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For example, can I convert chlorobenzene into benzonitrile by using potassium cyanide as the reagent?

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  • $\begingroup$ Replacing Cl in with CN is benzene can be done but requires a catalyst. Uncatalysed nothing with happen. $\endgroup$ – Waylander Nov 19 '18 at 19:28
  • $\begingroup$ Can you please tell me the catalyst $\endgroup$ – SLADE Nov 19 '18 at 20:08
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    $\begingroup$ There are many sets of conditions in the literature using Pd or Ni catalysis, more info here organic-chemistry.org/synthesis/C1C/arenes/cyanations.shtm $\endgroup$ – Waylander Nov 19 '18 at 21:04
  • $\begingroup$ If possible, you'd rather start with iodoarenes. One of the well-established method uses copper(I) cyanide. Please see my answer to an earlier question, chemistry.stackexchange.com/questions/63892/… $\endgroup$ – Klaus-Dieter Warzecha Nov 20 '18 at 5:51
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Chlorobenzene is generally inert to nucleophilic substitution. It was observed by Rosenmund and Braun that using an ethanolic solution of potassium cyanide and cuprous cyanide as catalyst at 200°C, chlorobenzene converts to benzoic acid. But if the ethanol-cyanide solvent is removed and temperature is raised, then the reaction proceeds to form cyanobenzene. Yield was further improved when ionic liquids like DMF was used. This is Rosenmund-Braun reaction.

Note: Working with cyanide is highly dangerous. Do not handle cyanide until and unless you are a professional chemist.

Reference

  1. https://en.m.wikipedia.org/wiki/Rosenmund–von_Braun_reaction
  2. Will cyanide substitute bromine in bromobenzene?
  3. Potassium ferrocyanide, $\ce{K4[Fe(CN)6]}$ can be used as a non-toxic source for cyanation.
  4. There are loads of other catalyst for cyanation like $\ce{ZnCl2}$, palladium or nickel salts.[@Waylander]
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