Are you aware that haloarenes can be produced by marine organisms? Haloarenes can be produced by marine organisms that can utilize the chloride and bromide found in ocean waters. They’ve been recognized to offer a variety of therapeutic qualities. As a result, both artificially and naturally, haloarenes undergo a variety of reactions. Let’s look at the concept Reactions of Haloarenes in more detail !

Reactions of Haloarenes-Electrophilic Substitution, Nucleophilic Substitution, Reaction with metals

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Are you aware that haloarenes can be produced by marine organisms? Haloarenes can be produced by marine organisms that can utilize the chloride and bromide found in ocean waters. They’ve been recognized to offer a variety of therapeutic qualities. As a result, both artificially and naturally, haloarenes undergo a variety of reactions. Let’s look at the concept Reactions of Haloarenes in more detail !

What are Haloarenes ?

Haloarenes are aromatic hydrocarbon halogen derivatives with the halogen atom bonded directly to a carbon atom of the aromatic ring. Aryl halides is another name for them. When a hydrogen atom linked to an aromatic ring is replaced with a halogen atom, haloarenes are formed.

Ar – H + X     ⇢    Ar – X + H

Haloarene has the general formula Ar–X, where Ar denotes an aryl group and X denotes a halogen atom.

Reactions of Haloarenes

Haloarenes or aryl halide reactions can be classified into three categories :

  1. Electrophilic Substitution Reactions
  2. Nucleophilic Substitution Reactions
  3. Reaction with metals

Electrophilic Substitution Reactions of Haloarenes

A species that seek electrons is known as an electrophile. In an organic compound, an electrophile replaces another electrophile in an electrophilic substitution process. The electrophilic processes of the benzene ring, such as halogenation, nitration, sulphonation, and Friedel-Crafts reactions, are all carried out on haloarenes. We’ll go through each one individually, but first, let’s look at how Haloarenes react to an electrophile’s attack :

  1. The benzene ring becomes slightly deactivated towards electrophilic substitution reactions due to the halogen’s electron-withdrawing tendency.
  2. There is more electron or negative charge in the ortho- and para- positions of the ring than in the meta-position due to its varied resonant patterns. As a result, haloarenes operate as both an o- and p- directive for electrophilic substitution reactions.

Because of the aforementioned factors, haloarenes are less active in electrophilic substitution reactions than regular benzene rings. As a result, compared to benzene, these reactions are slower and necessitate more extreme conditions.

Halogenation

Haloarenes react with chlorine in the presence of a solvent to produce haloarenes (say ferric chloride). The chlorine molecule has a small positive charge and tends to become polar. As a result, chlorine works as an electrophile, attacking the compound’s electron-rich Ortho and para positions.

Are you aware that haloarenes can be produced by marine organisms? Haloarenes can be produced by marine organisms that can utilize the chloride and bromide found in ocean waters. They’ve been recognized to offer a variety of therapeutic qualities. As a result, both artificially and naturally, haloarenes undergo a variety of reactions. Let’s look at the concept Reactions of Haloarenes in more detail !

Halogenation

Both ortho and para compounds will be formed as a result of this reaction. The reaction’s principal result will be the para isomer, while the minor product will be the ortho isomer. Chlorobenzene interacts with Lewis acid to produce ortho and para replacements of dihalo-benzenes in the following example.

Nitration

Because of the existence of two electronegative oxygen atoms in the molecule, NO2 is generated first from nitric acid, which is begun by the presence of sulphuric acid; NO2 has an electrophilic centre over N. The electron-rich ortho and para locations are attacked by NO2, yielding the para isomer as the main product and the ortho isomer as the minor product.

Are you aware that haloarenes can be produced by marine organisms? Haloarenes can be produced by marine organisms that can utilize the chloride and bromide found in ocean waters. They’ve been recognized to offer a variety of therapeutic qualities. As a result, both artificially and naturally, haloarenes undergo a variety of reactions. Let’s look at the concept Reactions of Haloarenes in more detail !

Nitration

Sulphonation

SO3 is an electrophile during sulphonation. At the ortho and para locations, it targets the electron-rich haloarene. Para and Ortho Chloro-benzene sulphonic acids are formed as a result of the reaction, with the para isomer being the predominant product and the ortho isomer being the minor.

Are you aware that haloarenes can be produced by marine organisms? Haloarenes can be produced by marine organisms that can utilize the chloride and bromide found in ocean waters. They’ve been recognized to offer a variety of therapeutic qualities. As a result, both artificially and naturally, haloarenes undergo a variety of reactions. Let’s look at the concept Reactions of Haloarenes in more detail !

Sulphonation

Friedel-Crafts Reactions

Because of the positive charge present in the carbon atom, the electrophile in this circumstance is the alkyl and acetonic group. There are two types of Friedel-Crafts Reactions :

Friedel-Crafts Alkylation Reactions:

Are you aware that haloarenes can be produced by marine organisms? Haloarenes can be produced by marine organisms that can utilize the chloride and bromide found in ocean waters. They’ve been recognized to offer a variety of therapeutic qualities. As a result, both artificially and naturally, haloarenes undergo a variety of reactions. Let’s look at the concept Reactions of Haloarenes in more detail !

Friedel-Crafts Alkylation

Friedel-Crafts Acylation Reactions:

Are you aware that haloarenes can be produced by marine organisms? Haloarenes can be produced by marine organisms that can utilize the chloride and bromide found in ocean waters. They’ve been recognized to offer a variety of therapeutic qualities. As a result, both artificially and naturally, haloarenes undergo a variety of reactions. Let’s look at the concept Reactions of Haloarenes in more detail !

Friedel-Crafts Acylation

Nucleophilic Substitution Reactions of Haloarenes

When it comes to haloarenes, nucleophilic substitution reactions are tricky. However, under some conditions, haloarenes undergo a nucleophilic substitution process. The following are the main causes for haloarenes reduced or nonreactive character in nucleophilic substitution reactions :

  • The hydroxyl group acts as a substitute: The halogen atom is replaced by a hydroxyl group when a haloarene is heated to 623K under 300 atmosphere with an aqueous sodium hydroxide solution, generating phenoxide. When dilute hydrochloric acid is used to acidify phenoxide, phenol is produced.
Are you aware that haloarenes can be produced by marine organisms? Haloarenes can be produced by marine organisms that can utilize the chloride and bromide found in ocean waters. They’ve been recognized to offer a variety of therapeutic qualities. As a result, both artificially and naturally, haloarenes undergo a variety of reactions. Let’s look at the concept Reactions of Haloarenes in more detail !
  • Effect of Resonance: The benzene ring’s π – electrons conjugate with the halogen atom in the haloarene structure in the case of haloarenes. The C-X bond develops partial double bonds as a result of this resonance. The haloarene has a more difficult partial double bond cleavage than the haloalkane. As a result, haloarenes are difficult to cleave by a nucleophile and have a lower reactivity in nucleophilic substitution reactions.
Are you aware that haloarenes can be produced by marine organisms? Haloarenes can be produced by marine organisms that can utilize the chloride and bromide found in ocean waters. They’ve been recognized to offer a variety of therapeutic qualities. As a result, both artificially and naturally, haloarenes undergo a variety of reactions. Let’s look at the concept Reactions of Haloarenes in more detail !

Example of Resonance

In a C-X bond, the difference in carbon atom hybridization. In the case of haloarenes, the member of the halogen group is bound to an sp2 hybridized carbon atom. In haloalkanes, on the other hand, the halogen is bound to the sp3 hybridized carbon atom. Compared to sp3C, sp2C has a stronger s character. sp2C is, therefore, more electronegative than sp3C.

As a result, sp2C is better at removing electrons from the C-X bond and retaining them close to itself. As a result, the bond length between haloarenes and haloalkanes is shorter. Bonds that are shorter in length are stronger. In haloalkane, for example, the C—Cl bond length is 177 pm, while in haloarene it is 169 pm.

Reaction of Haloarenes with Metals

Metals react with haloarenes in a limited way. There are two primary reactions :

Fitting Reaction 

The aryl group substitutes for the halogen atom in haloarene. When sodium metal is heated in the presence of dry ether, a diaryl is produced. A fitting reaction is what we call this.

Are you aware that haloarenes can be produced by marine organisms? Haloarenes can be produced by marine organisms that can utilize the chloride and bromide found in ocean waters. They’ve been recognized to offer a variety of therapeutic qualities. As a result, both artificially and naturally, haloarenes undergo a variety of reactions. Let’s look at the concept Reactions of Haloarenes in more detail !

Fitting Reaction

In this reaction, dry ether is used to react a mixture of haloarenes with sodium. Diaryl is the end result.

Wurtz-Fitting Reaction

When a halogen atom of a haloarene is heated in the presence of sodium in an ethereal solution of an alkyl halide, the halogen atoms of the haloarene are replaced by the alkyl group, resulting in the formation of a higher arene.

Are you aware that haloarenes can be produced by marine organisms? Haloarenes can be produced by marine organisms that can utilize the chloride and bromide found in ocean waters. They’ve been recognized to offer a variety of therapeutic qualities. As a result, both artificially and naturally, haloarenes undergo a variety of reactions. Let’s look at the concept Reactions of Haloarenes in more detail !

Wurtz-Fitting Reaction

In the presence of dry ether and sodium, a combination of alkyl halides interacts with an aryl halide. Alkyl arene is the finished product.

Sample Questions(FAQs)

Question 1: Define Haloarenes.

Answer:

Haloarenes are aromatic hydrocarbon halogen derivatives with the halogen atom bonded directly to a carbon atom of the aromatic ring. Aryl halides is another name for them. When a hydrogen atom linked to an aromatic ring is replaced with a halogen atom, haloarenes are formed.

Question 2: What causes electrophilic substitution of haloarenes? 

Answer:

Through the resonance effect, the halogen atom in haloarenes transfers electrons to the benzene nucleus, which is electron-deficient in comparison to the halogen atom. Electrophilic substitution reactions occur in haloarenes as a result of the electrophile attacking at both the ortho and para positions.

Question 3: Why is nucleophilic substitution in haloarenes so difficult?

Answer:

In haloarenes, the C–X bond takes on a partial double bond character and shortens. It boosts the C–X bond’s strength and gives haloarenes more stability. Cleavage of C–X bonds in haloarenes is substantially more difficult than in haloalkanes because of this.

Question 4: Explain the Mechanism of Aromatic Nucleophilic Substitution Reaction.

Answer:

The π – electrons migrate in such a way that the electron density in the benzene ring delocalizes at Ortho- and Para- positions as a nucleophile approaches and attacks the C-X bond. If an electron withdrawing group is present at the Ortho and Para locations of the benzene ring in this situation, it will withdraw the negative charge on the carbon atom, stabilizing the negative charge.

As a result, the presence of electron withdrawing groups like NO2 at the Ortho and Para positions aids the nucleophile’s attack. Furthermore, resonance as well as an electron withdrawing group like NO2 help to stabilize the carbocation.

The reaction will proceed in a sequence of fast and slow steps, resulting in the production of a high resonance stabilized sigma complex with a high resonance. Finally, when the negative charge delocalizes due to the elimination of the Cl bond, the π – electrons will be recovered. The final step is to form the product.

Question 5: Why do haloarenes have an ortho para directional effect?

Answer:

Ortho para directing is haloarenes. Because the halogen atoms on the benzene ring in haloarenes are ortho and para directing groups on the benzene ring, this is the case. The electron density at the o– and p– positions of the ring increases slightly due to resonance. The o- and p-positions in haloarenes have greater electron density centers than the m-positions due to resonance.

Question 6: What types of Friedel-Crafts reactions are there?

Answer:

There are Two types of Friedel-Crafts Reactions :

  1. Friedel-Crafts Alkylation Reactions
  2. Friedel-Crafts Acylation Reactions

Because of the positive charge present in the carbon atom, the electrophile in this circumstance is the alkyl and acetonic group.

Friedel-Crafts Alkylation Reactions:

Are you aware that haloarenes can be produced by marine organisms? Haloarenes can be produced by marine organisms that can utilize the chloride and bromide found in ocean waters. They’ve been recognized to offer a variety of therapeutic qualities. As a result, both artificially and naturally, haloarenes undergo a variety of reactions. Let’s look at the concept Reactions of Haloarenes in more detail !

Friedel-Crafts Alkylation

Friedel-Crafts Acylation Reactions:

Are you aware that haloarenes can be produced by marine organisms? Haloarenes can be produced by marine organisms that can utilize the chloride and bromide found in ocean waters. They’ve been recognized to offer a variety of therapeutic qualities. As a result, both artificially and naturally, haloarenes undergo a variety of reactions. Let’s look at the concept Reactions of Haloarenes in more detail !

Friedel-Crafts Acylation

Er. Neeraj K.Anand is a freelance mentor and writer who specializes in Engineering & Science subjects. Neeraj Anand received a B.Tech degree in Electronics and Communication Engineering from N.I.T Warangal & M.Tech Post Graduation from IETE, New Delhi. He has over 30 years of teaching experience and serves as the Head of Department of ANAND CLASSES. He concentrated all his energy and experiences in academics and subsequently grew up as one of the best mentors in the country for students aspiring for success in competitive examinations. In parallel, he started a Technical Publication "ANAND TECHNICAL PUBLISHERS" in 2002 and Educational Newspaper "NATIONAL EDUCATION NEWS" in 2014 at Jalandhar. Now he is a Director of leading publication "ANAND TECHNICAL PUBLISHERS", "ANAND CLASSES" and "NATIONAL EDUCATION NEWS". He has published more than hundred books in the field of Physics, Mathematics, Computers and Information Technology. Besides this he has written many books to help students prepare for IIT-JEE and AIPMT entrance exams. He is an executive member of the IEEE (Institute of Electrical & Electronics Engineers. USA) and honorary member of many Indian scientific societies such as Institution of Electronics & Telecommunication Engineers, Aeronautical Society of India, Bioinformatics Institute of India, Institution of Engineers. He has got award from American Biographical Institute Board of International Research in the year 2005.

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CBSE Class 12 Chemistry Syllabus Download PDF

Below is the CBSE Class 12 Syllabus along with the marking scheme and time duration of the Chemistry exam.

S.NoTitleNo. of PeriodsMarks
1Solutions107
2Electrochemistry129
3Chemical Kinetics107
4d -and f -Block Elements127
5Coordination Compounds127
6Haloalkanes and Haloarenes106
7Alcohols, Phenols and Ethers106
8Aldehydes, Ketones and Carboxylic Acids108
9Amines106
10Biomolecules127
Total70

CBSE Class 12 Chemistry Practical Syllabus along with Marking Scheme

The following is a breakdown of the marks for practical, project work, class records, and viva. The total number of marks for all parts is 15. The marks for both terms are provided in the table below.

Evaluation Scheme for ExaminationMarks
Volumetric Analysis08
Salt Analysis08
Content-Based Experiment06
Project Work and Viva04
Class record and Viva04
Total30

CBSE Class 12 Chemistry Syllabus (Chapter-wise)

Unit -1: Solutions

  • Raoult's law.
  • Colligative properties - relative lowering of vapour pressure, elevation of boiling point, depression of freezing point, osmotic pressure, determination of molecular masses using colligative properties, abnormal molecular mass.
  • Solutions, Types of solutions, expression of concentration of solutions of solids in liquids, solubility of gases in liquids, solid solutions.
  • Van't Hoff factor.

Unit -2: Electrochemistry

  • Redox reactions, EMF of a cell, standard electrode potential
  • Nernst equation and its application to chemical cells
  • Relation between Gibbs energy change and EMF of a cell
  • Kohlrausch's Law
  • Electrolysis and law of electrolysis (elementary idea)
  • Dry cell-electrolytic cells and Galvanic cells
  • Conductance in electrolytic solutions, specific and molar conductivity, variations of conductivity with concentration.
  • Lead accumulator
  • Fuel cells

Unit -3: Chemical Kinetics

  • Rate of a reaction (Average and instantaneous)
  • Rate law and specific rate constant
  • Integrated rate equations and half-life (only for zerfirst-order order reactions)
  • Concept of collision theory (elementary idea, no mathematical treatment)
  • Factors affecting rate of reaction: concentration, temperature, catalyst;
  • Order and molecularity of a reaction
  • Activation energy
  • Arrhenius equation

Unit -4: d and f Block Elements  

  • Lanthanoids- Electronic configuration, oxidation states, chemical reactivity and lanthanoid contraction and its consequences.
  • Actinoids- Electronic configuration, oxidation states and comparison with lanthanoids.
  • General introduction, electronic configuration, occurrence and characteristics of transition metals, general trends in properties of the first-row transition metals – metallic character, ionization enthalpy, oxidation states, ionic radii, color, catalytic property, magnetic properties, interstitial compounds, alloy formation, preparation and properties of K2Cr2O7 and KMnO4.

Unit -5: Coordination Compounds  

  • Coordination compounds - Introduction, ligands, coordination number, color, magnetic properties and shapes
  • The importance of coordination compounds (in qualitative analysis, extraction of metals and biological system).
  • IUPAC nomenclature of mononuclear coordination compounds.
  • Bonding
  • Werner's theory, VBT, and CFT; structure and stereoisomerism

Unit -6: Haloalkanes and Haloarenes  

  • Haloarenes: Nature of C–X bond, substitution reactions (Directive influence of halogen in monosubstituted compounds only). Uses and environmental effects of - dichloromethane, trichloro methane, tetrachloromethane, iodoform, freons, DDT.
  • Haloalkanes: Nomenclature, nature of C–X bond, physical and chemical properties, optical rotation mechanism of substitution reactions.

Unit -7: Alcohols, Phenols and Ethers   

  • Phenols: Nomenclature, methods of preparation, physical and chemical properties, acidic nature of phenol, electrophilic substitution reactions, uses of phenols.
  • Ethers: Nomenclature, methods of preparation, physical and chemical properties, uses.
  • Alcohols: Nomenclature, methods of preparation, physical and chemical properties (of primary alcohols only), identification of primary, secondary and tertiary alcohols, mechanism of dehydration, and uses with special reference to methanol and ethanol.

Unit -8: Aldehydes, Ketones and Carboxylic Acids   

  • Carboxylic Acids: Nomenclature, acidic nature, methods of preparation, physical and chemical properties; uses.
  • Aldehydes and Ketones: Nomenclature, nature of carbonyl group, methods of preparation, physical and chemical properties, mechanism of nucleophilic addition, the reactivity of alpha hydrogen in aldehydes, uses.

Unit -9: Amines    

  • Diazonium salts: Preparation, chemical reactions and importance in synthetic organic chemistry.
  • Amines: Nomenclature, classification, structure, methods of preparation, physical and chemical properties, uses, and identification of primary, secondary and tertiary amines.

Unit -10: Biomolecules     

  • Proteins -Elementary idea of - amino acids, peptide bond, polypeptides, proteins, structure of proteins - primary, secondary, tertiary structure and quaternary structures (qualitative idea only), denaturation of proteins; enzymes. Hormones - Elementary idea excluding structure.
  • Vitamins - Classification and functions.
  • Carbohydrates - Classification (aldoses and ketoses), monosaccharides (glucose and fructose), D-L configuration oligosaccharides (sucrose, lactose, maltose), polysaccharides (starch, cellulose, glycogen); Importance of carbohydrates.
  • Nucleic Acids: DNA and RNA.

The syllabus is divided into three parts: Part A, Part B, and Part C. Part A consist of Basic Concepts of Chemistry, which covers topics such as atomic structure, chemical bonding, states of matter, and thermochemistry. Part B consists of Topics in Physical Chemistry, which includes topics such as chemical kinetics, equilibrium, and electrochemistry. Part C consists of Topics in Organic Chemistry, which covers topics such as alkanes, alkenes, alkynes, and aromatic compounds.

Basic Concepts of Chemistry:

  • Atomic structure: This section covers the fundamental concepts of atomic structure, including the electronic configuration of atoms, the Bohr model of the atom, and the wave nature of matter.
  • Chemical bonding: This section covers the different types of chemical bonds, including ionic, covalent, and metallic bonds, as well as the concept of hybridization.
  • States of the matter: This section covers the three states of matter - solid, liquid, and gas - and the factors that influence their properties.
  • Thermochemistry: This section covers the principles of thermochemistry, including the laws of thermodynamics and the concept of enthalpy.

Chapters in Physical Chemistry:

  • Chemical kinetics: This section covers the study of the rate of chemical reactions and the factors that influence it, including the concentration of reactants, temperature, and the presence of catalysts.
  • Equilibrium: This section covers the principles of chemical equilibrium, including the concept of Le Chatelier's principle and the equilibrium constant.
  • Electrochemistry: This section covers the principles of electrochemistry, including the concept of half-cell reactions, galvanic cells, and electrolysis.

Chapters in Organic Chemistry:

  • Alkanes: This section covers the properties and reactions of alkanes, including their structure, isomerism, and combustion.
  • Alkenes: This section covers the properties and reactions of alkenes, including their structure, isomerism, and addition reactions.
  • Alkynes: This section covers the properties and reactions of alkynes, including their structure, isomerism, and addition reactions.
  • Aromatic compounds: This section covers the properties and reactions of aromatic compounds, including their structure, isomerism, and electrophilic substitution reactions.

In addition to the topics covered in the syllabus, the CBSE Class 12 Chemistry exam also tests students on their analytical and problem-solving skills, as well as their ability to apply the concepts learned in the classroom to real-world situations.

Students can also check out the Tips for the Class 12 Chemistry Exam. They can easily access the Class 12 study material in one place by visiting the CBSE Class 12 page at ANAND CLASSES (A School Of Competitions). Moreover, to get interactive lessons and study videos, download the ANAND CLASSES (A School Of Competitions) App.

Frequently Asked Questions on CBSE Class 12 Chemistry Syllabus

Q1

How many chapters are there in the CBSE Class 12 Chemistry as per the syllabus?

There are 10 chapters in the CBSE Class 12 Chemistry as per Syllabus. Students can learn all these chapters efficiently using the study materials provided at ANAND CLASSES (A School Of Competitions).

Q2

What is the marking scheme for CBSE Class 12 Chemistry practical exam according to the syllabus?

The marking scheme for CBSE Class 12 Chemistry practical exam, according to the syllabus, is 8 marks for volumetric analysis, 8 marks for salt analysis, 6 marks for the content-based experiment, 4 marks for the project and viva and 4 marks for class record and viva.

Q3

Which is the scoring chapter in Chemistry as per CBSE Class 12 syllabus?

The chapter Electrochemistry in Chemistry is the scoring chapter as per CBSE Class 12 syllabus.

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