Nomenclature of Saturated Hydrocarbons, Types of Alkanes, Questions (For CBSE, ICSE, IAS, NET, NRA 2022)

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Nomenclature of Saturated Hydrocarbons

Nomenclature is a system of terms or rules that are used for forming these terms or names in a distinct field of science and arts. In simple terms it names organic compounds. Saturated hydrocarbons are the organic compounds that consist of carbon and hydrogen single bond. There are the maximum number of hydrogen atom present for every carbon atom. For example, Alkanes.

The Saturated Hydrocarbons Are Named According to the Following Rules

  • Longest Chain Rule: The parent chain of the compound is considered as the longest chain of carbon atoms. This chain can either be straight or of any other shape.
  • Lowest Set of Locants: The numbering of the carbon atoms starts from the end which gives the lowest number to the carbon atom carrying the substituent.
  • Presence of Same Substituent More Than Once: Prefixes such as di, tri, etc. are given to the substituents which are present twice, thrice respectively on the parent chain.
  • Naming Different Substituents: If more than one substituent is present then the substituents are arranged in their alphabetical order.
  • Naming Different Substituents at Equivalent Positions: If two different substituents are present on the same position from the two ends then the substituents are named so that the substituent which comes first in the alphabetical order gets the lowest number.
  • Naming the Complex Substituents: Naming of complex substituent is done when the substituent on the parent chain has a branched structure (i.e.. , complex structure) . These substituents are named as a substituted alkyl group and the carbon atom of this substituent attached to the parent chain is numbered as 1. Name of this type of substituent is written in brackets.

Example

Nomenclature of Saturated Hydrocarbons
  • In this case we have 9 carbon atoms in the straight chain. 5th Carbon atom from both the ends of the straight chain, consists of substituent having 3 carbon chains. On the first two carbon atoms of the substituent group, there is one additional carbon atom attached.
  • Now if we consider this as a new parent chain, it has a substituent which has one additional carbon each. For naming them we will firstly number the parent chain. In this case we have 9 carbon atoms in a straight chain which is also the parent chain. Then we find that the substituent is on the fifth position.
Nomenclature of Saturated Hydrocarbons
  • Now taking the substituent we will observe that we have 3 substituent carbons and out of these three, two substituent has additional carbons attached. We find that the longest chain in this can be the first four carbon atom chain but this is wrong as the last carbon is not attached to the parent chain.
  • So, we will consider only three carbon atom chain as the main chain. Thus, it can be named as propane and on the first and second position we have methyl group. We can write the name as 1 - 2 Dimethyl propane, but it will be written as 1 - 2 Dimethyl propyl as it is a substituent group.
Nomenclature of Saturated Hydrocarbons

Now taking the substituent with the parent chain we will get 5- (1 - 2-Dimethyle Propyl) and as the parent chain has 9 carbon atoms so, it will be named as nonane. Thus, the final name of the compound will be 5- (1 - 2-Dimethyle Propyl) nonane.

Nomenclature of Saturated Hydrocarbons

Hydrocarbons

Compounds containing only carbon and hydrogen atoms are known as hydrocarbons.

Saturated Hydrocarbons

  • Hydrocarbons in which all the carbon atoms are linked to one another by only single bonds are called saturated hydrocarbons.
  • Saturated hydrocarbons may be either cyclic (closed chain) or acyclic (open chained) . Saturated acyclic hydrocarbons are called alkanes.

Types of Alkanes

Alkanes are of the following types:

Straight Chain Alkanes

In straight chain alkanes, no carbon atom is linked to more than two carbon atoms.

  • Nomenclature of saturated straight chain alkanes
  • The IUPAC names of straight chain alkanes are obtained by adding the suffix ane to word root.
  • We are given the following compound

Number the given compound

  • Clearly, the compound contains 5 carbon atoms; therefore, the word root of the given compound is pent (word roots are discussed in nomenclature introduction) .
  • IUPAC name of the compound .

Questions

How Do You Name a Saturated Hydrocarbon?

Answer:

  • Saturated hydrocarbons are given the general name of alkanes. The name of specific alkanes always ends in – ane and has a prefix to indicate how many carbon atoms it has.
  • Hydrocarbons may form straight chains, branched chains, or rings. Ring-shaped hydrocarbons are called cyclic hydrocarbons.

What Does Saturated Mean in Terms of Hydrocarbons?

Answer:

Saturated hydrocarbons are hydrocarbons that contain only single bonds between carbon atoms. They are the simplest class of hydrocarbons. They are called saturated because each carbon atom is bonded to as many hydrogen atoms as possible.

What Are the 4 Types of Hydrocarbons?

Answer:

  • By using this definition, four classes of hydrocarbons are included: alkanes, alkenes, alkynes and aromatic. SATURATED means that each carbon is bonded to four other atoms through single covalent bonds.
  • Hydrogen atoms usually occupy all available bonding positions after the carbons have bonded to each other.

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