Question

A reagent that can form a hydrocarbon with a Grignard reagent is (a) \(\mathrm{HCOOC}_{2} \mathrm{H}_{5}\) (b) \(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{NH}_{2}\) (c) \(\mathrm{CH}_{3} \mathrm{COCH}_{3}\) (d) \(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{COC}_{6} \mathrm{H}_{5}\)

Short answer

Answer: (c) \(\mathrm{CH}_{3}\mathrm{COCH}_{3}\) (acetone)

Step-by-step solution

Identify the structure of each reagent

Let's analyze the structure of the given reagents: (a) \(\mathrm{HCOOC}_{2}\mathrm{H}_{5}\) is ethyl formate (an ester). (b) \(\mathrm{C}_{6}\mathrm{H}_{5}\mathrm{NH}_{2}\) is aniline (an amine). (c) \(\mathrm{CH}_{3}\mathrm{COCH}_{3}\) is acetone (a ketone). (d) \(\mathrm{C}_{6}\mathrm{H}_{5}\mathrm{COC}_{6}\mathrm{H}_{5}\) is benzophenone (a ketone).

Evaluate the reactivity of each reagent with Grignard reagents

A Grignard reagent reacts with carbonyl compounds like aldehydes and ketones to form hydrocarbons. So, we need to find which of the given reagents has a carbonyl group that can react with a Grignard reagent. (a) Ethyl formate is an ester, and esters do not typically react with Grignard reagents to form hydrocarbons. (b) Aniline is an amine which does not have a carbonyl group; hence it does not react with Grignard reagents to form hydrocarbons. (c) Acetone has a carbonyl group and can react with a Grignard reagent to form a hydrocarbon. (d) Although benzophenone has a carbonyl group, it requires two Grignard reagent molecules for the complete reaction, and the product is not a hydrocarbon.

Select the reagent that can form a hydrocarbon with a Grignard reagent

Among the given reagents, option (c) \(\mathrm{CH}_{3} \mathrm{COCH}_{3}\) (acetone), can form a hydrocarbon with a Grignard reagent, because it contains a carbonyl group that readily reacts with a Grignard reagent. Thus, the correct answer is: (c) \(\mathrm{CH}_{3}\mathrm{COCH}_{3}\)

Key concepts

Organic Chemistry

Organic chemistry is the study of the structure, properties, and reactions of organic compounds and materials. These compounds primarily contain carbon atoms, often in combination with elements like hydrogen, oxygen, nitrogen, and more. Understanding the behavior of these compounds is essential in the field of chemistry, as they are involved in everything from industrial processes to biological mechanisms.

One of the significant aspects of organic chemistry is how carbon atoms bond to form various structures, leading to a vast diversity of chemicals. Carbon can form stable covalent bonds with other carbon atoms, allowing for complex molecules like rings, chains, and networks. This flexibility is a cornerstone of organic chemistry's versatility.

Within organic chemistry, reactions play a crucial role in transforming molecules from one form to another. The Grignard reaction, for instance, is a prominent organic reaction that involves the addition of a Grignard reagent to a carbonyl group to form a new bond, demonstrating the reactivity and utility of organic compounds in synthesis.

Carbonyl Compounds

Carbonyl compounds are a group of organic molecules that contain a carbonyl group, which is a carbon atom double-bonded to an oxygen atom, represented as \( C=O \). This functional group is a defining feature of several essential organic molecules, including ketones, aldehydes, esters, and more.

- **Ketones** have the structure \( R_2C=O \) where R can be a carbon-containing group or a hydrogen. Acetone, for example, is a simple ketone with the formula \( CH_3COCH_3 \).
- **Aldehydes** contain at least one hydrogen atom attached to the carbonyl carbon, exemplified by compounds like formaldehyde \( CH_2O \).

Carbonyl compounds are particularly reactive due to the polarized nature of the \( C=O \) bond. This makes them important in many synthetic reactions, including the Grignard reaction, which involves adding a Grignard reagent to the polar carbonyl group. Such reactions are vital for forming carbon–carbon bonds, aiding in the synthesis of complex organic molecules.

Hydrocarbons

Hydrocarbons are organic compounds composed exclusively of hydrogen and carbon atoms. They form the basic foundation of organic chemistry due to their simplicity and diverse structural possibilities. They can be categorized mainly into aliphatic hydrocarbons and aromatic hydrocarbons.

- **Aliphatic hydrocarbons** are further divided into alkanes, alkenes, and alkynes. Alkanes have single bonds, such as \( CH_4 \) (methane). Alkenes have at least one double bond, and alkynes have at least one triple bond between carbon atoms.
- **Aromatic hydrocarbons**, like benzene \( C_6H_6 \), have a distinct structure with alternating double and single bonds, forming a stable ring.

In Grignard reactions, forming a hydrocarbon often involves the addition of a Grignard reagent to a compound with a reactive group, such as a carbonyl, resulting in the formation of alcohols or hydrocarbons. This transformation is useful in creating complex molecules from simpler starting materials, demonstrating the versatility and importance of hydrocarbons in organic synthesis.