Learn
Games

9.1 - Structure of Amine

Interactive Audio Lesson

Listen to a student-teacher conversation explaining the topic in a relatable way.

Introduction to Amines

Unlock Audio Lesson

Signup and Enroll to the course for listening the Audio Lesson

Teacher
Teacher

Today we will discuss amines, which are organic compounds derived from ammonia. Who can tell me what happens when we replace hydrogen atoms in ammonia?

Student 1
Student 1

We get different types of amines!

Teacher
Teacher

Exactly! There are primary, secondary, and tertiary amines, based on how many hydrogens are replaced. Can anyone tell me the structure of a primary amine?

Student 2
Student 2

Is it R-NH2?

Teacher
Teacher

Correct! Now, defining the shapes: since nitrogen is sp3 hybridized, what shape do you think these compounds have?

Student 3
Student 3

Pyramidal shape!

Teacher
Teacher

Well done! Remember this pyramidal structure; it helps in understanding the bond angles too. The angle is slightly less than 109.5° because of the lone pair. Let’s move on to classification.

Classification of Amines

Unlock Audio Lesson

Signup and Enroll to the course for listening the Audio Lesson

Teacher
Teacher

So let's classify amines now. Can anyone differentiate primary, secondary, and tertiary amines?

Student 1
Student 1

Primary amines have one alkyl group replacing hydrogen, secondary have two, and tertiary have three!

Teacher
Teacher

Excellent! Let's look at some examples. What is an example of a secondary amine?

Student 4
Student 4

R-NR'R''.

Teacher
Teacher

Good job! Remember that naming can vary—primary amines can simply be named as alkane followed by 'amine'. What about secondary amines?

Student 2
Student 2

They use locants for nitrogen substituents.

Teacher
Teacher

Very good! Always remember to check the IUPAC naming conventions, as they can vary in complexity.

Physical Properties of Amines

Unlock Audio Lesson

Signup and Enroll to the course for listening the Audio Lesson

Teacher
Teacher

Let’s dive into the physical properties now, how do amines compare to alcohols in boiling points?

Student 3
Student 3

I think amines have lower boiling points than alcohols of similar mass.

Teacher
Teacher

Correct! Alcohols have stronger hydrogen bonding due to their -OH group compared to -NH2 in amines. How does this affect their solubility in water?

Student 1
Student 1

Lower amines are more soluble than higher ones!

Teacher
Teacher

Exactly! And tetra-substituted amines won't form hydrogen bonds with water, making them insoluble. Now, what about their basicity?

Student 4
Student 4

Amines can act as bases, right?

Teacher
Teacher

Right! The lone pair on nitrogen makes them Lewis bases. Let's remember this key property.

Preparation of Amines

Unlock Audio Lesson

Signup and Enroll to the course for listening the Audio Lesson

Teacher
Teacher

Amines can be synthesized through multiple methods. Can anyone name a method by which we can prepare amines?

Student 2
Student 2

From nitro compounds via reduction?

Teacher
Teacher

Yes! Reduction of nitro compounds is one way. What about another method?

Student 3
Student 3

Ammonolysis of alkyl halides?

Teacher
Teacher

Exactly! Ammonolysis replaces the halide with the amine and can yield mixtures of amines. Can anyone think of a disadvantage here?

Student 4
Student 4

It can result in a mixture of primary, secondary, and tertiary amines.

Teacher
Teacher

Well done! That's essential to remember when discussing preparation methods.

Importance of Amines

Unlock Audio Lesson

Signup and Enroll to the course for listening the Audio Lesson

Teacher
Teacher

Finally, let's talk about the significance of amines in real life. Why are they important?

Student 1
Student 1

They are used in making medicines!

Teacher
Teacher

Yes! They're critical in pharmaceuticals, dyes, and more. What else can you think of?

Student 2
Student 2

And they play roles in biochemical processes as well, like neurotransmitters?

Teacher
Teacher

Correct! Compounds like adrenaline contain amine structures. Remember their applications in both synthetic and natural contexts.

Student 3
Student 3

So, understanding amines is crucial in chemistry!

Teacher
Teacher

Absolutely! Great job, everyone!

Introduction & Overview

Read a summary of the section's main ideas. Choose from Basic, Medium, or Detailed.

Quick Overview

Amines are organic compounds derived from ammonia by replacing hydrogen atoms with alkyl or aryl groups, classified into primary, secondary, and tertiary amines based on the number of substituent groups.

Standard

Amines, important organic compounds, are classified as primary, secondary, or tertiary. They possess a pyramidal structure due to sp3 hybridization of the nitrogen atom. The section outlines nomenclature, preparation methods, and the significance of amines in various applications including pharmaceuticals and dyes.

Detailed

Detailed Summary

Amines are organic derivatives of ammonia () characterized by replacing one or more hydrogen atoms with alkyl or aryl groups. This results in compounds known as primary, secondary, and tertiary amines, based on the number of hydrogen replacements. The nitrogen atom exhibits a pyramidal structure due to its sp3 hybridization, with an unshared pair of electrons affecting bond angles and molecular geometry.

Key Classifications and Naming

  • Primary Amines: R-NH2 (one hydrogen replaced).
  • Secondary Amines: R-NR'R'' (two hydrogens replaced).
  • Tertiary Amines: R-NR'R''R''' (all three hydrogens replaced).
    The nomenclature follows both common naming systems and IUPAC standards, which adapt based on the complexity and types of substituents present.

Properties and Reactivity

Amines can be synthesized from nitro compounds, amides, and halides, among others. Physically, amines display varying solubility in water, with the ability to form hydrogen bonds affecting their boiling points and solubility. Tertiary amines lack hydrogen bonding, which decreases their boiling point compared to primary and secondary amines.

Amines also demonstrate basicity due to the lone pair on nitrogen, making them reactive with acids to form salts. The section highlights their role in synthesizing medicines and dyes, emphasizing the importance of both structural properties and reactivity in industrial applications.

Youtube Videos

Structure of Amine | Part 2 | class 12 | unit 13 | Amines | CBSE | Chemistry| |tricks by Vani ma'am
Structure of Amine | Part 2 | class 12 | unit 13 | Amines | CBSE | Chemistry| |tricks by Vani ma'am
Amines - Structure of Amines & Classification | Class 12 Chemistry Chapter 9 | CBSE 2024-25
Amines - Structure of Amines & Classification | Class 12 Chemistry Chapter 9 | CBSE 2024-25
Chemical Properties of Amines (Part 2) - Amines | Class 12 Chemistry Chapter 9 | CBSE 2024-25
Chemical Properties of Amines (Part 2) - Amines | Class 12 Chemistry Chapter 9 | CBSE 2024-25
Amines| Class 12 Chemistry One Shot| NCERT Chapter 13 | CBSE NEET JEE
Amines| Class 12 Chemistry One Shot| NCERT Chapter 13 | CBSE NEET JEE
Chemical Properties of Amines (Part 1) - Amines | Class 12 Chemistry Chapter 9 | CBSE 2024-25
Chemical Properties of Amines (Part 1) - Amines | Class 12 Chemistry Chapter 9 | CBSE 2024-25
1) Amines| Structure of Amines| Chapter-9 organic chemistry class 12 #neet #jee #chemistry
1) Amines| Structure of Amines| Chapter-9 organic chemistry class 12 #neet #jee #chemistry
Preparation of Amines - Amines | Class 12 Chemistry Chapter 9 | CBSE 2024-25
Preparation of Amines - Amines | Class 12 Chemistry Chapter 9 | CBSE 2024-25
CBSE Class 12 || Chemistry || Amines || Animation || in English
CBSE Class 12 || Chemistry || Amines || Animation || in English
Class 12th Chemistry | Structure of Amines | Chapter 9: Amines | NCERT
Class 12th Chemistry | Structure of Amines | Chapter 9: Amines | NCERT
(L-2) Amines (12th Organic) || Structure + Classification + IUPAC naming || JEE NEET
(L-2) Amines (12th Organic) || Structure + Classification + IUPAC naming || JEE NEET

Audio Book

Dive deep into the subject with an immersive audiobook experience.

Overview of Amines

Unlock Audio Book

Signup and Enroll to the course for listening the Audio Book

Amines can be considered as derivatives of ammonia, obtained by replacement of one, two or all the three hydrogen atoms by alkyl and/or aryl groups.

Detailed Explanation

Amines are organic compounds that derive from ammonia (NH₃). In ammonia, nitrogen is bonded to three hydrogen atoms. In an amine, one or more of these hydrogen atoms can be replaced by alkyl (carbon-based) or aryl (aromatic) groups, resulting in different types of amines. This means that if one hydrogen is replaced, we get a primary amine, if two are replaced, a secondary amine, and if all three are replaced, a tertiary amine.

Examples & Analogies

Imagine a three-bedroom house (ammonia) where you can replace one or more rooms (hydrogens) with different types of extensions or rooms designed for various purposes (alkyl or aryl groups). Each replacement gives the house a unique identity.

Pyramidal Structure of Amines

Unlock Audio Book

Signup and Enroll to the course for listening the Audio Book

Like ammonia, nitrogen atom of amines is trivalent and carries an unshared pair of electrons. Nitrogen orbitals in amines are therefore, sp3 hybridised and the geometry of amines is pyramidal. Each of the three sp3 hybridised orbitals of nitrogen overlap with orbitals of hydrogen or carbon depending upon the composition of the amines.

Detailed Explanation

In amines, the nitrogen atom is bonded to three other atoms (usually hydrogen or carbon) and has one pair of unshared electrons. This leads to the nitrogen being trigonal pyramidal in shape, similar to ammonia, but slightly squished. The sp³ hybridization means that nitrogen's electron orbitals have combined to form new orbitals suitable for bonding, resulting in a bond angle slightly less than 109.5° (about 108° in trimethylamine). This configuration allows amines to interact with other chemicals in unique ways due to their shape.

Examples & Analogies

Think of a tetrahedron where one corner is a bit lower than the others; this represents the nitrogen atom pushing down due to the repulsion from its unshared electrons while still reaching outward towards other groups. It's like a pyramid standing on its tip, but with one point pressed down into the ground.

Impact of Unshared Electrons on Bond Angles

Unlock Audio Book

Signup and Enroll to the course for listening the Audio Book

The fourth orbital of nitrogen in all amines contains an unshared pair of electrons. Due to the presence of unshared pair of electrons, the angle C–N–E (where E is C or H) is less than 109.5°; for instance, it is 108° in case of trimethylamine.

Detailed Explanation

The unshared electrons on the nitrogen atom exert a repulsive force on the adjacent bonds. This repulsion alters the ideal bond angles. Instead of being 109.5° as seen in a perfect tetrahedron, the bond angles become slightly smaller, leading to about 108° in molecules like trimethylamine. This mere degree difference may seem minor, but it significantly affects the molecule's reactivity and properties.

Examples & Analogies

Imagine a group of friends trying to fit in a car. If one person (the unshared electrons) takes up extra space by leaning over, the rest of the passengers (the atoms forming bonds) have to shift and squish together a little more, changing how the car feels when driving.

Definitions & Key Concepts

Learn essential terms and foundational ideas that form the basis of the topic.

Key Concepts

  • Amines are derived from ammonia by replacing hydrogen atoms with alkyl or aryl groups.

  • Classification into primary, secondary, and tertiary amines based on hydrogen substitution.

  • Amines have a pyramidal structure due to sp3 hybridization of nitrogen.

  • Basicity of amines is due to the unshared electron pair on nitrogen.

  • Amines are used in various applications, including pharmaceuticals and dyes.

Examples & Real-Life Applications

See how the concepts apply in real-world scenarios to understand their practical implications.

Examples

  • The primary amine methylamine (CH3NH2) has one alkyl group (methyl).

  • An example of a secondary amine is diethylamine (C2H5)2NH.

  • Tertiary amine example: Trimethylamine (CH3)3N.

Memory Aids

Use mnemonics, acronyms, or visual cues to help remember key information more easily.

🎵 Rhymes Time

  • Amines replace hydrogen, it's what they do, primary, secondary, tertiary too!

📖 Fascinating Stories

  • Imagine a chemistry lab where ammonia meets alkyl groups. As they dance, they transform into different amines based on how many partners join the fun!

🧠 Other Memory Gems

  • To remember classification: P (primary), S (secondary), T (tertiary) – just think of 'PST' like a schedule!

🎯 Super Acronyms

Remember 'ABO' for Amines - Basicity, Organic nature, and the Oxygen of hydrogen bonds!

Flash Cards

Review key concepts with flashcards.

Glossary of Terms

Review the Definitions for terms.

  • Term: Amines

    Definition:

    Organic compounds derived from ammonia by replacing hydrogen atoms with alkyl or aryl groups.

  • Term: Primary Amine

    Definition:

    An amine where one hydrogen atom of ammonia is replaced by an alkyl group.

  • Term: Secondary Amine

    Definition:

    An amine where two hydrogen atoms of ammonia are replaced by alkyl groups.

  • Term: Tertiary Amine

    Definition:

    An amine where all three hydrogen atoms of ammonia are replaced by alkyl groups.

  • Term: Sp3 Hybridization

    Definition:

    A type of hybridization where one s orbital and three p orbitals mix to form four equivalent orbitals, characteristic of tetrahedral and pyramidal shapes.

  • Term: Nomenclature

    Definition:

    The system of naming compounds in chemistry according to specific rules.

  • Term: Electrophile

    Definition:

    A reagent that is attracted to electrons and can accept an electron pair.