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How will you distinguish between : (i) Benzene and toluene ? (ii) Ethyl benzene and o-xylene ? (iii) Ethyl benzene and styrene ? (iv) Phenyl acetylene and styrene ? |
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Answer» `(##GRB_ORG_CHM_P1_C08_E01_011_S01##)` and toluene can also be easily oxidised to benzaldehyde with `CrO_(2)-CI_(2)`. `(##GRB_ORG_CHM_P1_C08_E01_011_S02##)` But benzen is quite stable and does not undergo oxidation with `CrO_(2)CI_(2)" or "KMnO_(4)`. (ii) Ethyl benzene gives benzoic acid on oxidation with acidic `KMnO_(4)`, while o-xylene gives phthalic acid. `(##GRB_ORG_CHM_P1_C08_E01_011_S03##)` (iii) Styrene `(C_(6)H_(5)CH=CH_(2))` or vinyl benzene having a double bond in the side chain, gives the following two tests : (a) It decolourises purple coloure of dilute cld `KmnO_(4)` solution. Brown precipitate of `MnO_(2)` is formed. This test is not given by ethyl benzene. `underset("Syrene")(3C_(6)H_(5)-CH=CH_(2))+2KMnO_(4)+4H_(2)Oto3C_(6)H_(5)-overset(OH)overset(|)(CH)-overset(OH)overset(|)(CH_(2))+2MnO_(2)+2KOH` (b) Styrene repidly decolourises red COLOUR of bromini in `C CI_(4)`. Ethyl benzene does noot decolourise under this condition. `C_(6)H_(5)CH=CH_(2)+Br_(2)toC_(6)H_(5)-overset(Br)overset(|)underset("Colourless")(CH)-overset(Br)overset(|)(CH_(2))` However, ethyl benzene reacts with bromine at high temperature or in presence of UV light. (vi) Phenyl acetylene `(C_(6)H_(5)-C-=CH)` give a precipitate with ammoniacal silver nitrate solution (due to acidic H-atom). Styrene does not react. `C_(6)underset("Phenyl acetylene")(H_(5)-C-=C-H)+AgNO_(3)+NH_(4)OHtoC_(6)H_(5)-C-=Ag+NH_(4)NO_(3)+H_(2)O` |
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