Amines Class 12 Chemistry One Shot | HSC Board + MHT-CET 2026 | By Siona Mam

Name: Amines Class 12 Chemistry One Shot | HSC Board + MHT-CET 2026 | By Siona Mam
Uploaded: 2025-09-25T03:30:06.000Z
Duration: 3 h 20 min 45 s

Understanding Amines in Organic Chemistry

Introduction to Amines

The session focuses on amines, considered one of the easiest topics in organic chemistry. The instructor promises to provide notes, exercise questions, and important articles for CET (Common Entrance Test).

The discussion begins with a welcome message and reiterates the importance of staying tuned for comprehensive coverage of the chapter.

Definition and Characteristics of Amines

Amines are defined as nitrogen-containing compounds. The instructor emphasizes understanding what constitutes an amine.

Nitrogen has two lone electrons that do not participate in bonding, referred to as a lone pair. This characteristic makes nitrogen-rich in electrons.

Compounds containing nitrogen are basic due to their electron-rich nature, which qualifies them as Lewis bases.

Importance of Amines

Amines play a crucial role in biological systems; they are present in proteins, vitamins, and hormones.

Classification of Amines

Primary Amines

A primary amine is formed when one hydrogen atom from ammonia (NH3) is replaced by an alkyl group (R), resulting in two remaining hydrogens.

Secondary and Tertiary Amines

In secondary amines, one more hydrogen is replaced by another alkyl group (R), leaving only one hydrogen attached to nitrogen.

Tertiary amines have no hydrogens left on nitrogen; all three positions are occupied by alkyl groups.

Structural Representation

Examples illustrate how primary (1°), secondary (2°), and tertiary (3°) amines can be represented structurally using R groups replacing hydrogen atoms.

IUPAC Nomenclature Rules for Amines

Basic Rules

The nomenclature rules differ significantly between primary, secondary, and tertiary amines based on the number of hydrogen atoms attached to nitrogen.

Identifying Types of Amines

Identification is based on the number of hydrogens: two for primary amines, one for secondary amines, and none for tertiary amines.

Aliphatic vs Aromatic Amines

Aliphatic Amines

Aliphatic amines contain carbon chains where R represents a carbon chain structure like CH3CH2NH2 or CH3NH2.

Aromatic Amines

Aromatic amines involve a benzene ring with NH2 attached; this compound is known as aniline.

Summary of Key Points

Recap on Classification

Primary means one alkyl group replaces one hydrogen; secondary means two replacements; tertiary means three replacements.

This structured overview provides clarity on the topic while allowing easy navigation through key concepts related to amines in organic chemistry.

Understanding Primary and Secondary Amines

Introduction to Primary Amines

The discussion begins with examples of primary amines, specifically mentioning methylamine (one carbon) and propylamine (three carbons).

Clarification is provided on the identification of primary amines, emphasizing that having two hydrogen atoms indicates a primary structure.

Naming Conventions for Amines

The naming convention for compounds like ethane-1,2-diamine is explained, highlighting the importance of numbering in relation to functional groups.

It is noted that when naming compounds with double bonds and amines, priority should be given to the amine group over double bonds.

Examples of Complex Structures

A complex structure involving six carbons is introduced as hexane-1,6-diamine, demonstrating how to name based on carbon count and functional groups.

The term phenylmethanamine is used for a compound with a benzene ring attached to an amine group.

Identifying Substituents in Aromatic Compounds

The position of substituents such as bromine in aromatic compounds is discussed; it’s named as 4-bromoaniline, indicating its position on the benzene ring.

Another example includes 4-methyl-aniline, showcasing how different substituents affect naming conventions.

Transitioning to Secondary Amines

The transition from primary to secondary amines introduces criteria for identification. A secondary amine has one hydrogen atom attached.

Emphasis is placed on using capital 'N' in IUPAC nomenclature when identifying secondary amines.

Structural Considerations in Naming

When determining names for secondary amines, the nitrogen atom must be positioned towards the side with more carbon atoms.

An example illustrates this concept: a compound named N-methylethanamine shows how structural positioning influences nomenclature.

Final Notes on Aromatic Structures

Further examples clarify how both sides can have phenyl rings leading to names like N,N-diphenylethanamine, reinforcing understanding through structural representation.

Understanding Amine Nomenclature

Primary, Secondary, and Tertiary Amines

The discussion begins with the example of N-phenylbenzene amine, illustrating how to identify and name amines based on carbon count.

In the case of propanamine (three carbons), it is identified as secondary due to one nitrogen atom being attached to two carbon chains. The correct nomenclature is N-ethylpropanamine.

For tertiary amines, two capital 'N's are used in naming. An example given is dimethylmethanamine, where the nitrogen is connected to three carbon atoms.

Naming Conventions for Amines

The naming convention emphasizes that if there’s only one nitrogen (NH), it indicates a tertiary amine; if NH2 is present, it's primary; and NH indicates secondary.

When identifying which side the nitrogen should be placed during naming, preference goes to the side with more carbons. This leads to names like N,N-dimethylmethanamine.

Examples and Practice

Further examples illustrate how to determine the correct placement of nitrogen based on carbon counts leading to names such as N,N-diethylpropanamine.

A systematic approach for naming involves alphabetical order when multiple substituents are present: e.g., N-ethyl-N-methylpropane.

Preparation Methods for Amines

Ammonolysis Process

Ammonolysis refers to the addition of ammonia in reactions involving alkyl halides. It results in products like methylamine from CH3Cl when reacted with NH3.

Reduction of Nitro Compounds

The reduction process involves adding hydrogen to nitro compounds (NO2). For instance, CH3NO2 becomes methylamine through this reduction process.

This structured overview captures key concepts related to amine nomenclature and preparation methods discussed in the transcript while providing timestamps for easy reference.

Understanding the Addition of Hydrogen in Chemical Reactions

The Role of Hydrogen in Water Formation

Six hydrogen atoms are needed for the reaction. The logic behind this is explained by considering two oxygen atoms, which require four hydrogen atoms to form two water molecules (2H2O).

After using four hydrogen atoms for water formation, two remain. These remaining hydrogens combine with CH3N to create a compound.

Examples of Amine Formation

In the example C2H5NO2 + six hydrogens, four hydrogens and two oxygens will again form H2O, leaving two hydrogens to bond with C2H5N.

Another example involves C3H7NO2 + 6H, where similar reactions occur leading to the formation of propanamine after accounting for water production.

Reduction Processes Explained

The reduction of nitro compounds involves adding six hydrogens in the presence of SN and HCN as catalysts.

A specific reaction called the Mendius reaction requires sodium and ethanol as catalysts; simply add four hydrogens during reduction.

Catalyst Importance in Reactions

Sodium and ethanol are crucial catalysts that facilitate the addition of hydrogen during reductions. Two hydrogens go to carbon and two to nitrogen.

This process results in amines corresponding directly to the number of carbons present in the original compound (e.g., ethylamine from two carbons).

Understanding Amides vs Amines

The difference between amides (which contain a carbonyl group C=O between carbon and nitrogen) and amines is clarified through examples like CH3NH2 versus CH3C(=O)NH2.

For reducing an amide like CH3C(=O)NH2, lithium aluminum hydride can be used as a catalyst along with adding four hydrogens.

Practical Applications: Propanamide Example

An example involving propanamide shows how adding lithium aluminum hydride leads to successful reduction into propanamine after accounting for water produced.

Final Thoughts on Gabriel Thalamide Reaction

The Gabriel thalamide reaction is highlighted as an important topic within this chemical discussion, emphasizing its significance alongside other reactions discussed earlier.

Understanding the Structure and Reactions of Thalidomide

Introduction to Thalidomide

The speaker discusses the importance of humor in their teaching style, using jokes in Marathi to engage students.

Transitioning to chemistry, the focus shifts to thalidomide's structure, which includes a benzene ring and carbonyl groups (C=O).

Steps Involved in Thalidomide Synthesis

The synthesis process is outlined as a three-step reaction involving KOH, CH3Cl, and NaOH.

In the first step with KOH, water is produced by combining H and OH groups; this modifies the initial structure.

Detailed Reaction Mechanism

The second step involves adding CH3Cl, resulting in the displacement of potassium chloride (KCl).

The final step requires NaOH to remove two hydrogen atoms from nitrogen (N), leading to the formation of CH3NH2.

Hofmann Bromamide Degradation Process

Overview of Bromamide Reactions

The discussion introduces bromamide reactions where bromine (Br2) interacts with amides.

A comparison is made between normal amide reactions and bromamide reactions highlighting differences in carbon retention.

Key Differences Between Amides and Bromamides

In normal amide reactions, carbon count remains constant; however, bromamide processes reduce carbon count by one.

Summary of Various Chemical Processes

Charting Chemical Procedures

A summary chart is proposed for various chemical procedures including ammonolysis and nitro reduction.

Each procedure's catalysts are listed for clarity: ammonolysis uses ammonia (NH3), while nitro reduction employs Sn and HCl.

This structured approach provides an organized overview of key concepts discussed regarding thalidomide synthesis and related chemical processes.

Physical Properties of Amines

Overview of Amines

The discussion begins with a focus on the physical properties of amines, emphasizing their significance in preparation for exams.

Polarity of NH Bond

The NH bond in amines is polar due to the electronegativity difference between nitrogen (N) and hydrogen (H), resulting in partial charges: nitrogen carries a partial negative charge while hydrogen carries a partial positive charge.

Hydrogen Bonding in Amines

Primary amines (RNH2) and secondary amines (RNHR) can form hydrogen bonds because they contain both nitrogen and hydrogen atoms.

Primary amines have two hydrogen atoms available for bonding, leading to stronger hydrogen bonding compared to secondary amines which have only one.

Comparison of Hydrogen Bonding Strength

Tertiary amines lack hydrogen atoms, thus do not participate in hydrogen bonding. This results in primary amines exhibiting the strongest hydrogen bonding followed by secondary, with tertiary having none.

Boiling Point Order

The boiling point order is established as primary > secondary > tertiary due to the extent of hydrogen bonding present; more bonds lead to higher boiling points.

Liquid State and Solubility of Amines

Physical States of Amines

Lower aliphatic amines are gases with unpleasant odors, middle-chain amines are liquids, and higher-chain amines are solids.

Color Characteristics of Anilines

Anilins and other arylamines are typically colorless but can develop colors when reacted with oxygen.

Intermolecular Hydrogen Bonding

Greater intermolecular hydrogen bonding occurs in primary and secondary amines compared to tertiary ones.

Solubility Trends Among Amines

Water Solubility

Lower aliphatic amines exhibit solubility in water due to their ability to form hydrogen bonds with water molecules.

Boiling Point Comparisons

A hierarchy for boiling points is presented: acids > alcohols > amines > alkenes. This ranking aids understanding for examinations.

Basic Strength of Aliphatic Amines

Definition of Bases

Bases are defined as electron donors; hence, nitrogen-containing compounds like aminies act as Lewis bases due to their lone pair electrons on nitrogen.

This structured approach provides clarity on key concepts related to the physical properties and basic strength of amines while ensuring easy navigation through timestamps for further study or review.

Understanding Basicity in Amines

Transition from Ammonia to Amines

The discussion begins with the transition from ammonia (NH3) to primary amines, secondary amines, and tertiary amines, highlighting that basic strength increases as we move along this path.

It is emphasized that amines are bases due to the presence of a lone pair of electrons, which contributes to their basic nature.

Factors Influencing Basicity

Various factors influence the basic nature of amines, including stabilization effects. The presence of a lone pair on nitrogen makes amines Lewis bases.

As we progress from ammonia to tertiary amine, the basic nature increases due to multiple influencing factors.

Order of Basicity

The order of basic strength is established: tertiary > secondary > primary > ammonia. Ammonia is noted as the least basic due to lacking alkyl groups.

Experimental observations reveal that secondary amines exhibit stronger basicity than expected compared to tertiary amines.

Reasons for Observed Basic Strength

Despite expectations for tertiary amines being the strongest bases, it is found that secondary amines actually have higher basic strength.

The first factor influencing this observation is the +I effect (inductive effect), where alkyl groups stabilize positive charges on nitrogen.

Inductive Effect and Stability

Alkyl groups provide stability by donating electron density when nitrogen donates its electrons. Tertiary amine has three stabilizing alkyl groups compared to one in primary and none in ammonia.

This leads to increased stability and thus higher basicity in tertiary over primary and ammonia.

Solvation Effects on Basicity

The influence of solvation is discussed; NH3 shows high solubility in water due to hydrogen bonding capabilities compared to R3N which does not dissolve well.

NH3's ability for hydrogen bonding stems from having more hydrogen atoms available for interaction with water molecules.

Summary of Key Points

Overall, understanding why certain factors like +I effect and solvation impact the basic nature helps clarify why some amines behave differently than expected based on theoretical predictions.

Understanding +I Effect and Solvation

Overview of +I Effect

The basic nature of the +I effect varies among compounds, with R3N exhibiting the highest influence, followed by decreasing effects in other amines.

The solvation effect is most pronounced in NH3 and least in R3NH, contrasting with the +I effect where R3N shows maximum influence.

Relationship Between Effects

The discussion transitions to diazotization and orange dye tests aimed at detecting aromatic primary amines.

These tests help determine if a given amine contains an aromatic ring structure.

Conducting Diazotization Tests

Test Procedure

To perform the test, start with a test tube containing the primary aromatic amine and add 1-2 ml of concentrated HCl.

After cooling, introduce NO2 into the mixture; no reaction indicates whether it is an aromatic primary amine.

Analyzing Results

Transfer the solution to another test tube containing beta-naphthol and NaOH.

If an orange color appears after mixing, it confirms that a primary aromatic amine is present.

Hofmann's Exhaustive Alkylation Process

Understanding Exhaustive Alkylation

This process involves adding CH3Cl to a primary amine until all hydrogen atoms are replaced by alkyl groups.

Reaction Steps

Each addition of CH3Cl results in HCl formation as one hydrogen atom from the amine reacts with Cl from CH3Cl.

Carbylamine Test for Primary Amines

Purpose of Carbylamine Test

This test specifically identifies primary amines; secondary or tertiary amines do not yield positive results.

Identifying Amines

If a compound passes the carbylamine test, it confirms its identity as a primary amine.

Understanding Primary Amines and Their Reactions

Identification of Primary Amines

Secondary and tertiary amines do not exhibit the test for primary amines, which is crucial for identification.

The reaction of primary amines with chloroform is a key method to confirm their presence.

A foul smell arises when primary amines react with chloroform due to the formation of isocyanide, indicating a positive result.

Importance of the Carbamyl Amine Test

The carbamyl amine test is specifically performed for primary amines; it does not apply to secondary or tertiary amines.

The reaction involves treating a primary amine (e.g., CH3NH2) with chloroform (CHCl3) and KOH, leading to the production of isocyanide.

Reaction Mechanism Overview

In the reaction, three moles of KOH are used in conjunction with three chlorine atoms from chloroform.

The resulting products include 3H2O as byproducts alongside isocyanide formation.

Example Reactions

Another example includes using C2H5NH2 (ethylamine), where similar principles apply: treat with chloroform and an equivalent amount of KOH.

When reacting a primary amine like CH3NH2 with nitrous acid (HNO2), specific catalysts such as NaNO2 and HCl are utilized.

Nitrous Acid Reaction Insights

The reaction produces nitrogen gas (N2), hydrochloric acid (HCl), and methanol (CH3OH).

This process highlights how nitrogen gas can be released during reactions involving nitrous acid.

Coupling Reactions in Aromatic Compounds

Understanding Diazonium Salts

Coupling reactions occur between aromatic diazonium salts and certain aromatic compounds like phenol.

In this context, diazonium salt reacts with phenol, leading to the release of HCl while forming new bonds in the aromatic ring structure.

Mechanism Details

The coupling results in connecting two rings through double-bonded nitrogen atoms while maintaining hydroxyl groups on both rings.

Additional Examples

Further examples illustrate that coupling can also involve other substituents like methyl groups without complicating the fundamental mechanism.

This structured overview captures essential concepts regarding primary amines, their identification through specific tests, and subsequent reactions including those involving diazonium salts.

Hinsberg Test Overview

Introduction to Hinsberg Test

The Hinsberg test is used to distinguish between primary and secondary amines, unlike the Carbylamine test which is only applicable for primary amines.

It specifically detects primary and secondary amines, while tertiary amines do not react in this test.

Hinsberg Reagent Structure

The reagent used in the Hinsberg test is known as Benzene Sulfonyl Chloride, characterized by a specific structure involving a benzene ring, sulfonyl groups (S=O), and chloride (Cl).

The full name of the reagent indicates its components: Benzene Sulfonyl Chloride. This compound plays a crucial role in identifying the type of amine present.

Reaction Mechanism

When a primary amine reacts with the Hinsberg reagent, it forms a soluble alkali product; thus indicating that it is indeed a primary amine. If it forms an insoluble alkali, it indicates a secondary amine. Tertiary amines show no reaction at all.

For example, when Ethylamine (C2H5NH2) reacts with Benzene Sulfonyl Chloride, HCl is released and results in a soluble product confirming its identity as a primary amine.

Secondary Amine Reaction

In contrast, when Diethylamine (a secondary amine) reacts with Benzene Sulfonyl Chloride, it produces an insoluble alkali product due to the absence of sufficient hydrogen atoms for solubility confirmation. Thus indicating its classification as a secondary amine.

Key Points for Examination

Important points regarding the Hinsberg test include:

It is observed only in primary and secondary amines.

The reagent used is Benzene Sulfonyl Chloride.

Primary amines yield soluble alkalis upon treatment with this reagent.

Secondary amines yield insoluble alkalis.

Tertiary amines do not react at all. These points are essential for answering exam questions related to this topic effectively.

Electrophilic Reactions Overview

Bromination Process

Bromination involves adding Br2 to Aniline resulting in substitution reactions where three bromides can attach to ortho and para positions on the aromatic ring while releasing HBr as byproduct. This process highlights electrophilic aromatic substitution mechanisms prevalent in organic chemistry studies.

Nitration Mechanism

Nitration entails adding nitric acid (HNO3) which dissociates into nitronium ions (NO2+). These ions then attack meta and para positions on Aniline due to repulsion from lone pairs on nitrogen preventing ortho attachment directly leading to water formation during this reaction process. Understanding these interactions helps clarify nitration's selectivity based on electronic effects within aromatic compounds.

Sulfonation Process

Sulfonation refers to introducing sulfuric acid into Aniline which leads to further electrophilic substitutions similar to nitration but involves different functional group transformations emphasizing how various reagents influence reactivity patterns among aromatic systems significantly impacting synthetic pathways utilized in organic synthesis methodologies today. Understanding these processes provides insight into broader applications within chemical manufacturing sectors globally enhancing practical knowledge bases across disciplines involved therein including pharmaceuticals agrochemicals etc., thereby fostering interdisciplinary collaborations aimed at advancing innovation frontiers continuously evolving over time through research endeavors undertaken collectively across institutions worldwide striving towards excellence consistently throughout their pursuits relentlessly!

Understanding the Reaction of Aniline with H2SO4

Mechanism of Reaction

The reaction begins with aniline (NH2) interacting with sulfuric acid (H2SO4), leading to the formation of NH3 and HSO4.

One hydrogen atom from NH3 is transferred, resulting in a new configuration where NH2 remains while HSO4 is present.

The process involves the removal of specific hydrogen atoms, ultimately forming water (H2O) and leaving behind SO3H as a product.

Formation of Sulfanilic Acid

After adding H2SO4 to aniline, one hydrogen atom is removed from NH3, converting it into NH2. This results in SO3H remaining intact.

The compound formed can be reversible; if a hydrogen ion moves up, it can revert back to NH3 and leave SO3 behind.

Naming the Compound

The final product is referred to as sulfanilic acid due to its structure derived from aniline and sulfonic acid components.

Transitioning to Practice Questions

Motivation for Learning

Despite feeling unwell, the speaker emphasizes the importance of mastering organic chemistry's last chapter for students' benefit.

Engaging with Practice Problems

Students are encouraged to take a short break before diving into practice questions related to previous discussions on reactions involving compounds like para-toluenesulfonyl chloride.

Reactions Involving Para-Toluenesulfonyl Chloride

Understanding Chemical Structures

The structure of benzene sulfonyl chloride is introduced, highlighting its ring structure and functional groups.

Reaction Process

When reacting para-toluenesulfonyl chloride with diethylamine (C2H5NH), Cl combines with H to form HCl while other components remain unchanged in their positions.

Ethane Amine Production via Hofmann Degradation

Key Concepts in Synthesis

Ethane amine (C2H5NH2) can be synthesized through Hofmann bromamide degradation by using a three-carbon amide due to carbon count reduction during synthesis.

Simplified Approach

A straightforward trick for this reaction involves using Br2 and KOH units effectively while ensuring that products align correctly based on carbon counts.

Basicity Order Among Alkyl Amines

Ranking Basicity

The order of basicity among alkyl amines in gaseous phase is tertiary > secondary > primary.

Explanation for Primary Aliphatic Amines' Strength

Primary aliphatic amines are stronger bases than ammonia due to electron-donating alkyl groups enhancing stability through inductive effects.

Conclusion on Stability Factors

The conjugate base formed from primary amines is also more stable compared to ammonia's conjugate base due to structural differences influenced by alkyl groups.

Nitrobenzene Reaction and Product Prediction

Understanding Nitrobenzene

The reaction involves nitrobenzene, which is a benzene ring with an NO2 group.

In the reaction, six hydrogen atoms (H) are added, resulting in the formation of aniline after accounting for the removal of four H atoms and two water molecules (H2O).

Identifying Reactants A and B

The reactants C6H5CH2Br and KCN are introduced; K+ combines with Br- to form KBr.

The product formed is C6H5CH2CN as CN attaches to the carbon chain.

Role of Sodium and Ethanol in Reactions

Mechanism Overview

Sodium and ethanol play crucial roles by providing four hydrogen atoms during reactions, facilitating transformations involving carbon and nitrogen.

Direct Questions on Amine Reactions

Key Reactions Discussed

Direct questions arise regarding carbil amine reactions and Gabriel's thalamide synthesis.

Homework is assigned related to coupling reactions, emphasizing their importance in understanding amine chemistry.

Diazotization Process Explained

Steps in Diazotization

Diazotization involves reacting primary amines with nitrous acid (HNO2), leading to products like N2Cl when combined with NaNO2 and HCl.

Homework Assignments on Important Concepts

Importance of Homework

Homework assignments are highlighted as critical for reinforcing knowledge about Gabriel's thalamide and carbil amine reactions.

IUPAC Naming Conventions for Amines

Classification of Amines

Secondary amines have specific naming conventions based on carbon count; NH groups are positioned according to carbon presence.

Examples of Amine Classifications

Detailed Examples Provided

Various examples illustrate how primary, secondary, and tertiary amines are classified based on their structure.

Reactions Involving Acetonitrile

Preparing Ethylamine from Acetonitrile

The process includes using sodium ethanol to introduce necessary hydrogen atoms into acetonitrile (CH3C≡N), transforming it into ethylamine (CH3CH2NH2).

Distinguishing Between Ethylamine Types Using Hinsberg Reagent

Reaction Outcomes Explained

Primary ethylamine reacts differently than secondary or tertiary amines when treated with Hinsberg reagent; only primary forms soluble products while tertiary does not react.

Announcement of a New Scholarship Test

Introduction to the News

The speaker begins by teasing an important announcement before concluding their session, indicating that it is significant enough to warrant attention.

Details of the Scholarship Test

The announcement reveals the launch of "Boss MBT," which is Vedantu's scholarship test. Students are encouraged to enroll quickly if they haven't already.

The speaker highlights enticing prizes for participants, including items like laptops and free study materials for MHT CET, emphasizing the value of participation.

Importance of Participation

While the test serves as a means to assess knowledge, it also provides access to valuable study materials, making attendance at offline centers on specified dates essential.

The speaker assures students that taking part in this test will be enjoyable and hints at a surprise awaiting them post-test, creating excitement around participation.