NCERT Solutions for Class 12 Chemistry Chapter 13 – Amines
Our well-structured NCERT Solutions for Class 12 Chemistry Chapter 13 – Amines are drafted as per the latest guidelines given by CBSE. This chapter tells you that amines are a class of organic compounds which are derivatives of ammonia having a pyramidal structure. Here you will learn to classify amines as primary, secondary and tertiary amines and how to give them common and IUPAC names.
Here you will also learn about key methods of preparation of amines and explain the properties of amines. This chapter will teach you how to differentiate between primary, secondary and tertiary amines by using chemical reagents. This chapter describes elaborately about the preparation methods of diazonium salts and their importance in the synthesis of other aromatic compounds and azo dyes.
This exercise at the end of the chapter comprises 14 questions. All of these questions have been designed to cover all the concepts taught in NCERT CBSE Class 12 Chemistry Chapter 13. The questions asked here need you to provide reasons, give explanations, provide preparation methods, predict products of given reactions in case of aliphatic and aromatic amines. Our NCERT Solutions answer all these questions in details and in an easy to follow step by step manner. Solutions of Class 12 Chemistry Chapter 13 – Amines precisely answer all of these questions, to help you learn faster and more efficiently. Our solutions help you to develop a firm grip on the concepts of this chapter. They have been devised to make learning fun, fascinating and highly effective.
NCERT Class 12 Chemistry Chapter 13: Important Topics
NCERT Solutions for Class 12 Chemistry Chapter 13 – Amines includes all the important topics of this chapter. They give you a complete overview and a thorough understanding of the subject matter. The main points given in this chapter are as follows
- Structure of Amines and Their Classification.
This portion of the CBSE NCERT Class 12 Chemistry Chapter 13 tells you that amines are obtained by replacement of hydrogen atoms of NH3 molecule with alkyl or aryl groups. Upon replacement of one hydrogen atom of ammonia, we obtain primary amine with a structure of R-NH2.
This chapter also teaches you that secondary amines have a characteristic structure of R2NH or R-NHR′ and tertiary amines are R3N, RNR′R′′ or R2NR′. In case the alkyl or aryl groups are the same on secondary and tertiary amines, they are known as simple amines bit if they have different groups attached to them then they are known as mixed amines. All the three types of amines behave as Lewis bases like ammonia, by virtue of having one unshared electron pair on the nitrogen atom.
This part of the chapter tells you that in the common system, an aliphatic amine gets the name of the alkyl group as a prefix to the word amine, and in IUPAC system, amines are named as alkanamines in case of aliphatic amines and arenamines (removing suffix ‘e’ of arene and adding amine to the names of arenes).
- Preparation of Amines
This part of the NCERT Class 12 Chemistry Chapter 13 deals with the processes for preparing aliphatic and aromatic amines. Amines are prepared by reducing nitro compounds by passing hydrogen in the presence of metal catalysts, performing ammonolysis of alkyl halides, reducing nitriles or amides in the presence of lithium aluminium hydrides.
Here you will also learn that Gabriel phthalimide synthesis and Hoffman bromamide degradation reaction performed on primary amines are also methods of preparing new amines.
- Physical Properties
This part of the Class 12 Amines chapter discusses the physical properties of aliphatic and aromatic amines. The N-H bond is polar, and the nitrogen atom has a lone pair on it, these two factors govern both the physical and chemical properties of amines. Primary and secondary amines exhibit hydrogen bonding which is the reason for lower amines being soluble in water.
NCERT CBSE Class 12 Chapter 13 further tells you that in alkylamines, there are three factors influencing the stability of ammonium cations (substituted), electron releasing, steric and H-bonding in polar protic solvents. These factors affect the basic nature of amines. Alkylamines behave as stronger bases compared to ammonia due to the electron releasing nature of the alkyl group which end up in increasing the density of electrons on N atoms. In aromatic amines, electron releasing groups attached to the ring increase and electron-withdrawing groups decrease their basic character. Ammonia is a stronger base than aniline.
- Chemical Properties
This part of the CBSE NCERT Class 12 Chemistry Book teaches you the chemical reactions shown by amines. It tells you that amines are Lewis bases and, hence they react with acids producing salts. Reactions of amines are directed by the presence of the unshared pair of electrons on nitrogen. The number of hydrogen atoms on the nitrogen atom influence the type of reaction amines undergo. The nature of products obtained out of the is responsible for identification and distinction between primary, secondary and tertiary amines.
This portion of the chapter further tells you that amines undergo alkylation and acylation reactions with alkyl halides and acyl halides, respectively. Aliphatic and aromatic primary amines undergo carbylamine reaction when treated with ethanolic KOH and CHCl3.
You further come to know that amines react with nitrous acid prepared in situ, where primary amines form aliphatic diazonium salts, and aromatic amines give arene diazonium salts.
This portion further tells you that primary and secondary amines react with Hinsberg’s reagent (benzene sulphonyl chloride) to give corresponding sulphonamides. Also, p-Toluenesulfonyl chloride is used for the identification of primary, secondary and tertiary amines.
This chapter further tells you that aliphatic amines undergo electrophilic substitution like bromination, nitration, sulphonation with suitable reagents. The amino group present in an aromatic ring increases the reactivity of the aromatic amines. This reactivity can be controlled by treating aromatic amine with CH3COCl/(CH3CO)2O.
- Diazonium Salts
This chapter next discusses aryldiazonium salts which are obtained from arylamines. These aryldiazonium salts are later on subjected to replacement of the diazonium group with a variety of nucleophiles to provide phenols, aryl halides, cyanides and arenes. Coupling reactions of aryldiazonium salts with arylamines or phenols produce azo dyes.
CBSE NCERT Class 12 Chemistry Chapter 13 Exercise
Our NCERT Solutions for Class 12 Chemistry Chapter 13 – Amines consists of answers to all 14 questions asked in the exercise given at the end of this chapter. The components of the exercise have been listed below.
- Question 1 asks to provide IUPAC names to the given formulas.
- Question 2 asks to distinguish between two chemicals using a chemical reaction.
- Questions 3, 12 and 14 are explanatory questions.
- Question 4 asks to arrange the given series of compounds according to a given property.
- Question 5 asks to provide synthetic steps for conversion from one compound to the other.
- Question 6 asks for a method of identification of the given compound.
- Question 7 is a direct question asking to write short notes on given terms.
- Question 8 asks to bring about conversion from starting material to product.
- Questions 9 and 11 ask to provide products of chemical reactions.
- Questions 10 is a word problem with a sequence of reactions, and you need to predict the product at each step.
- Question 13 asks you to write the chemical reaction of a given starting material with nitrous acid.
There are 9 intext questions asked in CBSE NCERT Class 12 Chemistry Chapter 13 to which top answers have been provided in our set of solutions.
Benefits of NCERT Solutions for Class 12th Chemistry Chapter 13 – Amines
NCERT Solutions for Class 12 Chemistry Chapter 13 – Amines is very helpful for you. Some of the advantages are as follows –
- They are easy to understand and help you remain conceptually clear.
- They help you to score good marks in your board examinations as well as help you to excel in various competitive exams.
- They are concise and accurate solutions.
- They are interactive and make the learning process more efficient.
- They provide important tips and techniques to solve the questions related to amines.
- They are excellent reference material for learning and revision during your board exams.
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