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Explain (1) Kolbe's reaction (2) Reimer-Tiemann reaction. |
Answer» Solution :(1) Kolbe's reaction : When phenol reacts with sodium hydroxide, sodium phenoxide is obtained. Phenoxide ion being more reactive than phenol towards electrophilic substitution. Phenoxide undergoes electrophilic substitution with carbon dioxide (a weak electrophile) forms salicylic ACID as major product.  (2) Reimer-Tiemann reaction : Phenol is heated with CHLOROFORM along with aqueous NaOH, this is followed by ACIDIFICATION With dil. HCI when salicyladehyde (2-hydroxy benzaldehyde) is formed a the major product, which can be separated from p-isomer by steam distillation. The stabilityof o-isomeris dueto intramolecularhydrogen bonding. 
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