Carbon and Its Compounds

Nomenclature of Organic Compound

Need of Nomenclature

Every chemical compounds have a particular name. But carbon forms many types of structure with common molecular formula due to which names of isomers are needed to be different.

Example:

Hexane: Molecular formula: C₆H₁₄

First Structural formula of Hexane

Second possible structural formula of hexane

Third possible structural formula of hexane

Forth possible structural formula of hexane

These all compounds have a general name Hexane while structural formulas of these compounds are different. Similarly many other carbon compounds exist with same molecular formula but different structural formulas.

Thus, particular naming for each of the compounds is needed to differentiate among them.

Nomenclature of Carbon Compounds

IUPAC Name: International Union of Pure and Applied Chemistry (IUPAC) made some rules to name the organic compounds so that each of the organic compounds can be differentiated by their names. Such names are commonly known as IUPAC names. And process to name is called the Nomenclature of Organic Compounds.

IUPAC name are based on the name of the basic carbon chain modified by a 'prefix' or 'suffix' indicating the nature and position of the functional group.

Rules for Nomenclature of Organic Compounds

Rule no. (i): Identify the number of carbon atoms in the compound and name the compound according to the number of carbon atoms.

Example:

If number of carbon atoms = 1

∴ Name of the parent compound will be 'Methane'

If number of carbon atoms = 2

∴ Name of the parent compound will be 'Ethane'

If number of carbon atoms = 6

∴ Name of the parent compound will be 'Hexane' and so on.

Rule no. (ii) Identify the functional group if any present.

If any functional group is present, add a 'prefix' or 'suffix' specified for the functional group with the name of the parent compound.

Prefix specified for the functional group:

Halo group:

For –Cl (Chloride) functional group: Add a 'prefix' chloro with the name of parent compound.

For –Br (Bromide) functional group: Add a 'prefix' bromo with the name of parent compound.

For –I (Iodide) functional group: Add a 'prefix' Iodo with the name of parent compound.

For –F (Fluoride) functional group: Add a 'prefix' Fluoro with the name of parent compound.

Prefix is added for only Halo group. And for rest of the functional groups suffix is added.

Example:

Naming of the compound CH₃Cl

Here number of carbon atom = 1

Thus, name of the parent compound will be 'Methane'

Now, functional group –Cl (Chloride) is attached with the compound.

Thus, add Chloro with the name of the parent compound.

Thus, IUPAC name of the given compound will be 'Chloromethane'

Structural Formula of Chloromethane

[Here functional group is indicated in red colour for convenience]

Common name for this compound: Methyl chloride

Similarly, naming for compound C₂H₅Cl

Here number of carbon atom is equal to 2

Thus, name of the parent compound will be 'Ethane'

Now, functional group –Cl (Chloride) is attached with the compound.

Thus, add Chloro with the name of the parent compound.

Thus, IUPAC name of the given compound will be 'Chloroethane' or 'Chloro–ethane'

Structural Formula of Chloroethane

Common name for this compound: Ethyl chloride

Similarly, naming for compound C₂H₅Br

Here number of carbon atom is equal to 2

Thus, name of the parent compound will be 'Ethane'

Now, functional group –Br (Bromide) is attached with the compound.

Thus, add Bromo with the name of the parent compound.

Thus, IUPAC name of the given compound will be 'Bromoethane' or 'Bromo–ethane'

Structural Formula of Bromoethane

Common name for this compound: Ethyl bromide

Similarly, naming for compound C₄H₉F

Here number of carbon atom is equal to 4

Thus, name of the parent compound will be 'Butane'

Now, functional group –F (Fluoride) is attached with the compound.

Thus, add Fluoro with the name of the parent compound.

Thus, IUPAC name of the given compound will be 'Fluorobutane' or 'Fluoro–Butane'

Structural Formula of Fluorobutane

Common name for this compound: Butyl fluoride

Similarly, naming for compound C₆H₁₃I

Here number of carbon atom is equal to 6

Thus, name of the parent compound will be 'Hexane'

Now, functional group –I (Iodide) is attached with the compound.

Thus, add Iodo with the name of the parent compound.

Thus, IUPAC name of the given compound will be 'Iodohexane' or 'Iodo–Hexane'

Structural Formula of Iodohexane

Common name for this compound: Hexyl iodide

Suffix specified for the functional group:

Naming for Alcohol (– OH) group

If alcohol (– OH) group is present in the compound, a 'Suffix' "ol" is added to the name of the parent compound.

Alkane – e + ol = Alkanol

Example:

IUPAC naming for CH₃OH

Here number of carbon atom is equal to 1

Thus, name of the parent compound will be 'Methane'

Now, functional group –OH (Alcohol) is attached with the compound.

Thus, add "ol" as suffix with the name of the parent compound.

Thus, IUPAC name of the given compound will be 'Methanol'

Structural Formula of Methanol

Common name for this compound is Methyl alcohol.

IUPAC naming for C₃H₇OH

Here number of carbon atom is equal to 3

Thus, name of the parent compound will be 'Propane'

Now, functional group –OH (Alcohol) is attached with the compound.

Thus, add "ol" as suffix with the name of the parent compound.

∴ Propane – e + ol = Propanol

Thus, IUPAC name of the given compound will be 'Propanol'

Structural Formula of Propanol

Common name for this compound is Propyl alcohol.

IUPAC naming for C₆H₁₃OH

Here number of carbon atom is equal to 6

Thus, name of the parent compound will be 'Hexane'

Now, functional group –OH (Alcohol) is attached with the compound.

Thus, add "ol" as suffix with the name of the parent compound.

∴ Hexane – e + ol = Hexanol

Thus, IUPAC name of the given compound will be 'Hexanol'

Structural Formula of Hexanol

Naming for Aldehyde (– CHO) group

Structural formula for aldehyde group

IUPAC Name of the alkane with 'aldehyde' functional group

Alkane – e + al = Alkanal

Naming of compound CH₃CHO

Here number of carbon atoms in parent compound = 2

Thus, name of parent compound is 'Ethane'

Thus, functional group –CHO (Aldehyde) is attached with the compound.

Thus, a suffix 'al' is attached with the parent compound.

Thus, name of this compound

Ethane – e + al = Ethane

Hence, name of this compound will be 'Ethanal'

Structural formula of Ethanal

Common name of this compound: Ethanldehyde

Naming of compound C₃H₇CHO

Here number of carbon atoms in parent compound = 4

Thus, name of parent compound is 'Butane'

Thus, functional group –CHO (Aldehyde) is attached with the compound.

Thus, a suffix 'al' is attached with the parent compound.

Thus, name of this compound

Butane – e + al = Butanal

Hence, name of this compound will be ' Butanal'

Structural formula of Butanal

Common name for this compound: Butanaldehyde

Naming for Ketone (– CO –) group

Structural formula for ketone group

IUPAC naming: Alkane – e + one = Alkanone

IUPAC naming of CH₃COCH₃

Here number of carbon atoms = 3

Thus, name of parent carbon compound having three carbon atoms is Propane

Here, Ketone (– CO –) is present as functional group

∴ 'one' will be added as 'suffix' with the name of parent compound.

∴ Propane – e + one = Propanone

∴ IUPAC name of CH₃COCH₃ will be 'Propanone'

Structural formula of 'Propanone'

Common name of this compound: Dimethyl ketone

IUPAC naming of C₂H₅COCH₃

Here number of carbon atoms = 4

Thus, name of parent carbon compound having three carbon atoms is Butane

Here, Ketone (– CO –) is present as functional group

∴ 'one' will be added as 'suffix' with the name of parent compound.

∴ Butane – e + one = Butanone

∴ IUPAC name of C₂H₅COCH₃ will be 'Butanone'

Structural formula of 'Butanone'

Common name of this compound is Ethyl methyl ketone.