Number | Multiplier | Number | Multiplier |
---|---|---|---|
1 | mono- | 32 | dotriaconta- |
2 | di- | 40 | tetraconta- |
3 | tri- | 50 | pentaconta- |
4 | tetra- | 60 | hexaconta- |
5 | penta- | 70 | heptaconta- |
6 | hexa- | 80 | octaconta- |
7 | hepta- | 90 | nonaconta- |
8 | octa- | 100 | hecta- |
9 | nona- | 200 | dicta- |
10 | deca- | 300 | tricta- |
11 | undeca- | 400 | tetracta- |
12 | dodeca- | 500 | pentacta- |
13 | trideca- | 600 | hexacta- |
14 | tetradeca- | 700 | heptacta- |
15 | pentadeca- | 800 | octacta- |
16 | hexadeca- | 900 | nonacta- |
17 | heptadeca- | 1000 | kilia- |
18 | octadeca- | 2000 | dilia- |
19 | nonadeca- | 3000 | trilia- |
20 | icosa- | 4000 | tetralia- |
21 | henicosa- | 5000 | pentalia- |
22 | docosa- | 6000 | hexalia- |
23 | tricosa- | 7000 | heptalia- |
30 | triaconta- | 8000 | octalia- |
31 | hentriaconta- | 9000 | nonalia- |
The numerical multiplier (or multiplying affix) in IUPAC nomenclature indicates how many particular atoms or functional groups are attached at a particular point in a molecule. The affixes are derived from both Latin and Greek.
The prefixes are given from the least significant decimal digit up: units, then tens, then hundreds, then thousands. For example:
While the use of the affix mono- is rarely necessary in organic chemistry, it is often essential in inorganic chemistry to avoid ambiguity: carbon oxide could refer to either carbon monoxide or carbon dioxide. In forming compound affixes, the numeral one is represented by the term hen- except when it forms part of the number eleven (undeca-): hence
In compound affixes, the numeral two is represented by do- except when it forms part of the numbers 20 (icosa-), 200 (dicta-) or 2000 (dilia-).
IUPAC prefers the spelling icosa- for the affix corresponding to the number twenty on the grounds of etymology. However both the Chemical Abstracts Service and the Beilstein database use the alternative spelling eicosa-.
There are two more types of numerical prefixes in IUPAC organic chemistry nomenclature.^{[1]}
Numerical prefixes for multiplication of compound or complex (as in complicated) features are created by adding kis to the basic numerical prefix, with the exception of numbers 2 and 3, which are bis- and tris-, respectively.
Number | Multiplier |
---|---|
2 | bis- |
3 | tris- |
4 | tetrakis- |
... |
An example is the IUPAC name for DDT.
Number | Multiplier |
---|---|
5 | quinque- |
6 | sexi- |
7 | septi- |
8 | octi- |
9 | novi- |
10 | deci- |
11–9999 | Ending "a" in the basic numerical prefix is replaced with "i", and/or "deka" is replaced with "deci".^{[citation needed]} |
"mono-" is from Greek monos = "alone". "un" = 1 and "nona-" = 9 are from Latin. The others are derived from Greek numbers.
The forms 100 and upwards are not correct Greek. In Ancient Greek, hekaton = 100, diakosioi = 200, triakosioi = 300, etc. The numbers 200-900 would be confused easily with 22 to 29 if they were used in chemistry. khīlioi = 1000, diskhīlioi = 2000, triskhīlioi = 3000, etc., and 13 to 19 are treiskaideka etc. with the Greek for "and"inserted (as in triskaidekaphobia).