In chemistry, compounds with the same molecular formula and different structures are called isomers, also called structural isomers. The phenomenon that has the same molecular formula but different structures is called isomerism. [1]
Silver fulminate and Silver cyanate It is the first isomer discovered by human beings. In 1830, Bezilias A new chemical concept, called "isomorphism", was proposed. It means that the same chemical composition can form compounds with different properties. He believes that, Cyanic acid And Fulvic acid They belong to "isomorphism". Their chemical compositions are the same, but they are compounds with different properties. Before that, the chemical community had always believed that a compound had one component, and no two different compounds had the same chemical component. In organic chemistry, isomers can be divided into structural isomers, stereoisomers and electron tautomers. [1]
Structural isomers refer to isomers caused by different connection order or bonding properties of atoms in molecules. It can be divided into five types: carbon frame isomer, positional isomer, functional group isomer, tautomer, and valence bond isomer.
Carbon isomer
Isomers due to different carbon frames are called carbon frame isomers. For example:
Illustration Positional isomer
The isomers produced by the different positions of functional groups on the carbon chain or carbon ring are called positional isomers. For example:
Illustration Functional isomer
The isomers produced by the different types of functional groups contained in the molecules are called functional group isomers. For example:
Illustration Tautomer
The isomers of functional groups produced by the rapid movement of an atom in a molecule at two positions are called tautomers. For example:
Illustration Valence bond isomer
The distribution of some valence bonds in the molecule has changed, changing the geometric shape of the molecule, resulting in isomerism, which is called valence bond isomer.
The isomers caused by the different spatial arrangement of atoms or clusters in molecules with the same connecting order and bonding substances are called stereoisomers. It can be divided into configurational isomers and conformational isomers (rotational isomers).
Configurational isomers
Isomers caused by bond length, bond angle, double bond or ring in the molecule are called configurational isomers. Configuration isomers can be divided into cis trans isomers (geometric isomers) and optically active isomers (photo active isomers).
1. Cis trans isomer
The isomers caused by the non free rotation of the double bond or the single bond of the ringed carbon atoms are called cis trans isomers. For example:
Illustration 2. Optical isomer
Stereoisomers with different optical rotations due to the absence of anti axial symmetry in the molecule are called optical rotations isomers.
Conformational isomer
The stereoisomers caused only by the rotation of the single bond are called conformational isomers.
