. Blumen-Zeitung. Floriculture -- Germany; Flower gardening -- Germany. 1^4 Plant Pigments [March, fere with color formation. Thus, diazomethane, CH2\ II is yel- low, but tolazone, ^ CH3 CH3 - \ / N N is but slightly colored. 0£ special interest is the influence that the position of the double bonds may have. Benzene, as has been pointed out, though color- less, shows absorption bands in the ultra-violet part of the spec- trum; fulvene, CH = CH. I >C = CH2 CH = CH' an isomer of benzene, with the same nuniber of double bonds, is yellow. The most important " auxochromes " are the am
. Blumen-Zeitung. Floriculture -- Germany; Flower gardening -- Germany. 1^4 Plant Pigments [March, fere with color formation. Thus, diazomethane, CH2\ II is yel- low, but tolazone, ^ CH3 CH3 - \ / N N is but slightly colored. 0£ special interest is the influence that the position of the double bonds may have. Benzene, as has been pointed out, though color- less, shows absorption bands in the ultra-violet part of the spec- trum; fulvene, CH = CH. I >C = CH2 CH = CH' an isomer of benzene, with the same nuniber of double bonds, is yellow. The most important " auxochromes " are the amino and hy- droxyl groups, of which the former is the stronger. The color is usually intensified by increasing the number of auxochromes, or, in the case of the amino group, by substituting aklyl and aryl rad- icles for the hydrogen atoms. On the other band, acetylating a hydroxyl group inhibits auxochromic action: O O. Fluoran (chromo- Fluorescein, Diacetyl fluorescein, gen), colorless brown colorless That the position of the " auxochrome " group may be of impor- tance is shown by contrasting quinolphthalein, O HO\A/\/OH which is colorless, with its isomer, fluorescein.^ c Hewitt: Chromophores and chromogens, Thorpe's Dict, of Applied Chem., 1912, ii, p. 59-. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Hssler, Friedrich. Weissensee, G. F. Grossmann [etc. ]
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