System Nomenclature
This is a systematic nomenclature formulated by adopting the universal IUPAC naming principles and combining the characteristics of Chinese characters.
The naming of straight-chain alkanes is basically the same as that of ordinary nomenclature, except that the word “normal” is omitted and branched-chain alkanes are regarded as alkyl derivatives of straight-chain alkanes, and are named according to the following rules:
(1) The longest carbon chain in the molecule is selected as the main chain, and the branched alkyl group is regarded as a substituent on the main chain. The alkane is called according to the number of carbon atoms contained in the main chain.
(2) Starting from the end closest to the branch chain, the carbon atoms of the main chain are numbered with Arabic numerals, and the position of the branch chain is indicated by the number of the carbon atom to which it is connected.
(3) Write the name of the substituent in front of the name of the alkane. If the main chain contains several different substituents, they are arranged in ascending order; if they contain several identical substituents, they can be listed in The name is indicated by two, three, four …
If the position of the first substituent is the same from either end of the carbon chain, the sum of the numbers representing the positions of all substituents is required to be the smallest number.