question_answer

Ethylene is converted to X on passing through a mixture of an acidified aqueous solution of palladium chloride and cupric chloride. Which of the following reagents readily take part in addition reaction with X?

A)  \[\text{B}{{\text{r}}_{\text{2}}}\]                                          

B)  \[HBr\]

C)  \[HCl\]                                

D)  \[HCN\]

Correct Answer: D

Solution :

                 Wackcr process: This process is used in the preparation of acetaldehyde from ethylene. This process involves the treatment of ethylene with an acidified aqueous solution of palladium chloride and cupric chloride as: \[\underset{C{{H}_{2}}}{\overset{C{{H}_{2}}}{\mathop{||}}}\,+PdC{{l}_{2}}+{{H}_{2}}O\xrightarrow{CuC{{l}_{2}}/{{H}^{+}}}\] \[\underset{\begin{smallmatrix}  \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,X \\  (Acetaldehyde) \end{smallmatrix}}{\mathop{C{{H}_{3}}CHO}}\,\,+Pd+2HCl\] So, the compound X is acetaldehyde. The compound X reacts readily with HCN and undergoes addition reaction to give acetaldehyde cyanohydrin as: