The constitutional features of anthoxanthins in relation to the morin reaction in analytical chemistry. Part I. Some naturally occurring hydroxy-flavonols and flavanones

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A new fluorescence reaction for the detection of boric acid

A new fluorescence reaction for the detection of boric acid with resacetophenone and phosphoric acid has been described. None of the metallic radicles examined interferes while among the acid radicles chromate, bromate, chlorate, nitrite and fluoride do so to a limited extent. The reaction compares favourably with those described in the literature both as regards limit of identification and also interference. It has been shown that the test is applicable for the detection of micro-quantities of boric acid

The lanthanum nitrate test for acetate in inorganic qualitative analysis

The lanthanum nitrate test for the acetate ion has been examined for use in the routine analysis of mixtures of inorganic substances including the acetate, oxalate and tartrate radicles. A distillation method for the preparation of the test solution and a modification of this procedure in the presence of sulphites and thiosulphates are described. The results obtained are quite satisfactory and the test is recommended for general use

Constitution of patuletin Part III. A study and synthesis of O-pentaethyl patuletin

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5-Hydroxy and methoxy flavylium salts

Starting from γ-resorcylic aldehyde some typical 5-hydroxy and methoxy flavylium salts have been prepared and studied. They exhibit negligible fluorescence even in concentrated sulphuric acid. The structural factors that affect fluorescence in flavylium salts are discussed and comparison effected with coumarins

Fluorescence reactions with boric acid and o-hydroxy-carbonyl compounds, and their application in analytical chemistry. Part II. Detection of aromatic compounds containing C, H and O only

1. Addition of boric acid to aromatic compounds (C, H, and O only) of various types containing the, dissolved in concentrated sulphuric acid generally produces a marked intensification or a change in colour of the fluorescence exhibited by them in daylight or under the lamp In several cases the solution of the compound in sulphuric acid is itself non-fluorescent and fluorescence appears on adding boric acid. 2. In a few cases even when this group is present no fluorescence effects are obtained with boric acid. 3. 3 : 7-Dihydroxy-flavone and its 7-methyl ether are exceptions in that they give positive reactions with boric acid even though the above group is absent. 4. The fluorescence effects obtained with boric acid could be utilised for the detection of the in various types of aromatic compounds containing carbon, hydrogen and oxygen only. A positive reaction indicates the presence of this group but the converse is not true. 5. This reaction is more general than all the others described in literature and is also easily carried out

Synthesis of 5 : 6-hydroxy-flavonols - Part III

The synthesis of 3 : 5 : 6 : 3': 4'-pentahydroxy-flavone was already reported. The lower members of this group of 5 : 6-hydroxy flavonols with one and no hydroxyl group in the side-phenyl nucleus have now been prepared by Kostanecki's method. The characteristic properties are described

Synthesis of 5 : 6-dihydroxyflavonols - Part I

Methyl ethers of 5 : 6-dihydroxy-chalkones and flavanones have been prepared. 2 : 5-Dihydroxy-6-methoxy acetophenone has been condensed with vanillin and 5 : 6-dimethoxy-2-hydroxy-acetophenone with veratric aldehyde and anisaldehyde; the resulting chalkones have been converted into the flavanones. In the above reactions mixtures of chalkones and flavanones result

Nuclear oxidation in flavones and related compounds. Part XXXVI. Oxidation of some hydroxy isoflavones

Using methods of nuclear oxidation 7 : 8-dihydroxy-2-methyl isoflavone, 5 : 7 : 8-trihydroxyisoflavone and 5 : 7 : 8-trihydroxy-2-methyl isoflavone and their derivatives have been prepared. Demethylation of the 5 : 7 : 8-trimethoxy isoflavones with or without a 2-methyl group does not produce isomeric change in the trihydroxy product. It could therefore be concluded that a phenyl group in the 3-position prevents this isomeric change just like a methoxyl (hydroxyl) in the same position and that substitution in the 2-position has no influence

6 : 7-Dihydroxy-flavonols - Part II

Starting from ω-methoxy-resacetophenone and adopting the procedure described in Part 1, 6 : 7-dihydroxy flavonols with 0, 1 and 3 hydroxyls in the side-phenyl nucleus have been prepared. The characteristic properties of the group with reference to the hydroxy-compounds and their partial and complete methyl ethers are described. An alternative method starting with hydroxy-quinol has also been investigated and the simplest member of the group prepared by this method also