NCERT Class 12 Chemistry Chapter 10 Notes Haloalkanes and Haloarenes - Download PDF

NCERT Class 12 Chemistry chapter 10 notes deal with the relationship between sp³ hybridized carbon atom or a chain of carbon atoms attached to a halogen atom. Haloalkanes and haloarenes Class 12 notes cover a brief outline of topics such as preparation methods for haloalkanes and haloarenes, Chemical and Physical properties of haloalkanes, and haloarenes. The NCERT Class 12 chapter 10 notes are a continuation of NCERT Class 11 chapter 13.

Some of the topics covered in haloalkanes and haloarenes Class 12 notes are reactions for the synthesis of haloalkanes and haloarenes, Physical properties of haloalkanes and haloarenes, Chemical properties of haloalkanes and haloarenes. CBSE class 12 chemistry ch 10 notes contain all the important reactions of this unit. Haloalkanes and Haloarenes notes class 12 also include quick points to remember from the exam point of view. CBSE Class 12 Chemistry Ch 10 notes provide a structured overview of the syllabus, guiding students through the essential topics and highlighting crucial points for effective revision. All the topics mentioned here can be easily downloaded by the student from chemistry class 12 chapter 10 notes pdf.

Also, students can refer,

• NCERT Notes Class 12 Chemistry
• NCERT Solutions for Class 12 Chemistry Chapter 10 Haloalkanes and Haloarenes
• NCERT Exemplar Class 12 Chemistry Chapter 10 Solutions Haloalkanes and Haloarenes

NCERT Class 12 Chapter 10 Notes-

Haloalkanes and Haloarenes Class 12 Notes – Topic 1:

1. Nomenclature-

• For haloalkanes-

Common name- alkyl halides

Example- methyl chloride, ethyl bromide, n-propyl iodide

IUPAC Name- haloalkane

Example- bromoethane, chloromethane, iodopropane.

• For haloarenes-

Halo+ name of aromatic hydrocarbon

Example- chlorobenzene, Iodobenzene, 3-chlorotoluene.

2. Methods of Preparation of Haloalkanes-

• From phosphorus halides-

• From alkanes-

• From alkenes-

• Addition of halogens-

3. Methods of Preparation for Haloarenes-

• By direct halogenation of aromatic ring-

It is an electrophilic substitution reaction.

• By the use of silver salt of aromatic acids-

This reaction is known as the Hunsdieker reaction

4. Physical Properties of Haloalkanes-

• Haloalkanes are colorless and their taste sweet-smelling.

• Since haloalkanes cannot break the hydrogen bonds of water, these are slightly soluble in water.

• As the size of the alkyl group increases, density increases.

• The boiling, as well as melting points of haloalkanes, are higher than their parent hydrocarbon.

• These are not as flammable as hydrocarbons.

• Dipole moment decreases on going from methyl chloride, methyl bromide, and methyl iodide. However, the dipole moment of methyl fluoride is lower as compared to methyl chloride.

5. Physical Properties of Haloarenes-

• Haloarenes are colorless in nature and heavier than water.

• Mostly soluble in organic solvents and insoluble in inorganic solvents.

• As the size of the halogen attached to benzene increases, the boiling point also increases.

• Out of the three isomers, the boiling point of the ortho isomer is the highest.

• The dipole moment of the ortho isomer is larger than the meta isomer. Para isomer has zero dipole moment.

6. Chemical Properties of Haloalkanes-

1. Nucleophilic substitution reaction-

• Substitution by hydroxyl group-

• Substitution by cyano group-

• Substitution by isocyanide group-

• Substitution by ammonia group-

The following reaction is known as the Hofmann ammonolysis reaction.

Two types of nucleophilic substitution reaction-

Substitution nucleophilic reaction (SN² reaction)-

• Rate is given as -

Rate=k[CH₃Br][OH^-]

• This reaction occurs in a single concerted step.

• In SN² reaction alkyl halide reacts in the following manner-

Methyl halide > primary halide> secondary halide> tertiary halide

Substitution nucleophilic reaction (SN¹ reaction)-

• Rate is given as –

Rate=k[(CH₃Br]

• This reaction occurs in two steps. The first step leads to the formation of a carbocation and the second step leads to the nucleophilic attack on carbocation.

• In SN¹ reaction alkyl halide reacts in the following manner-

• Tertiary alkyl halide> secondary alkyl halide> primary alkyl halide> primary alkyl halide> methyl halide

2. Elimination reaction-

• Formation of alkene takes place.

• Also known as dehydrohalogenation reaction.

• The general reaction is given as –

• The reaction proceeds by the removal of hydrogen from a carbon atom situated next to a carbon atom carrying a halogen atom.

Example-

Saytzeff’s rule- This rule decides which alkene will be formed if there are chances of elimination of more than one hydrogen atom. That alkene will be formed in which more substituted alkene is formed.

3. Reaction with active metals-

• Reaction with magnesium-

• Reaction with sodium-

• Reaction with active metals-

4. Reduction –

• The reaction of an alkyl halide with nickel, platinum, or palladium in the presence of a metal catalyst.

• The reaction of ethyl alcohol with zinc-copper couple

• The reaction of hydroiodic acid in presence of red phosphorus.

5. Rearrangement reactions-

The reaction of haloalkane in presence of anhydrous aluminum chloride.

7. Chemical Properties of Haloarenes-

• Resonance effect- Due to resonance, haloarenes are not reactive towards nucleophilic substitution reactions.

• Hybridization of carbon atoms in haloarenes and haloalkanes- In haloalkanes carbon is sp³ hybridized whereas, in haloarenes, carbon is sp² hybridized.

• The polarity of carbon and hydrogen bond-

Sp² hybridized carbon of haloarene attached to halogen is has a lesser tendency to release its electrons to a halogen atom. Hence, the bond is less polar compared to the carbon and halogen bond of haloalkanes.

• Instability of phenyl cation- Phenyl cation is not stable since there is no resonance. Therefore, SN¹ mechanism cannot occur.

• Nucleophilic substitution reactions-

Replacement by the hydroxy group-

Reaction for the replacement by the amino group-

Reaction for substitution with cyano group-

• Reactions with metal-

Reaction with magnesium-

Reaction with lithium-

Reaction with sodium-

Reaction with copper powder-

• Reduction reaction-

• Electrophilic substitution reactions-

Halogenation-

Nitration-

Sulphonation-

Alkylation-

Acylation-

Significance of NCERT Notes for Class 12 Chemistry Chapter 10-

Haloalkanes and haloarenes Class 12 notes contain step vise step headings and sub headings as per mentioned in the chapter 14 of Class 12 NCERT. Ch 10 chemistry class 12 notes are very helpful for a quick revision for competitive exams like VITEEE, BITSAT, JEE Main, NEET, etc. Integrating ch 10 Chemistry Class 12 notes into one's study routine facilitates a deeper comprehension of haloalkanes and haloarenes, enhancing problem-solving skills and analytical abilities. Chemistry class 12 chapter 10 notes pdf download can be used for an offline revision.

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