Alkanes: Find the longest C chain and name it according to the number of C atoms (methane, ethane, propane, butane, pentane, hexane, heptane, octane, nonane, decane, etc. ) Find the branch chain: determine the location and name of the branch chain. The principle is to start numbering from the end closest to the branch chain, and the main chain and the branch chain merge. When the branches are the same, they should be merged. Position serial numbers are separated by ",",and the number of branches is indicated before the name.

Alkenes are similar to alkynes, and their branching positions should be close to double bonds and triple bonds.

Benzene correlation; Named after benzene as the matrix; The number of benzene rings is 1, and the substituent is small. When there are multiple substituents, the position of each substituent can be marked with O, M, P or 1, 2, 3, 4, 5. Sometimes phenyl is used as a substituent.

Halogenated hydrocarbon: Named after alkanes with halogen atoms as substituents.

Alcohol: Named for olefins with hydroxyl groups as functional groups.

Phenol: Named like a homologue of benzene, the hydroxyl group of phenol is at 1.

Ethers and ketones: Pay attention to the number of carbon atoms when naming.

Aldehydes and carboxylic acids: aldehydes and acids.

Ester: An ester of an acid.

In stereoisomerism, cis-trans isomerism: two identical atoms or groups located on the same side of a double bond or ring are cis-trans, and the opposite side is trans.

Optical isomerization is very troublesome. Let the atoms or groups on C* be a, b, c, d and A > B > C > D (priority), where d is farthest from the eyes, a b c is r clockwise, and s is counterclockwise.

If it is high school, there seems to be not many tests on stereoisomerism. If it is a university, just pay attention to the three-dimensional heterogeneity mentioned by the class teacher.