Question

Five isomeric para-disubsituted atomatic compounds `(A)` to `( E)` with molecular formula `C_(8) H_(8) O_(2)` were given for identification. Based on the following observations give structures of the compounds.
(i) Both `(A)` and `(B)` form silver mirror with Tollens reagent. Further, `(B)` gives a positive test with `FeCl_(3)` solution.
(ii) `(C)` gives positive iodoform test.
(iii) `(D)` is readily extracted in aqueous `NaHCO_(3)` solution.
(iv) `(E )` on acid hydrolysis gives `1,4-`dihydroxy benzene.

Answer 1

(i) Compound `(A)` gives positive Tellens test , contains `(-CHO)` group.

(ii) Compound `(B)` gives positive Tellens and positive `FeCl_3` solution test , it contains both `(-CHO)` and phenolic `(OH)` group.
(p-Hydroxy phenyl acetaldehyde).
(iii) Compound `(C)` gives positive iodoform test , it contains `(MeCO-)` group.

(iv) compound `(D)` gives `NaHCO_3` test , it contains `(-COOH)` grouo.

(v)
From the reaction, it appears that `(E)` is an ester, `(C_(8) H_(10) O_(2))`, but its molecular formula does not correspond to the molecular formula given `(C_(8) H_(8) O_(2))`.
`D.U of C_(8) H_(8) O_(2) = ((2n_C +2)-n_H)/(2) = (18 -8)/(2) = 5^@`
`4 D.U` is accounted for the benzene ring : `1 D.U` should be due to the `(C=C)` bond.
.