ether product. (c) Friedel-Crafts Alkylation of Anisole:
In Friedel-Crafts alkylation, anisole (C$_6$H$_5$OCH$_3$) reacts with an alkyl halide (CH$_3$Cl) in the presence of AlCl$_3$ catalyst to form an alkylated product. The reaction is as follows:
Here, the methyl group is added to the aromatic ring, forming methyl anisole. (d) Reimer-Tiemann Reaction:
The Reimer-Tiemann reaction involves the reaction of phenol (C$_6$H$_5$OH) with chloroform (CHCl$_3$) in the presence of aqueous NaOH, followed by acidification to form salicylaldehyde (C$_7$H$_6$O$_2$). The reaction is as follows:
Here, the formyl group (-CHO) is introduced to the phenol to form salicylaldehyde.
