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I know that diazotization of amines proceeds via the generation of the electrophile $\ce{NO+}$ and thereafter, the $\ce{NH2}$ group acts as a nucleophile and shares it's charge density with $\ce{NO+}$. After a series of rearrangements the diazonium salts are obtained. However, if one had to compare the ease/ rate of diazotization, what should we look at?

  1. The nucleophilic nature of the $\ce{NH2}$ group and it's ability to share it's electron density?
  2. Or something else?

As an example if we had the following compounds (see following diagram):

Amines for diazotization.jpg

So how would we compare the Diazotization and what would be the order? I compared the nucleophilicity and got the order as: 1-aminocyclohexanoic acid < 2-aminoacetophenone < m-acetoxyaniline < aniline.

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  • $\begingroup$ $\ce{NO+}$ is not the nucleophile here. $\endgroup$ Feb 21, 2020 at 19:31
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    $\begingroup$ It is not just about the nucleophilicity. You need to consider the stability of the diazo compound produced. You don't see too many alkyl diazo compounds., they're not stable. $\endgroup$
    – Waylander
    Feb 21, 2020 at 19:44
  • $\begingroup$ Why do you say that NO+ is nucleophile ? It is not $\endgroup$
    – Maurice
    Feb 21, 2020 at 20:13
  • $\begingroup$ My sincere apologies, I meant electrophile. Editing it right away. $\endgroup$ Feb 22, 2020 at 3:55
  • $\begingroup$ @Waylander can you please answer this question and explain how do we proceed to check the stability of the diazonium salts obtained and also do we not look at the nucleophilic nature of the NH2 group altogether? I understand that there is nothing like ignoring all together in chemistry, but is it like the stability of the product is the dominating factor and there's no need to look into the mechanism? $\endgroup$ Feb 22, 2020 at 4:15

1 Answer 1

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You are correct in your reasoning in respect of the aromatic amines, that the rate of diazotisation is driven by the nucleophilicity and the same factors that influence that stabilise the +ve charge of the diazonium species formed. With regard to the cyclohexyl amino acid the diazonium species will not be stable. The reaction will be very slow and the primary product will be the alpha lactone.

Nitrosation of the amino acids RR′C(NH2)(CH2)nCOOH is very slow and kinetic studies are reduced to initial rate measurements. The final products are α-, β-, or γ-lactones for n = 0, 1 and 2, by internal attack by the carboxylate ion at the central carbon atom, which may be concurrent with, or follow, loss of nitrogen, Eq. (99), [168]. Source: https://www.sciencedirect.com/topics/chemistry/primary-aliphatic-amine

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  • $\begingroup$ if you are happy with answer, please accept it $\endgroup$
    – Waylander
    Feb 22, 2020 at 13:31

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