1. Structural heterogeneity:
The isomerization of (1) carbon chains, such as n-butane and isobutane, is caused by the different shapes of carbon chains in the molecule.
(2) positional isomerization. Isomerization is caused by different positions of substituents or functional groups on carbon chains or carbon rings, such as 1- methylbutyne and 2- methylbutyne 1- methylpropanol and 2- methylpropanol.
(3) Isomerization phenomena caused by different functional groups in functionally isomeric molecules, such as monoolefins and cycloalkanes, alcohols and ethers, aldehydes and ketones, alkynes and dienes, esters and carboxylic acids, phenols and aromatic alcohols.
2. Stereoisomerism: the structure is similar, but slightly different, and the structure is different. Specifically, it can be divided into conformational isomerization and conformational isomerization.
(1) Geometrical Isomerism: A kind of stereoisomerism, which is caused by the fact that the double bonds of olefins or the substituents of polysubstituted cyclic hydrocarbons are located on different sides of the ring. Also known as cis-trans isomerization, geometric isomerization also occurs in cyclic hydrocarbons. (2) Enantiomer: A stereoisomer with mirror image relationship with each other, called enantiomer (abbreviated as enantiomer). All enantiomers are enantiomers. One of them is left-handed and the other is right-handed. Therefore, enantiomers are also called optical isomers. Simply put, the relationship between the two isomers is like the three-dimensional structure of an object when it looks in the mirror. This three-dimensional structure and its image in the mirror are enantiomers.
pay attention to
(1) isomerism is mainly manifested in organic matter.
(2) There are two conditions for two compounds to be isomers: 1, and the molecular formula should be the same. 2. Their structures should be different. (3) The two compounds are isomers, and their physical properties are definitely different, but their chemical properties are similar (such as n-butane and isobutane) but different (such as ethanol and dimethyl ether).
(4) If the two compounds are isomers, the relative molecular weight of the two compounds and the composition (content) of each element must be the same, but the two compounds with the same relative molecular weight are not necessarily isomers (for example, CO and C2H4 are not isomers).