The OH group in alcohols, phenols and acids

R-OH + H2O <-> R-O- + H3O+

H-OH + H2O <-> H-O- + H3O+

At one time, a small number of water molecules donate H+ ions to other water molecules = behaves as a weak acid.

With phenols, the equilibrium lies further to the right so it is more acidic than water.

Ethanol < water < phenol < carboxylic acids

The stability of the R-O- formed determines how strong the acid is and where the equilibrium lies.

If the negative charge on the O atom can be shared with other atoms it will be more stable.

If the R-O- is derived from a phenol or carboxylic acid the charge gets spread out - delocalisation.

Phenols and carboxylic acids can react with strong bases to form salts. (React with NaOH to form their sodium salts)

Iron (III) Chloride is test for phenol and its derivatives

The enol group (-C=C-OH) reacts with the Fe3+ ion to form a complex

Alcohol + Carboxylic Acid <-> Ester

Concentrated Sulphuric of Hydrochloric acid must be added to speed up reaction & heated

Can be made using phenols instead of alcohols (& use acyl chloride or acid anhydride instead of carboxylic acid)

Salicylic Acid > esterify the -OH group --> Aspirin (soluble in water/absorbed into bloodstream)

Salicylic Acid > esterify the -COOH group --> Oil of wintergreen (soluble in fat/absorbed through skin)