IUPAC NOMENCLATURE part 3

IUPAC NOMENCLATURE part 1

IUPAC NOMENCLATURE  part 2

IUPAC NOMENCLATURE 

 IUPAC NOMENCLATURE OF ALICYCLIC COMPOUNDS :

( 1 ) The names of alicylic compounds are obtained by adding the prefix "cyclo".

(2) The numbering of the carbon atoms in the ring is done in such a way that the substituent which comes first in the alphabetical order is given the lowest possible number provided it does not violate the lowest set of locants rule.

 Example :

(3)When the ring contains more or equal number of carbon atoms than the alkyl group attached to it, then it is named as a derivative of cycloalkane and the alkyl group is treated as substituent.

Example :

(4)The alkane chain contains greater number of carbon atoms than present in the ring, the compound is considered as the derivative of alkane and the ring is designated as substituent. 

Example :

(5)If ring has unsaturation and side chain is saturated then ring is selected as parent chain. 

If side chain has unsaturation and ring is saturated then side chain is selected as parent chain. 

If both have unsaturation the chain with maximum unsaturation has selected as parent chain. 

If equal unsaturation then longest chain is selected as parent chain. 

If unsaturation and number of carbon atoms both are equal then ring is selected as parent chain. 

Example :

(6)If, more than one alicyclic ring is attached to a single chain, the compound is named as a derivative of alkane and the ring is treated as a substituent group. 

Example

(7)) If a multiple bond and some other substituents are present in the ring, the numbering is done in such a way that the multiple bond gets the lowest number. Example :

(8)If a compound contains an alicyclic ring directly linked to the benzene ring. It is named as a derivative of benzene. 

Example :

(9)If functional group is present in cyclic compounds the main chain is taken there principal functional is lie, if the principal functional group is present in ring also then main chain will be taken for the maximum no. of carbon atoms.

(10)When chain terminating functional group is directly attached with ring then ring is taken as parent chain & special suffix used for functional group.

S.NO.	Functional group	Suffix
1	-CHO	Carbaldehyde
2	-COOH	Carboxylic acid
3	-COX	Carbonyl halide
4	-COOR	Alkyl Carboxylate
5	-CONH2	Carboxamide
6	-CN	carbonitrile

example :

IUPAC NOMENCLATURE OF COMPOUNDS CONTAINING FUNCTIONAL GROUP

Rules for non chain terminating functional groups :

1. Parent chain : Select the longest possible chain with maximum functional group and maximum unsaturation with out caring whether it also denotes the longest possible chain or not.  Example:
   
   (parent chain contains four rather than five carbon atoms )
2. Lowest number for the functional group : 

Numbering is done from that side of the chain which gives lowest locant to the principle functional group followed by double and triple bonds.

Example: 

( ＞C=O group gets lowest number 3 ) ( ＞C=O group gets number 4 which is not lowest)

 Rules for chain terminating functional groups :

1. When a chain terminating functional group such as –CHO, –COOH, – COOR, –CONH₂ , –COCl ,– C☰N etc. is present, it is always given number 1 (one.)

Example:

2. If a compound contains two or more like groups, the numerical prefixes di, tri, tetra etc. are used

Example : 

 3.The name for benzene as substituent is phenyl. In case the phenyl ring is further substituted, the carbon atoms of the ring directly attached to the parent chain in such a ways that the substituent on the ring gets the least possible number.

 Example: 

 4.If the organic molecule contain more than one similar complexes subtitutents, then the numerical prefixes such as di, tri, tetra etc. are replaced by bis, tris, tetrakis etc. respectively.

Example : 

 Rules for IUPAC nomenclature of polyfunctional compounds :

1. When an organic compound contains two or more different functional groups is selected as the principal functional group while other groups are treated as substituents.

S.NO.	Functional group	Prefix	Suffix
1.	-(C) OOH (Carboxylic acid) -COOH	carboxy	oic acid  carboxylic acid
2	-SO3H (sulphonic acid)	sulpho	sulphonic acid
3			oic anhydride
4	-(C)OOR (ester)  COOR	alkoxy carbonyl  or carbalkoxy	alkyl  ......... oate   alkyl ...... carboxylate
5	-(C)OX (acid halide )  -COX	halo formyl	oly halide carbonyl halide
6	-(C)ONH2 (amide  -CONH2	carbamoyl	amide  carboxamide
7	-(C)N  (cyanide ) -CN	cyano	nitrile  carbonitrile
8	-N☰(C) (isocyanide ) -NC	isocyano/carbyl amino	isonitrile
9	-(C)HO   (aldehyde ) -CHO	oxo formyl	al carbaldehyde
10		keto /oxo	one
11	-OH (alcohol)	hydroxy	ol
12	-SH (thio alcohol)	mercapto	thiol
13	-NH2 (amine )	amino	amine
14	-OR  (ether )	alkoxy

 2.Some functional group such as all halo groups. (Fluoro, bromo, chloro, iodo) nitrosol, (NO) nitro (–NO₂)

 Example:

 

 

Numbering the principal chain order is

 [Principal functional group > double bond > triple bond > substituents]

3.The longest possible chain of carbon atoms containing the functional group the maximum number of multiple bonds is selected as parent chain.

 Example :

              parent chain contains four rather than five carbon atoms.

4.If more than one same chain terminating group are present then the principal chain is selected including the functional groups and numbering is done from that side which gives lowest locant to unsaturation substituent.

Example: 

 

IUPAC Nomenclature of Aromatic Compounds :

The aromatic compounds are cyclic compounds contains one or more benzene type rings. Benzene is the simplest hydrocarbon of aromatic series which has planar cyclic ring of six carbon atoms having three double bonds in alternate positions as shown below.

 ( A ) Nuclear Substituted – 

The functional group is directly attached to benzene ring in the IUPAC system, they are named as derivative of benzene. The position of the substituents in disubstituted benzenes are indicates either by prefixes such as o–(ortho) for 1, 2, m–(meta) for for 1, 3 and p (para) for 1, 4 position. However, many of their common names have also been adopted by the IUPAC system.

( B ) Side–Chain Substituted – 

The functional group is present in the side chain of the benzene ring in the IUPAC systems, these are usually named as phenyl derivatives of the corresponding aliphatic compounds. The IUPAC and common names of a few important members of each formly are given below : 

(a) Aromatic hydrocarbons (arenes) : Hydrocarbons which contain both aliphatic and aromatic units are called arenes. These are of two types 

(i) Hydrocarbon containing one ring only.

Examples: 

(ii) Hydrocarbon containing condensed or fused ring :

 Aryl Groups:

Halogen derivatives :

Hydroxy derivatives :

The nuclear hydroxy derivatives are called phenols while the side chain substituted hydroxy derivatives are called aromatic alcohols. 

(i) Phenols–monohydric

(ii) Dihydric and polyhydric phenols

(iii) Aromatic Alcohols :

(iv) Aromatic ethers

(v) Aldehydes

(vi) Ketones

(vii) Nitro Compounds

(viii) Amines

(a) Aryl amines

(b) Aryl alkyl amine

(ix) Arenediazonium Salts :

(x) Cyanides and Isocyanides

(xi) Carboxylic Acids

(xii) Anhydrides

(xiii) Esters

(xiv) Amides