Alkyl

What is an alkyl group?

Alkyl group is created by removing a hydrogen atom from an alkane molecule. Alkanes are frequently represented as R-H, where R represents an alkyl group.

CnH2n+1 is the general formula for the alkyl group. The smallest alkyl group is methyl or CH3.

A cycloalkyl is produced by removing a hydrogen atom from the ring of a cycloalkane. CnH2n-1 is the general formula for cycloalkyl.

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Nomenclature of alkyl groups

An alkyl group is named by replacing the suffix “ane” of the alkane with the suffix – “yl”.

Example:

CH₄ – H → CH₃

(Methane) (Methyl)

Number of carbon atom	Word Root	Name of alkyl group	Structure of alkyl group
1	C1	Meth	Methyl	CH3–
2	C2	Eth	Ethyl	CH3-CH2–
3	C3	Prop	Propyl	CH3-CH2-CH2–
4	C4	But	Butyl	CH3-CH2-CH2-CH2–
5	C5	Pent	Pentyl	CH3-CH2-CH2-CH2-CH2–
6	C6	Hex	Hexyl	CH3-CH2-CH2-CH2-CH2-CH2–
7	C7	Hept	Heptyl	CH3-CH2-CH2-CH2-CH2-CH2-CH2–
8	C8	Oct	Octyl	CH3-CH2-CH2-CH2-CH2-CH2-CH2-CH2–
9	C9	Non	Nonyl	CH3-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2–
10	C10	Dec	Decyl	CH3-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2–

Formation of alkyl groups

The Alkyl group is created by eliminating a hydrogen atom from alkane molecules. Depending on the nature of the carbon atoms from which hydrogen is to be removed, an alkane molecule may result in more than one alkyl group. For instance,

(1) Since both carbon atoms in ethane (C2H6) are primary, only one alkyl group can form.

(2) Since Propane (C3H8) contains two different types of carbon atoms, two distinct alkyl groups can be formed.

The secondary propyl group is called the isopropyl group.

(3) n-Butane has two types of carbon atoms, which result in two alkyl groups.

(4) Since isobutane contains both primary and secondary carbon, it contains the following alkyl groups.

The tertiary butyl group is also called the neo-butyl group.

Attached to other atoms or atom groups are alkyl groups. Alkyls can exist as neutral compounds, anions, or cations. Usually, these species are only encountered as transitory intermediates, but some of them are quite stable.

Alkyl cations

In the alkyl carbocation, the carbon atom’s valence shell contains six electrons, resulting in a positively charged species. Based on the nature of the carbon atoms, these compounds are classified as primary, secondary, or tertiary carbocation.

Alkyl anions

The carbon atom with eight electrons in its valence shell forms a negatively charged species in the alkyl anion or carbanion. These are

Alkyl radicals

Carbon’s valence shell contains seven electrons in the alkyl free radical. Alkyl free radicals are classified as primary, secondary, or tertiary in nature based on the nature of the carbon atoms carrying unpaired electrons. Examples are:

Frequently Asked Questions on Alkyl