Notes On Specific Reactions Of Phenols And Commercially Important Alcohols - CBSE Class 12 Chemistry
The hydroxyl group of phenols tends to make the ring more likely to undergo substitution. Hydroxyl group activates the ring to substitution. Thus Phenols undergo substitution reactions more readily than benzene. The hydroxyl group of phenols tends to direct further substitutions of the aromatic ring to the ortho and para positions (2 and 4 positions) because the resonance structures of phenols make the ortho and para positions electron rich. Nitrophenols can be produced by reacting phenol with nitric acid. The outcome of nitration of phenol varies with the reaction conditions. When a phenol reacts with concentrated nitric acid, the reaction produces 2, 4, 6-trinitrophenol, commonly known as picric acid. Phenol also undergoes halogenation reactions. The reaction of phenol with bromine gives different products, depending on the reaction conditions. The reaction of phenol with bromine gives different products depending on the solvent used. Kolbe's synthesis is used to prepare ortho-hydroxylbenzoic acid from phenol. In Kolbe's reaction, sodium phenoxide is prepared and then subsequently heated with carbon dioxide under pressure. Carbon dioxide, the neutral electrophile, attacks phenoxide ion to form sodium salicylate . The sodium salicylate, when acidified, forms 2-hydroxybenzoic acid, or salicylic acid. The Reimer-Tiemann reaction converts phenol into salicylaldehyde. Heating phenol vapours with zinc dust produces benzene as phenol undergoes reduction in the presence of zinc dust to form benzene. Phenol can be oxidised to form quinones. Phenols are oxidised more readily than alcohols. Phenols can be oxidised either by chromic acid or silver oxide, a weak oxidising agent, to produce conjugated diketones which are commonly called benzoquinones. Methanol is prepared commercially by the catalytic hydrogenation of carbon monoxide. This reaction requires high temperature and pressure as well as a zinc oxide-chromium (lll) oxide catalyst. Methanol is used as a solvent in paints and varnishes. It is used as an antifreeze and windshield wiper fluid. About 50 % of all methanol produced commercially is used to make formaldehyde. Ethanol can be prepared by the fermentation of sugars (or) by the hydration of ethene. Ethanol is used as a solvent for paints, markers, perfumes and other products. It is used to prepare various organic compounds. It is used as a motor fuel and fuel additive. Many bacterial hand sanitizers contain ethanol. Alcoholic beverages contain ethanol.

#### Summary

The hydroxyl group of phenols tends to make the ring more likely to undergo substitution. Hydroxyl group activates the ring to substitution. Thus Phenols undergo substitution reactions more readily than benzene. The hydroxyl group of phenols tends to direct further substitutions of the aromatic ring to the ortho and para positions (2 and 4 positions) because the resonance structures of phenols make the ortho and para positions electron rich. Nitrophenols can be produced by reacting phenol with nitric acid. The outcome of nitration of phenol varies with the reaction conditions. When a phenol reacts with concentrated nitric acid, the reaction produces 2, 4, 6-trinitrophenol, commonly known as picric acid. Phenol also undergoes halogenation reactions. The reaction of phenol with bromine gives different products, depending on the reaction conditions. The reaction of phenol with bromine gives different products depending on the solvent used. Kolbe's synthesis is used to prepare ortho-hydroxylbenzoic acid from phenol. In Kolbe's reaction, sodium phenoxide is prepared and then subsequently heated with carbon dioxide under pressure. Carbon dioxide, the neutral electrophile, attacks phenoxide ion to form sodium salicylate . The sodium salicylate, when acidified, forms 2-hydroxybenzoic acid, or salicylic acid. The Reimer-Tiemann reaction converts phenol into salicylaldehyde. Heating phenol vapours with zinc dust produces benzene as phenol undergoes reduction in the presence of zinc dust to form benzene. Phenol can be oxidised to form quinones. Phenols are oxidised more readily than alcohols. Phenols can be oxidised either by chromic acid or silver oxide, a weak oxidising agent, to produce conjugated diketones which are commonly called benzoquinones. Methanol is prepared commercially by the catalytic hydrogenation of carbon monoxide. This reaction requires high temperature and pressure as well as a zinc oxide-chromium (lll) oxide catalyst. Methanol is used as a solvent in paints and varnishes. It is used as an antifreeze and windshield wiper fluid. About 50 % of all methanol produced commercially is used to make formaldehyde. Ethanol can be prepared by the fermentation of sugars (or) by the hydration of ethene. Ethanol is used as a solvent for paints, markers, perfumes and other products. It is used to prepare various organic compounds. It is used as a motor fuel and fuel additive. Many bacterial hand sanitizers contain ethanol. Alcoholic beverages contain ethanol.

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