Amines NCERT Solutions: A Comprehensive Guide

Amines NCERT Solutions: Concepts related to amines with easy-to-understand amines NCERT Solutions including pdf download, exemplar, notes, and use of amines in everyday life.

Introduction to Amines:

Amines are organic compounds that contain a nitrogen atom with a lone pair of electrons. These compounds are derived from ammonia (NH3), in which one or more hydrogen atoms are replaced by an alkyl or aryl group. Amines are classified into three types: primary, secondary, and tertiary amines, based on the number of alkyl or aryl groups attached to the nitrogen atom. In this article, we will discuss Amines NCERT Solutions, which will help students understand the concepts related to amines.

amines ncert solutions
amines ncert solutions

NCERT Solutions for Amines

NCERT Solutions for Amines are a set of well-structured solutions designed to help students understand the concepts related to amines. The solutions cover all the topics mentioned in the NCERT textbook, and the language used in the solutions is easy to understand. The solutions include step-by-step explanations, diagrams, and examples to make the concepts clear to the students.

The NCERT Solutions cover the following topics related to amines:

  1. Nomenclature of Amines: The solutions cover the IUPAC and common names of amines and their derivatives.
  2. Structure and Physical Properties of Amines: The solutions discuss the basicity of amines, their boiling points, solubility, and other physical properties.
  3. Preparation of Amines: The solutions cover various methods for the preparation of amines such as reduction of nitro compounds, Gabriel phthalimide synthesis, and Hofmann degradation.
  4. Chemical Reactions of Amines: The solutions explain the chemical reactions of amines, including acylation, alkylation, oxidation, and reduction.
  5. Diazonium Salts: The solutions cover the preparation and reactions of diazonium salts, which are important intermediates in the synthesis of various compounds.
  6. Aromatic Amines: The solutions discuss the properties and reactions of aromatic amines, which contain an aromatic ring in their structure.
  7. Polyamines: The solutions cover the properties and reactions of polyamines, which are compounds that contain more than one amino group.

The NCERT Solutions provide in-depth explanations of the concepts related to amines and include solved examples and exercises to help students understand the topics better. The solutions are designed to help students prepare for their exams and provide a strong foundation for further studies in organic chemistry.

Amines NCERT Exemplar – 10 important questions

  1. Name the type of reaction in which an amine reacts with nitrous acid. Write the chemical equation of the reaction.

Solution: The reaction between an amine and nitrous acid is called diazotization. The chemical equation for the reaction is as follows:

R-NH2 + HNO2 → R-N2+Cl- + H2O

  1. Why do aromatic amines undergo nitration less easily than benzene?

Solution: Aromatic amines have an electron-donating group (–NH2) attached to the benzene ring, which decreases the electron deficiency of the ring. As a result, the ring becomes less susceptible to electrophilic attack and undergoes nitration less easily than benzene.

  1. Why are primary amines more basic than secondary amines?

Solution: Primary amines have a greater electron-donating effect than secondary amines because the nitrogen atom is only attached to one alkyl group. As a result, primary amines have a greater electron density and are more basic than secondary amines.

  1. How can you convert aniline to benzene diazonium chloride?

Solution: Aniline can be converted to benzene diazonium chloride by treating it with nitrous acid in the presence of hydrochloric acid. The reaction proceeds as follows:

C6H5NH2 + HNO2 + HCl → C6H5N2Cl + 2H2O

  1. Why do aliphatic amines have a higher boiling point than comparable alkanes?

Solution: Aliphatic amines have hydrogen bonding between the amine groups, which increases their boiling point compared to comparable alkanes.

  1. Write the structural formula of primary amine having the molecular formula C4H11N.

Solution: The primary amine with the molecular formula C4H11N is 1-Butanamine.

  1. Why is it not possible to prepare aniline by Gabriel phthalimide synthesis?

Solution: Gabriel phthalimide synthesis involves the formation of a primary amine by the reaction of phthalimide with an alkyl halide, followed by hydrolysis. However, this method cannot be used to prepare aniline as it does not contain a suitable leaving group that can be replaced by an amine group.

  1. Write the structural formula of the amine obtained by reduction of nitrobenzene with Sn/HCl.

Solution: The amine obtained by reduction of nitrobenzene with Sn/HCl is aniline.

  1. Why is it difficult to separate primary, secondary, and tertiary amines by steam distillation?

Solution: Primary, secondary, and tertiary amines have similar boiling points and cannot be easily separated by steam distillation.

  1. Why are aromatic amines less basic than aliphatic amines?

Solution: Aromatic amines have an electron-withdrawing group (–NH2) attached to the benzene ring, which decreases the electron density of the nitrogen atom. As a result, aromatic amines are less basic than aliphatic amines.

NCERT Solutions Amines class 12

Amines are an important topic in organic chemistry that is covered in NCERT Solutions Class 12. The NCERT Solutions provide a comprehensive understanding of the properties, synthesis, and reactions of amines.

The NCERT Solutions cover the nomenclature of amines, including the use of common names and IUPAC names. The solutions also cover the physical properties of amines, such as boiling points, solubility, and basicity. These properties are related to the structure and bonding of amines and are important in predicting the behavior of amines in chemical reactions.

Nomenclature of Some Alkylamines and Arylamines

AmineIUPAC Name
CH3NH2Methanamine
C2H5NH2Ethanamine
C3H7NH2Propan-1-amine
C4H9NH2Butan-1-amine
C6H5NH2Phenylamine
C6H5CH2NH2Benzylamine
(CH3)2NHN,N-Dimethylethanamine
(C2H5)2NHN,N-Diethylethanamine
(C6H5)2NHDiphenylamine
CH3NHCH2CH32-Aminobutane
C6H5NHCH3N-Methylphenylamine

Note: IUPAC names are the systematic names given to organic compounds according to the rules set by the International Union of Pure and Applied Chemistry (IUPAC).

The NCERT Solutions also cover the synthesis of amines through various methods, including the reduction of nitro compounds, Gabriel synthesis, and Hofmann degradation. The solutions explain the mechanisms of these reactions and provide examples of their applications in organic synthesis.

The reactions of amines are also covered in the NCERT Solutions. These reactions include acylation, alkylation, and oxidation reactions. The mechanisms of these reactions are explained, and examples of their applications in organic synthesis are provided.

Reactions of Amines:

Amines undergo several reactions due to the presence of a lone pair of electrons on the nitrogen atom. Some of the important reactions are:

  1. Reaction with Acids:

Amines react with acids to form ammonium salts. The reaction between an amine and an acid is an acid-base reaction, in which the amine acts as a base and the acid acts as an acid. The general equation for the reaction is:

R-NH2 + HX → R-NH3+X-

Where R is an alkyl or aryl group, NH2 is the amino group, HX is an acid, and X- is the anion of the acid.

  1. Reaction with Nitrous Acid:

Primary amines react with nitrous acid (HNO2) to form diazonium salts, which are important intermediates in the synthesis of aromatic compounds. The general equation for the reaction is:

R-NH2 + HNO2 → R-N2+X- + H2O

Where R is an alkyl or aryl group, NH2 is the amino group, X- is the anion of the acid, and R-N2+ is the diazonium salt.

  1. Reaction with Halogens:

Amines react with halogens such as chlorine (Cl2) or bromine (Br2) to form alkyl or aryl halides. The general equation for the reaction is:

R-NH2 + X2 → R-X + NH3

Where R is an alkyl or aryl group, NH2 is the amino group, X is a halogen, and R-X is the alkyl or aryl halide.

  1. Reaction with Carbonyl Compounds:

Amines react with carbonyl compounds such as aldehydes or ketones to form imines or enamines, respectively. The general equation for the reaction is:

R-NH2 + R’CHO → R-N=CHR’ + H2O

Where R and R’ are alkyl or aryl groups, NH2 is the amino group, and R-N=CHR’ is the imine or enamine.

The NCERT Solutions also cover the properties and reactions of aromatic amines, which are a subclass of amines that contain an aromatic ring. These compounds have unique properties and reactions due to the presence of the aromatic ring.

Overall, the NCERT Solutions Class 12 provide a comprehensive understanding of amines and their properties, synthesis, and reactions. These solutions are essential for students studying organic chemistry and provide a strong foundation for further studies in the field.

Amines NCERT Solutions Practice Exercises

  1. Identify the primary, secondary, and tertiary amines in the following compounds: a) CH3CH2NH2 b) (CH3)2NH c) (CH3)3N

Solution: a) Primary amine b) Secondary amine c) Tertiary amine

  1. Write the IUPAC name for the following compound: CH3CH2NHCH3

Solution: N-methylpropan-1-amine

  1. Classify the following compounds as aliphatic or aromatic amines: a) CH3NH2 b) C6H5NH2 c) (CH3)2NH

Solution: a) Aliphatic amine b) Aromatic amine c) Aliphatic amine

  1. Identify the product formed when aniline reacts with HNO3/H2SO4.

Solution: p-nitroaniline

  1. Write the structure of the amide formed by the reaction of acetic acid with ethylamine.

Solution: CH3CONHCH2CH3

  1. Predict the product formed when benzylamine is heated with NaNO2/HCl.

Solution: Benzyl alcohol

  1. Write the structural formula of the secondary amine that can be prepared by the reaction of propanamine with methyl iodide.

Solution: CH3CH2CH(NHCH3)CH3

  1. Identify the amine that can be prepared by the reduction of nitrobenzene.

Solution: Aniline

  1. Write the reaction mechanism for the preparation of a primary amine using Gabriel’s phthalimide synthesis.

Solution:

  1. Write the products formed when benzylamine is treated with each of the following reagents: a) HNO2 b) HCl c) CH3COCl

Solution: a) N2 gas and benzaldehyde b) Benzylammonium chloride c) N-benzylacetamide

Amines NCERT Notes (20 Important Notes)

  1. Amines are organic compounds that contain a nitrogen atom bonded to one or more alkyl or aryl groups.
  2. Amines are classified as primary (1°), secondary (2°), or tertiary (3°) based on the number of alkyl or aryl groups attached to the nitrogen atom.
  3. Aromatic amines contain a nitrogen atom that is part of an aromatic ring, while aliphatic amines do not.
  4. Amines can be synthesized by a variety of methods, including reduction of nitro compounds, reductive amination, and Gabriel synthesis.
  5. Amines are basic in nature and can react with acids to form salts. The basicity of amines increases with the number of alkyl or aryl groups attached to the nitrogen atom.
  6. Amines can also undergo reactions such as nucleophilic substitution, oxidation, and acylation.
  7. Amines are important building blocks for the synthesis of many pharmaceuticals, dyes, and other organic compounds.
  8. Aromatic amines are known to be carcinogenic and can cause DNA damage.
  9. Amines can form intermolecular hydrogen bonds, which can affect their physical properties such as boiling point and solubility.
  10. Amines play an important role in biological systems, serving as neurotransmitters and hormones.
  11. Amines can be used as ligands in coordination chemistry, forming complexes with metal ions.
  12. Amines can be used as solvents for organic reactions, as they are often polar and can dissolve a wide range of compounds.
  13. Amines can undergo Hofmann degradation, a reaction that converts primary amides into primary amines.
  14. Amines can be used as reagents in organic synthesis, such as in the formation of imines and enamines.
  15. Amines can undergo Hofmann elimination, a reaction that converts primary amides into primary amines.
  16. Amines can react with alkyl halides in the presence of a base to form secondary and tertiary amines.
  17. Amines can be used as chiral auxiliaries in asymmetric synthesis.
  18. Amines can be protonated to form ammonium ions, which can undergo Hofmann rearrangement.
  19. Amines can be used as corrosion inhibitors for metals, as they can form a protective layer on the metal surface.
  20. Amines can be used in the production of polymers, such as nylon and polyurethane.
amines derivatives of ammonia
amines derivatives of ammonia

Preparation of Amines:

Amines can be prepared by several methods. Some of the important methods are:

  1. Reduction of Nitro Compounds:

Nitro compounds can be reduced to amines by using reducing agents such as hydrogen gas (H2) or metal hydrides such as LiAlH4 or NaBH4.

  1. Gabriel Phthalimide Synthesis:

In this method, phthalimide (C6H4(CO)2NH) is treated with an alkyl halide to form an N-alkyl phthalimide, which is then treated with hydrazine (NH2NH2) to form the corresponding primary amine.

  1. Hoffmann Bromamide Reaction:

In this method, an amide is treated with bromine (Br2) in the presence of a strong base such as sodium hydroxide (NaOH) or potassium hydroxide (KOH) to form a primary amine.

  1. Reduction of Nitriles:

Nitriles can be reduced to amines by using reducing agents such as lithium aluminum hydride (LiAlH4) or hydrogen gas (H2) in the presence of a catalyst such as nickel (Ni).

Pyramidal shape of trimethylamine
Pyramidal shape of trimethylamine

Properties of Amines:

The properties of amines depend on the type of amine and its structure. Some of the important properties are:

  1. Basicity:

Amines are basic in nature due to the presence of a lone pair of electrons on the nitrogen atom. The basicity of amines increases with the increase in the number of alkyl or aryl groups attached to the nitrogen atom.

  1. Solubility:

Amines are soluble in water due to the formation of hydrogen bonds between the nitrogen atom of the amine and the hydrogen atoms of water molecules. The solubility of amines decreases with the increase in the number of alkyl or aryl groups attached to the nitrogen atom.

  1. Boiling Point:

The boiling point of amines increases with the increase in the number of alkyl or aryl groups attached to the nitrogen atom. This is because the intermolecular forces of attraction between the molecules increase with the increase in the size of the molecule.

  1. Nucleophilicity:

Amines are nucleophilic in nature due to the presence of a lone pair of electrons on the nitrogen atom. The nucleophilicity of amines increases with the increase in the number of alkyl or aryl groups attached to the nitrogen atom.

Structure of Amines:

Amines can be classified as primary, secondary, or tertiary depending on the number of alkyl or aryl groups attached to the nitrogen atom.

amines-structure
amines

The general formula for a primary amine is RNH2, where R is an alkyl or aryl group. In this case, the nitrogen atom is bonded to one alkyl or aryl group and has one lone pair of electrons.

The general formula for a secondary amine is R2NH, where R is an alkyl or aryl group. In this case, the nitrogen atom is bonded to two alkyl or aryl groups and has one lone pair of electrons.

The general formula for a tertiary amine is R3N, where R is an alkyl or aryl group. In this case, the nitrogen atom is bonded to three alkyl or aryl groups and does not have any lone pairs of electrons.

The structure of amines can be represented using structural formulas or molecular models. Structural formulas use lines to represent bonds between atoms and show the arrangement of atoms in a molecule. Molecular models use three-dimensional representations to show the spatial arrangement of atoms in a molecule.

amines
amines

pKb Values of Amines in Aqueous Phase

AminepKb
NH34.74
CH3NH23.36
C2H5NH23.27
(CH3)2NH3.22
C6H5NH24.65
NH2CH2CH2NH23.17
NH(CH3)23.00
C6H5N(CH3)22.83
(C2H5)2NH3.25
C6H5NH(CH3)3.23

Note: The pKb values in the table were obtained from various sources and may vary depending on the conditions of the experiment. pKb is the negative logarithm of the base dissociation constant, which is a measure of the basicity of an amine.

Ammonolysis of alkyl halides
Ammonolysis of alkyl halides

Steps to Convert of 4-nitrotoluene to 2-bromobenzoic acid

Step 1: Reduction of 4-nitrotoluene to 4-aminotoluene 4-nitrotoluene can be reduced to 4-aminotoluene using a reducing agent such as tin and hydrochloric acid or iron and hydrochloric acid. The reaction can be represented as follows:

4-nitrotoluene + 6HCl + Sn or Fe → 4-aminotoluene + 3H2O + SnCl2 or FeCl2

Step 2: Diazotization of 4-aminotoluene The 4-aminotoluene is then converted to its diazonium salt by treating it with sodium nitrite and hydrochloric acid in cold conditions. The reaction can be represented as follows:

4-aminotoluene + NaNO2 + 2HCl → 4-nitroso-2-methylaniline + 2H2O + NaCl

Step 3: Sandmeyer reaction to obtain 2-bromobenzoic acid The nitroso compound is then treated with copper(I) bromide and hydrobromic acid to form the corresponding bromo compound, which upon further oxidation with a strong oxidizing agent such as potassium permanganate or sodium dichromate, yields 2-bromobenzoic acid. The overall reaction can be represented as follows:

4-nitroso-2-methylaniline + CuBr + 2HBr → 2-bromo-4-nitroso-1-methylbenzene + CuBr2 + H2O 2-bromo-4-nitroso-1-methylbenzene + KMnO4 or Na2Cr2O7 → 2-bromobenzoic acid + MnO2 or Cr2O3

The above steps outline a possible route for the conversion of 4-nitrotoluene to 2-bromobenzoic acid. However, it is important to note that the reaction conditions and reagents may vary depending on the specific experimental conditions and desired yields.

amines basic character
amines basic character

20 Important factors related to Amines

  1. Amines are organic compounds that contain a nitrogen atom bonded to one or more alkyl or aryl groups.
  2. Amines can be classified as primary, secondary, or tertiary based on the number of alkyl or aryl groups attached to the nitrogen atom.
  3. Amines are basic in nature and can act as nucleophiles in chemical reactions.
  4. Amines can form hydrogen bonds with water molecules due to the presence of the nitrogen lone pair of electrons.
  5. Amines can be synthesized through various methods including reductive amination, Gabriel synthesis, and Hofmann degradation.
  6. Amines are commonly used as solvents, pharmaceuticals, and in the production of dyes and pigments.
  7. Amines can undergo reactions such as acylation, alkylation, and oxidation.
  8. Amines can react with acids to form salts, which are more water-soluble than the corresponding amine.
  9. Amines can undergo Hofmann elimination to form an alkene and a primary amine.
  10. Amines can undergo Hofmann rearrangement to form an isocyanate and a primary amine.
  11. Amines can be used as ligands in coordination chemistry and can form complexes with metal ions.
  12. Amines can be used as catalysts in various chemical reactions such as hydrogenation and polymerization.
  13. Amines can be used as surfactants and emulsifiers due to their ability to form micelles in water.
  14. Amines can be toxic and irritating to the skin, eyes, and respiratory system.
  15. Amines can be used as inhibitors to prevent corrosion in metals.
  16. Amines can be used as chiral auxiliaries in asymmetric synthesis.
  17. Amines can be used as precursors in the synthesis of various materials such as polymers, nanoparticles, and biomolecules.
  18. Amines can form stable complexes with carbon dioxide, which can be used for carbon capture and storage.
  19. Amines can undergo oxidative deamination, where the nitrogen atom is converted to a carbonyl group.
  20. Amines can undergo reductive amination, where a carbonyl group is converted to an amine using a reducing agent.

FAQs related to Amines

  1. What are amines? Amines are organic compounds that contain a nitrogen atom bonded to one or more alkyl or aryl groups.
  2. What is the general formula of amines? The general formula of amines is R-NH2, where R represents an alkyl or aryl group.
  3. What is the difference between primary, secondary, and tertiary amines? Primary amines have one alkyl or aryl group attached to the nitrogen atom, secondary amines have two, and tertiary amines have three.
  4. What are aromatic amines? Aromatic amines are a subclass of amines that contain an aromatic ring in their structure.
  5. What is the basicity of amines? Amines are basic in nature due to the presence of the lone pair of electrons on the nitrogen atom.
  6. How are amines named? Amines can be named using either common names or IUPAC names, depending on their structure.
  7. What are the physical properties of amines? Amines have a characteristic odor, and their physical properties such as boiling points, solubility, and density vary depending on their structure.
  8. How are amines prepared? Amines can be prepared through various methods such as reduction of nitro compounds, Gabriel phthalimide synthesis, and Hofmann degradation.
  9. What is the Gabriel synthesis? The Gabriel synthesis is a method for the preparation of primary amines using phthalimide and alkyl halides.
  10. What is the Hofmann degradation? The Hofmann degradation is a method for the preparation of primary amines from amides using bromine and aqueous sodium hydroxide.
  11. What is acylation of amines? Acylation of amines is a reaction in which an acyl group is added to an amine.
  12. What is alkylation of amines? Alkylation of amines is a reaction in which an alkyl group is added to an amine.
  13. What is oxidation of amines? Oxidation of amines involves the addition of oxygen or removal of hydrogen from an amine to form an imine or an oxime.
  14. What is reduction of nitro compounds? Reduction of nitro compounds is a method for the preparation of amines using reducing agents such as iron and hydrochloric acid.
  15. What are diazonium salts? Diazonium salts are important intermediates in the synthesis of various compounds and are formed by the reaction of aromatic amines with nitrous acid.
  16. What is the Sandmeyer reaction? The Sandmeyer reaction is a method for the synthesis of aryl halides using diazonium salts.
  17. What are polyamines? Polyamines are compounds that contain more than one amino group and are important in biological systems.
  18. What is the role of amines in biological systems? Amines are important in biological systems as they play a role in the synthesis of proteins, neurotransmitters, and other molecules.
  19. What are some common uses of amines? Amines are used in the production of dyes, pharmaceuticals, and pesticides, among other applications.
  20. What are some hazards associated with amines? Amines can be toxic and may cause skin irritation, respiratory problems, and other health issues. Proper handling and safety precautions are necessary when working with amines.

Amines in Daily Life (Amines in Everyday Life) – Examples of Amines in Everyday Life

  1. Pharmaceuticals: Many drugs contain amines as active ingredients. For example, morphine, a painkiller, contains an amine functional group.
  2. Food flavoring: Amines are used in the production of food flavorings, such as vanilla and chocolate.
  3. Fertilizers: Amines are used as intermediates in the production of fertilizers, such as urea and ammonium nitrate.
  4. Dyes: Amines are used in the production of dyes for textiles and other materials.
  5. Rubber: Amines are used in the production of rubber, as they can act as accelerators in the curing process.
  6. Water treatment: Amines are used as coagulants in water treatment processes, helping to remove impurities and contaminants.
  7. Pesticides: Amines are used as active ingredients in some pesticides, such as insecticides and herbicides.
  8. Personal care products: Amines are used in the production of personal care products, such as shampoos and conditioners.
  9. Adhesives: Amines are used in the production of adhesives, such as epoxy and polyurethane adhesives.
  10. Petroleum production: Amines are used in petroleum production, helping to remove impurities and contaminants from crude oil.
  11. Cleaning products: Amines are used in the production of cleaning products, such as detergents and disinfectants.
  12. Plastics: Amines are used as intermediates in the production of some plastics, such as polyamides.
  13. Textile production: Amines are used in textile production, helping to improve dye uptake and stability.
  14. Photography: Amines are used in photographic developing agents, helping to develop images on photographic film.
  15. Cosmetics: Amines are used in the production of cosmetics, such as hair dyes and skin care products.
  16. Flame retardants: Amines are used in the production of flame retardants, helping to reduce the flammability of materials.
  17. Solvents: Amines are used as solvents in some industrial processes, such as paint and resin production.
  18. Corrosion inhibitors: Amines are used as corrosion inhibitors, helping to prevent metal from rusting or corroding.
  19. Rubber additives: Amines are used as additives in the production of rubber, helping to improve properties such as strength and durability.
  20. Metal extraction: Amines are used in the extraction of metals, such as copper and gold, from ores.

Amines NCERT Solutions PDF Download

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amines ncert solutions pdf download
amines ncert solutions pdf download

Conclusion:

Amines are important organic compounds that have several applications in various fields such as pharmaceuticals, agrochemicals, and dyes. NCERT Solutions for Amines are designed to help students understand the concepts related to amines in an easy and effective manner. The solutions cover all the topics mentioned in the NCERT textbook, and the language used in the solutions is easy to understand. The exercises included in the solutions are designed to test the knowledge and understanding of students on the topic. Overall, NCERT Solutions for Amines are an excellent resource for students who want to learn and understand the concepts related to amines.