How will you distinguish between : (i) Ethylbenzene and o-xylene ? (ii) Ethylbenzene and styrene ? (iii) Phenytl acetylene and styrene ? (iv) Benzene and toluene ?

How will you distinguish between : (i) Ethylbenzene and o-xylene ? (i

1.	How will you distinguish between : (i) Ethylbenzene and o-xylene ? (ii) Ethylbenzene and styrene ? (iii) Phenytl acetylene and styrene ? (iv) Benzene and toluene ?
Answer» Solution :(i) Ethylbenzene gives benzoic acid on OXIDATION with `KMnO_(4)` while o-xylene gives phthalic acid. (II) Styrene, Having a double bound in the side-chain, gives the following two tests : (a) It decolourises purple colour of dilute cold `KMnO_(4)` solution. BROWN precipitate of `MnO_(2)` is formed. This test is not GIVEN by ethylbenzene. (b) Styrene repidly dicolourises red colour of bromine in `C CI_(4)`. Ethylbenzene does not decolourise under this condition. `C_(6)H_(5)CH=CH_(2)+Br_(2)tounderset("Coloureless")(C_(6)H_(5)CHBrCH_(2)Br)` However, ethylbenzene reacts wiith bromine at thgh temperature or in presence of UV LIGHT. (iii) Phenyl acetylene gives a precipitate with ammoniacal silver nitrate solution. Styrene does not react. `C_(6)H_(5)-C-=CH+AgNO_(3)+NH_(4)OHtounderset(("ppt"))(C_(6)H_(5)-C-=Ag+NH_(4)NO_(3)+H_(2)O)` (iv) Toluene is easily oxidised to benzaldegyde with `CrO_(2)CI_(2)` or benzoic acid with `KMnO_(4)`. Benzene is quite stable and does not undergo oxidation with `CrO_(2)CI_(2)" or "KMnO_(4)`.