Benzidine treatment

The conversion of a hydrazobenzene into a diaminodiphenyl upon treatment with acid is termed the benzidine rearrangement. The following mechanism for the formation of benzidine from hydrazobenzene appears reasonable ... 

Benzidine chemistry involves reduction. The nitro precursor is reduced either by zinc and alkali or electrolyticaUy to the hydrazo intermediate, which is then transformed to the benzidine by treatment with acid. 

It is known that not all reactions proceed in the same manner on all adsorbent layers because the material in the layer may promote or retard the reaction. Thus, Ganshirt [209] was able to show that caffeine and codeine phosphate could be detected on aluminium oxide by chlorination and treatment with benzidine, but that there was no reaction with the same reagent on silica gel. Again the detection of amino acids and peptides by ninhydrin is more sensitive on pure cellulose than it is on layers containing fluorescence indicators [210]. The NBP reagent (. v.) cannot be employed on Nano-Sil-Ci8-100-UV2S4 plates because the whole of the plate background becomes colored. 

Reduction of the nitroaromatic with NaBH4 in DMSO or Zn in NaOH/EtOH leads to the hydrazo derivative and treatment with aqueous HC1 gives benzidine rearrangement.115... 

In addition the role played by the sorbent on which the chromatography is carried out must not be neglected. For instance, it is only on aliuninium oxide layers and not on silica gel that it is possible to detect caffeine and codeine by exposure to chlorine gas and treatment with potassium iodide — benzidine [37]. The detection limits can also depend on the sorbent used. The detection limit is also a fimction of the h/ f value. The concentration of substance per chromatogram zone is greater when the migration distance is short than it is for components with high h/ f values. Hence, compounds with low h/ f values are more sensitively detected. 

Baird, R., Carmona, L., and Jenkins, R.L. Behavior of benzidine and other aromatic amines in aerobic wastewater treatment, J. Water Pollut. Control Fed, A9(1) IG09-1615, 1977. 

One of the major uses of 1,2-diphenylhydrazine is as a starting material in the production of benzidine however, it is no longer produced in the United States. 1,2-Diphenylhydrazine rearranges to benzidine upon treatment with strong acid benzidine is used by the dye industry for the production of benzidine-based dyes including many of the Direct dyes (e.g.. Direct Red 28, Direct Black 4, Direct Blue 2) (Ferber 1978 Lurie 1964). Fabricolor, the last producer of benzidine based dyes, discontinued production in 1988 (Personal communication, Alvarez 1989). 

According to the Toxics Release Inventory (TRI), in 1996, a total of 2 pounds (1 kg) of 3,3 -dichloro-benzidine was released to the environment from one processing facility (TRI96 1998). Table 5-1 lists amounts released from this facility. In addition, an estimated 250 pounds (118 kg) were released by manufacturing and processing facilities to publicly owned treatment works (POTWs), and an estimated 51,550 pounds (23,432 kg) were transferred offsite (TRI96 1998). The TRI data should be used with caution because only certain types of facilities are required to report. Therefore, this is not an exhaustive list. 

Benzidine-2,2 -disulfonic acid (61) affords the diamine 62 (Scheme 13) on treatment with aqueous sodium hydroxide. " ... 

Benzidine Rearrangement. Treatment of hydrazobcnzcnc with strong acids. 

Although several peroxidase enzymes obtained from plant, animal, and microbial sources have been investigated for their ability to catalyze the removal of aromatic compounds from wastewaters, the majority of studies have focused on using HRP. In particular, it has been shown HRP can transform phenol, chlorophenols, methoxyphenols, methylphenols, amino-phenols, resorcinols, and various binuclear phenols [7], HRP was also used for the treatment of contaminants including anilines, hydroxyquinoline, and arylamine carcinogens such as benzidines and naphthylamines [7,8]. In addition, it has been shown that HRP has the ability to induce the formation of mixed polymers resulting in the removal of some compounds that are either poorly acted upon or not directly acted upon by peroxidase [7], This phenomenon, termed coprecipitation or copolymerization, has important practical implications for wastewaters that usually contain many different pollutants. This principle was demonstrated when it was observed that polychlorinated biphenyls (PCBs) could be removed from solution through coprecipitation with phenols [20]. However, this particular application of HRP does not appear to have been pursued in any subsequent research. 

Lacher, M., N. Lahav, and S. Yariv. 1993. Infrared study of the effects of thermal treatment on montmorillonite-benzidine complexes. II. Lithium-, sodium-, potassium-, rubidium- and cesium-montmorillonite. J. Therm. Anal., 40 41-57. 

VI. Treatment with Diphenylbenzidine Reagent. Place a few small crystsof unknown in an indenture of a white porcelain spot test, add 2 drops of diphenyl-benzidine reagent(a satd soln of C Hg.NH.CgH. C5H. NH.CgHj in glac AcOH), and then 1 drop of coned H SO. Observe the color after 1 min. A blue color indicates one of the following expls TNT, TNAns or HNDPhA yel color or no color -PA, AmmPic or DNPh (See also Chart B)... 

Chemical oxidizing agents have been used for the control of organic residues in wastewaters and in potable water treatment. Among the organics for which oxidative treatment has been reported are aldehydes, mercaptans, benzidine, and unsaturated acids. For these applications, sodium hypochlorite, calcium hypochlorite, potassium permanganate, and hydrogen peroxide have been reported as effective oxidants. In one application nitrous acid was used. 

Ozone-based AOPs are being used increasingly to treat landfill leachates. " They are also used for ground-water treatment to destroy trichloroethylene (TCE), tetrachloroethylene, and pentachlorophenol. In addition, they are used for groundwater remediation at Superfund sites in the United States to destroy volatile organic compounds and benzidines. Another application of ozone-based AOPs involves their use at U.S. ammunition plants to destroy explosives. ... 

Similar spectra of molecular cation radicals have been obtained earlier in the author s laboratory for diphenylamine, iV-methyldiphenyl-amine, N, iV -dimethyl-p-phenylenediamine (77a) and also for benzidine (27), when adsorbed from their vapors on the natural alumosilicate, bentonite. However, in these instances the degassing and vacuum treatment of the adsorbent could not be pushed so far, as for silica-alumina. Therefore doubt might arise whether the coloration should not be ascribed to traces of active oxygen (cf. Section V, G). 

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