FUNCTIONAL GROUPS 1.1 Functional group: - Functional group are atom or group of atom which participate in chemical reaction of organic compound. Chemical properties of organic compound depend upon the function group. Functional group has specific name, definite structure and consists of specific atoms.
Functional group is attached to a chain of hydrocarbon. Hydrocarbon chain generally does not participate in the chemical reaction and remains passive. Chemically a molecule behaves similar to any other molecule which has the same functional group. 1.2 Family name of groups of groups
1.3
Alcohol, Aldehyde, Alkane, Alkene, Alkyne, Amide, Amine, Azo compound, Benzene derivative, Carboxylic acid, Cyanate, Disulfide, Ester, (alphabetical Ether, Haloalkane , Imine , Isocyanide , Isocyanate , Ketone Nitrile ,order) Nitro compound, Nitroso compound , Peroxide , Phosphoric acid Pyridine derivative, Sulfone, Sulfonic acid, Sulfoxide, Thioester, Thioether, Thiol.
1.4 Nomenclature
International Union of Pure and Applied Chemistry (IUPAC) recommended a scientific and systematic method of vast variety of organic compound. Every effort has been made to ensure that an undisputable unambiguous structure must be developed based on IUPAC names of organic compounds
However in practice and in day to day communication IPUAC names are generally not followed. Trivial names or common names are well in use. Some of the trivial names are so popular that IUPAC has adopted them IUPAC name essentially consists of three parts. Prefix, Parent and Suffix. The parent parts indicates base name of the molecule. Suffix identifies the functional group family. Prefix gives location of functional group and the other substituents (a group attached as a branch to the longest chain on the parent) The Parent part of name of name depends on number of carbon atom forming the longest chain in the molecule. These carbon atoms must be bonded to each other and should form an unbroken chain. Each parent name represents a specific number of carbons.
The suffix and prefix in the name indicates type of bond (single, double, or triple), functional group as well as substituent group. Location of functional group and multiple bonds is indicated by designating each carbon in the longest chain by a number
1.5 Determining the Name as per IUPAC Rules :
1. Identify the longest unbroken carbon chain in the molecule and select a parent name depending upon the number of carbon atoms present in the longest chain. The longest chain must include maximum number of multiple bonds, functional and substituent groups.
(Higher than ten number of carbons are indicated by Greek counting number) 2. Identify the type of bonds (single, double or triple) in the parent carbon chain 3. Select a suitable suffix such as ’ane’, ‘ene’, and, ‘yne’ for single double and triple bond respectively.
4. Attach name of functional group to suffix if its name appear in suffix column of table in section 1.3. However if the functional group name is also present in prefix column the name of the functional group is decided as per functional priority (section1.3)
5. Determine the name of substituent group if it is present. 6. Substituent group is named by adding ‘ yl ’to the base name of substituent group ;e.g. if there there is one carbon in substituent group then it is named as ( meth+yl) methyl and if there are two carbons then the name is (eth+yl) ethyl and so on 7. Substituent group is always written as prefix and function group always as suffix 7. Number the carbon in chain consecutively, starting at the end nearest a substituent group in such a way that substitutent multiple bonds and functional group get the number as per the priority list 9. Designate the location of each substituent group by an appropriate number and name.
10. Assemble the name, listing groups in alphabetical order. 11. The prefixes di, tri, tetra etc., used to designate several groups of the same kind. 12. Only one functional group is treated as suffix. However if there are more then one functional group then highest priority group is treated as functional group and others as substituent group. The priority of the groups is as follows Carboxylic acid,> Thiocarboxylic acid, > Sulfonic acid, > easter, > acyl chlorides, > amides, > nitriles,> aldehydes,> ketones, > alcohols, > amines, > eather,> double bond, triple bond, > substituent group
13. The word ‘cyclo’ should be attached to the prefix for naming the cyclic compound 14. Certain common name, and prefix are adopted by IUPAC and should be treated as part of IUPAC nomenclature
neo
Example of IUPAC name
Base name – oct- Longest chain has 8 carbons Suffix – ane – only single bond present Number – start from left as function group halid gets lower number Prefix – all function group are in prefix and in alphabetical order
-COOH is a principal functional group and gets priority over keton and amine which are treated as substituent
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