\[{\rm{C}}{{\rm{O}}_{\rm{2}}}\] on reaction with ethyl magnesium bromide gives
A. Ethane
B. Propanoic acid
C. Acetic acid
D. None of these

Hint: A Grignard reagent belongs to the group of organometallic compounds. Its common formula is R-Mg-X. Here, R is for the alkyl group, Mg is for magnesium atom and X is for halogen. Here, we have to find the reaction of a Grignard reagent (ethyl magnesium bromide) with carbon dioxide.

Complete Step by Step Solution:
Let's understand the reaction of Carbon dioxide with the Grignard reagent in detail. When a Grignard reagent undergoes a reaction with carbon dioxide (solid form) formation of a carboxylic acid takes place.
It is to be noted that, the reaction of \[{{\rm{C}}_{\rm{2}}}{{\rm{H}}_{\rm{5}}}{\rm{Br}}\]with carbon dioxide is not possible. Here, we have to identify the product given by ethyl magnesium bromide in the reaction with carbon dioxide. So, the chemical reaction is,
Let's understand the reaction of Carbon dioxide with the Grignard reagent in detail. When a Grignard reagent undergoes a reaction with carbon dioxide (solid form) formation of a carboxylic acid takes place.
It is to be noted that, the reaction of \[{{\rm{C}}_{\rm{2}}}{{\rm{H}}_{\rm{5}}}{\rm{Br}}\]with carbon dioxide is not possible. Here, we have to identify the product given by ethyl magnesium bromide in the reaction with carbon dioxide. So, the chemical reaction is,

Image: Reaction of carbon dioxide with ethyl magnesium bromide

Let’s understand the mechanism of the above reaction. In the first step, the bromide ion leaves the Grignard reagent and the nucleophilic attack of the oxygen atom of carbon dioxide at the positively charged Grignard reagent. Then, in an acidic medium, the formation of propanoic acid takes place.

Therefore, the product formed from the reaction of carbon dioxide and ethyl magnesium bromide is propanoic acid.

Hence, option B is right.

Note: Grignard reagent is one of the important compounds in organic chemistry. It is beneficial for the preparation of various organic compounds such as acetals, amides, amino compounds, etc. It is used for the manufacture of many compounds that are useful in the pharmaceutical field.