Functional Groups

Definition of Functional Groups

An atom or a group of atoms or a double bond or a triple bond whose presence imparts particular properties to organic compounds is called a functional group because they are the chemically functional parts of molecules.

The Role of Functional Groups

In organic chemistry, a functional group is a specific group of atoms or bonds within a compound that is accountable for the characteristic chemical reactions of that substance. The same functional group will act in a similar fashion, by going through similar reactions, no matter the substance of which it is a part.

Functional groups likewise play a vital role in organic substance nomenclature; integrating the names of the functional groups with the names of the parent alkanes provides a way to identify compounds.

The atoms of a functional group are linked together and to the rest of the substance by covalent bonds. The first carbon atom that attaches to the functional group is described as the alpha carbon; the 2nd, the beta carbon; the third, the gamma carbon, etc. Likewise, a functional group can be described as main, secondary, or tertiary, depending on if it is connected to one, 2, or three carbon atoms.

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Functional Groups and Reactivity

Functional groups play a significant function in directing and controlling natural reactions. Alkyl chains are often nonreactive, and the direction of site-specific reactions is difficult; unsaturated alkyl chains with the presence of functional groups enable higher reactivity and specificity.

Typically, substances are functionalized with specific groups for a particular chain reaction. Functionalization refers to the addition of functional groups to a compound by chemical synthesis. Through routine synthesis methods, any sort of natural compound can be attached to the surface. In product science, functionalization is employed to accomplish preferred surface properties; functional groups can also be utilized to covalently connect functional molecules to the surfaces of chemical devices.

In organic chemistry, the most common functional groups are carbonyls (C =O), alcohols (- OH), carboxylic acids (CO2H), esters (CO2R), and amines (NH2). It is very important to be able to recognize the functional groups and the physical and chemical properties that they manage substances.

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Some Essential Functional Groups

Alkyl and periodically aryl (aromatic) functions are represented by the R- Methyl: CH3–.

  • Ethyl: CH3CH2–.
  • Propyl: CH3CH2CH2–.
  • Isopropyl: (CH3) 2CH–.
  • Phenyl: C6H5– and so on.
Alkyl halide

Alkyl halides [haloalkanes] include an alkyl group connected to a halogen: F, Cl, Br, I. Chloro, Bromo and iodo alkyl halides are often vulnerable to elimination and/or nucleophilic substitution reactions.

Primary alcohol

Primary alcohols have an -OH functional group attached to an R-CH2- group. Primary alcohols can be oxidized to aldehydes and on to carboxylic acids. (It can be difficult to stop the oxidation at the aldehyde stage.).

Secondary alcohol

Secondary alcohols have an -OH functional group connected to an R2CH- group. Secondary alcohols can be oxidized to ketones.

Tertiary alcohol

Tertiary alcohols have an -OH function attached to an R3C- group. Tertiary alcohols are resistant to oxidation with acidified potassium dichromate(VI), K.


Aldehydes have a hydrogen and an alkyl (or aromatic) group attached to a carbonyl function. Aldehydes are quickly oxidized to carboxylic acids, and they can be reduced to primary alcohols. Aldehydes can be identified from ketones by offering favorable test results with Fehling’s solution (brick red precipitate) or Tollens reagent (silver mirror). Aldehydes give red-orange precipitates with 2,4-dinitrophenyl hydrazine.

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Ketones have a pair of alkyl or aromatic groups attached to a carbonyl function. Ketones can be identified from aldehydes by providing negative test results with Fehling’s solution (brick red precipitate) or Tollens reagent (silver mirror). Ketones give red-orange speeds up with 2,4-dinitrophenyl hydrazine.

Carboxylic acid

Carboxylic acids have alkyl or aromatic groups connected to a hydroxy-carbonyl function. Carboxylic acids can be displayed in the text as: RCOOH Carboxylic acids are weak Bronsted acids and they free CO2 from carbonates and hydrogen carbonates.

Carbonyl functional group

The carbonyl group is an extremely function since numerous typical functional groups are based on a carbonyl, including aldehydes, ketones, carboxylic acids, esters, amides, acyl (acid) chlorides, acid anhydrides.


Esters have a pair of alkyl or aromatic groups attached to a carbonyl + linking oxygen function. Esters can be shown in text as: RCOOR or (occasionally) ROCOR. carboxylic acid + alcohol and ester + water This is an acid-catalyzed equilibrium.