Carbon and Its Compounds Nomenclature of Hydrocarbons

Part 2

These notes are based on the chapter Carbon and its Compounds from class 10 science of NCERT book and CBSE syllabus.

• Hydrocarbon with halo group
• Alcohol group
• Aldehyde
• Carboxyllic acid
• Ketone group
• Homologous Series

Naming of hydrocarbon with Halo group:

Example: (CH₃Cl) The common name of this molecule is methyl chloride. There is one carbon atom in this compound. So its parent name is Methane. Since one chloro group is present in this compound, hence its IUPAC name is chloro-methane. Following is the structural formula of chloro-methane.

Example: (C₃H₇Cl) The common name of this compound is propyl chloride.

IUPAC Name:

Number of carbon atoms = 3
Functional group: Chloro
Thus, IUPAC Name is Chloro-propane.
Following is the structural formula of chloro-pentane.

Example: C₃H₇Br

Common name of this compound is propyl bromide. Its IUPAC name is bromo-propane. Following is the structural formula of bromo-propane:

Example: CH₃H₇I

Common name of this compound is hexyl iodide. Its IUPAC name is iodo-hexane. Following is the structural formula of iodo-hexane:

Naming of alcohol group

Example: CH₃OH

The common name of this compound is methyl alcohol.

IUPAC Name:

Number of carbon atom: 1
Functional group: Alcohol (suffix : ol)
IUPAC Name: Methane – e Methane – e + ol = Methanol.
Following is the structural formula of methanol.

Example: CH₃CH₂OH

The common name of this compound is ethyl alcohol.

IUPAC Name:

Number of carbon atoms: 2
Functional group: Alcohol
Hence, IUPAC name is ethanol.
Following is the structural formula of ethanol.

Example: C₆H₁₃OH

The common name of this compound is hexyl alcohol.

IUPAC Name:

Number of carbon atoms: 6
Functional group: Alcohol
Hence, its IUPAC name is hexanol
Following is the structural formula of hexanol.

Naming of Aldehyde group (−CHO):

IUPAC name of alkane having aldehyde group is written as follows:

The suffix of aldehyde group is “al”.
Alkane – e + al = Alkanal
Methane – e + al = Methanal
Ethane – e + al = Ethanal, and so on.

Example: HCHO

Common name of this compound is formaldehyde.

IUPAC Name:

Number of carbon atom: 1
Hence, IUPAC name is methanal.
Following is the structural formula of methanal.

Example: CH₃CHO

Common name of this compound is acetaldehyde.

IUPAC Name:

Number of carbon atoms: 2
Functional group: Aldehyde
Hence, IUPAC name is ethanal.
Following is the structural formula of ethanal.

Example: C₆H₁₃CHO

Number of carbon atoms in this compound is 7 and hence, its IUPAC name is heptanal.

Naming of Carboxylic Acid (−COOH):

Suffix for carboxylic acid is "oic acid".
Thus an alkane having carboxylic acid is named as:
Methane – e + oic acid = Methanoic acid
Ethane – e + oic acid = Ethanoic acid.

Answer: HCOOH

Common name of this compound is formic acid. It has one carbon atom, hence its IUPAC name is methanoic acid. Following is the structural formula of methanoic acid.

Example: CH₃COOH

Common name of this compound is acetic acid. It has two carbon atoms, hence its IUPAC name is ethanoic acid. Structural formula of ethanoic acid is as follows:

Example: C₄H₉COOH

It has five carbon atoms, hence its IUPAC name is pentanoic acid. Structural formula of pentanoic acid is as follows:

Naming of Ketone (−CO−):

Example: CH₃−CO−CH₃

Common name of this compound is dimethyl ketone. It has three carbon atoms and functional group is ketone, hence its IUPAC name is propanone. Structural formula of propanone is as follows:

Example: C₂H₅−CO−C₂H₅

Common name of this compound is dethyl ketone. It has five carbon atoms and functional group is ketone, hence its IUPAC name is pentnone. Following is the structural formula of pentanone:

Homologous Series:

Series of compounds with same general formula and functional group is known as homologous series. Compounds belonging to the same homologous series show similar properties. Compounds of homologous series differ by CH₂ from their consecutive members. Each subsequent compound in a homologous series differs by 14 au. Example: Alkanes; such as, Methane, Ethane, Propane, Butane, etc. belong to same homologous series.

Properties of Compounds of Same Homologous Series

• Compounds of same homologous series have same general formula.
• Compounds of same homologous series differ from their consecutive members by one carbon atom and two hydrogen atoms, homologous series differ from their consecutive members by one carbon atom and two hydrogen atoms, i.e. by CH₂
• Compounds of same homologous series have same chemical properties.
• Compounds of same homologous series differ by physical properties with increase or decrease in molecular mass.