10.05.2006, 20:11 | #13 | ||||
Рег-ция: 28.11.2002 Адрес: Deutschland Сообщения: 2,182 Благодарности: 4 Поблагодарили 96 раз(а) в 62 сообщениях | Цитата:
Цитата:
Цитата:
Цитата:
L.A. MIKESKA, H. L. HAULER AND R. Q. ADAMS. [FORTY-THIRD CONTRIBUTION FROM THE COLOR LABORATORY OF THE BUREAU of CHEMISTRY.] SYNTHESIS OF PHOTOSENSITIZING DYES (II), DICYANINE A,1 BY Louis A. MIKESKA, HERBERT L. HALLER AND ELLIOT Q. ADAMS. Received September 9, 1920. The photosensitizing dyes (derived from quinoline) in use prior to 1919 were of 4 general types: isocyanin.es, e. g., piriaverdol, sensitizing to green and yellow; cyanines and pinacyanols, both sensitizing to orange and red; and dicyanines, which extend the sensitiveness of the plate to, or even beyond 9000 A. The dye of this last type which, from the point both of preparation and of use, we have found most satisfactory is that termed by the German manufacturers "Dicyanin A." We have prepared this dye by the action of sodium me'thylate (or ethylate) in absolute methyl (or ethyl) alcoholic solution, in the presence of air, on 2,4-dimethyl-6-ethoxy-quinoline ethnitrate, obtained by the action of silver nitrate on the ethiodide of the same base. The base is prepared from p-phenetidine by condensation with paraldehyde and acetone.2 The corresponding dicyanine A iodide is more difficult to use in the . plate-staining bath, but has somewhat better keeping qualities. Preparation of 2,4-dimethyl-6-ethoxy-quinoline. — A mixture of 300 g. of acetone and 200 g. of paraldehyde, cooled on ice, is saturated with hydrogen chloride. After standing at o° for 2 hours, the saturation is repeated, the mixture removed from the ice-bath and allowed to stand at room temperature for 20 hours. It is then added slowly to a solution of 300 g. of phenetidine in 600 g. of cone, hydrochloric acid (sp. gr. 1.2). The mixture, in a flask attached to a reflux condenser, is heated in a water-bath for 2 hours, then it is cooled, neutralized with a concentrated solution of sodium hydroxide, and extracted with ether. The ether extract is dried with anhydrous sodium sulfate, the ether removed by distillation and the residue distilled under reduced pressure. To the distillate is added. an equal weight of acetic anhydride; this mixture is heated on a steam-bath for half an hour and poured into water, The phenacetine, and mi-changed anhydride are removed by filtration, the filtrate neutralized with a concentrated solution of sodium hydroxide, and extracted with ether; then the ether is removed and the residue distilled as before. The distillate is dissolved in twice its weight of cone, hydrochloric acid and a slight excess of sodium nitrate solution added at o. The solution is extracted with ether at o°, and the extract discarded. The diazo-compounds are... 1 The preparation of pinaverdol and pinacyanol has been described by L. E. Wise, E. Q. Adams, J. K. Stewart and C. H. Lund. J. Ind. Eng. Chem,, n, 460 (1919). 2 The preparation of 2,4-dimethyi-quinoline is described by L. A. Mikeska, J. K. Stewart and Louis E. Wise. J. Ind. Eng. Chem., 11, 456 (1919). | ||||
|