896 mL of a hydrocarbon 'A' having carbon 87.80 % and hydrogen 12.19% weighs 3.28 g at STP. Hydrogenation of 'A' gives 2-methylpentane. Also 'A' on hydration in the presence of H_(2)SO_(4) and HgSO_(4) gives a ketone 'B' having molecular formula C_(6)H_(12)O. The ketone 'B' gives a positive iodoform test. Find the structure of 'A' and give the reaction involved.

896 mL of a hydrocarbon 'A' having carbon 87.80 % and hydrogen 12.19%

1.	896 mL of a hydrocarbon 'A' having carbon 87.80 % and hydrogen 12.19% weighs 3.28 g at STP. Hydrogenation of 'A' gives 2-methylpentane. Also 'A' on hydration in the presence of H_(2)SO_(4) and HgSO_(4) gives a ketone 'B' having molecular formula C_(6)H_(12)O. The ketone 'B' gives a positive iodoform test. Find the structure of 'A' and give the reaction involved.
Answer» Solution :`"896 ML of" C_(x)H_(y) (A) "weigh"=3.28 g` `"22400 mL of" C_(x)H_(y) (A) "weigh"=(3.28)/(896) xx 22400` `=82 g mo1^(-1)` `:. "Molecular mass of " C_(x)H_(y)=82 g mo1^(-1)` `"Empirical formula of A"=C_(3)H_(5)` `"Empirical formula mass"= 3 xx 12 +5 xx 1=41` `n=("Molecular formula mass")/("Empirical formula mass")=(82)/(41)=2` `:. "Molecular formula" =(C_(3)H_(5))_(2)=C_(6)H_(10)` Now `underset((A))(C_(6)H_(10)) overset("2 mole")to "2-Methylpentane" CH_(3)-underset(CH_(3))underset(\|)CH-CH_(2)CH_(2)-CH_(3)` The molecular has a chain of 5 carbon atoms with a METHYL group at the second carbon atom. Since A adds a molecule of `H_(2)O` in the presence of `Hg^(2+)` and `H^(+)` to give a ketone (B), it should be an alkyne. Two possible structures of .A. are Since the compounds B does not react with `AgNO_(3)` solution, the triple bond is not terminal and therefore, structure (I) is the CORRECT structure.