Rules for Naming Organic Molecules
Page numbers refer to the 5th edition of Vollhardt and Schore
Note that these rules are changed (thank IUPAC) as of 2008. Older HW and exams have slightly different answers.
Basic Rules (pp. 71-76):
1. Find the longest chain in the molecule and name it.
2. Name all groups attached to the chain as alkyl substituents.
3. Number the carbons of the longest chain beginning with the end that is closest to a substituent.
4. Write the name of the alkane by first arranging all of the substituents in numerical order (each preceded by the number of the carbon to which it is attached and a hyphen), and then add the name of the stem.
Haloalkanes (pp. 75-76):
5. The halogen is treated as an alkyl substituent, without any priority.
6. Ethers (p. 346-347) are named as alkoxyalkanes. The first carbon of the alkoxy substituent is numbered as C-1 of that substituent.
7. Amines (pp. 957): Amines are named as alkanamines, with the amino group defining the chain numbering, so 2-hexanamine.
Alkenes (pp. 447):
8. Find the longest chain that includes both carbons of the double bond(s).
9. Numbering starts with the end of the chain nearer the double bond. In cycloalkenes, the two carbons of the alkene are defined to be C-1 and C-2. Alcohol numbering takes priority over alkene numbering: thus, an alkenol.
10. Substituents are named and numbered as above.
11. If the larger substituents at each end of the alkene are on opposite sides from each other, the alkene is (E). If they are on the same side, it is (Z).
Alkynes (pp. 562):
12. The alkyne functional group has priority over the alkene in naming, thus, an alkenyne. Numbering is done to give the smaller numbers, without preference for one or the other. In symmetrical situations, the alkene receives the lower number. Alcohols have priority over alkynes: thus, an alkynol
Sulfides and Thiols (p. 364):
13. Thiol takes priority over alkyl and halo, but not alcohol. The -SH group, if named as such, is "mercapto". Thioethers are named as alkylthio- compounds, and like halo substituents do not define C-1 of a chain.
14. Alcohols (pp. 286): The base is the longest chain containing the alcohol substituent. The chain is numbered from the end nearer the alcohol.
Cyclic alcohols are named cycloalkanol (e.g. "cyclohexanol"), with the carbon bearing the -OH being C-1.
Ketones (pp. 764-766):
15. Ketones take priority over other groups mentioned so far.
16. Ketones are named as alkanones. If some other group has taken priority, the ketone carbon is numbered and bears an "oxo" substituent
Nitriles (pp. 937)
17. Nitriles are named from the parent hydrocarbon: "pentanenitrile" . The nitrile carbon is by definition C-1 of the parent chain. The nitrile takes priority over other groups mentioned so far.
18. If it is not the dominant substituent, the nitrile group is named "cyano".
Aldehydes (pp. 764):
19. Aldehydes are named as alkanals. Cyclic aldehydes are named as "cycloalkanecarbaldehyde".
20. If some other group has taken priority, the aldehyde carbon is numbered and bears an "oxo" substituent .
Carboxylic acids (pp. 857-858):
21. Carboxylic acids are named as alkanoic acids. The carboxylic acid group takes precedence over all others. Diacids are alkanedioic acids.
22. Esters are named as alkyl alkanoates (p. 920). The point of ester attachment is C-1 of the alcohol chain. Amides are named as alkanamides (pp. 928).
23. Stereochemical descriptors: Absolute configuration comes before geometry, so "(2R,4S)-(7E)-". In printed form, the R,S and Z, E are italicized.