Compounds, colored acid esters

The BF2 chelates are hydrolytically stable (the majority of them may be recrystallized from water) whereas the BC12 chelates are easily hydrolyzed. The boric acid ester complex triptych boroxazolidines are also stable towards hydrolysis as are other aminoalcohol esters.83 A great number of the boron chelates are colored several spectrophotometric methods are based on chelate formation81 84 for the analytical determination of boric acid, organoboric acids and chelating organic compounds. The boron chelates are remarkable for their pharmacological properties as well.84 Various aspects of the boron chelates have been reviewed.81,83-86... 

Water-insoluble vat dyes are converted to soluble anthrahydroquinones by reducing agents, such as sodium dithionite (hydrosulfite) in the presence of sodium hydroxide. The sodium salts of these mostly deep colored leuco compounds penetrate cellulose fibers. The insoluble dye is attached firmly to the fiber after reoxidation (see Section 4.5). Representative of a special form are the water-soluble sulfuric acid esters of the anthrahydroquinone compounds, namely, the leuco esters of vat dyes). 

A pink precipitate or coloration is produced by the action of acid solutions of alkali germanates with the yellow alcohol solution of 9-phenyl-2,3,7-trihydroxy-6-fluorone (I). The composition of the reaction product is not known. In view of the phenolic nature of the dyestuff serving here as reagent, the possibility of ester formation as indicated by (II) is not excluded. Consideration must also be given to the production of an adsorption compound (color lake)2 between GeOa aq and (I). 

The four main components of wood resin from most species are the resin acids, free fatty acids, combined fatty acids (esters), and unsaponifiable sterols, alcohols, terpenes, and waxes. (The resins from tropical hardwoods (e.g., Shorea spp.) can be mainly terpenoid and steroid compounds (e.g., 88, 89, 156, 157, 184, 187) and the cause of color reversion and resin spots (156, 157) (see Sect. 9.3.7.2).) As mentioned, the composition of canal and parenchyma resins differ, and in living Picea and Pinus spp. woods, levopimaric acid predominates in the canal resin over abietic, neoabietic, and palustric acids. The resin acids are the most brittle or hardest, whereas the others range between the fluid and solid state. Consequently, variations in composition will affect the plasticity or stickiness of the resultant pitch (30). Deposits at different points in a paper mill processing ther-... 

The intense reddish-brown color of the acetylacetone titanium complexes impart a yellow discoloration to white inks. This discoloration is accentuated when the inks are used to print substrates that contain phenol-based antioxidants. The phenoHc compounds react with the organic titanate to form a highly colored titanium phenolate. Replacement of 0.25 to 0.75 moles of acetylacetone with a malonic acid dialkyl ester, such as diethyl malonate, gives a titanium complex that maintains the performance advantages of the acetyl acetone titanium complexes, but which is only slightly yellow in color (505). These complexes still form highly colored titanium phenolates. 

Colorless phosphate ester surfactants were also prepared by treating P4O,0 with an organic OH-containing compound in the presence of a phosphinic acid color inhibitor, e.g., bis(hydroxymethyl)phosphinic acid color inhibitor. Thus, 558 parts dodecanol containing 2.4 parts of phosphinic acid color inhibitor was treated with 142 parts P4O10 at 100-135°C. The phosphate ester surfactant had a VCS color value of 1, whereas a sample prepared without the color inhibitor had a VCS color value of 5. Twenty-eight similar surfactants were prepared using various alcohols and alcohol-alkylene oxide condensates [22]. 

Tetrabromophthalein ethyl ester potassium salt is a pH indicator that changa from blue to yellow in the pH range 4.2-3. It is known that proteins and alkaloids fordli blue-colored salt-like adsorption compounds with this indicator that are not destroyeti by weak acids [3]. Thiophosphate pesticides and triazines possibly form similar conhi pounds. 

Carotenoids are also present in animal products such as eggs, lobsters, greyflsh, and various types of hsh. In higher plants, they occur in photosynthetic tissues and choloroplasts where their color is masked by that of the more predominant green chlorophyll. The best known are P-carotene and lycopene but others are also used as food colorants a-carotene, y-carotene, bixin, norbixin, capsanthin, lycopene, and P-apo-8 -carotenal, the ethyl ester of P-apo-8-carotenic acid. These are Upid-soluble compounds, but the chemical industry manufactures water-dispersible preparations by formulating coUoid suspensions by emulsifying the carotenoids or by dispersing them in appropriate colloids. ... 

Dimalone [bicyclo-(2.2.1)-5-heptene-2,3-dicarboxylic acid dimethyl ester] and Octa-cide 264 [the V-octyl imide of bicyclo-(2.2.1)-5-heptene-2,3-dicarboxylic acid] do produce a red color with an absorption maximum in the same region as that obtained in the analysis of Compound 118. However, because Dimalone is an insect repellent and Octacide 264 is a pyrethrum synergist, neither of these products is likely to be encountered in commercial mixtures of Compound 118. The response to the colorimetric test for Compound 118 of some chemicals commonly used for insect control is listed in Table V. 

Other applications dealt with the development of a luciferin ester substrate to measure the luciferase activity in living cells [141], the detection of toxic compounds such as sodium azide, fluoroacetic acid, and antibiotics [142], the development of a biosensor for the determination of bioavailable mercury [143], the use of eukaryotic luciferases as bacterial markers with different colors of luminescence [144], the determination of complement-mediated killing of bacteria [145], and the development of a bioassay for the determination of HIV type 1 virus and HIV-1 Tat protein activity, valuable also for analysis of HlV-inhibi-tory agents [146],... 

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