Haloalkanes and haloarenes class 12 notes pdf

Monohalogen derivatives definition dihalogen derivatives types of dihalogen derivatives quaternary halide derivative monohalogen derivatives of alkanes are called alkyl halides are which derivatives of alkanes vinyl

Haloalkanes and haloarenes class 12 notes pdf

Halide derivative allylic halide derivative quaternary halide derivative draw the structure of any allylic halide derivative acid halide derivative derivative of halide halide derivatives of silane halide derivatives synthesis halides derivative acid halide derivatives aryl halides derivative dihalogen derivatives

 

 

Halide derivative

Halideo is classified into the following parts

(A) alkyl halide (aliphatic halide)

(1) mono halide

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(2) Di halide

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(3) tri halide

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(4) Tetra Halide

Note – In case of more than four halides, it is called poly halide.

 

(B) Aryl halide (aromatic halide)

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(C) Vinyl halide

the addition of a halide to a sp2 hybridized carbon

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(D) Aryl halide (allylic halide)

In this, a halogen is attached to the sp3 transition carbon but the adjacent carbon of this sp3 carbon should be sp2

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(E) benzyl halide – image

Nature of carbon-halogen bond:-

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As if IUPAC name of halide

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Methods of preparation of alkyl halide –

(1) Halogenation of alkene

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=> In the presence of sunlight the reaction with Cl2 takes place at a faster rate whereas with Br2 at a slower rate

=> Reaction with F2  in the dark and after adding some amount of N2 while adding a little iodic acid (Hio3) to it to react with i2

=> All possible haloalkanes are obtained in this reaction

 

Q-1 Prepare all possible monochloro products that can be obtained on halogenation of all isomers of pentane in the presence of sunlight?

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(2) Hydrohalogenation of alkenes

This reaction takes place by Markonikoff’s law

Markonikoff’s law – According to this law, when an asymmetric, unsaturated hydrocarbon is reacted with HX, then the highly electronegative X part is added to the unsaturated carbon on which the number of hydrogen is less or the number of substituents is more.

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Peroxide effect– When an asymmetric alkyl or alkyne is reacted with only H-Br in the presence of peroxide, then this reaction is contrary to Markonikoff’s law (anti-Markonikoff).

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Reason :- Because the bond energy of peroxide is more than that of H-Br, so in the presence of peroxide, H-Br will break into free radical, that is why the addition of H-Br will be by anti-Markonikoff’s law.

bond energy order
H-F > H-Cl > Peroxide > H-Br > H-I

 

=> Peroxide effect is not applicable on H-F and H-Cl because energy of peroxide is less than these

=> Whereas hydrogen halogenation reaction does not take place in the presence of peroxide from H-I because I2 gas is released by free radical breakdown.

 

(3) Hunsdication reaction

In this, a silver salt is reacted with Br in the presence of organic solvent CCl4 to give only bromides.

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(4) Reaction of primary amine with nitrosyl chloride

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(5) Halogens are interchangeable by –

(a) Fichlestein reaction – In this, if any R-Cl or R-Br is reacted with NaI with acetone or methanol, then only RI will be obtained.

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(b) Swarts reaction –

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(6) from alcohol

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Physical properties of mono halides : – C1-C2 is found in gaseous state at room temperature, after this all alkyl halides are liquid with a sweet smell. All alkyl halides are colorless but this iodide decomposes in the presence of light to release iodide. Due to which its color becomes purple, on burning it burns with a green flame, the density of alkyl halide is proportional to the molecular weight.

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Chemical Properties of Mono Halides :-