What will be the major product when propyne is treated with aqueous `H_2SO_4` ? Explain with equation.

Explanation

(i) Propyne does not react with aqueous `H_(2)SO_(4)` in absence of `H^(2+)` ion. In presence of `Hg^(2+)` ion, propyne reacts with aqueous `H_(2)SO_(4)` to give unstable compound prop-2-enol (according to Markownikoff's rule) which tautomerises to give acetone.

(iii) The problem is solved by assuming that the compound 'B' has the molecular formula `C_(7)H_(6)OBr_(2)`

If the compound, A be insoluble in NaOH and shows the above reactions, then the compound A is likely to be anisole (A'). It should, however, be noted that anisole does not react with bromine water, but it reacts with bromine (2 equivalent) in presence of Fe as catalyst to form 2,4-dibromoanisole

An alternative possibility is that the compound A may be benzyl alcohol, `C_(6)H_(5)CH_(2)OH` (A''). it does not dissolve in NaOH or `NaHCO_(3)`, but it undergoes oxidation by `Br_(2)` water to give benzaldehyde.