Prefixes numerical, multiplicative

Proportions of the various parts are expressed by Greek numerical prefixes but there are extremely important qualifications that mono (for unity) is usually omitted and that other numerical prefixes may also be omitted if no ambiguity results. Multiplicative numerical prefixes (bis, tris, tetrakis, etc,) are used when followed directly by another numerical prefix and may be used whenever ambiguity might otherwise be caused and prefixes may be delimited by parentheses to aid clarity further (examples are on pp. 28, 29). The terminal a of tetra, penta, etc., has normally been elided in English before another vowel in inorganic chemistry, but this is now expressly forbidden by the lUPAC 1965 revision. 

Nomenclature based on a parent term with an appended suffix accounts for most natural product names. However, as related compounds are identified, or even when a suffix has to denote multiple functional groups, a variety of modifying terms can be employed. For example, the common prefix nor- denotes the removal of a skeletal atom from the parent structure the loss of two or more skeletal atoms is indicated by combining an appropriate numerical prefix with nor- , e.g., dinor- , trinor- (Giles 1999). Table 1.2 lists additional examples of commonly encountered modifying terms. 

Use of multiplicative prefixes. The proportions of the constituents, be they mono-atomic or polyatomic, may be indicated by numerical prefixes (mono-, di-, tri-, tetra-, penta-. etc.) as detailed in [Table 1-3]. These precede the names they modify, joined... 

SECTION 24.3 The names of alkenes and alkynes are based on the longest continuous chain of carbon atoms that contains the multiple bond, and the location of the multiple bond is specified by a numerical prefix. Alkenes exhibit not only structural isomerism but geometric (cis-tmiis) isomerism as well. In geometric isomers the bonds are the same, but the molecules have different geometries. Geometric isomerism is possible in alkenes because rotation about the C=C double bond is restricted. 

The numbers of ligands are indicated by Greek numerical prefixes (di, tri, tetra, penta, hexa, etc.). Where these would create ambiguity, multiplicative prefixes (bis, tris, tetiakis, pentakis, hexakis, etc.) and brackets are used, e.g. bis(methylamine). 

There is also in Great Britain less tendency to use multiplicative prefixes (bis, tris, etc.) than in USA. Chemical Abstracts have a rigid rule that if any compound radical name is replicated the numeral prefix should be of the replicative type. Thus, bis(2 -chloroethyl)benzene and 3,4-bis(trichloromethyl)-l,6-hexanediol would be prescribed. In Great Britain bis-2 -chloroethylbenzene or di-(2-chloroethyl)benzene would be considered sufficiently unambiguous. I ote also the omission of the prime (dash) after 2 in parentheses in British but not in American practice. 

Unsaturated acyclic hydrocarbons with double and/or triple bonds are generally designated as alkenes, alkynes, and alkenynes multiple unsaturation is indicated by the numerical prefixes di, tri, etc. alkatrienes, alkenediynes etc. 

Compound Units. It is usually recommended that only one prefix be used in forming a multiple of a compound unit, and that it should be attached to the numerator. An exception is the base unit kilogram, where it appears in the denominator. Multiples of kilogram are formed by attaching the prefix to the word gram (g). Compound prefixes are not used eg, 1 pF is correct, not 1 )J.)J.F. 

Metallocene derivatives may be named by either standard organic suffix (functional)7 or prefix nomenclature. Substituents are given the lowest numerical locants in the usual manner on the equivalent cyclopentadienyl rings of the ocene entity. The first ring is numbered 1 to 5 and the second ring is numbered V to 5. In metallocenes composed of multiple ocene groupings the cyclopentadienyl rings are further numbered 1" to 5", V" to 5", etc. The radical names -ocenyl, -ocenediyl, -ocenetriyl, etc. are used. For examples see Table 25. 

Wherever possible, every value and every uncertainty that is cited in a protocol or quoted in the implementation of a protocol shall be expressed in a unit of the SI (with or without prefix) associated with a number commonly called the numerical value [5], Thus, the value and its uncertainty are multiples or fractions of that SI unit. If an SI unit for the relevant quantity is not in... 

Mathematical operations have specific rules for the use of mathematical symbols with SI units. A space or a half-high dot represents the multiplication of units a negative exponent, horizontal line, or slash represents the division of units, and if these mathematical symbols appear in the same line, parentheses must differentiate them. The percent sign (%) denotes the number 0.01 or 1/100, so that 1%= 0.01, 30% = 0.30, and so forth. Arabic numerals with the appropriate SI or recognized unit indicate the values of quantities. Commas are not used to separate numbers into groups of three. If more than four digits appear on either side of the decimal point, a space Table 3. Prefixes. separates the groups of three. 

Parentheses are placed around prefixes defining substituted substituents and after the numerical multiplicative prefixes... 

Note Any of these prefixes may be combined with any of the symbols permitted within the SI. Thus, kPa and GPa will both be common combinations in measurements of pressure, as will mL and cm for measurements of volume and length, respectively. As a general rule, however, the prefix chosen should be 10 raised to that multiple of 3 that will bring the numerical value of the quantity to a positive value less than 1000. 

Ligands in polynuclear complexes are cited in alphabetical order both in formulae and names. The number of each ligand is specified by subscript numerical multipliers in formulae (Sections IR-9.2.3.1 to IR-9.2.3.4) and by appropriate multiplicative prefixes in names (Sections IR-9.2.2.1 to IR-9.2.2.3). The number of central atoms of a given kind, if greater than one, is indicated similarly. 

Decimal Multiples and Submultiples of SI Units In practical application of SI units, certain values are too large or too small to be expressed conveniently in the base or derived units. Numerical values can be brought to convenient size when the unit is appropriately modified by official SI prefixes. In general the prefixes are such that the value of the unit changes 1000-fold. However, certain common previously accepted multiples or sub multiples, such as deci- and hecto-, are still accepted in the SI framework. The SI prefixes are listed in Table 1-5 together with their symbols. 

Table 5 gives the SI prefixes that are used to form decimal multiples and submultiples of SI units. They allow very large or very small numerical values to be avoided. A prefix attaches directly to the name of a unit, and a prefix symbol attaches directly to the symbol for a unit. For example, one kilometer, symbol 1 km, is equal to one thousand meters, symbol 1000 m or 10 m. When prefixes are attached to SI units, the units so formed are called "multiples and submultiples of SI units in order to distinguish them from the coherent system of SI units. 

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