# What exactly is the mechanism of “nascent hydrogen”? [closed]

I put the quotes because Wikipedia says it's an outdated theory.

What exactly happens when nitrobenzene is converted to aniline using $\ce{Sn/conc HCl}$?

According to a few books which haven't been updated, even $\ce{Na}$/ethanol, $\ce{Zn/dil H2SO4}$ produce this. I guess a metal may have an important role in the actual mechanism.

Is there any specific reason why $\ce{Na}$/ethanol is used to reduce cyanides to amines, and $\ce{Sn/conc HCl}$ to reduce nitrobenzene? (and not the other way around)

Even $\ce{KMnO4}$ produces "nascent oxygen"? What exactly is going on?

## closed as too broad by Mithoron, bon, airhuff, Todd Minehardt, ronFeb 16 '18 at 19:00

Please edit the question to limit it to a specific problem with enough detail to identify an adequate answer. Avoid asking multiple distinct questions at once. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

• Which question are you asking? Currently there's three ? marks in your post (excluding the one in your title) :( As for the middle one, I was taught that tin+conc HCl will reduce cyanide to amine, but then further reduce it to aldehydes because it is in an aqueous medium. A similar thing won't happen with sodium/ethanol (alcoholic medium). I am not sure of the exact mechanism though. – Gaurang Tandon Feb 15 '18 at 7:56
• – Mithoron Feb 15 '18 at 15:15