S prefix

Step 3 A propyl group is attached to the nitrogen atom. Thus, the compound s prefix is N-propyl-. 

When a compound has several substituents, list the substituents in alphabetical order disregarding the presence of N, O or S prefixes and the descriptors sec-, tert-, cis- and trans- but see rule 2.5 below. 

Compounds that contain an asymmetric substitutions on a carbon atoms exist in enantiomorphic forms. These differ only in the direction of rotation of polarized light. When the absolute configuration has been identified in the original report, these compounds are identified by (R)- and (S)- prefixes. Sometimes prefixes such as d-, /-, (+)-, and (-)-, which are given in the original report have been used. Very often no identification of the optical isomer is given even when the compound contains an asymmetric carbon atom Then it is assumed that the samples are racemic mixtures. However, none of these distinctions affect the densities of liquids, therefore all the isomers of this type are combined to determined the recommended values. If a compound contains more than one asymmetric carbon atom diasteieomers can exist. In principle, these might have different densities, but no examples have been found. 

Again, the name of the compound (BOM) is from the RBO-S prefix of this family (from benzyl + oxy), plus the RMS of mescaline (which has provided the ring substitution pattern). 

In comparison, a simplified nomenclature for the flavan-3,4-diols (Fig. 7.6.1, 18 21) is not necessary. The hydroxylation patterns of these compounds are readily recognized from their common names guibourtacacidins (18, 7,4 -dihy-droxy), mollisacacidins (19, 7,3, 4 -trihydroxy), robinetinidins (20, 7,3, 4, 5 -tetra-hydroxy), leucocyanidins (21, 5,7,3, 4 -tetrahydroxy), teracacidins (7,8,4 -trihy-droxy), and melacacidins (7,8,3, 4 -tetrahydroxy). Because only three chiral centers need to be defined, their absolute stereochemistry is readily denoted through use of the Rox S prefix. This is clearly preferable to the use of common names. For example, 2/ ,3S,4/ -mollisacacidin has been variously named (+)-mollisacacidin, (+)-gleditsin and (+)-leucofisetinidin (377). Use of the R and 5 prefix to define the absolute stereochemistry of these compounds avoids the considerable confusion that has occurred with the informal nomenclature used in the past. 

No relationship exists between the R and S prefixes that designate configuration and the (h-) and (-) designations indicating optical rotation. For example, the S enantiomer of lactic acid is dextrorotatory (H-), whereas the S enantiomer of glyceraldehyde is levorotatory (-). 

Note that only in the last two cases must the cis/trans nature of the cyanide ligands be specified. In the first three cases, they have to be trans, cis, and cis, respectively. Why must this be so The answer comes down to the fact alluded to earlier That once one pair of ligands is cis in this coordination sphere, there must always be another cis pair. To see why this is so, take the second case, shown in general in Figure 3.7b, as an example. Note that once the A s are specified to be trans and the B s to be cis, the C ligands (CN in our specific compound) are required to be cis. In the last two cases in which both the A s and B s are cis, however, the C s could be either trans as shown in case 4 or cis as in case 5. The last geometric isomer, the cis-cis-cis case, is chiral, and so the R/S- prefix must be added to indicate the existence of optical isomers. Compounds of this type are difficult to resolve into enantiomers this latter compound was in fact not resolved until 1979. 

Table l.S Prefixes Commonly Used to Designate Multiples of Units... 

The prefix sila- designates replacement of carbon by silicon in replacement nomenclature. Prefix names for radicals are formed analogously to those for the corresponding carbon-containing compounds. Thus silyl is used for SiH3—, silyene for —SiH2—, silylidyne for —SiH<, as well as trily, tetrayl, and so on for free valences(s) on ring structures. 

Bivalent Sulfur. The prefix thio, placed before an affix that denotes the oxygen-containing group or an oxygen atom, implies the replacement of that oxygen by sulfur. Thus the suffix -thiol denotes — SH, -thione denotes —(C)=S and implies the presence of an =S at a nonterminal carbon atom, -thioic acid denotes [(C)=S]OH [(C)=0]SH (that is, the O-substituted acid and the 5-substi-... 

The prefix thioxo- is used for naming =S in a thioketone. Sulfur analogs of acetals are named as alkylthio- or arylthio-. For example, CH3CH(SCH3)OCH3 is l-methoxy-l-(methylthio)ethane. Prefix forms for -carbothioic acids are hydroxy(thiocarbonyl)- when referring to the O-substituted acid and mercapto(carbonyl)- for the S-substituted acid. 

Salts are formed as with oxygen-containing compounds. For example, C2H5 — S—Na is named either sodium ethanethiolate or sodium ethyl sulfide. If mercapto- has been used as a prefix, the salt is named by use of the prefix sulfido- for —S . 

Sulfonium Compounds. Sulfonium compounds of the type R R R S X are named by citing in alphabetical order the radical names followed by -sulfonium and the name of the anion. For heterocyclic compounds, -ium is added to the name of the ring system. Replacement of > CH by sulfonium sulfur is denoted by the prefix thionia-, and the name of the anion is added at the end. 

Organosulfur Halides. When sulfur is directly linked only to an organic radical and to a halogen atom, the radical name is attached to the word sulfur and the name(s) and number of the halide(s) are stated as a separate word. Alternatively, the name can be formed from R—SOH, a sulfenic acid whose radical prefix is sulfenyl-. For example, CH3CH2—S — Br would be named either ethylsulfur monobromide or ethanesulfenyl bromide. When another principal group is present, a composite prefix is formed from the number and substitutive name(s) of the halogen atoms in front of the syllable thio. For example, BrS—COOH is (bromothio)formic acid. 

Prefix Abrasive type Grain size Grade Structure Bond type Manufacturer s record... 

The Stock Oxidation-Number System. Stock sought to correct many nomenclature difficulties by introducing Roman numerals in parentheses to indicate the state(s) of oxidation, eg, titanium(II) chloride for TiCl2, iron(II) oxide for FeO, titanium(III) chloride for TiCl, iron(III) oxide for Fe203, titanium(IV) chloride for TiCl, and iron(II,III) oxide for Fe O. In this system, only the termination -ate is used for anions, followed by Roman numerals in parentheses. Examples are potassium manganate(IV) for K2Mn02, potassium tetrachloroplatinate(II) for K PtCl, and sodium hexacyanoferrate(III) for Na3Fe(CN)3. Thus a set of prefixes and terminations becomes uimecessary. 

Specifications. Among the many specifications covering refractory products, the best known are those pubUshed by ASTM. In addition, specifications are issued by the U.S. Government and the armed forces. The former are generally preceded by the prefix HH and the later by the prefix MIL. The ASTM refractory specifications always suggest a use, whereas federal and military specifications are iaconsistent ia this respect. 

Both common and systematic names of compounds are used throughout this volume, depending on which the Editor-in-Chief feels is most appropriate. Preparations appear in the alphabetical order of names of the compound or names of the synthetic procedures. The Chemical Abstracts indexing name for each title compound, if it differs from the title name, is given as a subtitle. Because of the major shift to new systematic nomenclature adopted by Chemical Abstracts in 1972, many common names used in the text are immediately followed by the bracketed, new names. Whenever two names are concurrently in use, the carre CChemical Abstracts name is adopted. The prefix n- is deleted from -alkanes and w-alkyls. All reported dimensions are now expressed in S st me International units. 

The eight possible types of simply supported (prefix S) and clamped (prefix C) edge boundary conditions [combinations of the conditions in Equation (5.9)] are commonly classified as (see Almroth [5-6]) ... 

It is also possible to define spin restricted open shell models (keyword prefix RO). See he Gaussian User s Reference for more information. 

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