# Mechanism for reaction of NOCl (Tilden reagent) with primary amines

According to my textbook, the reaction between $$\ce{NOCl}$$ and $$\ce{CH3CH2-NH2}$$ is as follows:

$$\ce{CH3CH2-NH2 + NOCl -> CH3CH2Cl + N2 + H2O}$$

But how exactly does the reaction proceed?

The first step (what I think) could be that $$\ce{NOCl}$$ dissociates into $$\ce{NO+}$$ and $$\ce{Cl-}$$ ions and then the $$\ce{Cl-}$$ ion attacks the amine group and replaces it by $$\mathrm{S_N2}$$ mechanism.

But according to this site, a diazonium product is produced. Even though a diazo product is formed, how does it produce an alkyl halide according to my textbook?

• Umm, judging from your idea for this mechanism, perhaps you should brush up on basics rather then get into details of less known reactions... – Mithoron Nov 26 '19 at 23:48
• If you know how to form a diazonium salt with NOCl (or HONO/HCl) then you are an SN2 reaction away from the answer. – user55119 Nov 27 '19 at 16:30
• Please cite the textbook (as in 'according to my textbook'), or leave out that statement if it is not relevant. Always cite the sources you are using. – Martin - マーチン Nov 28 '19 at 16:17

Why would the chloride ion attack the electron rich amine? The amine is the best nucleophile is the system and will attack the NO+. This gives a RNH-NO nitroso species which is then protonated on Oxygen, loses water and gives the diazonium cation. This adds loses nitrogen rapidly and adds Chloride to give the primary alkyl chloride.

More can be read about this process here (which I where I sourced the reaction scheme) or by searching the term "nitrosation of primary amine"

• I don't understand how amine is a better nucleophile than chloride ion. – user85683 Nov 26 '19 at 11:29
• @praig_ Well, what you don't understand? You have some serious misunderstandings there. Probably wanted to get too much while not knowing necessary facts. This is such fact. You can get amine from halide and ammonia, not otherwise (unless it's silyl amine) – Mithoron Nov 26 '19 at 23:58