1: General rules for the order of substituents
When there are multiple substituents on the main chain, the order of the groups in the name is determined by the order rules. The general rule is:
1. The greater the mass of the first atom of the substituent, the higher the order;
2. If the first atoms are the same, then compare their first The order of the atoms connected to each atom; if there are double bonds or triple bonds, it is regarded as connecting 2 or 3 identical atoms
The functional group with the highest order is regarded as the main functional group and is named last. . For other functional groups, the lower the order, the higher the name.
Selection of the main chain or main ring system
The longest carbon chain containing the main functional group is used as the main chain, and the end close to the functional group is marked as carbon No. 1.
If the core of the compound is a ring (system), then the ring system is regarded as the parent; except for the benzene ring, each ring system determines the No. 1 carbon according to its own rules, but at the same time the number of substituents must be ensured. The position number is the smallest.
The carbon atom in the branch chain connected to the main chain is labeled as carbon 1.
Numbers
Position numbers are represented by Arabic numerals.
The number of functional groups is expressed in Chinese characters.
The number of carbon atoms in the carbon chain is expressed by Tiangan if it is within 10, and it is expressed by Chinese characters if it is more than 10.
Specific rules for various types of compounds
Alkanes
Find the longest carbon chain as the main chain, and name the main chain according to the number of carbons. The first ten are named after heavenly stems (A, B, C...) represents the number of carbons. When the number of carbons is more than ten, it is named with Chinese numbers, such as: undecane.
Number from the nearest substituent position: 1, 2, 3... (make the position number of the substituent as small as possible). The position of the substituent is represented by a number. Numbers and Chinese numbers are separated by -.
When there are multiple substituents, use the carbon chain with the smallest and longest substituent number as the main chain, and list all substituents in the order of methyl, ethyl, and propyl.
When more than two substituents are the same, add Chinese numbers in front of the substituents: one, two, three..., such as: dimethyl, whose positions are separated by, and are listed together in in front of the substituent. Methyl CH3-
Ethyl CH3CH2-
(n-)propyl CH3CH2CH2-
(n-)butyl CH3CH2CH2CH2-
Alkenes
The naming method of alkenes is similar to that of alkanes, but the longest bond containing a double bond is used as the main chain.
Start with the carbon closest to the double bond and indicate the positions of the substituents and double bonds respectively.
If there are two or more double bonds in the molecule, it is named "diene" or "triene".
Cis and trans isomers often appear among the isomers of alkenes, so "cis" or "trans" must be indicated.
Alkynes
The naming method is similar to alkenes, but the longest bond containing a triple bond is used as the main chain.
Start with the carbon closest to the triple bond and mark the positions of the substituents and triple bonds respectively.
Alkynes do not have cycloalkynes and cis-trans isomers.
When there are both double bonds and triple bonds in the molecule, the name starts with alkene followed by alkyne, and the position number is marked respectively, and the carbon number is written in front of "alkene".
Halogenated hydrocarbon?6?1 ether
The naming of halogenated hydrocarbons uses the corresponding hydrocarbon as the parent and the halogen atom as the substituent.
If there is a carbon chain substituent, the carbon chain should be written in front of the halogen atom according to the order rules; if there are multiple halogen atoms, the order of listing is fluorine, chlorine, bromine, and iodine.
The name of the ether is based on the longer end of the carbon chain as the parent, and the other end is combined with the oxygen atom as a substituent, which is called an alkoxy group.
Alcohols
Alcohols are named with the longest carbon chain containing the alcohol hydroxyl group as the main chain;
The name is determined by the number of carbons in this chain. For alcohols, when numbering, keep the position number of the alcohol hydroxyl group as small as possible;
Other groups are treated as substituents.
When there are multiple alcohol hydroxyl groups on the main chain, they can be called diols, triols, etc. according to the number of hydroxyl groups.
Aldehydes
The naming of aldehydes is based on the longest carbon chain containing the aldehyde group as the main chain, and the other parts are used as substituents;
The carbon that determines the name The number includes one carbon of the aldehyde group.
If there are multiple aldehyde groups, the longest carbon chain containing 2 aldehyde groups will be the main chain, which is called dialdehyde.
When the aldehyde group is used as a substituent, it is called a formyl group (or oxo group).
Ketone
The longest carbon chain containing the ketone carbonyl group is the main chain, and the number of carbons in this chain (including the carbonyl group) is called "a certain ketone"; and the carbonyl group The position number is marked in front, try to keep the position number as small as possible.
If there are multiple carbonyl groups on the main chain, it can be called diketone, triketone, etc.
When carbonyl is used as a substituent, it is called "oxo".
Carboxylic acid
With the longest carbon chain containing carboxyl groups as the main chain, it is called an acid according to the number of carbon atoms (including carboxyl groups).
When there are two carboxyl groups on the main chain, it is called a diacid.
Carboxylic anhydride
An acid anhydride is called an acid anhydride by the name of the acid that forms it, followed by the word "anhydride".
(For example: CH3CO-O-CO-C2H5 - acetic acid propionic anhydride)
If the two molecules of acid that form the acid anhydride are the same, it is directly called "a certain acid anhydride".
Ester
It is named after the acid and alcohol that form the ester, and is called a certain acid (alcohol) ester or a certain alcohol and acid ester.
If there are multiple alcohol or acid molecules involved in ester formation, then the number should be added in front of the corresponding alcohol or acid.
Amines
The longest carbon chain connected to a nitrogen atom is the main chain, and it is called an "amine" according to the number of carbon atoms on the chain;
< p>If it is an imine, the shorter hydrocarbon group on the nitrogen atom is regarded as a substituent, and is called "N-a certain group" when naming (N means that the substituent is attached to the nitrogen)Alicyclic hydrocarbons
p>Monoalicyclic hydrocarbons
The naming of cycloalkanes is similar to that of alkanes, just add the word "cyclo" in front of the alkanes.
The naming of cyclic alkenes is similar to that of alkenes. The numbering is first set to carbon 1 and carbon 2 based on the double bond.
Bridged cycloalkanes
In bridged cycloalkanes, the carbon atoms common to multiple rings are called bridgehead carbons;
Number the carbon atoms, starting from a bridgehead carbon Starting from the atom, number all the carbon atoms in order from largest to smallest ring;
When naming, first name the number of rings, and then indicate in brackets the carbon atoms between the bridgehead carbons of each ring. The number is separated by dots, and the number of numbers is always one more than the number of rings;
Finally, according to the number of carbon atoms in the ring system, it is called "a certain alkane".
For example:
It is called bicyclo[3.2.0]heptane.
Spirocycloalkanes
In spirocycloalkanes, a fourth-order carbon atom common to the two rings is called a spiro atom;
The numbering starts from the small ring, 1 The carbon number is the carbon atom next to the spiro atom;
When naming, first call the word "snail", and then indicate the number of non-spiro atoms in each ring in brackets, with dots between the numbers Separate;
Finally, according to the number of carbon atoms in the ring system, it is called "a certain alkane".
For example:
It is called spiro[3.5]nonane.
Polycyclic alkenes and alkynes
Name them according to the rules for polycyclic alkanes. When numbering, try to keep the position number of the heavy bond to the smallest, and then replace the word "alkane" with "alkene" Or "alkyne" will do.
Aromatic compounds
Benzene ring system
For benzene halides, alkyl substitutes, etc., first call the position number and name of the substituent, and then add " The word "benzene". The word "base" for simple alkyl groups such as methyl and ethyl can be omitted. (For example: 1,2-xylene)
Benzene, alkyne, alcohol, aldehyde, ketone, carboxylic acid, sulfonic acid, amino substitute, etc., with the original form of the substituent as the parent, are first called "Benzene" (indicating phenyl) is also called the original form of the substituent. When numbering, the substituent is the main chain, the benzene ring is the branch chain, and the carbon connected to the substituent is carbon No. 1. (For example: styrene)
The hydroxyl substitute of aromatic hydrocarbons is called phenol, which is phenol for benzene. When there are two hydroxyl groups directly connected to the benzene ring, it is called benzene.
Other ring systems
Various aromatic ring systems have different names, and the naming method of their substituents is similar to that of benzene rings. However, these ring systems generally have a fixed numbering sequence (rather than being determined only by substituents like the benzene ring):
Naphthalene ring system
Anthracene ring system
< p>Wait.Heterocyclic compounds
Consider a heterocycle as a ring formed by replacing carbon atoms with heteroatoms in a carbon ring, which is called "a hetero (name of the ring)"; (such as : oxolane)
Number the heteroatoms so that the position number of the heteroatoms is as small as possible.
Other functional groups are considered substituents.
1. Branched alkanes
Main chain Choose the one with the longest carbon chain and the most branches.
Numbering is based on lowest series rules. Numbering starts from the nearest end of the * side chain. If the numbers at both ends are the same, the position of the next substituent will be compared sequentially, and the system with the smallest position first encountered will be the lowest system (regardless of the nature of the substituent).
2,3,5-Trimethylhexane is not called 2,4,5-trimethylhexane because 2,3,5 is the lowest series compared with 2,4,5.
IUPAC stipulates that the order of substituents is arranged in alphabetical order of the English name. Our country stipulates the "order rule" in stereochemistry: the priority group is placed last, and if the first atom is the same, the next atom is compared.
2-Methyl-3-ethylpentane, because -CH2CH3>-CH3, so put -CH3 in front.
2． Monofunctional compounds
The main chain is the one with the longest carbon chain and the most side chains containing functional groups, which is called an alkene (or alkyne, alcohol, aldehyde, ketone, acid, ester,...). Halogenated hydrocarbons, nitro compounds, and ethers use hydrocarbons as the parent, and use halogen, nitro, and alkoxy groups as substituents, and the positions of the substituents are indicated.
The numbering starts from the end closest to the functional group (or the above-mentioned substituent), and the priority group is listed next in order.
3. Multifunctional compounds
(1) Aliphatic
Select the longest carbon chain with the most functional groups (including multiple bonds as much as possible) as the main chain. It is customary to take the endings of functional groups in the following order,
—OH>—NH2 (=NH)>C≡C>C=C
For example, when alkenes and alkynes are in the same position Then give the double bond the lowest number.
(2) Alicyclic and aromatic
If the side chain is simple, choose the ring as the parent; if the substituent is complex, choose the carbon chain as the main chain.
(3) Heterocycle
Number starting from the heteroatom. When there are multiple heteroatoms, number them in the order of O, S, N, and P.
4. Cis and trans isomers
(1) Cis and trans nomenclature
Cyclic compounds are represented by cis and trans. Identical or similar atoms or genes on the same side are called cis, and on opposite sides are called trans.
(2) Z, E nomenclature
When a compound contains a double bond, it is represented by Z and E. Compare the size of the groups connected to the double bond atoms according to the "order rule". The larger group on the same side is called Z, and the larger group on the opposite side is called E.
The order rules are:
(Ⅰ) The one with the larger atomic number is given priority, such as I＞Br＞Cl＞S＞P＞F＞O＞N＞C＞H, not * **Sharing of electron pairs: is the smallest;
(Ⅱ) Isotope with high mass is given priority, such as D>H;
(Ⅲ) The first atomic phase of the two groups At the same time, compare the second and third atoms in turn;
(IV) multiple bonds
can be regarded as
(V) Z has priority over E, R takes precedence over S.
5． Optical isomers
(1) D, L configuration
Mainly used in sugars and related compounds. Using glyceraldehyde as the standard, the right-handed configuration is D, and the left-handed configuration is The configuration is L. Sugars whose chiral carbon atom farthest from the carbonyl group in the molecule has the same configuration as D-(+)-glyceraldehyde are called D-type; otherwise, they are L-type.
Amino acids are also traditionally labeled with D and L. Except for the non-optical rotation of glycine, the configurations of the carbon atoms of α-amino acids are all L-shaped.
The rest of the compounds can be determined by chemical transformation and correlation with standard materials.
(2) R, S configuration
When naming a compound Cabcd containing a chiral carbon atom, first press the " "Order rules" arrange from large to small (such as a>b>c>d), then place the smallest d in the direction away from the observer, and the other three groups point to the observer, then a→b→c clockwise is R , counterclockwise is S; if d points to the observer, then clockwise is S and counterclockwise is R.
In actual use, the most commonly used expression is the Fischer projection,
(R)-2-chlorobutane. Because Cl>C2H5>CH3>H, the smallest group H is above and below the C atom (meaning backward) and in the direction away from the observer, so the nomenclature stipulates that Cl→C2H5→CH3 clockwise is R.