What is IUPAC Nomenclature?
IUPAC Nomenclature is a system for naming organic chemical compounds, but no two compounds can have the same name.
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IUPAC Nomenclature
Historically, the majority of compounds with the same structural formula had different names depending on where they were synthesized. This naming system was extremely trivial, as it caused much confusion. IUPAC (International Union of Pure and Applied Chemistry) has finally established a common naming system for compounds that includes the standard rules. This naming system is referred to as IUPAC naming or IUPAC nomenclature.
Nomenclature the manner in which things are given names is a key distinction between the language of chemistry and other scientific disciplines and natural languages. The second is the comparative value of the written and spoken languages. In chemistry, there are numerous nomenclatures; not only elements and compounds, but also reaction methods, apparatus components, and theoretical concepts must be named.
IUPAC Nomenclature of Alkanes, Alkynes, and Alkenes
This naming system is referred to as IUPAC naming or IUPAC nomenclature. The IUPAC nomenclature of alkanes, alkynes, and alkenes is explained in the following section.
Alkanes are the most basic hydrocarbons that we are aware of. They possess the general formula CnH2n+2. Alkanes are members of the family of saturated hydrocarbons, as they contain only carbon-hydrogen sigma bonds. The organic compounds form a series, referred to as a homologues series, in which successive compounds share the same functional group and are distinguished by a ‘–CH2’ group.
In contrast, alkenes and alkynes are unsaturated hydrocarbons. In the case of alkenes, double-bond linkages are present, whereas alkynes contain triple-bond linkages. The IUPAC nomenclature of alkanes, alkenes, and alkynes is governed by the following rules:
- In the case of alkanes, the longest hydrocarbon chain is chosen and referred to as the parent chain. As parent chain for alkenes and alkynes, double- and triple-bonded hydrocarbon chains are selected. The parent chain is designated by Greek letters such as hexa, octa, etc.
- For alkanes, the suffix ‘-ane’ is used, for alkenes ‘-ene’ is used, and for alkynes ‘yne’ is used. For instance, C2H6 is referred to as ethane, C2H4 as ethene, and C2H2 as ethyne.
- The parent chain is numbered such that double- or triple-bonded carbon atoms are reached first. The position of the double-bonded carbon atom is indicated numerically. CH3CH=CHCH2CH3 is referred to as Pent-2-ene.
- In the case of multiple double bonds in the carbon chain, Greek numerical prefixes such as di and tri are utilized to denote their quantity.
Unsaturated Carbon Chains – Alkene Formula
Unsaturated hydrocarbons are those in which one or more carbon atoms in the chain are bonded to another by a double or triple bond. Alkenes and alkynes are the two classes of unsaturated hydrocarbons.
Hydrocarbon alkenes have one double bond between carbon atoms. Similar to alkenes, their molecular formula increases by a constant amount with the addition of each carbon atom to the chain. A homologous series describes a family of compounds that expands in this way. CnH2n is the general formula for alkenes. Note that this is identical to the alkane formula, except that two hydrogen atoms are subtracted to accommodate the double bond.
IUPAC System of Alkenes
- As the parent alkene, the carbon chain with the longest carbon-carbon double bond is selected.
- The alkane’s ‘ane’ suffix is replaced with ‘ene’ If there are two or three double bonds in the parent chain, the alkene is referred to as diene or triene, respectively.
- The position of double bonds or side chains as indicated by 1, 2, 3, etc.
- From this end, the longest chain is numbered, giving the lowest number to the carbon atom of the double bond, which is written just before the suffix ‘ene’. If, when numbering the chain, the double bond receives the same number from both ends, the carbon chain is numbered so that the substituent receives the lowest number.
- If there are two or more double bonds, the rule of the lowest sum must be applied.
- Prefixes indicate the name and position of other groups (substitutes)
Alkene Formula
Unsaturated molecules are designated alkenes. This indicates that alkenes contain at least one double bond of carbon-carbon, which displaces two hydrogen atoms; therefore, alkenes do not possess the maximum number of hydrogen atoms per atom.
The general formula for the homologous series of alkenes is CnH2n, where n is the number of carbon atoms. Due to the fact that alkenes are hydrocarbons, the homologous series of alkenes begins with ethene C2H4, which contains at least one carbon-carbon double bond.
The compounds are referred to as alkanes but with the suffix “ene” instead of “ane.” Each successive molecule in the homologous series of alkenes is formed by adding one carbon and two hydrogen atoms or one CH2 atom to the previous molecule (methylene group). The incremental change in relative molecular mass is therefore 14.
Frequently Asked Questions – FAQs
Q.1 What does IUPAC nomenclature mean?
The International Union of Pure and Applied Chemistry (IUPAC) is an internationally recognized organization that has systematically named all organic chemical substances.
Q.2 How do you identify an alkene?
A simple bromine water test could be used to distinguish between alkanes and alkenes. Due to the reaction between the bromine and the carbon-carbon double bond, an alkene can turn brown bromine water colorless. This reaction will actually occur for unsaturated compounds with carbon-carbon double bonds.
Q.3 How do we name alkenes?
Alkenes and alkynes are named for the longest double or triple bond chain they contain. The chain is numbered in order to reduce the number of double and triple bonds. The compound suffix for an alkene is “-ene,” and for an alkyne, “-yne.”
Q.4 What are the basic rules to be followed while naming the carbon compound?
The name of the compound is written in alphabetical order, beginning with the substituents and then the base name (derived from the number of carbons in the parent chain). Commas are used for numbers, while dashes are used for letters and numbers. There are no spaces in the Name.
Q.5 What is the prefix in the name of IUPAC?
The prefix oct- indicates that there are eight carbon atoms in the longest chain…. The prefix hex- indicates that there are six carbon atoms in the longest row. The suffix -ane indicates that the molecule is an alkane with only single carbon-carbon bonds and no other functional groups.
Q.6 What is the structure of aldehyde?
Aldehyde is a class of organic compounds in which a carbon atom is double-bonded to an oxygen atom, single-bonded to a hydrogen atom, and single-bonded to another atom or group of atoms.
Q.7 Is aldehyde a functional group?
Aldehydes and ketones are organic compounds that incorporate a carbonyl functional group, C = O. Two remaining bonds on the carbon atom of this group are available for hydrogen, alkyl, or aryl substituents. If one of these substituents is hydrogen, the compound is an aldehyde.
