IUPAC numerical multiplier

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-
1000000	mega-	1000000000	giga
1000000000000	tera-	1000000000000000	peta

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.

Compound affixes[]

The prefixes are given from the least significant decimal digit up: units, then tens, then hundreds, then thousands. For example:

548 → octa- (8) + tetraconta- (40) + pentacta- (500) = octatetracontapentacta-

9267 → hepta- (7) + hexaconta- (60) + dicta- (200) + nonalia- (9000) = heptahexacontadictanonalia-

The numeral one[]

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

241 → hen- (1) + tetraconta- (40) + dicta- (200) = hentetracontadicta-

411 → undeca- (11) + tetracta- (400) = undecatetracta-

The numeral two[]

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-).

Icosa- v. eicosa-[]

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-.

Other numerical prefix types[]

There are two more types of numerical prefixes in IUPAC organic chemistry nomenclature.^[1]

Numerical terms for compound or complex features[]

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.

Multiplicative prefixes for naming assemblies of identical units[]

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]}

Examples are biphenyl or terphenyl.

Etymology[]

"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).

Notes and references[]

Panico, R. & Powell, W. H., eds. (1994). A Guide to IUPAC Nomenclature of Organic Compounds 1993. Oxford: Blackwell Science. ISBN 0-632-03488-2.

^ IUPAC Blue Book, 2013

[1] IUPAC Blue Book, 2013

[1]