Phenol character

Hydroxy derivatives of type (503) show more phenolic character thus 4-hydroxy-isothiazoles are normally O-methylated and O-acylated (72AHC(14)l). 

The hydroxy-l-thia-2,4-diazole 125 is reported to exhibit phenolic character and to give a red color with ferric chloride. Infra-rediooa.142,143 ultraviolet spectral evidence indicates that 1-thia-3,4-diazoles of type 126 exist predominantly in an oxo form,... 

Hydroxy-l,2,4-thiadiazoles possess phenolic character they give red to purple colors with ferric chloride, and fail to afford ketonic derivatives.130,178 They resist the action of hot alkaline sodium plumbite.130 The 3-alkoxy homologs are neither alkali soluble nor give colors with ferric chloride.130... 

The colouring matter does not contain sulphur and Is of basic or phenolic character Inda mines, indophenols, oxasincs. 

Resinous amorphous, brown substances are also formed, and found in dinitro-and trinitro-naphthalenes. They are partly soluble in alkalis, hence the suggestion that they are of an acidic or phenolic character and come from products of oxidation of naphthalene. 

Pyro-catechinol, i-2-Di-hydro3iy Benzene.—The ortho-di-hydroxy benzene is known as pyro-catechinol or pyro-catechin. The first name is preferable as the termination ol indicates its phenol character. Its name also indicates its relation to a resin known as catechu, obtained from an acacia tree. On distillation it yields the phenol, the prefix pyro meaning heat. It is also present in the dry distillation products of wood, coal or bituminous shale. Various plant materials such as resins and the leaves of ampelopsis yield it by alkali fusion. It is also associated with phenol as a sulphuric acid ester in the urine of horses. 

The preferred solvent system used for the separation of flavonoids on reversed-phase stationary phases is methanol-water, followed closely by acetonitrile-water. Usually, acetic or formic acid is added (sometimes phosphoric acid, potassium dihydrogen phosphate, ammonium dihydrogen phosphate, and perchloric acid), which enables improved separation and prevention of peak tailing with respect to the phenolic character of the flavonoids. Ion pairing has also been used for improving the separation of neutral glycosides from flavonol sulfates. 

It was interesting to know how other chemisorbed elements affect the catalytic behavior of carbons. When carbons are heated in oxygen or air to 573 to 673 K, acidic surface oxides are formed [4,5]. In these surface oxides one finds carboxyl groups, lactones or lactols, and hydroxyl groups of phenolic character... 

The Volatile Phenols Responsible for Olfactory Defects in Wines Known Collectively as the Phenol Character... 

Barrels used Sulfuring method Bung position Free SO2 at racking S Ethyl-phenols (Egd) Phenol character (0-5)... 

Hydroxyl groups substituted at positions 2- and 4-(6-) of the pyrimidine nucleus exist mainly in the pyrimidone form [1-4]. The only true hydroxyl position on this ring system is position 5. This hydroxyl group is of phenolic character and all 5-hydroxypyrimidines give a positive (blue-violet coloration) test with ferric chloride. Because of the relative difficulty in synthesis of all but a few compounds, most 5-hydroxypyrimidines have not been extensively studied. 

S. is also cleaved on heating sesamolin. S. and sesaminol have antioxidant properties as a result of their phenolic character they thus contribute to the stability of sesame oil towards oxidation. - Color test S. forms a red pigment with furfural and hydrochloric acid in ethanol (Baudouin s reaction), which can be used to identify sesame oil in fats and oils... 

We have found that the action of nitrous acid on isobarbituric add (IV) leads to the formation of an isomer of violuric acid which we term iso-violuric acid (VI). Since the phenolic character of isobarbituric add has been established by its behavior toward acetic anhydride, hydroxylamine, hypobromous acid, diazomethane and potassium ferricyanide, it was anticipated that 5-hydroxy-6-nitrosouracil (V) would be obtained. The behavior of the product, however, indicated it to be the tautomeric form (VI) (alloxan-6-oxime). 

Properties Depending upon Their General Phenolic Character. 268... 

II. Pbofbbties op Flavonoid Compounds Significant in Foods 1, Properties Depending upon Their General Phenolic Character... 

In spite of their frequently brilliant color, it is not so much this property which is important in foods as their tendency to undergo dis-coloration. This is due to their general phenolic character which allows them to serve as effective substrates for oxidase action. They are, in fact, of all classes of phenolic substances, those most universally present in the plant kingdom. Seldom does the analysis of a plant extract fiul to reveal one or more substances of flavonoid character, and if these are absent, chlorogenic acid or one of the closely related coumarins is almost certain to be present. Thus the flavonoid compounds and coumarins are the most commonly available substrates, actual or potential, for polyphenol-oxidase or peroxidase activity. 

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