An amine can react with an acid just like any other base to form a salt:

$$\ce{RNH2 + HCl-> RNH3+ Cl-}$$

According to my textbook (unreliable), amines also react with bases just like any other acid:

$$\ce{RNH2 + NaOH -> RNH- Na+}$$

Do amines (if not all amines, at least the ones substituted with a strong withdrawing group) react with bases as shown in the above reaction?

In other words: Are amines amphoteric?

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    $\begingroup$ One easy way to verify the second reaction is to check if SA + SB -> WA + WB condition is satisfied. Here in the second reaction one of the products is $\ce{H2O}$ which is more acidic than $\ce{RNH2}$. So the forward reaction isn't feasible. $\endgroup$
    – user38977
    May 6, 2017 at 4:06
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    $\begingroup$ This makes for a good read: www2.chemistry.msu.edu/faculty/reusch/virttxtjml/chapt16.htm $\endgroup$ May 6, 2017 at 5:55
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    $\begingroup$ Their acidity is quite low and only very strong bases, like $\ce{CH3-}$ or $\ce{N^{3-}}$ can deprotonate amines. $\endgroup$ May 6, 2017 at 6:11
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    $\begingroup$ Certainly $\ce{NaOH}$ isnt strong enough to deprotonate it, so that doesnr happen. $\endgroup$ May 6, 2017 at 6:18
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    $\begingroup$ @NilayGhosh I believe that's incorrect. Zwitterions hve two functional groups, one acidic and one basic, and have both positive and negative charges at the same time within the ion. An amine cannot be a zwitterion. $\endgroup$ May 6, 2017 at 6:20

1 Answer 1


Amines do not react with hydroxide to give amide ions - not significantly at least.

The typical $\mathrm pK_\mathrm a$ of an amine is $\sim 30$ (see Evans pKa table) and that of $\ce{H2O}$ is $\sim 15$. The equilibrium constant for the second equation you wrote is therefore on the order of $10^{-15}$.

In order to generate any amide ions you need a much stronger base than simply hydroxide. A typical choice is an alkyllithium (LDA is commonly made by reacting diisopropylamine with BuLi).

Back to the question whether amines are amphoteric: If your definition of an amphoteric compound is simply "can react either as an acid or a base", then yes, it technically is, since it reacts both with acids ($\ce{HCl}$) or bases ($\ce{RLi}$).

However, it may be useful to draw the line at reacting with aqueous acid and aqueous base. Otherwise, nearly everything with a hydrogen can be considered to be amphoteric (for example, $\ce{HF}$ can technically act as a base to form $\ce{H2F+}$). Under this definition amines are not amphoteric.


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