Phenol: Bodily properties, Acidity, Oxidation and Reaction
Bodily properties of phenols
Just like alcohols, phenols have hydroxyl teams that may take part in intermolecular hydrogen bonding; in actual fact, phenols are inclined to type stronger hydrogen bonds than alcohols. (See chemical bonding: Intermolecular forces for extra details about hydrogen bonding.) Hydrogen bonding ends in greater melting points and far greater boiling points for phenols than for hydrocarbons with related molecular weights. For instance, phenol (molecular weight [MW] 94, boiling point [bp] 182 °C [359.6 °F]) has a boiling level greater than 70 levels greater than that of toluene (C6H5CH3; MW 92, bp 111 °C [231.8 °F]).
The flexibility of phenols to type sturdy hydrogen bonds additionally enhances their solubility in water. Phenol dissolves to present a 9.3 % resolution in water, in contrast with a 3.6 % resolution for cyclohexanol in water.
Acidity of phenols
Though phenols are sometimes thought of merely as fragrant alcohols, they do have considerably totally different properties. The obvious distinction is the enhanced acidity of phenols. Phenols usually are not as acidic as carboxylic acids, however, they’re much extra acidic than aliphatic alcohols, and they’re extra acidic than water. In contrast to easy alcohols, most phenols are utterly deprotonated by sodium hydroxide (NaOH).
Like different alcohols, phenols endure oxidation, however, they provide several types of merchandise from these seen with aliphatic alcohols. For instance, chromic acid oxidizes most phenols to conjugated 1,4-diketones referred to as quinones. Within the presence of oxygen within the air, many phenols slowly oxidize to present darkish mixtures containing quinones.
Hydroquinone (1,4-benzenediol) is a very straightforward compound to oxidize, as a result of it has two hydroxyl teams within the correct relationship to surrender hydrogen atoms to type a quinone. Hydroquinone is utilized in growing photographic movies by lowering activated (uncovered to light) silver bromide (AgBr) to black metallic silver (Ag↓). Unexposed grains of silver bromide react extra slowly than the uncovered grains.
Reactions of phenols
A lot of the chemistry of phenols is like that of alcohols. For instance, phenols react with acids to present esters, and phenoxide ions (ArO−) may be good nucleophiles in Williamson ether synthesis.