Question

In the following groups

$- OAc$	$- OMe$	$- OS{O_2}Me$	$- S{O_2}C{F_3}$
I	II	III	IV

The order of the leaving ability is:
A.I > II > III > IV
B.IV > III > I > II
C.III > II > I > IV
D.II > III > IV > I

Answer 1

A leaving group can be identified as an atom or a molecule which can break away from the parent molecule, while taking a lone pair of electrons with it while leaving. These electrons would be the ones that are involved in the bond formed between the leaving species and the parent molecule. Usually, this bond breaking or bond scission occurs due to heterolytic bond cleavage.

Complete Step-by-Step Answer:
Before we move forward with the solution of the given question, let us first understand some important basic concepts.
A good leaving group are classified as those groups of atoms which are weak bases. Hence, we can say that the leaving group characteristics increases with the increase in the acidic character of the species. The basic character of the given options is:
$- OAc$ : In this molecule, the central atom is oxygen which is linked directly to an acetyl group. This acetyl group has a carbonyl substituent which is an electron withdrawing group.
$- OMe$ : In this molecule, the central atom is oxygen which is linked directly to a methyl group. This methyl group has only one carbon atom and no other electron withdrawing substituent.
$- OS{O_2}Me$ : In this molecule, the central atom is oxygen and it is linked to $S{O_2}Me$ which has a sulphur atom which is more electronegative than carbon along with a methoxy group.
$- S{O_2}C{F_3}$ : In this molecule, the central atom is oxygen, which is linked with a sulphur atom, which is linked to chlorofluoromethane group. The chlorofluoromethane group is the most electronegative substituent form the given lot.
Hence, the order of acidic character of the given molecules can be given as:
$- S{O_2}C{F_3} > - OS{O_2}Me > - OAc > - OMe$
Hence, the order of the leaving ability is:
IV > III > I > II

Hence, Option B is the correct option.

Note: Now, any chemical species can be differentiated as either acids, bases or neutral compounds. Acids are those chemical species that accept electrons to form a stable electronic configuration.
Acidic compounds are highly electronegative in nature. On the other hand, bases are those species which donate valence electrons to achieve more stable electronic configuration. These compounds are highly electropositive or nucleophilic in nature.