1-propanamine to cyclopropane? I was solving some questions on amines when I happened to see the below question:


  propan-1-amine + ($\ce{NaNO2 + HCl}$)= a mixture of products 
  (originally, the mixture in brackets on the reactant side was just
  written as $\ce{HNO2}$)
  
  The mixture contains:
  
  a.    1-Propanol
  
  b.    2-Propanol
  
  c.    Cyclopropane
  
  d.    All of these


The answer happened to be "d. All of these". I could understand the formation of 1-propanol and 2-propanol but not cyclopropane. The answer given in the textbook wasn't clear and I couldn't understand. It said that the carbocation intermediate had something to do with it which I couldn't follow.

Can someone explain what is behind all this?
Diazotisation of primary amines gives the diazonium salt which decomposes to the primary cation and $\ce{N2}$. From this, in aq. $\ce{HCl}$, you directly get the primary alcohol, primary chloride and primary nitro by immediate trapping of the primary cation by ions in solution and the terminal alkene by 1,2 elimination. 
A cation shift to give the secondary cation also occurs to give secondary alcohol and secondary chloride. 
The cyclopropane arises from a 1,3-elimination of the primary cation. 








pics from reference 1 

References


Amines with Nitrous Acid - chem.libretexts.org
Nitrosation, diazotisation, and deamination by J. H. Ridd  Q. Rev. Chem. Soc., 1961, 15, 418-441 DOI: https://doi.org/10.1039/QR9611500418