Haloalkanes and Haloarenes Part 1

When 1-bromo-prop-1-ene reacts with NaNH2 (a strong base), β-elimination or dehydrobromination, (−HBr) takes place to give propyne in next step. When propyne is passed through red hot iron tube, cyclic trimerisation (aromatisation also) occurs to produce mesitylene (A) as major product.