In Q29 of Joint Entrance Exam (JEE) 2016 India, the official answer key mentions that benzoin gives Tollen's test. However, I saw this post which says that it doesn't: Why do α-hydroxy ketones give Tollens' test?
Benzoin:
I'm very confused now. If benzoin does give the test, how? And what is the mechanism/intermediate involved?
I thought of all possible reactions benzoin may undergo in basic medium:
- I did its aldol condensation but the product was too crowded and seemed quite unlikely. It didn't have any aldehyde group.
- Another possibility seemed oxidation to benzil, but I'm not sure. I don't think $\ce{Ag+}$ is strong enough.
- I was thinking about cleavage of central $\ce{C-C}$ single bond — as the hydroxyl $\ce{O}$ donated its lone pair to the carbon it is attached to, but am not sure on this too.
I couldn't find any related reaction of benzoin or any rearrangement on the internet.