Phenols chromatographic properties

This reference documents the chromatographic properties of over 100 rubber-related amine and phenolic antioxidants, antiozonants, guanidines, accelerators, and amine hydrochlorides. This reference examined the chromatographic characteristics of the cited additives and, thus, did not characterize acmal polymers. 

The simple rule for the prediction of the possibility of GC analysis of organic compounds is based on the reference data of their boiling points. If any compound can be distilled without decomposition at the pressures from atmospheric to 0.01-0.1 torr, it can be subjected to GC analysis, at least on standard nonpolar polydi-methylsiloxane stationary phases. In accordance with this rule, most of the monofunctional —OH compounds (alcohols, phenols) and their S analogs (thiols, thiophenols, etc.) may be analyzed directly. The confirmation of chromatographic properties of any analytes must be not only verbal (at the binary level yes/no ) but also based on their GC Kovats retention indices as the most objective criteria for example ... 

Garci a-March, F.J., Ant6n-Fos, G.M., Perez-Gimenez, R, Salebert-Salvador, M.T., Cercos-del-Pozo, R.A. and De Julidn-Qrtiz, V. (1996). Prediction of Chromatographic Properties for a Group of Natural Phenolic Derivatives by Molecular Topology. J.Chromat., 719A, 45-51. 

A number of various derivatization reactions have been used, as shown in Table 14.25. The derivatization has been carried out as off-column or on-column derivatization, mostly in order to give morphine and related alkaloids with phenolic or alcoholic hydroxyl groups better gas chromatographic properties. Especially for quantitative determination of morphine in opium or biological material such derivatization was necessary. Street et al. found, however, that the problem of adsorption of a phenolic alkaloid, such as morphine, because of "active sites" on the solid support could be solved by deactivation of the solid support by treatment of it (diatomaceous earth) with benzoyl chloride in pyridine before coating it with the stationary phase. 

It is recommended that these reactions be conducted in the presence of bases without active hydrogen atoms (pyridine, triethyl amine, etc.). These basic media are necessary for the conversion of acidic by-products into non-volatile salts to protect the acid-sensitive analytes from decomposition and to avoid the appearance of extra peaks of by-products on the chromatograms. Exceptions are indicated by reagent/(H ). Phenols can be converted into Na salts before acylation. A large variety of anhydrides of perfluormated carboxylic acids are recommended for derivatization because of the favorable chromatographic properties of perfluoroacyl derivatives. 

In this section the thin-layer chromatographic properties of phenolic compounds as revealed by their / /Values are given. The first part covers essentially the substituted derivatives of monocyclic phenols, the second part is concerned with phenolic acids (with their derivatives), and the final one with more complex phenolic compounds such as phenolic glycosides, flavonoids, anthocyanins, lignan derivatives, phenolic steroids, cannabinoids, and other types. Some overlap between subsections is inevitable, but this feature serves incidentally to interrelate the thin-layer chromatographic properties of phenolic compounds as a whole. The material in the last section has been dealt with in other monographs (1), and more emphasis has been placed in this review on substituted phenols and phenolic acids and their simple derivatives. 

Alumina. The migration properties on alumina of a larger range of phenols and their derivatives have been detailed (35). Some of the most comprehensive work on the relation between molecular structure and thin-layer chromatographic properties has been carried out on various alumina systems (62,63). Alumina-calcium hydroxide layers (2 1) have been used for phenol separations (64). Thin-layer procedures have been studied generally by statistical methods (65). 

Selected examples of chromatographic properties of substituted phenols on... 

Alumina and cellulose. Although neither alumina nor cellulose was favored in early woik compared with silica gel G, classic studies of these two substances have been made with a very wide range of alkyl, nitro, and other substituted phenols (62,63,67). Table S lists the chromatographic properties of a number of halogenated phenols on alumina and on cellulose, the former obtained by the normal adsorption method and the latter by a reversed phase procedure. Alumina layers were prepared from column-grade neutral alumina (Brockmann activity I-II, 100-200 mesh) by crushing... 

Analytes that are not suitable candidates for electron capture can often be made so by suitable derivatization. Perfluoracyl, pentafluorobenzyl, pentafluorobenzoyl and nitrobenzyl derivatives are often used not only to increase the electron capture rate constants but also to enhance chromatographic properties. However, in contrast to electron capture gas chromatography, it is not sufficient that electron capture be facile in addition, ions characteristic of the analyte must be formed since ions characteristic only of the derivatizing agent leaves the identity of the analyte in question. This is illustrated by the data in Table 4 for derivatization of phenols, where it can be seen that the perfluoroacyl derivatives yield ions characteristic only of the derivatizing agent, whereas the pentafluorobenzyl and pentafluorobenzoyl derivatives yield ions characteristic of the analyte. Also... 

Phenolic compounds are important components of many fruits, vegetables, and beverages, to which they contribute to flavor, color, and sensory properties such as bitterness and astringency. Recent interest in functional foods and the medicinal use of phenolic compounds have also stimulated interest in their chromatographic separation. 

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