Alicyclic, Spiro, Bicyclo and Aromatic Compounds - Class 11 PDF Download

NOMENCLATURE OF CYCLIC HYDROCARBONS
Rule 1: Name of monocyclic, saturated hydrocarbons are formed by attaching the prefix “cyclo” to the names of acyclic, saturated hydrocarbon with same number of carbons

Rule 2: Name of unsaturated monocyclic hydrocarbons (With no side groups) is formed by substituting “-ene” , “-yne”, “- adiene”, “-atriene”, “-adiyne” etc for “ane” in the name of corresponding cycloalkane eg,

Rule 3: If a straight chain substituent attached to monocyclic hydrocarbon has greater number of carbon in the main chain than the cyclic ring becomes substituent as

NOMENCLATURE OF SUBSTITUTED BENZENE COMPOUNDS
For naming the substituted benzene compounds, the prefix used for the substituent is prefixed to the word ‘benzene’ simply.
Example:

Disubstituted Benzene Compounds
If two atoms of hydrogen of benzene are replaced by two monovalent atoms or group of atoms, the resulting product is called disubstituted benzene derivable. For such compounds the position of substituents is defined by numbering the carbon atoms of the ring such that the substituents get the lowest numbers.

There can be three forms of disubstituted benzene compounds. 
(i) 1, 2 (ortho)-form : When the two substituents are on the adjacent carbon atoms.
(ii) 1, 3 (meta)-form : When the two substituents are on the alternate carbon atoms.
(iii) 1, 4 (para)-form : When the two substituents are on diagonally situated carbon atoms.

Tri-or higher substituted benzene derivatives
For naming the tri- or higher substituted benzene derivatives, the positions of the substituents on the ring is identified following the lowest locant rule.
(i) Compound with three functional groups is named as a derivative of the compound with the principal functional group at position 1
Example:
(ii) Suffix of the base compound is assigned number 1 and then the directional of numbering is choosen such that the next substituent gets the lowest number.
Example:
(iii) When a substituent is such which when taken together with the benzene ring gives a special name to the molecule then it is named as derivative of that molecule with the sustituent.
(iv) When the benzene ring is attached to an aliphatic chain having a functional group, it is named as phenyl (C₆H_5-) derivative of that aliphatic compound.

BICYCLIC COMPOUNDS
Bicyclic Compounds are the compounds which contain two rings.
(i) If the two rings share one  carbon, the compound is a spirocyclic compound or simply spiro compound.
For example:
(ii) If the two rings share two adjacent carbons , the compound is a fused bicyclic compound.
(iii) If the two rings share more than two carbons, the compound is a bridged bicyclic compound.

IUPAC NOMENCLATURE OF BICYCLIC COMPOUNDS
(i) Bicyclic compounds are named by using the alkane name to designate the total number of carbons and the prefix bicylo or spiro to indicate the number of shared carbons.

(ii) Prefix spiro indicates ne shared carbon and bicycle indicates two or more shared carbons. The following compound. 
Example: contains seven carbon atoms and is therefore, a bicycloheptene
The carbon atoms common to both rings (Number of such carbons is either one in spiro or two in bicyclic) are called bridgeheads and each carbon chain of atoms, connecting the bridgehead atoms is called a bridge.

(iii) After the prefix (spiro or bicyclic), come brackets that contain numbers indicating the number of carbons in each bridge.
(a) Number of carbons in bridges are listed in increasing order in case of spiro compounds.
(b) These numbers are listed in order of decreasing bridge length in case of bicyclic compounds.
(iv) Numbering in bicyclic compounds starts from any one bridgehead carbon and moves along the longest carbon bridge to the next bridgehead carbon. Continue along the next longest carbon bridge to return to the first bridgehead carbon so that the shortest bridge is numbered last.

Examples:

NAMING ALICYCLIC COMPOUNDS
For alicyclic compounds, prefix cyclo is used
Example:

If the alkyl chain contains a greater number of C-atoms than the ring, the ring is designated as substituent.
Example:

If side chain contains a multiple bond or a functional group, the ring is treated as a substituent.
Examples:

Other examples are: 

Naming Spiro Compounds:
Prefix ‘spiro’ is used for the compounds in which one carbon is present between two rings:
Here, smaller ring is numbered first,
Examples:

NAMING BICYCLO COMPOUNDS
Prefix ‘bicycle’ is used for such compounds
Examples:
In bicycle compounds, numbering is done first in larger ring, then in smaller ring.

Naming Aromatic Compounds
IUPAC accepted their common trivial names
Example: