Functional Groups

Introduction

Organic compounds are normally, the chemical compounds that contain carbon (C)-hydrogen (H) or only carbon (C)-carbon (C) bonds. There are several (million) organic compounds because of carbon (C)-carbon (C) bond forming capability.

The percentage (by number) of organic compounds on the surface of the earth (earth’s crust) is very small but it is very important for all forms of life-sustaining on the surface of the earth. A Functional group is the group of some atoms that is responsible for the characteristic reactions of a particular compound. Functional groups that are the same or like each other undergo the same or similar reactions (chemical) and do not depend on the composition of the molecule. Some examples of functional groups are- carboxylic acid, ketone, hydroxyl, etc.

What is Organic Compound?

Organic compounds are those chemical compounds that contain either carbon (C)-hydrogen (H) or, carbon (C)-carbon (C) bond linkages or bonds. There are millions of organic compounds present on the surface of the earth due to the catenation (chain forming capability) of the carbon atoms with other carbon atoms. The percentage of organic compounds on the surface of the earth is quite low, but still, it is very useful and important for all possible forms of life on the earth. Along with the natural occurrence of the organic compounds, there are some synthetic (man-made) organic compounds, that are usually derived from petrochemicals (products formed from petroleum) and contain mostly hydrocarbons, which are formed (themselves) under high pressure (p) and temperature (T).

What is a Functional Group?

A Functional group is a group of various atoms (substituents) present in a molecule, that provides characteristic chemical reactions to the molecules. Similar functional groups, undergo similar (same) chemical reactions and will not get affected by the composition of the molecule. The reactivity (ability to react) of any functional group can be modified or influenced by the other functional groups.

The atoms of the functional groups are linked (joined) to one another and linked with the rest of the molecules with the help of covalent bonds. In complex compounds, functional groups binding to a central atom are known as ligands. Combining (joining) the names of two (2) or more functional groups with the parent (main) alkanes gives the systematic nomenclature (unique) for naming that organic compound. Some examples of functional groups are- hydroxyl, amine, ketone, etc.

Lhunter2099, Ochem 6 important functional groups, CC BY-SA 4.0

Priority Order of Functional Groups in IUPAC Nomenclature

Priority order of the functional groups is very important while writing nomenclature because the higher (highest) priority order group form the principal functional group and, and it is numbered (marked) in such a manner that it has the lowest number. This priority order is not only important for nomenclature but also to recognize (identifying) their reactions. Priority order of the functional groups are listed below −

• Carboxylic Acids are represented by the formula- (R-COOH).

• Acid Anhydrides are represented by the formula- (R-COOCOR).

• Esters are represented by the formula- (R-COOR').

• Acyl Halides are represented by the formula- (R-COX).

• Amides are represented by the formula- (R-CONR'R'').

• Nitriles are represented by the formula- (R-C≡N).

• Aldehydes are represented by the formula- (R-COH).

• Ketones are represented by the formula- (R-COR').

• Alcohols are represented by the formula- (R-OH).

• Thiols are represented by the formula- (R-SH).

• Amines are represented by the formula- (R-NR'R'').

• Ethers are represented by the formula- (R-OR').

• Sulphides are represented by the formula- (R-S-R').

• Alkenes are represented by the formula- (C=C).

• Alkynes are represented by the formula- (HC≡CH).

• Alkyl Halides are represented by the formula- (R-X).

• Nitro is represented by the formula- (R-NO_2).

• Alkanes are represented by the formula- (H₃ C-CH₃).

Steps for Nomenclature Functional Groups

• In the beginning, we need to select (determine/identify) the longest carbon-containing chain.

• Then, we need to identify all the substituents (side chains/ atoms) from the parent chain.

• Then, we should recognize or identify the functional group present in the given compound.

• We should count or determine the number of carbon (C) containing compounds and, the number of carbon (C)-hydrogen (H) bonds.

• Finally, we should write the nomenclature according to the priority order of the functional groups along with the other above-mentioned rules or factors for IUPAC nomenclature rules.

Give any 5 examples

• Carboxylic acid group - This is a functional group with the highest priority order while writing the IUPAC nomenclature of the compound. It is written or denoted by the formula- (-COOH). These are highly acidic.

• Aldehyde group - This is another example of the functional group. This is written or represented by the formula- (-COH). And the suffix attached for an aldehyde is -al at the ending of the compound name.

• Ketonic group - This is also a very important functional group. This is written or represented by the formula- (-COR'). And the suffix attached for ketone is -one at the ending of the compound name.

• Hydroxyl group - This is a well-known functional group denoted or written by the formula- (-OH). Here, the oxygen and hydrogen atoms are covalently bonded to each other.

• Hydrocarbon group (alkanes/alkenes/alkynes) - These are lower priority order, functional groups.

Conclusion

Organic compounds are normally (generally), compounds (chemical) that contain carbon(C)-hydrogen(H) or only carbon(C)-carbon(C) bonds. There are several (million) organic compounds because of carbon(C)-carbon(C) bond forming capability called catenation of carbon atoms. A Functional group is the group of some atoms that is responsible for the characteristic reactions of a particular compound. Functional groups that are the same or like each other undergo the same or similar reactions (chemical) and do not depend on the composition of the molecule. Some examples of functional groups are- carboxylic acid (-COOH), ketone (R-COR'), hydroxyl (-OH), etc.

FAQs

1. What do you mean by functional groups?

A Functional group is a group of various atoms (substituents) present in a molecule, that provides characteristic chemical reactions to the molecules. Some examples of functional groups are- carboxylic acid (-COOH), ketone (R-COR'), hydroxyl (-OH), etc.

2. What are ligands?

Ligand is an ion or a molecule that is used to bind the central metal atom or ion to form a coordination complex in coordination chemistry. And, also (mostly) the functional groups binding to a central atom in a complex compound are known as ligands.

3. Which functional group has the highest priority order?

Carboxylic acid (a functional group) is having the highest priority order.

4. Among ketone and aldehyde which one is having more priority in IUPAC nomenclature?

Aldehyde is having more priority during IUPAC nomenclature as compared to the ketone.

5. What is the other name for the alkyl halide functional group?

Haloalkane functional groups are the other name for alkyl halide functional groups.