Question

In a reaction

Where, M = Molecules, R = Reagent.
M and R are
(a) \[C{H_3}C{H_2}Cl\] and \[NaOH\]
(b) \[C{H_2}Cl - C{H_2}OH\] and aq. \[NaHC{O_3}\]
(c) \[C{H_3}C{H_2}OH\] and \[HCl\]
(d) \[C{H_2} = C{H_2}\] and heat

Answer 1

Hint: The halohydrin functional group containing a halogen and a hydroxyl group, which are connected to the adjacent carbon atoms. For example: 2-chloroethanol, 3-chloropropane-1,2-diol, etc. Bromohydrin and chlorohydrin are also examples of halohydrin.


Complete Step by Step Answer:
The addition of hypohalous acids (\[HOX\], \[X = Br,Cl\]) to the alkene is an example of an additional reaction. In the given question, we have to determine the molecule (M) and Reagent (R).

As we know that when a molecule of hypohalous acids (\[HOX\], \[X = Br,Cl\]) is added to the double bond of an alkene, the formation of \[C{H_2}Cl - C{H_2}OH\] i.e., formation of M is occurred.
\[C{H_2} = C{H_2} + HOCl \to C{H_2}Cl - C{H_2}OH\]

After that molecule, M undergoes hydrolysis with aqueous sodium bicarbonate (\[NaHC{O_3}\]) OR with reagent R to hydrolyze the \[C - Cl\] bond and form the ethylene glycol (\[C{H_2}OH - C{H_2}OH\]).
\[\begin{array}{l}C{H_2}Cl - C{H_2}OH + aq.NaHC{O_3} \to C{H_2}OH - C{H_2}OH\\\end{array}\]

Like the electrophilic addition reaction of an alkene with bromine, the formation of halohydrin also involves the electrophilic addition reaction, in which anti-addition of chlorine and hydroxyl functional groups occurs with the formation of trans products.

In the question, options (a), (c), and (d) will be the incorrect option because the structure of M is \[C{H_2}Cl - C{H_2}OH\]and reagent R is \[NaHC{O_3}\].
  Therefore, we can conclude that option (b) will be the correct answer.

Note: The halohydrins are not formed by the direct addition of hypohalous acid (\[HOX\]), instead the alkene reacts with bromine (\[B{r_2}\]) or chlorine (\[C{l_2}\]) in the presence of water(\[{H_2}O\]). Sodium bicarbonate (\[NaHC{O_3}\]) is also known as baking soda.