Chemguide: Support for CIE A level Chemistry

34.2: Phenylamine and azo compounds

Learning outcome 34.2.2

This statement is about the reactions of phenylamine with bromine water and with nitrous acid.

Before you go on, you should find and read the statement in your copy of the syllabus.

Learning outcome 34.2.2(a)

You will find what you need to know on the page phenylamine and bromine water.

You will be expected to know the reaction, and the reason that the ring is activated.

Learning outcome 34.2.2(b)

This is about the reaction of phenylamine with very cold nitrous acid, HNO₂, to give a diazonium salt, and its further reaction on heating to give phenol.

This is described on the page about making diazonium salts from phenylamine.

In the first instance, ignore the section at the beginning talking about the reaction being done warm to produce phenol, and just read about the reaction done very cold. That produces the diazonium salt.

Make sure that you remember the conditions for the reaction producing the diazonium salt, and that you can draw the structure for the diazonium ion accurately.

Now follow the link at the bottom of the page to "look at the reactions of diazonium ions". Just read the beginning of this, down to and including "substitution by an OH group".

That gives you a clearer match to the syllabus order than the approach on the first page you read.

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