Acid brown

With rates of nitration in sulphuric acid, Brown s (r+-constants do not correlate well. ... 

Resorcine Brown R [5850-16-8] (27) (Cl Acid Brown 14, Cl 20195) is a symmetrical primary disazo dye with bihmctional coupling component (resorcinol). 

Acid Brown 14 (27) (2 mol of naphthionic acid, ie, 4-amino-1-naphthalenesulfonic acid 1 mol resorcinol) and Acid Black 1 (28). Two other azo acid blacks. Acid Black 52 (43) and Acid Black 63 (44) are both metallized with chromium. 

Reactions that occur with the development of an electron deficiency, such as aromatic electrophilic substitutions, are best correlated by substituent constants based on a more appropriate defining reaction than the ionization of benzoic acids. Brown and Okamoto adopted the rates of solvolysis of substituted phenyldimeth-ylcarbinyl chlorides (r-cumyl chlorides) in 90% aqueous acetone at 25°C to define electrophilic substituent constants symbolized o-. Their procedure was to establish a conventional Hammett plot of log (.k/k°) against (t for 16 /wcra-substituted r-cumyl chlorides, because meta substituents cannot undergo significant direct resonance interaction with the reaction site. The resulting p value of —4.54 was then used in a modified Hammett equation. 

Saure-bindungsvermogen, n. power to combine with acids, acid capacity, -bottich, m. acid vat. -braun, n. acid brown, -bromid,... 

HA turnover is rapid in the brain, with a half-life of about 30 min. This can change very quickly depending on neuronal activity. There is no high-affinity uptake system for HA once released, HA is inactivated by catabolism. In the brain, released HA is methylated almost exclusively by the enzyme histamine-N-methyltransferase (E.C. 2.1.1.8). The tele-methyl-HA is subsequently degraded by monoamine oxidase-B (MAO-B) and aldehyde dehydrogenase to produce tele-methylimidazoleacetic acid (Brown et ah, 2001). 

Another RP-HPLC method was applied for the investigation of the effect of TiOz on the photocatalytic degradation of the leather dye Acid brown 14. The chemical structure of Acid brown 14 is shown in Fig. 3.54. Chromatographic measurements were performed in an ODS column using methanol-water (10 90, v/v) as the mobile phase. The flow rate was 1 ml/min and analytes were detected at 212 nm. The results demonstrated that Acid brown 14 is rapidly decomposed under solar light in the presence of a Ti02 photocatalyst [125],... 

Fig. 3.54. Chemical structure of Acid brown 14. Reprinted with permission from S. Sakthivel et al. [125].

Thus, RP-HPLC-MS has been employed for the analysis of sulphonated dyes and intermediates. Dyes included in the investigation were Acid yellow 36, Acid blue 40, Acid violet 7, Direct yellow 28, Direct blue 106, Acid yellow 23, Direct green 28, Direct red 79, Direct blue 78 and some metal complex dyes such as Acid orange 142, Acid red 357, Acid Violet 90, Acid yellow 194 and Acid brown 355. RP-HPLC was realized in an ODS column (150 X 3 mm i.d. particle size 7 /.an). The composition of the mobile phase varied according to the chemical structure of the analytes to be separated. For the majority of cases the mobile phase consisted of methanol-5 mM aqueous ammonium acetate (10 90, v/v). Subsituted anthraquinones were separated in similar mobile phases containing 40 per cent methanol. The flow rate was 1 ml/min for UV and 0.6 ml/min for MS detection, respectively. The chemical structure of dye intermediates investigated in this study and their retention times are compiled in Table 3.28. It was found that the method is suitable for the separation of decomposition products and intermediates of dyes but the separation of the original dye molecules was not adequate in this RP-HPLC system [162],... 

Anthracene acid brown, acid anthracene brown, acid alizarine brown, anthracene chromate brown, diamond brown, acid chrome brown, palatine chrome brown, sail cine brown, oxy-chrome brown, metachrome brown, monochrome brown, mercerol brown, etc Also Man ganese brown (Mh in ash). 

Nitrogen(iv) oxide (N02) Brown (very choking smell) Pink-weakly acidic Brown colour Turns moist indicator paper pink... 

Hou (1992) used a simple screening test to determine whether acid and direct dyes precipitate at calcium concentrations typical of hard waters of the SE Piedmont region of the U.S. Of the 52 dyes tested, only three direct dyes (Direct Black 19, Direct Black 22, and Direct Blue 75) and seven acid dyes (Acid Red 88, Acid Red 114, Acid Red 151, Acid Brown 14, Acid Black 24, Acid Orange 8, and Acid Blue 113) precipitated. Although the Ca salts of acid and direct dyes were thought to be the most likely metal salts to precipitate after dye discharge to natural waters, the precipitation is not likely to occur unless dye concentrations exceed 0.02 to 0.6 mg/L, a level far greater than reported concentrations of dyes in surface waters. 

TV-Arylation of y acid results in a strong deepening of the shade. The usually brown to black dyes thus obtained are fast to light and milling and go onto wool and silk from a neutral liquor. Example C.I. Acid Brown 20, 17640 [6369-33-1] (11). 

Browns are the most important shades for leather after blacks. Despite then-higher molecular weight and sole use on leather, these dyes are normally also classified as acid dyes. C.I. Acid Brown 123, 35030 [6473-04-7] (9), for example, although a tetrakisazo compound, is classified as an acid dye. The dyeing is more on the surface. 

Ulmic acid (brown) and Humic acid (black), the components soluble in alkali... 

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