Would HCN (liquid) react with halogenoalkanes?

[yucheng]

Halogenoalkanes would undergo nucleophilic substitution if reluxed with HCN in ethanolic KCN solution. We would say that the cyanide ion, $\text{CN}^-$ ion is the nucleophile, while the HCN molecule is not the nucleophile, right? Because if we were to reflux halogenoalkanes with pure HCN (not ethanolic HCN as we would not want the cyanide ions), without KCN, I suppose no reaction would occur?

 

[member38644]

Yes, you are correct. In this scenario, the cyanide ion is the nucleophile and the HCN molecule is not. The presence of ethanolic KCN allows for the formation of the cyanide ion, which is necessary for the nucleophilic substitution reaction to occur. Without ethanolic KCN, pure HCN would not produce the necessary nucleophile and therefore no reaction would occur with the halogenoalkanes.