Question

Identify the final product Z in the series of chemical reactions.
\[C{{H}_{3}}CN\xrightarrow{Na,{{C}_{2}}{{H}_{5}}OH}X\xrightarrow{HN{{O}_{2}}}Y\xrightarrow{Cu/573K}Z\]
(A) \[C{{H}_{3}}COOH\]
(B) \[C{{H}_{3}}C{{H}_{2}}NHOH\]
(C) \[C{{H}_{3}}CON{{H}_{2}}\]
(D) \[C{{H}_{3}}CHO\]

Answer 1

Hint: In this question, at each step we have to use different reactions and mechanisms. In the first step Mendius reaction is used, in the second step catalyst plays an important role and in the last step, the reactant is oxidised to give the final product.

Complete Step by Step Solution:
 In the first step, the Mendius reaction is used, Mendius reaction involves the reduction of an organic compound having a cyanide group in the presence of an alkali metal and alcohol and results in the formation of amines. With the help of Mendius’s reaction, acetonitrile is converted to ethylamine which is compound X.
\[C{{H}_{3}}C\equiv N+4\left[ H \right]\xrightarrow{Na/Alcohol}C{{H}_{3}}C{{H}_{2}}N{{H}_{2}}\]

In the second step, ethylamine is converted to ethyl alcohol which is compound Y. Process to convert is at a temperature of 0 to 5 degrees Celsius, ethyl amine reacts with a Nitrous acid (obtained from\[NaN{{O}_{2}}\]solution and dilute \[HCl\]), to give ethyl diazonium chloride. This can be given a little heat in an aqueous medium to give ethanol.
\[{{C}_{2}}{{H}_{5}}N{{H}_{2}}+HONO\xrightarrow{NaN{{O}_{2}}/HCl}{{C}_{2}}{{H}_{5}}OH+{{H}_{2}}O+{{N}_{2}}\].

In the last step, ethyl alcohol is then oxidised to acetaldehyde which is compound Z. Process to convert ethyl alcohol to acetaldehyde is when smaller quantities of acetaldehyde can be prepared by the partial oxidation of ethanol in an exothermic reaction. This process typically is conducted over a silver catalyst at about 500–650 °C.
\[C{{H}_{3}}C{{H}_{2}}OH+1/2{{O}_{2}}\to C{{H}_{3}}CHO+{{H}_{2}}O\]
The final product that we get from this reaction is acetaldehyde which is compound Z.
The correct answer is option D, that is\[C{{H}_{3}}CHO\].

Note: At every step different reactions are used with different mechanisms so make sure that we use the reaction and catalyst accurately.