Question

Which of these compounds is not formed when gaseous ethene is bubbled into the aqueous solution of bromine, $NaCl$ and $NaN{O}_2$?

• A. $BrC{H}_{2}C{H}_{2}Cl$
• B. $ClC{H}_{2}C{H}_{2}OH$
• C. $BrC{H}_{2}C{H}_{2}N{O}_2$
• D. $BrC{H}_{2}C{H}_{2}OH$

Answer 1

Answer: (B)

$ClC{H}_{2}C{H}_{2}OH$

Chlorobromoethane is mainly produced when aqueous bromine reacts with ethene in the presence of sodium chloride, indicating that the bromine is added to the double bond by slow electrophilic addition before the rapid addition of the chloride ion:

$C_2{H}_4+B{r}_2\to C_2{H}_{4}B{r}^{+}+B{r}^{-}$

$C_2{H}_{4}B{r}^{+}+C{l}^{-}\to C_2{H}_{4}BrCl$

There must be at least one bromine in the product because bromonium ion is the reactive intermediate. So, second option is not possible.$-N{O}_2$ and $-O$ can be added instead of $-Cl$