Chemical examination of the leaves of Rhododendron nilagiricum Zenk.

The examination of the leaves of Rhododendron nilagiricum Zenk. by extraction with solvents is described. Ursolic acid, epifriedelinol and hyperoside have been isolated and characterized

Crystalline chemical components of the flowers of Rhododendron nilagiricum Zenk.

The flowers of Rhododendron nilagiricum Zenk. have been examined for their crystalline components by extraction with organic solvents and fractionation along usual lines. Quercitrin and ursolic acid could be isolated as such and quercetin after hydrolysis of one of the crude fractions

Polyphenols from the stem bark of Rhododendron grande Wight

Taxifolin (a dihydro flavonol) and a procyanidin have been isolated from the stem bark of Rhododendron grande Wight. It is of special interest that they represent neighbouring stages in the biogenetic evolution of polyphenols. The procyanidin occurs as a dimer for which probable structures are proposed based upon chemical and spectral evidence. This dimer represents a new type

Colorimetric estimation of boric acid with pentamethylquercetin

A new method for the approximate colorimetric estimation of boric acid depending on the yellow colouration yielded by boric acid with pentamethyl-quercetin in presence of citric acid in anhydrous acetone medium has been described. The method is empirical in character and gives results with a maximum error of about 15% with quantities of boric acid ranging from 0·4 to 1·8 mg

Constitution of coumarinopyrones derived from 7-hydroxy- coumarins

When umbelliferon condenses with malic acid two isomeric compounds are formed. The angular coumarino-7:8-α-pyrone is the major product (95%) and its constitution is established from its preparation from umbelliferon-8-aldehyde by the Perkin's reaction. The second compound which should be the linear coumarino-7:6-α-pyrone is formed in a very small yield only (5%). Under the same conditions 4-methylumbelliferon produces only one compound whose constitution as 4-methylcoumarino-7:8-α-pyrone is arrived at from its independent synthesis from 4-methylumbelliferon-8-aldehyde. The constitution of this aldehyde is deduced not only from analogy but also from its reduction to 4:8-dimethyl-7-hydroxycoumarin which has been prepared from 2-methylresorcinol and ethylacetoacetate. 4-Methylumbelliferon and ethylacetoacetate also give only one compound which is given the constitution 4:4'-dimethylcoumarino-7:8-α-pyrone. This compound has been found to be produced in good yield from resorcinol and ethylacetoacetate in the presence of alcoholic hydrogen chloride. It is concluded that the angular isomer is the one invariably and most predominantly formed though the formation of the linear variety is not altogether precluded

Chemistry of Pongamol- Part I

Pongamol, which is the second important crystalline component of the pongamia oil, has the molecular formula C18H14O4 and contains a methoxyl group. It has also a phenolic or enolic hydroxyl group. Demethylation with aluminium chloride yields nor-pongamol whereas treatment with hydriodic acid gives rise to a product which is probably isomeric but does not possess phenolic properties. Treatment with bromine produces a tetrabromo derivative which on boiling with acetone yields a tribromo compound. Oxidation with potassium permanganate or decomposition with alkali yields benzoic acid. From these properties and from colour reactions it is suggested that pongamol is a flavone derivative containing a hydroxyl, a methoxyl and an ethylene double bond

Constitution of vogeletin: the pigment from the seeds of Tephrosia vogelii Hook.

The constitution of the pigment isolated from the seeds of Tephrosia vogelii Hook. (now designated as vogeletin) has been established, by a study of its derivatives and by chemical degradation, as 5-methoxy-3, 6, 7, 4'-tetrahydroxyflavone

3-Benzoyl-7-hydroxyflavone

3-Benzoyl-7-hydroxyflavone has been prepared and its properties have been studied

Constitution of kanugin- Part I

By the oxidation of kanugin with potassium permanganate in acetone solution 4-o-methylresorcylic acid (I) and a neutral compound (II) containing methoxyl groups and having the formula C7H8O2 or C11H14O3 have been obtained. Hydrolysis with alcoholic alkali yielded an acid which seemed to be impure (I). The presence of a resorcinol unit in the molecule seemed to be thus established. Demethylation of kanugin gave rise to nor-kanugin. It had the properties of a flavonol (C16H12O7) and gave bright colours in alkaline buffer solutions. When its crystalline acetate was methylated a new methyl ether which was different from kanugin was produced. It was therefore concluded that by the action of hydriodic acid, besides demethylation some other changes were brought about

Anthoxanthin pigments of the leaves of Digitalis lanata Ehrh. and the constitution of a new pigment dinatin

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