other organic solvents. The bases are liberated on adding sodium 

 hydroxide to their solution. The salts yield double salts with gold, 

 platinum chloride, etc. ; these are of use for determining the molecular 

 weight of the base (p. 45). 



Reactions of a Primary Amine (Methylamine). 



(1) On treating a solution of methylamine hydrochloride, or about 

 2 gm. of the solid, with sodium hydroxide, the base is liberated : 



CH 3 . NH 2 . HCl + NaOH = CH 3 . NH 2 + NaCl + H./X 



Methylamine resembles ammonia in odour, but is " fishy," turns 

 red litmus blue, and fumes with vapours of hydrochloric acid. It 

 differs from ammonia in being combustible. 



(2) A double ?alt is formed on adding an alcoholic solution of gold or 

 platinum chloride to an alcoholic solution of methylamine hydrochloride. 



(3) Action of Nitrous Acid. On adding dilute hydrochloric acid and 

 a few drops of sodium nitrite solution to a solution of methylamine 

 hydrochloride, there is an evolution of nitrogen (the gas extinguishes 

 a glowing splinter) and methyl alcohol is formed : 



CH 3 . NH 2 . HCl + NaNO 2 = CH 3 OH + N 2 + NaCl + H 2 O. 

 This reaction is characteristic of primary amines ; they are converted 

 into the corresponding alcohol. 



(4) Carbylamine Reaction. On warming a solution of methylamine 

 hydrochloride with one drop of chloroform and alcoholic sodium 

 hydroxide, methylcarbylamine, or isocyanide, is formed : 



CH 3 . NH 2 + CHCLj + aNaOH = CH 3 . N ; C + aNaCl + sH 2 O. 



(5) Reaction with Acetyl Chloride. Primary amines react with acetyl 

 chloride, benzoyl chloride, etc., to form substituted amides : 



CH 3 . NH 2 + CH 3 COC1 = HCl + CH 3 . CO . NH . CH 3 . 

 These compounds are crystalline and serve for identifying the amine. 



Reactions of a Secondary Amine (Dimethylamine). 



(1) Dimethylamine is liberated from a solution of dimethylamine 

 hydrochloride on treatment with sodium hydroxide : 



(CH 3 ) 2 : NH . HCl + NaOH = (CH 3 ), : NH + NaCl + H 2 O. 

 It is a gas with an ammoniacal and fishy odour and resembles 

 methylamine. 



(2) A double salt is formed with alcoholic solutions of the heavy metals. 



(3) Action of Nitrous Acid. On adding dilute hydrochloric acid 

 and some nitrite to a solution of dimethylamine hydrochloride, there 

 is no evolution of nitrogen, but dimethylnitrosamine is formed : 



(CH 3 ) 2 : NH . HCl + NaNO 2 = (CH 3 ) 2 : N . NO + NaCl + H 2 O. 



Dimethylnitrosamine is a yellowish oil which is volatile with 

 steam and can thus be separated. 



It is reconverted into the secondary amine by the action of con- 

 centrated hydrochloric acid. 



