Question

(a) \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CONHCH}_{3}\) (b) \(\mathrm{CH}_{3} \mathrm{CONH}_{2}\) (c) \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{~N}\left(\mathrm{CH}_{3}\right)_{2}\) (d) \(\mathrm{CH}_{3} \mathrm{CON}\left(\mathrm{CH}_{3}\right)_{2}\)

Short answer

Question: Identify the functional group(s) present in the following organic compounds: (a) CH3CH2CONHCH3 (b) CH3CONH2 (c) CH3CH2~N(CH3)2 (d) CH3CON(CH3)2 Answer: (a) Amide (b) Primary amide (c) Tertiary amine (d) Tertiary amide

Step-by-step solution

Identify functional group

In this compound, we see the presence of the \(\mathrm{CONH}\) functional group, which represents an amide functional group. (b) \(\mathrm{CH}_{3} \mathrm{CONH}_{2}\)

Identify functional group

In this compound, we see the presence of the \(\mathrm{CONH}_{2}\) functional group, which represents a primary amide functional group. (c) \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{~N}\left(\mathrm{CH}_{3}\right)_{2}\)

Identify functional group

In this compound, we see the presence of the \(\mathrm{~N}\left(\mathrm{CH}_{3}\right)_{2}\) functional group, which represents a tertiary amine functional group. (d) \(\mathrm{CH}_{3} \mathrm{CON}\left(\mathrm{CH}_{3}\right)_{2}\)

Identify functional group

In this compound, we see the presence of the \(\mathrm{CON}\left(\mathrm{CH}_{3}\right)_{2}\) functional group, which represents a tertiary amide functional group.

Key concepts

Primary Amide

Amide functional groups are a cornerstone in organic chemistry, often serving as a focal point for identifying the backbone structure of proteins and synthetic polymers. A primary amide is characterized by its CONH₂ functional group, where a carbonyl group is bonded to a primary amine. In the given example (b) CH₃CONH₂, the amide is considered primary because the nitrogen atom is only bound to one carbon atom.

Understanding the structure of primary amides is crucial for students preparing for exams like the Organic Chemistry IIT JEE, where the identification of such functional groups can be a common question type. The 'H₂' in CONH₂ signifies that the nitrogen atom has two single bonded hydrogens, confirming the primary nature of the amide.

Tertiary Amine

Moving from amides to amines, which are functional groups containing nitrogen, a tertiary amine features a nitrogen atom connected to three alkyl or aryl groups. For example, in compound (c) CH₃CH₂N(CH₃)₂, the presence of the N(CH₃)₂ functional group indicates a tertiary amine. Here, no hydrogen atoms are attached to the nitrogen, which differentiates it from primary and secondary amines, where one or two hydrogens would be present, respectively.

It's essential for students to recognize this difference, as a tertiary amine's chemical reactivity and properties are distinct from its primary and secondary counterparts. For students studying for the IIT JEE Organic Chemistry section, such knowledge is not just important, it's imperative for solving complex questions around nitrogen-containing compounds.

Organic Chemistry IIT JEE

The Indian Institutes of Technology Joint Entrance Examination (IIT JEE) is one of the most challenging engineering entrance exams worldwide, and a solid grasp of organic chemistry is a must for success. A significant part of the syllabus includes understanding and identifying various functional groups in organic molecules. In particular, questions may ask students to determine whether a molecule contains groups such as primary amides or tertiary amines.

For success in the Organic Chemistry section of the IIT JEE, students should focus on the functional groups' nomenclature, their physical and chemical properties, and how they can be transformed through chemical reactions. This rigorous preparation helps in interpreting complex organic synthesis pathways and reaction mechanisms, which are often at the heart of the examination questions.

Functional Group Identification

Identifying functional groups is a foundational skill in organic chemistry that involves recognizing and categorizing the various groups of atoms within a compound that confer specific chemical properties. Compounds (a) CH₃CH₂CONHCH₃ and (d) CH₃CON(CH₃)₂ contain different types of amide groups. Distinguishing between the primary, secondary, and tertiary amides, as well as primary, secondary, and tertiary amines, is critical.

For instance, in a tertiary amide, the nitrogen is bonded to the carbonyl carbon and two additional carbon atoms, as opposed to a hydrogen atom in primary amides. Proper functional group identification not only is key to understanding the structure and reactivity of organic compounds but is also an essential skill for students tackling modern organic chemistry syllabi, including those preparing for competitive exams like the IIT JEE.