Subtractive nomenclature

This nomenclature type uses substractive prefixes to indicate removal of atoms or groups of atoms from a trivially or systematically named parent structure. While additive nomenclature is used above all for hydrogenated cyclic systems, subtractive nomenclature focuses primarily on the opposite phenomenon, i. e. introduction of unsaturation. This has already been dealt with extensively in the discussions relating to hydrocarbon systems, where the terminal syllables. .. ene and. ..yne signify loss of two and four hydrogen atoms with concomitant formation of a double and triple bond, respectively. A more explicit symbolization of dehydrogenation in the guise of a subtractive prefix is particularly recommendable for certain natural products of the steroid and carbohydrate series as well as for dehy-droarenes (less precisely also named arynes) and dehydroannulenes. 

Also restricted mainly to complex and/or trivially named natural products (e.g. alkaloids) remains a method for indicating replacement of N-methyl groups by hydrogen with the prefix de... 

Similar limitations apply for the specification of an analogous replacement of hydroxy groups by hydrogen, as occurs frequently in carbohydrate chemistry. 

Several compound classes obtainable by dehydration of appropriate precursors have subtractive class names anhydrides, lactones, sultams, etc. The prefix anhydro for indicating removal of water from two hydroxy groups is again mainly used for carbohydrates (see Chapter 5). 

Special conventions apply for the use of the prefix nor. another manifestation of subtractive terminology. In the terpene series, nor-com-pounds are those which have undergone replacement of all methyl groups on a ring by hydrogen atoms (see Appendix, Table 21). For steroids (Appendix, Table 22) nor... means first of all loss of a CH2 group from a chain and, in a second sense, ring contraction with the expulsion of one CH2 unit, i. e. the opposite of homo. 

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Other minor systems are also in use. Some are traditional, and some are very restricted in their application. These include acid nomenclature (inorganic, for oxoacids and derivatives), replacement nomenclature (mainly organic, to denote replacement of skeletal atoms in a parent rather than replacement of hydrogen atoms — oxa-aza replacement is one variant), functional class nomenclature (this is again principally organic and involves the use of type names such as alcohol, acid and ether) and subtractive nomenclatures (such as organic-deoxy and inorganic-debor). These will all be referred to briefly as appropriate. 

For example, substitution can be made on an oxygen atom in the case of esters and ethers. It is characterised by the symbol O, which is placed after the locant. The compound prefix deoxy- is composed of the prefixes de-, meaning without in subtractive nomenclature, and oxy-, to indicate the subtraction of an oxy group from an -OH group C-O-H C-H. Such an operation is needed when an -OH group is replaced by another group, such as an amino group. 

Gottlieb O R, Kaplan MAC 1986 Replacement-nodal-subtractive nomenclature and codes of chemical compounds. J Chem Inf Comp Sci 26 1-3... 

If you ever have to interconvert between these two nomenclatures, it may be easier for you to write down a representation of the structure rather than to try to figure out the relationships between the length, number of double bonds, and how you add and subtract what to get whatever. 

Current IUPAC and Chemical Abstracts nomenclature has been employed in this index with the former given preference. Substitutive nomenclature has been given preference over radicofunc-tional, additive, subtractive, conjunctive or replacement nomenclature, except where this becomes unwieldy. With many bicyclic and polycyclic compounds bearing heteroatoms, standard bicyclic or polycyclic oxa, aza, and thia replacement nomenclature has often been used. With certain functional groups, where the names are rather complex and probably not familiar to most organic chemists, such as ylides, those compounds have simply been named as sulfur, tellurium and arsonic ylides. Metal catbenes have been treated similarly. With more complex functionality and many heterocycles, the Beilstein Commander Crossfire nomenclature system has been used with certain modifications. 

What about static leg It must be added to Eq. (6.14) AP If the flowing fluid elevation rises, then the AP of static leg APs will be a negative number to be subtracted from AP On the other hand, if the flowing fluid has a falling elevation sum, pipe start to pipe termination, APs will be a positive addition to AP. Equation (6.7) is to be applied again, but here with slightly different nomenclature, making Eq. (6.15) ... 

Subtractive. Loss of certain atoms or groups from a parent structure, e.g., A-demethylnitidine. Relatively common in natural product nomenclature, rare in mainstream organic chemistry. 

This correspondence between facts, ideas, and words would allow Lavoisier to formulate a chemical algebra or embryonic chemical equations. Insofar as each chemical substance was designated by a unique idea and a unique word, chemists could trace their operations as an algebra of these words. The definition of elements as the limit of chemical analysis provided the first step in this chemical algebra. Each substance that was stabilized in analytic practice would be given a unique identity and a unique name. Their combination would be reflected in the name of the compound in the same way that the name of a neutral salt was given in terms of its acid and alkali. Ideally, chemical nomenclature should be designed so that the addition or subtraction of chemical substances would be reflected exactly in the name. 

Subtractive operations are also regarded as part of the machinery of substitutive nomenclature. 

The lUPAC-IUB Combined Commission on Biochemical Nomenclature has promulgated two sets of abbreviations and symbols for nucleotides and related compounds. While these are suited for description of polynucleotides, the distinction between bases and nucleosides is not always immediately obvious and this distracts from their pedagogical use. The abbreviations used here are, we feel, intuitively obvious and well suited to the portrayal of reaction schemes in which the addition or subtraction of groups occurs. 

The cell voltage Tceii is obtained by calculating the Nernst voltage liNemst and subtracting the losses caused by ohmic resistance R, activation overpotential tjact. and mass transport limitations t trans- The nomenclature follows that used in Section 29.2 (see Table 29.2). The following assumptions were made in order to discuss a very simple model ... 

Out of the specific necessities of steroid nomenclature another highly useful subtractive descriptor came into being, namely, cyclo..., for designating an additional direkt link between any non vicinal C atoms of a parent structure with concomitant loss of two H atoms. 

Another very specific subtractive naming mode has been developed for cyclic compounds containing (if only formal) contiguous double bonds -cyclic cumulenes - whose treatment with conventional nomenclatural means would often lead to rather cumbersome combinations of ene , dehydro , and indicated H notations. 

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