Question

How would you detect the halogens in an organic compound?

Answer 1

• To a portion of the Lassaigne’s filtrate. dil. HNO₃ is added, warmed gently and AgNO₃ solution is added. 
• Appearance of curdy white precipitate soluble in ammonia solution indicates the presence of chlorine. 
• Appearance of pale yellow precipitate sparingly soluble in ammonia solution indicates the presence of bromine.
• Appearance of yellow precipitate insoluble in ammonia solution indicates the presence of iodine.

Na + X \(\overset{\Delta}{\rightarrow}\) NaX (Where X = Cl,Br,I)

AgNO₃ + NaX → AgX↓ + NaNO₃