Alcohol, Phenol and Ether MCQ Questions & Answers in Organic Chemistry | Chemistry

When phenol is heated with chloroform $$\left( {CHC{l_3}} \right)$$   and alcoholic $$KOH,$$  salicylaldehyde is formed. This reaction is known as Reimer-Tiemann reaction.

  \[OH\xrightarrow[{{H}_{2}}O]{{{K}_{2}}C{{r}_{2}}{{O}_{7}},{{H}_{2}}S{{O}_{4}}}\]      \[COOH\xrightarrow[{{H}^{+}}]{C{{H}_{3}}OH}\]       \[COOC{{H}_{3}}\xrightarrow[\text{Excess}/{{H}_{3}}{{O}^{+}}]{C{{H}_{3}}MgBr}\]        

Stability order of carbocation $${3^ \circ } > {2^ \circ }.$$

Thus $$94\,g$$  of phenol require $$B{r_2} = 480\,g$$
$$2\,g$$  of phenol require $$B{r_2} = \frac{{480}}{{94}} \times 2 = 10.22\,g$$

No explanation is given for this question. Let's discuss the answer together.

$${C_2}{H_5} - O - {C_2}{H_5} + \mathop {2HI}\limits_{\left( {{\text{excess}}} \right)} \to $$       $$2{C_2}{H_5}I + {H_2}O$$

The reaction of alkyl halides with sodium alkoxide or sodium phenoxide to form ethers is called Williamson synthesis. Here, in this reaction alkyl halide should be primary and alkoxide, should be bulkier as shown below,
\[\underset{\begin{smallmatrix} \text{Alkyl} \\ \text{halide} \end{smallmatrix}}{\mathop{R}}\,-X+\underset{\text{Sodiumalkoxide}}{\mathop{R'-ONa}}\,\to \underset{\text{Ether}}{\mathop{R-O-R'}}\,+NaX\]

TIPS/Formulae :
Secondary alcohols oxidise to produce kenone.
\[\underset{\text{2-Butanol}}{\mathop{C{{H}_{3}}CHOHC{{H}_{2}}C{{H}_{3}}}}\,\xrightarrow{\left( O \right)}\underset{\text{Ethyl methyl ketone}}{\mathop{C{{H}_{3}}COC{{H}_{2}}C{{H}_{3}}}}\,\]

$$tert$$  - Butyl alcohol is preferentially protonated because its corresponding carbocation is highly stable than that of $${C_2}{H_5}OH$$
\[\begin{align} & {{\left( C{{H}_{3}} \right)}_{3}}COH\xrightarrow{{{H}^{+}}}{{\left( C{{H}_{3}} \right)}_{3}}C\overset{+}{\mathop{O}}\,{{H}_{2}}\xrightarrow{-{{H}_{2}}O}\underset{\text{Stable}}{\mathop{{{\left( C{{H}_{3}} \right)}_{3}}}}\,\overset{+}{\mathop{C}}\,\xrightarrow{C{{H}_{3}}C{{H}_{2}}\underset{\scriptscriptstyle\centerdot\centerdot}{\ddot{O}}H} \\ & {{\left( C{{H}_{3}} \right)}_{3}}C\overset{{}}{\mathop{\overset{H}{\mathop{{{O}^{+}}}}\,C{{H}_{2}}C{{H}_{3}}\xrightarrow{-{{H}^{+}}}{{\left( C{{H}_{3}} \right)}_{3}}COC{{H}_{2}}C{{H}_{3}}}}\, \\ & C{{H}_{3}}C{{H}_{2}}OH \\ \end{align}\]
The $$tert$$  - butyl cation is preferentially attacked by \[C{{H}_{3}}C{{H}_{2}}OH\]    rather than bulky \[{{\left( C{{H}_{3}} \right)}_{3}}COH\]