Nature of C-X Bond in Haloalkanes

Nature of C-X Bond in Haloalkanes: Haloalkanes and haloarenes have a particular bonding in them whereby the halogen atom, chlorine, bromine, iodine or fluorine is bonded on to the aliphatic or fragrant carbon. The resultant ({rm{C – X}}) bond assumes a particular character due to the electronegativity distinction between the 2 atoms within the bond-  carbon and the halogen atom. Because of the electronegativity distinction and the character of the carbon atom- aliphatic or fragrant, the haloalkanes and arenes are extremely reactive in nature.

On this article, we are going to focus on the kind of bonding and nature of ({rm{C – X}})  bonding in haloalkanes and haloarenes and their typical traits.

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Bonding in Haloalkanes and Haloarenes

Halogens, as we all know, are extremely reactive parts and are most electronegative too. They, due to this fact, kind numerous derivatives of natural compounds, that are extremely helpful in a number of purposes, together with synthesis of different natural compounds, industrial purposes, and many others.  The electronegativity distinction between the 2 atoms makes the character of the ({rm{C – X}}) bond a particular research. The reactions of the natural compounds shaped by halogens have particular significance due to the character of the ({rm{C – X}}) bond. For the reason that natural compounds shaped by halogens are proof against soil micro organism, they’re present in nature too. 

The 2 kinds of natural compounds that the halogens kind embody:

  1. Haloalkanes: Changing a hydrogen atom from aliphatic hydrocarbons with halogens ends in haloalkanes. The halogens in haloalkanes are hooked up to the ({rm{s}}{{rm{p}}^{rm{3}}}) hybridized carbon atom of an alkyl group. Haloalkanes or alkyl halides, allylic halides, and benzylic halides have a C-X bond with ({rm{s}}{{rm{p}}^{rm{3}}}) hybridization (halogen bonded to ({rm{s}}{{rm{p}}^{rm{3}}}) carbon) 
  2. Haloarenes: When a hydrogen atom from an fragrant hydrocarbon is changed by a halogen atom ({rm{(F,Cl,Br,orI)}}) offers haloarenes. The halogens in haloarenes are hooked up to the ({rm{s}}{{rm{p}}^2}) hybridized carbon atom of an aryl group.Vinylic halides and aryl halides have halogens hooked up to the ({rm{s}}{{rm{p}}^2})  carbon atom.

The haloalkanes and haloarenes are additional categorized into mono, di, tri, and poly-halogen compounds and on the character of the ({rm{C – X}}) bond current in them.

Nature of C-X Bond

In each haloalkanes and haloarenes, the carbon atom within the hydrocarbon-aliphatic or fragrant – is bonded with the halogens. Since halogens are extremely electronegative, the bond between carbon (much less electronegative than halogen) and a halogen atom ({rm{(F, Cl, Br, or, I)}}) are affected and is polar.

It’s important to know the character of the ({rm{C – X}}) bond current earlier than learning the reactions of those compounds since a polar bond can affect the way in which a compound reacts with different compounds.

Nature of C-X Bond in Haloalkanes

To start with, a easy haloalkane has the method: R-X. Carbon from aliphatic hydrocarbon straight bonds to the halogen atom in a covalent bond. 

For the reason that electronegativity of halogens is way larger than that of carbon, the electron cloud within the ({rm{C – X}}) bond shifts nearer to the halogen atom. Therefore, the halogen within the bond will get a partial unfavourable cost, whereas the carbon good points a partial constructive cost.

Nature of C-X Bond in Haloalkanes

Relying upon the kind of halogen hooked up to the haloalkanes, the partial cost on the ({rm{C – X}}) bond and the polarity could differ. As an illustration, once we go down the group, from fluorine to iodine, the atomic radii or the dimensions of the halogens will increase. Therefore, the bond size between carbon and the halogen will increase as we go from ({rm{C – F}}) to ({rm{C – I}}).

Additionally, because the electronegativity of the halogens decreases with a rise in dimension or as we transfer down the group from fluorine to iodine, the polarity of the bond between Carbon and halogens decreases from ({rm{F}}) to ({rm{I}}). The bond enthalpies and dipole moments of the Carbon-halogen bond as we transfer from fluorine to iodine is as follows:

C-X Bond The bond size in pm C-X Bond Enthalpies in KJ/mol Dipole second in Debye
(mathrm{CH}_{3}-mathrm{F}) (139) (452) (1.847)
(mathrm{CH}_{3}-mathrm{Cl}) (178) (351) (1.860)
(mathrm{CH}_{3}-mathrm{Br}) (193) (293) (1.830)
(mathrm{CH}_{3}-1) (214) (234) (1.636)

Therefore, in accordance with the dipole second values, it’s clear that the polarity of the ({rm{C – X}}) bond decreases with a rise within the radius of halogens or their dimension and a lower in electronegativity. 

Nature of C-X Bond in Haloarenes

Haloarenes have the halogens bonded to ({rm{s}}{{rm{p}}^{rm{2}}}) hybridized carbon of the benzene ring. The ({rm{C – X}}) bond is polar, too, as in haloalkanes. Nevertheless, the distinction between the ({rm{C – X}}) bond in haloalkanes and haloarenes is that the ({rm{C – X}}) bond acquires a partial double bond character as a result of the partial cost on the halogens is concerned in resonance with the ring. 

Therefore, the polarity of the ({rm{C – X}}) bond in haloarenes is lesser than the haloalkanes, and the bond size of the ({rm{C – X}}) can also be shorter than the haloalkanes. The explanations are as follows:

  1. Haloarenes, because of the ring construction and the partial double bond, are extra electron-rich than the haloalkanes.
  2. The resonance makes the ring construction interested in the halogens extra strongly than the haloalkanes.

For instance, the dipole second of Chlorobenzene is ({rm{1}}{rm{.69D}}), whereas that of chloromethane is ({rm{1}}{rm{.83D}})

Abstract

The ({rm{C – X}}) bond shaped between carbon and halogens in haloalkanes and haloarenes has particular significance as a consequence of their polar nature. Haloalkanes have ({rm{s}}{{rm{p}}^3}) hybridized carbon hooked up to the halogens, whereas haloarenes have ({rm{s}}{{rm{p}}^{rm{2}}}) hybridized carbon hooked up to the halogens. The polarity of the ({rm{C – X}}) bond in haloalkanes decreases once we transfer from fluorine to iodine as a result of the atomic dimension will increase and electronegativity lower from ({rm{F}}) to ({rm{I}}). The polarity or the dipole second values present sufficient indication of the actual fact. Additionally, in haloarenes, because of the ring construction and resonance, the ({rm{C – X}}) bond good points partial double bond character, and due to this fact, the bond size turns into shorter. Therefore, the polarity of the ({rm{C – X}}) bond in haloarenes is lesser than the haloalkanes 

FAQs

Q.1. What kind of hybridization is seen within the C-X bond in Haloalkanes and Haloarenes?
Ans: In haloalkanes or alkyl halides, the halogen is hooked up to the ({rm{s}}{{rm{p}}^3}) hybridized carbon, whereas in haloarenes, the halogens are hooked up to the ({rm{s}}{{rm{p}}^{rm{2}}}) hybridized carbon of the ring construction.

Q.2. What’s the nature of the carbon halogen bond?
Ans:
The carbon-halogen bond in haloarenes and haloalkanes are polar because of the distinction within the electronegativity between the 2 atoms- carbon and halogens.

Q.3. Why are C-X bonds polar?
Ans:
The polarity of the ({rm{C – X}}) bond in haloalkanes and haloarenes is as a result of there’s a massive electronegativity distinction between halogens and carbon atoms. When a covalent bond is shaped between two atoms with a big electronegativity distinction, the bond that’s shaped is polar in nature. 

Q.4. Which of the 2 Haloalkane or Haloarene have better C-X bond size?
Ans:
Haloarenes have a shorter bond size as a consequence of the truth that the ring construction and the resonance within the ring give the ({rm{C – X}}) bond a double bond character. The polarity, due to this fact, decreases. This may be seen in the truth that the dipole second of Chlorobenzene is ({rm{1}}{rm{.69D}}), whereas that of chloromethane is ({rm{1}}{rm{.83D}}).

Q.5. Why do the polarity of the C-X bond decreases as we transfer down the group? Which is probably the most polar C-X bond in haloalkanes?
Ans:
Once we transfer down a gaggle (halogens), two issues occur: atomic dimension will increase and electronegativity decreases. In halogens, too, as we transfer down from fluorine to iodine, the dimensions will increase, and due to this, the electronegativity decreases. Therefore, the polarity of the ({rm{C – X}}) bond from ({rm{C – F}}) to ({rm{C – I}}) decreases.
Probably the most polar ({rm{C – X}}) bond in haloalkanes, due to this fact, could be the ({rm{C – F}}) bond. It’s as a result of fluorine, owing to the smaller dimension, is most electronegative, due to this fact growing the electronegativity distinction between C and F and growing polarity too.

Q.6. What’s the hybridization of the C-X bond in Haloarenes?
Ans:
Haloarenes, comparable to chlorobenzene, have the halogens hooked up to the ({rm{s}}{{rm{p}}^2}) hybridized carbon atom of the ring. 

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