Solving the first alternative
(i) Williamson's synthesis: This is a nucleophilic substitution route to ethers. The two pieces are an alkoxide (or phenoxide) salt and an alkyl halide. Because the alkoxide oxygen carries a negative charge it acts as the nucleophile and displaces halide from the carbon in a back-side \(S_N2\) attack, stitching an \(R{-}O{-}R'\) bond: \[R'ONa + R{-}X \rightarrow R{-}O{-}R' + NaX\] A worked example is diethyl ether: \(C_2H_5ONa + C_2H_5Br \rightarrow (C_2H_5)_2O + NaBr\). A practical rule: pick the primary halide as the \(R{-}X\) partner, because bulky secondary/tertiary halides mostly eliminate to alkenes rather than substitute. To make anisole one combines sodium phenoxide with methyl iodide. Thus both mixed and simple ethers are accessible.
(ii) Phenol from cumene: Industrially phenol is obtained together with acetone by the cumene process. Air oxidises cumene at the benzylic C–H to cumene hydroperoxide; treatment with acid then rearranges and cleaves it: \[C_6H_5CH(CH_3)_2 \xrightarrow{O_2} C_6H_5C(CH_3)_2{-}O{-}OH\] \[C_6H_5C(CH_3)_2{-}O{-}OH \xrightarrow{\text{dil. } H_2SO_4} C_6H_5OH + CH_3COCH_3\]
(iii) Phenol to salicylaldehyde: Use the Reimer-Tiemann reaction. Chloroform in the presence of aqueous alkali provides dichlorocarbene \(:CCl_2\), an electrophile that bonds to the ortho carbon of the phenoxide ring. On acidic work-up the ortho-substituted intermediate is hydrolysed to an aldehyde group, giving 2-hydroxybenzaldehyde: \[C_6H_5OH \xrightarrow[\text{then } H_3O^+]{CHCl_3, \ NaOH} o\text{-}OHC{-}C_6H_4{-}OH\]
Solving the second alternative (OR — equations only)
(i) Phenol with dilute nitric acid nitrates the ring at ortho and para: \[C_6H_5OH + HNO_3(\text{dil}) \rightarrow o\text{-}O_2NC_6H_4OH + p\text{-}O_2NC_6H_4OH + H_2O\] (ii) Ethyl methyl ether with hot conc. HI cleaves at the smaller (less hindered) alkyl group, giving methyl iodide and ethanol: \[CH_3{-}O{-}C_2H_5 + HI \rightarrow CH_3I + C_2H_5OH\] (iii) Phenol with conc. \(HNO_3\) and conc. \(H_2SO_4\) gives 2,4,6-trinitrophenol (picric acid): \[C_6H_5OH + 3HNO_3 \xrightarrow{\text{conc. }H_2SO_4} 2,4,6\text{-}(NO_2)_3C_6H_2OH + 3H_2O\] (iv) Ethanol with thionyl chloride and pyridine gives ethyl chloride (Darzens method): \[C_2H_5OH + SOCl_2 \xrightarrow{\text{pyridine}} C_2H_5Cl + SO_2 + HCl\] (v) Phenol with bromine water gives a white precipitate of 2,4,6-tribromophenol: \[C_6H_5OH + 3Br_2 \rightarrow 2,4,6\text{-}Br_3C_6H_2OH + 3HBr\]