Organic Compounds are formed due to sharing of electrons between two or group of atoms. The movement (displacement) of electrons is under the influence of other species. This leads to a number of effects which are: Inductive effect, Electromeric effect, Hyperconjugation effect, Resonance effect. Broadly speaking, a chemical reaction means the shifting or sharing of electrons takes place between the atoms.
What is Inductive Effect (i effect)
The inductive effect arises in the organic molecules when some atoms or group of different electronegativity is attached to the carbon atom chain. A covalent bond is formed by the equal sharing of electrons between the two atoms.
- In case of a covalent bond between two similar atoms, the electron pair of the bond occupies the central position between the nuclei of the two concerned atoms. Such a covalent bond is known as nonpolar bond.
- On the other hand, in case of a covalent bond between the two dissimilar atoms, the electron pair forming the bond is never shared absolutely equally between the two atoms but is attracted a little more towards the more electronegative (property of attracting electrons) atom.
Inductive Effect Definition
|The permanent displacement of the electrons along the chain of carbon atoms due to the presence of an atom or group of atoms of different electronegativity at the end of the chain.|
- Inductive effect is a permanent effect.
- It is caused due to the electronegative difference.
- It operates on σ bonded electron.
Inductive Effect Examples
- To understand the Inductive effect well let’s take an example. In the compound C-X where X is more electronegative than C, the electron pair forming the C-X bond is somewhat more attracted towards the atom X with the result the latter attains partial negative charge (denoted by ? -) while the carbon atom attains a partial positive charge (denoted by ?+).
- On the other hand, in compounds like C-Y where Y is an electropositive element or group, i.e., C is more electronegative than Y, the electron pair forming the C-Y bond is somewhat displaced towards the carbon atom and thus C and Y attain partial negative and partial positive charges respectively.
- Chlorine is having greater electronegativity value than carbon.This cause the electron pair between CA and Cl will be displaced towards the chlorine atom. Hence, Cl will acquire a small negative charge, and the CA will acquire a small positive charge. Since CA is positively charged, it will attract the electron pair forming the covalent bond between CA and CB.This will result CB will also acquire a small positive charge, but the charge on CB will be smaller than on CA. Further, the effect of chlorine atom (source) has been transmitted through CA to CB than to CC. This effect decreases with the increase of distance from the electronegative element.
If atom or group attracts electrons less strongly than hydrogen it is said to have + I effect (electron repelling or electron-releasing).
Any atom or group, if attracts electrons more strongly than hydrogen, it is said to have a -I effect (electron-attracting or electron-withdrawing). The important atoms or groups are arranged below in the order of decreasing order.
|+I Effect||-I Effect|
|Electron releasing group.||Electron accepting group.|
|EN less than H.||EN greater than H.|
|Those group which Shows +I effect disperses.||Group shows –I effect disperses positive charge on the C-chain.|
Applications of Inductive Effect
The phenomenon of inductive effect is very important in organic chemistry as it explains several facts, most important of which are given here.
Reactivity of alkyl halides
Alkyl halides(R-X), in general, are more reactive than the corresponding alkane the reason being the presence of C-X bond in alkyl halides due to which they undergo inductive effect.
Strength of carboxylic acids
An acid is a species that has the tendency to lose a proton. Furthermore, the strength of an acid depends upon the ease with which an acid ionizes to give proton. Thus any structural unit like a strongly electronegative group that helps in removing the proton from the hydroxyl group of the acid will have the effect of making the corresponding carboxylic acid a stronger one.
Basic character of amines
A compound is said to be basic in nature if it is capable of accepting a proton. The basic character of amines is due to the presence of unshared electron pair on nitrogen atom which accepts a proton, the readiness with which the lone pair of electrons is available for coordination with a proton determines the relative basic strength of amines.
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