(a)Give a chemical test to distinguish between saturated and unsaturated hydrocarbons. (b) (i) Name the products formed when ethanol burns in air. ‘

Options

A.
B. 0
C.
D.

Answer

A

Explanation

i. (A) gives colour with `FeCI_(3)`, suggesting phenolic group.
ii. (A) gives positive Tollens reagent test, suggesting `(---CHO)` group.
iii. (A) contains only one `(---OH)` group, since it reacts with 1 mol of `CH_(3)` I to form mono methyl ether.
iv. (A) is not steam distilled, which suggests that `(---OH)` and `(---CHO)` groups are not in o-position.
v. Total C atom and O atom, 6C (benzene) `+ ---CHO+(---OH)` group.
vi. Formula of (A) `= C_(8)H_(8)O_(3)`
vii. To count for one additional C atom and one additional O atom, `(---OCH_(3))` group must be present in (A).
viii. A mmust contain

and `(---OH)` and `(---CHO)` not in ortho-position.
ix. Formation of (D), suggests two possible

But the compound `F(C_(7)H_(6)Br_(2)O_(2))` contains `Br_(2)`, which is only possible with compound (II). Therefore, structure (A) is (II).

Alternative method of solving the problem:
Start form (D) and proceed reverse to (C ), (D) is obtained form (C ) by HI, so two structure are possible for (A).
So, (A) is II and then proceed to find out other products.