Question

The acid formed when propyl magnesium bromide is treated with carbon dioxide is:
A.)${C_3}{H_7}COOH$
B.) ${C_2}{H_5}COOH$
C.) both A and B
D.) none of the above

Answer 1

The compound like propyl magnesium bromide which contains an alkyl or aryl group, a halogen, and magnesium in it is called Grignard reagent. Grignard reagent can be represented as $RMgX$.

Complete step by step answer:
In this question, the given compound that is propyl magnesium bromide is called Grignard reagent. A Grignard reagent is any reagent which consists of magnesium element, an alkyl or aryl group and a halide group. Grignard reagent has the general chemical formula as $RMgX$. Here, $R$ is alkyl or aryl group and $X$ is a halide group. Grignard reagent is formed when magnesium metal is reacted with alkyl or aryl halide.
When Grignard reagent is reacted with carbon dioxide then a carboxylic acid is formed which includes the carbon chain of Grignard reagent and one carbon of carbon dioxide.
When propyl magnesium bromide that is $C{H _3}C{H_2}C{H_2}MgBr$ reacted with carbon dioxide ($C{O_2}$) then butanoic acid that is ${C_3}{H_7}COOH$is formed and $Mg(OH)Br$ is formed as by product. Here, $C{H_3}C{H_3}C{H_3}MgBr$ is called the Grignard reagent. This reaction can be represented as:
$C{H _3}C{H_2}C{H_2}MgBr + C{O_2} \to C{H_3}C{H_2}C{H_2}COOH + Mg(OH)Br$

Hence, option A.) is the correct answer.

Note: Always remember that when a Grignard reagent is reacted with carbon dioxide then the carboxylic acid is formed at the end which consists of the alkyl carbon chain and one more carbon from carbon dioxide. For example- when $C{H_3}MgX$ that is methyl magnesium bromide is reacted with carbon dioxide($C{O_2}$) then ethyl bromide that is $C{H_3}COOH$ is formed in the product. This includes the alkyl group of Grignard reagent and one carbon of carbon dioxide.