IUPAC Nomenclature of Organic Chemistry

The International Union of Pure and Applied Chemistry recommends the IUPAC nomenclature of organic chemistry as a system of naming organic chemical compounds in chemical nomenclature (IUPAC). It’s in the Journal of Organic Chemistry’s Nomenclature (informally called the Blue Book). Every potential organic compound should, in theory, have a name that can be translated into an unambiguous structural formula. Inorganic chemistry has its own IUPAC nomenclature.

IUPAC Nomenclature

The nomenclature of compounds must follow the following rules, as noted in the IUPAC Guidelines

Longest Chain Rule 

As per this rule, the parent hydrocarbon needs to be identified in the chain, and the compound will then be named after it. This parent hydrocarbon is generally the longest carbon atom chain present in the compound. This chain may be branched or straight.

The Lowest Set of Locants 

In a compound, as per this rule, the parent hydrocarbon is numbered using only natural numbers (no Roman or any other numbers) and must begin with the carbon atom that has the lowest number of substituents.

If the same substituents occur multiple times in an organic compound, then one must use the prefixes – ‘di, tri, etc.’ to denote the multiple substituents present in the organic compound.

The Naming of Distinct Substituents 

In a compound where there are different substituents with the same number or whether completely distinct, they need to be written in alphabetical order as per the IUPAC rules.

Various substituents at the same location are given different names 

If there are two or more substituents present in the same location with the same numbering, then they will be named in ascending alphabetical order as per the IUPAC rules.

Naming Complex Substituents 

If in an organic compound, there are complex substituents present such as ranched alkyl groups, then these complicated branch substituents must be written in brackets while naming.

Other Rules Followed In Naming Compounds

Start With the Root

The word root denotes the total number of carbon atoms contained in the compound’s longest carbon chain. For example, a chain with one carbon atom is called ‘Meth,’ whereas a chain with five carbon atoms is called ‘Pent.’

Suffixes

In IUPAC nomenclature, a suffix is usually a functional group of the molecule that follows the root of the name. It is further subdivided into the types listed below.

As in the case of alkanes, where the suffix is ‘ane,’ a Primary Suffix is written right after the word root.

A secondary suffix is one that is added after the primary suffix has been written. An alkanol, for example, is a compound with an alkane and an alcohol group linked to it, with ‘ol’ being the secondary suffix for the alcohol group.

The suffix of a compound can be written as part of the IUPAC name of the compound according to these rules.

Use A Prefix

In IUPAC nomenclature, prefixes are added before the root of the compound. Prefixes are particularly valuable since they show whether or not an organic molecule contains side chains or substituent groups. These prefixes also reveal whether the chemicals in question are cyclic or acyclic in nature.

Prefixes (Primary) Indicate whether the provided compound is cyclic or acyclic. For cyclic compounds, for example, the prefix ‘cyclo’ is employed.

Sidechains or substituent groups are indicated by secondary prefixes. The methyl group, often known as the ‘CH3’ group, is an example of these types of prefixes.

Examples Of Compounds Named Using IYPAC Nomenclature 

Alcohols Alcohols are termed by substituting the ‘–ane’ suffix with the ‘-anol’ suffix. This suffix is expanded to include an appropriate prefix if there is more than one hydroxyl group. Anediol, anetriol, pentanol, butanediol, and other similar compounds are examples of this group.

Ethers Ethers are referred to by their common names. To do so, two alkyl groups are bonded to an oxygen atom, and the names are then arranged alphabetically with space between them. The word ether comes after them. In addition, if both alkyl groups are identical, the ‘di-‘ prefix is used. Diethyl ether, ethyl methyl ether, and other ethers are examples of this category.

Conclusion

The International Union of Pure and Applied Chemistry (IUPAC) has a long history of supplying nomenclature for organic and inorganic substances. This naming system was created with the goal of creating a set of universally recognised names. This eliminates the confusion caused by scientists identifying compounds in a variety of ways. There are a set of guidelines that every scientist must follow when naming compounds that belong to specific groups under the IUPAC nomenclature of organic chemistry.

Furthermore, the IUPAC nomenclature of organic compounds is divided into three sections substituents, carbon-chain length, and chemical end. The substituents are functional groups connected to the main carbon chain in this case. This is the longest continuous carbon chain conceivable. The molecule’s kind is also represented by the chemical ending.