Alcohols, Phenols and Ethers

Alcohols are organic compounds characterized by the presence of a hydroxyl functional group ($-\text{OH}$) attached to an aliphatic carbon atom. They are classified as primary ($1^\circ$), secondary ($2^\circ$), or tertiary ($3^\circ$) depending on the carbon atom bonded to the $-\text{OH}$ group. For board exams, pay special attention to the industrial preparation of methanol from water gas and the fermentation process for ethanol. Key chemical properties involve reactions breaking the $\text{C-OH}$ bond (such as with $\text{HX}$ or $\text{PCl}_3$) and reactions involving the cleavage of the $\text{O-H}$ bond (such as reactions with active metals). Examiners frequently test the Lucas test and the iodoform test, which are crucial laboratory methods used to distinguish between $1^\circ$, $2^\circ$, and $3^\circ$ alcohols.

Phenols contain a hydroxyl group directly attached to an aromatic benzene ring, giving them significantly acidic properties compared to aliphatic alcohols due to the resonance stabilization of the phenoxide ion. Important synthetic routes often asked in exams include the Dow's process and the hydrolysis of diazonium salts. The chemical reactivity of phenols is heavily dictated by the activating and ortho/para-directing nature of the $-\text{OH}$ group. You must thoroughly prepare electrophilic substitution reactions like nitration, halogenation, and Kolbe's synthesis or Reimer-Tiemann reaction, as these are absolute favorites for board long-questions.

Ethers are represented by the general formula $R-\text{O}-R'$ and are considered anhydrides of alcohols. They are relatively inert compounds, often used as solvents. The standard laboratory preparation of ethers involves Williamson's synthesis, which is a vital name reaction frequently appearing in conversion and mechanism-based questions. Understanding the symmetrical and asymmetrical nature of ethers, along with their general unreactivity towards bases and active metals, completes the core requirements for this section of the syllabus.