a. Given the decreasing order of Lewis basicities of the following:
i. ii. `overset (C_(2)H_(5)--O--C_(2)H_(5) underset (Dirthyl ether)`
iii.
b. i. ii. iii.
c. Completer the following reaction :

d. (A) (B) `overset (Nitration) rarr`
e.
f. How are the ethers distinguished form alcohols ?

Explanation

a. Greater the steric hindrance in the ether molecule encountered in the formation of the coordination bond, weaker is the Lewis basicity. In (i), R groups (the side of the ring) are 'tied back' leaving a very exposed O atom free to serves as basic site. In other works, more compact the molecule (due to ring), more easily O atom can donate its LP `bar e` to the Lewis acids, and therefore, stronger the Leis base. The decreasing order of Lewis basicities : (i) gt (ii) gt (iii).
b. In (ii) and (iii), the LP `bar e` density is decreaity in LP `bar e` density is more pronounced in (iii) than in (ii), due to more resonating structure.
i.
ii.
decreasing order of Lewis basicities: (i) gt (ii) gt (iii).
c.
d. `(--OMe)` group is activating group and o- and p- directing, since p-position is bloked. So `(--NO_(2))` group ethers at o-position w.r.t. `(--OMe)` group.

e. The `(--OH)` group is a somewhat stronger activator than `(--OR)` group, thus `(--Br)` enters at ortho position w.r.t. `(--OH)` group (since p-position is blocked). A minor amount of 3-bromo product is also obtained.

f. i. All alcohols give `CH_(4)` (methane gas) when reacted with MeMgBr.

ii. `K_(2)Cr_(2)O_(7)` in acid has a bright orange coloour. When it oxidises `1^(@)` or `2^(@)` alcohol, it is reduced to blue green due to the formation of `Cr^(3+)` .

iii. All alcohols evolve `H_(2)` gas on addition of sodium (Na). `2R --- OH + 2Na rarr 2RONa + H_(2)`
iv. Dry ethers give negative test with all the regents (a, b, and c).