Physical Properties of the Aminoazobenzene Dyes. VII. Absorption Spectra of 4-Aminoazobenzene Dyes in Ethanol1

1957 ◽  
Vol 22 (8) ◽  
pp. 915-919 ◽  
Author(s):  
EUGENE SAWICKI
Keyword(s):  
Physical Properties ◽  
Absorption Spectra

scholarly journals Absorption spectra of pyrone derivatives in the near infra-red

1926 ◽  
Vol 113 (763) ◽  
pp. 208-220 ◽  
Keyword(s):  
Oxygen Atom ◽  
Physical Properties ◽  
Absorption Spectra ◽  
Considerable Importance ◽  
Ketonic Group ◽  
Infra Red ◽  
High Result

The question of the constitution of pyrone compounds is of considerable importance, because many interesting pyrone derivatives are found in the vegetable world. Examples of these are the colouring matters such as chrysin and fisetin, acids such as meconic and chelidonic, and perfumes such as coumarin. Some of these pyrone compounds possess the rare property amongst oxygen compounds of being basic, forming salts with acids, the oxygen atom being presumably quadrivalent. The chemical and physical properties of pyrone compounds are, however, entirely at variance with those predicted by the accepted formulae. Dimethyl pyrone is assigned the following structure:— CO / H—C C—H ║ ║ CH 3 —C C—CH 3 / O Nevertheless, the ketonic group does not react with hydroxylamine or phenylhydrazine. It also should be unsaturated, but is unacted on by nascant hydrogen. The molecular refractivity also does not agree with the above formula, for it is found to be 35·34, the calculated figure for the above formula being 33·30. Numerous other pyrone compounds give a similar high result.

scholarly journals Studies on pigments of the myxomycete Physarum nudum. II. Separation and optical properties of the pigments from plasmodia cultured in darkness

2015 ◽  
Vol 41 (3) ◽  
pp. 411-423
Author(s):  
L. Raczkowski
Keyword(s):  
Optical Properties ◽  
Acid Solution ◽  
Thin Layer ◽  
Physical Properties ◽  
Thin Layer Chromatography ◽  
Absorption Spectra ◽  
Fluorescence Emission ◽  
Dark Pigment ◽  
Rf Values ◽  
Layer Chromatography

The paper presents the data on Separation and some optical properties of the pigments obtained from the plasmodium of the myxomycete <i>Physarum nudum</i> grown in the dark. Pigment Separation was performed by means of thin-layer chromatography with celulose MN 300 as adsorbent and with the solvent: tert.-butylalcohol, H<sub>2</sub>O, 3N NH<sub>4</sub>OH at the ratio 5:2:1 In these conditions the chromatograms revealed 12 coloured bands from which pigments were eluted and their absorption spectra as well as the spectra of fluorescence emission were determined. The isolated pigments differ from one another by their physical properties (different Rf values, localization of absorption maxima, and behaviour in acid solution). Nevertheless, certain analogies perceptible between particular pigments per-mitted to distinguish 3 families of the studied pigments demonstrating similar properties.

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