Compound classes

Specinfo has an additional tool for calculating NMR spectra that is based on the data sets of the compounds contained in the database. This leads to quite reliable calculated spectral parameters for the compound classes which are registered in the database. 

Compound class or type of proton Chemical shift (5) ppm ... 

Generic name CAS Registry Number Compound class Molecular formula Trade name Producer Use... 

Phenols as a compound class are readily oxidi2ed by potassium permanganate and, if sufficient oxidant is added, phenol (qv) can be completely oxidi2ed into carbon dioxide and water. 

Fig. 4. Distribution of compound classes in cmde oils as a function of boiling point. Region A represents normal paraffins B, isoparaffins C, naphthenes ...

Chemical antiozonants comprise the second general class of commercial antiozonants. Of the many compounds reported to be chemical antiozonants, nearly all contain nitrogen. Compound classes include derivatives of l,2-dihydro-2,2,4-trimethylquinoline, A/-substituted ureas or thioureas, substituted pyrroles, and nickel or zinc dithiocarbamate salts (see also Antioxidants). The most effective antiozonants, however, are derivatives of -phenylenediamine... 

Temperature reaction rate profiles for representatives compounds are available (21,26). Particularly important are the operating temperatures required before destmction is initiated. Chemical reactivity by compound class from high to low is (27) alcohols > cellsolves/dioxane... 

Expectorants enhance the production of respiratory tract fluid and thus faciUtate the mobilisation and discharge of bronchial secretions. Historically, expectorants have been divided iato two classes based on specific mechanisms of action. Stimulant expectorants iacrease respiratory tract secretion by a direct effect on the bronchial secretory cells. Sedative expectorants act by gastric reflex stimulation. Many compounds classed as expectorants have been iaadequately studied and the mechanisms of action are not known with certainty. 

The nomenclature of penicillins requires special comment. Compound (2) can be named as follows (a) penicillin G (b) benzylpenicillin (note that the term penicillin may refer to the compound class (1), to the structural fragment (3) or, especially in the medical literature, to compound (2) itself) (c) 6/3-phenylacetamidopenicillanic acid (d) 2,2-dimethyl-6/3-phenylacetamidopenam-3a -carboxylic acid (e) (2S,5i ,6i )-3,3-di-methyl-7-oxo-6-(2-phenylacetamido)-4-thia-l-azabicyclo[3.2.0]heptane-2-carboxylic acid and (f) [2S-(2a,5a,6/3)]-3,3-dimethyl-7-oxo-6-[(phenylacetyl)amino]-4-thia-l-azabicyclo-[3.2.0]heptane-2-carboxylic acid. The numbered system shown in (2) is the one most commonly used in the penicillin literature and will be used in this chapter note that different number is used when (2) is named according to (e) and (f) above. 

Values of a, h, c, and m for various compound classes are found in Table 2-399. Average errors are about 8 percent. 

TABLE 2-399 Values of Constant Parameters in Eq. (2-142) for Various Compound Classes... 

The final chapter in this volume is authored by O. N. Chupakhin and D. N. Kozhevnikov (Ekaterinburg, Russia) and deals with 1,2,4-triazines N-oxides, an interesting compound class, which has not previously been reviewed comprehensively. 

With comprehensive GC, we can now choose a rational set of columns that should be able to tune the separation. If we accept that each column has an approximate isovolatility property at the time when solutes are transferred from one column to the other, then separation on the second column will largely arise due to the selective phase interactions. We need only then select a second column that is able to resolve the compound classes of interest, such as a phase that separates aromatic from aliphatic compounds. If it can also separate normal and isoalkanes from cyclic alkanes, then we should be able to achieve second-dimension resolution of all major classes of compounds in petroleum samples. A useful column set is a low polarity 5 % phenyl polysiloxane first column, coupled to a higher phenyl-substituted polysiloxane, such as a 50 % phenyl-type phase. The latter column has the ability to selectively retain aromatic components. 

Lack of recognition of a number of important compound classes 10 Preparative amounts of template required... 

In a contribution dealing with two related compound classes, space could be saved by treating them together in domains where they display close similarities. However, the only spheres where this applies to sulphones and sulphoxides are elemental sulphur determination and chromatography. The former is too unspecific to be considered for inclusion in this chapter. Chromatographic behaviour is determined by the whole molecule, but the widespread use of chromatographic methods does justify its treatment. At the risk of a very little duplication it has been deemed more suitable to provide separate accounts of the two compound classes. 

Some publications have described studies of sulphones together with representatives of other compound classes, such as sulphoxides, sulphides and ethers. As a rule only those are mentioned in which sulphone examples make up at least about one quarter of the total. 

In general, the publications cited here pertain to methods valid for several sulphoxides, even though some other compound classes may have been studied at the same time. However, many methods for dimethyl sulphoxide alone are also given on account of the considerable current importance of this compound. 

The Ley group also investigated the PS-base/tosyl chloride methodology developed by Brain (see above. Scheme 8) for the synthesis of 2-aminooxadiazoles from semicarbazides, especially with a view to directly synthesize 2-aminosulfonamide substituted 1,3,4-oxadiazoles, a compound class of interest for agrochemical and pharmaceutical apphcations (Scheme 10) [71]. In this case, the choice of the supported base was crucial for the result of the reaction weak bases (PS-DIEA, PS-NMM) could still afford the cyclized 2-aminooxadiazole product, but could not efficiently... 

A compound index constructed by these principles tells whether a given compound is present. It cannot provide information about compound classes, for example, all aluminum derivatives or all compounds containing phosphorus. 

The subject index provides access to the text by way of methods, techniques, reaction types, apparatus, effects and other phenomena. Also, it lists compound classes such as organotin compounds or rare-earth hydrides which cannot be expressed by the empirical formulas of the compound index. 

Compound (class, n° of group) Pvap experimental Pvap estimated... 

Betalains consist of two groups of pigments of similar structure, the yellow compounds classed as betaxanthins and the purple as betacyanins [14]. Both groups contain a betalamic acid residue coupled to an amine or an amino acid to form an iminium salt. Whereas the amino components of the betaxanthins vary considerably. 

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