• Rules:IUPAC


source: Khan academy

Rules:IUPAC of  Aliphatic compounds containing one functional group-

i) Longest chain-

Selection of longest parent chain including functional group, even if it is not the actual longest continuous chain.

ii) Numbering of parent chain-

a) The numbering of parent carbon chain is carried out in such a way that carbon linked  to functional group gets the lowest number  even if alkyl groups are  present  because alkyl groups  are placed very below in priority table.

b) When chain terminating group such as -CHO, -COOH, -COOR, -CONH2, -CN etc. is present as functional group, it must be assigned number  one (1).

iii) The last ‘e’ of the primary suffix is dropped  & secondary  suffix representing the functional group is added . The number  giving the position of functional group is written as –

iv) If  two or more identical groups are present then di, tri, tetra etc. is added  before the designation  of functional group present.

Other Examples-