Salicylates, C6H4 OH COO- or

40 SALICYLATES, C6H4(OH)COO OR C7H5Oj Solubility Salicylic acid, C6H4(OH)COOH (o-hydroxybenzoic acid), forms colourless needles, which melt at 155°. The acid is sparingly soluble in cold water, but more soluble in hot water, from which it can be recrystallized. It is readily soluble in alcohol and ether. With the exception of the lead, mercury, silver, and barium salts, the monobasic salts, C6H4(OH)COOM - these are the most commonly occurring salts - are readily soluble in cold water. 

To study these reactions use a 05m solution of sodium salicylate, C6H4(OH)COONa or Na.C7H503. 

Concentrated sulphuric acid solid sodium salicylate dissolves on warming charring occurs slowly, accompanied by the evolution of carbon monoxide and sulphur dioxide. 

Concentrated sulphuric acid and methanol ( oil of wintergreen test) When 0 5 g of a salicylate or of salicylic acid is treated with a mixture of 15 ml concentrated sulphuric acid and 3 ml methanol and the whole gently warmed, the characteristic, fragrant odour of the ester, methyl salicylate(I) ( oil of wintergreen ), is obtained. The odour is readily detected by pouring the mixture into dilute sodium carbonate solution contained in a porcelain dish. 

Dilute hydrochloric acid crystalline precipitate of salicylic acid from solutions of the salts. The precipitate is moderately soluble in hot water, from which it crystallizes on cooling. 

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