Identity the following compounds :
Saturated ether with fewest C atom atoms (I) that cannot be prepared by Williamson's synthesis.
Unsaturated ether with fewest C atoms (II) that cannot be prepared by Williamson's synthesis.

Explanation

a. One DU in (A) and unreactivity with cold alk. `KMnO_(4)` (Baeyer's reagent) suggest (A) to be a ring compound. (A) is optically active, suggesting a ttrans epoxide.
or

b. Zero DU in (C) and (D) suggests that both are saturated compounds, (C) can be either diol or containinh one (OH) and one (OMe) group since only one mole of MeI reacts with (C) (five C atoms) to give (D) (six C atoms). Compounds (C) contains one (OH) and one (OMe) given at adjacent positions to make (C) chiral.

Another possiblity is:

c. i. Zero DU in (E) and 1 DU in (F). Here, (F) cannot be an alkene because it is inert to `KMnO_(4)` . It must be a cyclic be a cyclic ether. THP (tetrahlydropyran ) therefore (E) must be pentan 1,5-diol.

ii. (E) cannot be
or
because `(E_(1))` on reaction with conc. `H_(2)SO_(4)` would give alkene and `(E_(2))` is chiral.

iii. (E) cannot be vicinal diol of the type for example or because with
an acide they would undergo pinacol-pinacolone rearrangement reaction to give ketone which would undergo oxidation with `KMnO_(4)` .
d. (G) must be a symmetrical ether since on reaction with excess of HI, it gives single RI (G), di-n-propyl ether, or di-isopropyl ether.
e. Williamson's synthesis cannot be carried out in the following six types.
i. Both C atoms are `2^(@)` `R_(2)CH--O--CHR_(2)`
ii. One C is `2^(@)` and one is `3^(@)` `R_(2)CH--O--CR_(3)`
iii. Both C atoms are `3^(@)` `R_(3)C--O--CR_(3)`
iv. Both aryl groups `Ar--O--Ar`
v. Both vinyl groups `H_(2)C=CH--O--CH=CH_(2)`
vi. Both neopntyl groups

Satured ether (I) with fewest C atom is `(Me_(2)CH--O--CHMe_(2))` (Di-isopropyl ether).
f. Unsaturated ether (II) with fewest C atoms is divinyl ether `(H_(2)C=CH--O--CH=CH_(2))`.