Indigo formula

Fig. 3.73. Developed formulae of indigo and indigo carmine. Reprinted with permission from M. Vautier et al. [141].

Pelletier etatee that galbanum resin has the remarkable property of yielding an indigo-blue oil when heated to from 248° to 266°. Johnston assigns the formula OwHfl Q os representing the composition of tho resin. 

The first laboratory synthesis of indigo was achieved by Adolf von Baeyer in 1878, and in 1883 he revealed the structural formula 1 to Heinrich Caro, at that time head of the research laboratories at BASF [4],... 

Bond orders and charge densities in the indigo molecule have been calculated [7] and compared with the results of X-ray analysis [8], These studies confirm the structural formula 1 and answer questions about the basic chromophore of the dye (see Section 2.4). 

Vivianite, Fe2+3(P04)2.8H20, is the classic example of a mineral showing an intervalence charge transfer transition (Wherry, 1918 Bums, 1981). Vivianite has a diagnostic indigo-blue colour and a well characterized Fe2+ —> Fe3+ IVCT absorption band in the polarized spectra illustrated in fig. 4.12 and is the datum with which electron interaction parameters for other minerals are compared. The chemical formula of vivianite is not indicative of a mixed-valence compound. However, the pale-green colour of newly cleaved vivianite crystals or fleshly... 

Isatin, Indole, etc.—By oxidation indigo yields isatin which by successive reductions as recently explained yields di-oxindole, oxindole and finally indole. Also indoxyl, the isomer of oxindole, yields indigo by oxidation. The composition formulas of indigo and these last compounds are as follows ... 

On treatment of isatin chloride with zinc dust and acetic acid the chlorine is eliminated and two hydrogens added with the formation of indigo. The reaction, with the formula for indigo which is supported, as we shall find, by other syntheses, is as follows ... 

On heating indigo blue with acetic anhydride, sodium acetate, and zinc powder, a diacetylindigo white is obtained. On oxidation with nitrous acid in presence of acetic acid, diacetylindigo blue is formed. This compound forms small glittering red crystals, soluble in benzene with a beautiful red colour. Its constitution is expressed by the formula ... 

The colour reaction with Indigo Carmine is useful for determining oxygen dissolved in water [2-4]. The yellow reduced form of the reagent (leucobase) turns red (Xmax = 555 nm) under the influence of oxygen. Leuco forms of other dyes have also been proposed for determining oxygen. These include Methylene Blue [4-7], Berbelin Blue (formula 35.1) [8], Methyl Red [9], and Safranine T [4]. 

Blue Jeans Indigo, the dye used to color blue jeans, is prepared using sodium amide. Sodium amide contains the following mass percents of elements hydrogen, 5.17 percent nitrogen, 35.9 percent and sodium, 58.9 percent. Find an empirical formula for sodium amide. 

Dyes that in practice in the United States have been found to be useful because of their resistance to decomposition by heat and their capability to evaporate and recondensc as a brilliant cloud or trail are enumerated in Table 13. They have been taken from the standardized smoke formulas, from a Picatinny Arsenal report, which also gives a number of experimental formulas and their variation of burning time and duration with the formulation, and from an AMC Pamphlet. A number of other dyestuffs are mentioned in the foreign literature, sudi as indigo, methylene blue, rhodamine B, etc. ... 

Baeyer at first gave no structural formula for indigo, but in 1882 he suggested two ... 

In a letter of July 1809 to William Allen Dalton refers to experiments on respiration made two or three years before, which will perhaps appear in our next volume , showing that all the oxygen which disappears is to be found in the carbonic acid , but his results differed in some respects from Allen s. In a paper on indigo Dalton altered Crum s formula CiaH4N02, which is nearly correct (it should be CnHsNOg), to CgH20iV with Dalton s atomic weights. 

If a student is asked about the formula of indigo during an examination and replies that he believes that A. von Baeyer s formula is the right one, this would not be enough to pass the examination. He surely would be asked how the formula was proved. Similarly, it is necessary to know exactly the proofs for the macromolecular structure of cellulose and many other natural products, as well as those of synthetic products, if one intraids to wrak with them on the basis of this macromolecular concept. 

Sodium amide, known cormnercially as sodamide, is used in preparing indigo, the dye used to color blue jeans. It is an ionic compound with the formula NaNH2- What is the electron-dot formula of the amide anion, NH2 ... 

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