# Ethyne reaction with HCN (red hot Fe) and CH2N2 (cold ether solution)

I have tried this and according to me

$$\ce{C2H2 + HCN -> C5H5N (pyridine)}$$

and

$$\ce{C2H2 + CH2N2 -> C3H3N2H (pyrazole)}$$

But according to my teacher the case should be vice versa, i.e.
$$\ce{C2H2 + CH2N2->pyridine}$$
I am not able to understand the reasoning.

• These are reactions of acetylene not ethylene Jul 23 at 13:30
• Ethylene is the alkene, $\ce{C2H4}$. Ethyne or acetylene as @Waylander said is the correct name for $\ce{C2H2}$. Also, for formatting chemical equations, refer this - chemistry.stackexchange.com/help/notation - it's understandable if you didn't know of it in the first place, but the very least you could do was to capitalize the carbon and hydrogen atoms in your equations. Please be careful in the future. Better framed questions are seen more favourably.
– TRC
Jul 23 at 14:19

It appears that your teacher is wrong!

The synthesis of pyridine from acetylene and hydrogen cyanide over red hot iron was originally reported by William Ramsay in 1876 wikipedia. Further examples have been reported JACS paper here, patent with Rhodium and Cobalt catalysis here

The second reaction is the Pechmann Pyrazole synthesis article here.

The preparation of pyrazole derivatives with the participation of a 1,3-dipolar cycloaddition between diazomethane (or diazonium salt in some cases) and a molecule with carbon-carbon double or triple bonds with subsequent oxidation (if they are double bonds) of the Pyrazoline is generally known as Pechmann's pyrazole synthesis.