Question

Find the structure of (A), `C_(10)H_(10)O_(2)`, a sweet-smelling liquid that has the following properties: It does not dissolve in NaOH or given a colour with `FeCI_(3)` , it adds one equivalent of `H_(2)` on catalytic hydrogenation. Reductive ozonolysis affords `H_(2)C=O` and `C_(9)H_(8)O_(3)` (B) that gives a positive Tollens test. Oxidation of (A) with `KMnO_(4)` gives an acid (C) (MW = 166) which gives no colour with `FeCI_(3)`. When (C) is refluxed with concentrated HI, `H_(2)C=O` and 3,4-dihydroxybenzoic acid are isolated and identified.

Answer 1

i. Six DU in (A) and `(C:H~~1:1)` suggest benzene ring (4 DU).
ii. (A) does not contain phenolic group since it does not dissolve in NaOH and does not give colour with `FeCI_(3)`.
iii. (A) reacts with 1 Eq. of `H_(2)`, which suggests one `(C=C)` bond. Ozonolysis also suggests one `(C=C)` bond. It also conuts one more DU.
iv. To count one more DU, since the total DU is 6. It suggest a fused ring with benzene.
v. There is no other side chain in benzene except `(HC=CH_(2))` group, otherwise it would give a dicarboxylic acid.
vi. Remaining two oxygen atoms must be present in fused ring (which is confirmed by the formation of 3,4-dihydroxybenzoic and with HI) (Acetal ring).
Reactions:

(A) is Safrole isolated form the oil of Sassafras.