can phenylamine be oxidised? if yes, what oxidising agent is used?

Answer 1

I think the question maybe confused, you asked for phenylamine. But as the first answer wrote we don’t normally call aniline by that name. Although it is perfectly valid, just like dihydrogen oxide (nasty stuff that – a woman just died last week from ingesting it – watch out for it)

Perhaps you meant aspartame (Nutrasweet)– the compound made with aspartic acid and phenylalanine. The spelling is close and this is a trendy compound right now.

Yes it does oxide with long exposure to air or heat. And after either of those events the flavor of the food is really effected.

Answer 2

You mean aniline right? - Yes it can be oxidized - but I would not recommend it.

People have successfully oxidized aniline with ALL oxidizing agents (including air) to get mixtures of dyes, most of which were either insoluble, or unidentifyable.