With Tropaeolin

Perlmutter-Hayman and Shinar (15, 16) have studied by temperature-jump the reactions of bases with different acid-base indicators having intramolecular hydrogen bonds. With Tropaeolin 0, direct attack of the base on the hydrogen bridge predominates according to their interpretation, whereas, for Alizarin Yellow G, the observed relaxation is ascribed chiefly to diffusion controlled reaction between the base and that part of the indicator present in the open form. Thus, data exist that lead one to doubt the generality of statement number 5. 

Three drops of pure nonanoic acid, colored with Tropaeoline (to saturation) on the curved side of a watch glass, allows us to evaluate the mobilization of viscous substances during a washing operation. See the effect of a washing with tap water (flow rate 120 mL per minute). Water does not dilute the product but just pushes it off, making a ring around the point of impact (Fig. 4.3). 

Some modifications to the cyclodextrin structure have also been found to improve their complexing ability. Casu and coworkers prepared 2,3,6-tri-O-methyl and 2,6-di-O-methyl derivatives of alpha and beta cyclodextrin. They observed that tri-O-methyl-alpha cyclodextrin shows an almost ten-fold increased stability of the complex with the guest, Methyl Orange, compared with the unmodified alpha cyclodextrin. A possible reason for this increase in stability is that the methyl groups are responsible for an extension of the hydrophobic cavity of the cyclodextrin. Other workers,however, observed a much smaller enhancement of stability of complexes on methylation of the cyclodextrin, and a decrease in stability has even been reportedfor the one host-two guests complex of tropaeolin with beta cyclodextrin. Thus, the effect of methylation on the stability of a complex varies with the guest species involved, and cannot be readily predicted. 

The nitrated tropaeolines split off nitrous acid when dissolved in hot water and this acid attacks the copper equipment used by the dyers. There is a demand, therefore, for a nitrous acid-free azo yellow which is prepared in the following way. The freshly filtered azo yellow is heated to 90°C. with 4 parts of water, splitting off most of the nitrous and nitric acids. After about 3 hours, 5 per cent sodium bisulfite solution is added to remove the last traces of nitric acid. The mass gives off red fumes and foams strongly, so the process must be done in large vats. This treatment always results in a loss of 15 to 20 per cent of the dye. (See also azo fiavine FF, page 272). 

It is known also as helianthine and as tropaeolin D. It is not prepared by starting with amino azo benzene but with sulphanilic acid which is para-amino benzene sulphonic acid. This is diazotized and then coupled with di-methyl aniline yielding the azo compound. 

The colorimetric reaction of Tropaeolin 00 with alkaloids under acidic conditions is used for microquantitation of alkaloids (Haussler 84) ... 

The aqueous solution of an alkaloid (5 ml) (containing 100 pg) is mixed with a similar quantity of an acetic buffer (pH 4.6) and 3 ml of a saturated aqueous Tropaeolin 00. The resulting mixture is then extracted with chloroform (4x5 ml). The combined extracts are acidified with 2 ml of an acid reagent (1 ml concentrated HzSO4 and 99 ml methanol) and diluted to 25 ml with chloroform. The alkaloid is then determined spectro-photometrically at 545 nm and calculated from a standard curve. 

The sequential stages used were - (i) selective extraction of the alkaloids into benzene or toluene (wetting the raw material with aq. 5% Na acetate improved the extraction), (ii) back-extraction of the alkaloids into 2% citric or tartaric acid, (iii) adjustment of pH to 6.0 with aq. 5% NH3 and re-extraction of the alkaloids into toluene, (iv) separation of the alkaloids on LH-20 with methanol - CHCI3 (7 3), separation of the dimeric alkaloid fraction on silica gel, with CHCI3 - benzene -acetone - ethyl acetate - methanol (20 20 15 5 3) (vi) elution of the alkaloids with 1% HCl, and (vii) addition of 0.2 ml of 1% tropaeolin 000-1 (C.l. Acid Orange 20) and then CHCI3. The color so produced is measured at 490 nm. 

Figure 3.6 Illustrations of a urea-linked ji-cyclodextrin dimer a) complexing Tropaeolin 000 No. 2, and matching b) the orientation required for binding indirubin/indirubin-5 -sulfonate, and therefore c) the orientation required to template the reaction of indoxyl with isatin/isatin-5-sulfonate...

Orange I [tropaeolin 000 Nrl, 4-(4-hydroxy-l-naphthylazo)benzenesulfonic acid sodium salt] [523-44-4] M 350.3, m >260°(dec). Pirrify the dye by dissolving it in the minimum volume of H2O, adding, with stirring, a... 

Figure 3 Changes of SCD values with pcHci04 in acetic acid medium. QR, quanaldine red RD, 4 -dimethylaminobenzalrhoda-nine MY, metanil yellow TR, tropaeolin 00 BG, brilliant green CV, crystal violet MG, malachite green S, Sudan III PNB, p-naphtholbenzein BN, nile blue.

In 1876 the dye firm of Poirrier in Paris introduced what were called oranges , which were said in the Paris Exhibition in 1878 to have been discovered by Z. Roussin. These dyes were investigated by Hofmann,who concluded that they were formed by coupling diazobenzene with naphthol-sulphonic acid, and Witt announced that the dye tropaeoline, then made in England, was formed from sulphonic acids of hydroxy and amino azo-bodies . 

For the quantitative determination of Solarium alkaloids in plant materials some new methods have been developed for instance, gravimetric procedures using the afore-mentioned cholesterol precipitation (15) for tetraosides, especially with saturated aglycones volumetric methods with titration of the bases in water-free solvents using aromatic sulfonic acids (26c, 47, 48) a number of simplified spectrophotometric methods by applying the Clarke reaction (49), that is, the hlue color obtained with paraformaldehyde-phosphoric acid in the case of J -unsaturated steroid alkamines and their glycosides (12, 50-52a, 525), or with the aid of amphi-indicators of the tropaeolin type (52,53-57,57a). The well-known Liebermann-Burchard reaction is not applicable to nitrogenous 3 -hydroxy-J -steroids (55). ... 

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