Of benzidine

It is prepared by reduction of nitrobenzene with iron and NaOH. It is also prepared by an electrolytic reduction of nitrobenzene. It is widely used for the preparation of benzidine. 

When hydrazobenzene, or 5ym-diphenylhydrazine, is warmed with acids, it undergoes an intramolecular rearrangement, with the formation of benzidine,... 

Required Hydrazobenzene, lo g. zinc dust, lo g. HYDRAZOBENZENE. The above preparation of benzidine... 

Difluorodiphenyl. Bis-diazotise a solution of 46 g. of benzidine (Section IV,88) in 150 ml. of concentrated hydrochloric acid and 150 ml. of water by means of a solution of 35 g. of sodium nitrite in 60 ml. of water add about 200 g. of crushed ice during the process (compare p-Fbtorotoluene above). Filter the solution and add it to a filtered solution of 85 g. of sodium borofluoride in 150 ml. of water. Stir for several minutes, collect the precipitated bis-diazonium borofluoride by suction filtration, wash with 5 ml. of ice-cold water, and dry at 90-100°. Place the dry salt in a flask fitted with an air condenser, immerse the flask in an oil bath, and slowly raise the temperature to 150° (Fume Cupboard ). When decomposition of the salt is complete, steam distil the mixture collect the 4 4 difluoro-diphenyl which passes over and recrystallise it from ethanol. The yield is 21 g., m.p. 92-93°. 

In the presence of acids, hydrazobenzene rearranges to give about 0 per cent, of benzidine (4 4 -diaminodiphenyl) and about 30 per cent, of diphenyline (2 4 -diaminodiphenyl) ... 

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 hydrochloride solution (for sulfate determination) mix 6.7 g of benzidine [Ci2H8(NH2)2] or 8.0 g of the hydrochloride [Ci2H8(NH2)2 2HC1] into a paste with 20 mL of water add 20 mL of HCl (sp. gr. 1.12) and dilute the mixture to 1 liter with water each mL of this solution is equivalent to 0.00357 g H2SO4. 

Smectite [12199-37-0] from an oxidized outcrop is stained light blue by a dilute solution of benzidine hydrochloride. The color does not arise from smectite specifically, but from reaction of a high oxidation state of elements such as Fe " and Mn " (46)46. 

DlsaZO Pigments. The diaiylide yeUows and oranges also known as benzidines are derivatives of benzidine coupled to two moles of substituted acetoacetanilide. Benzidine Yellows AAMX, AAOT, AAOA, and HR (PY 13, 14, 17, and 83) ate examples (Fig. 1). Yellows AAMX and AAOT are used in flexible vinyls. AAOA also colors polyethylene and polypropylene. These three differ only slightly in shade. Benzidine YeUow HR is redder. 

Although manufacture of benzidine itself has virtually ceased in Europe and the United States, similar rearrangement processes are operated for 3,3 -dichlotobenzidine [91-94-1J, o-dianisidine (3,3 -dimethoxybenzidine), and benzidine-2,2 -disulfonic acid. 

In a 5-1. three-necked flask, fitted with an eflicient stirrer (Note 1), a stopper, and a reflux condenser, are placed, in order, 184.2 g. (1 mole) of benzidine (Note 2), 500 ml. of commercial absolute ethanol, about 125 g. of Raney nickel, and 500 ml. of ethanol. The mixture is heated under reflux with stirring for a total of 15 hours (Note 3). The volume is brought to 3 1. with 05% ethanol, and about 150 g. of filter aid ( Super-Cel ) is added with stirring. The mixture is heated to boiling, filtered rapidly... 

Sodium dodecyl sulfate and hydrogen dodecyl sulfate have been used as catalysts in the denitrosation iV-nitroso-iV-methyl-p-toluenesulfonamide [138]. The kinetics of condensation of benzidine and p-anisidine with p-dimethylamino-benzaldehyde was studied by spectrophotometry in the presence of micelles of sodium dodecyl sulfate, with the result that the surfactant increases the rate of reaction [188]. The kinetics of reversible complexation of Ni(II) and Fe(III) with oxalatopentaaminecobalt(III) has been investigated in aqueous micellar medium of sodium dodecyl sulfate. The reaction occurs exclusively on the micellar surface [189]. Vitamin E reacts rapidly with the peroxidized linoleic acid present in linoleic acid in micellar sodium dodecyl sulfate solutions, whereas no significant reaction occurs in ethanol solution [190]. 

Add 5 ml of sodium hypochlorite (Clorox) to 50 ml of acetic acid prepare the benzidine solution by dissolving 0.5 g of benzidine and one crystal of KI in 50-ml ethanol-HjO (1 1) spray the plates with the Clorox reagent and let dry then spray with benzidine reagent... 

Zenser, T.V., Lakshmi, V.M. and Davis, B.B. (1999) Human and Escherichia coli /3-glucuronidase hydrolysis of glucuronide conjugates of benzidine and 4-aminobiphenyl, and their hydroxy metabolites. Drug Metabolism and Disposition The Biological Fate of Chemicals, 27, 1064—1067. 

Bafana A, Chakrabarti T, Muthal P, Kanade G (2009) Detoxification of benzidine-based azo dye by E. gallinarum Time-course study. Ecotoxicol Env Safety 72 960-964... 

Kalme SD, Parshetti GK, Jadhav SU, Govindwar SP (2007) Biodegradation of benzidine based dye Direct Blue-6 by Pseudomonas desmolyticum NCIM 2112. Bioresour Technol 98 1405-1410... 

Kumar K, Devi SS, Krishnamurthi K (2006) Decolorisation, biodegradation and detoxification of benzidine based azo dye. Bioresour Technol 97 407413... 

The determination of neomycin by non-aqueous titration has been described by Penau et all2l. Neomycin base is allowed to react with standardised perchloric acid the excess acid is then back-titrated with potassium hydrogen phtha-late using crystal violet as indicator. To determine the neomycin content of the sulphate salt the same authors precipitated the sulphate with benzidine before reacting the neomycin with perchloric acid. The amount of benzidine required to precipitate the sulphate is calculated from the sulphate content which is itself determined by titration with sodium hydroxide. 

Other recent developments, including fluorescent pigments, polymeric pigments and the problems which have arisen concerning health hazards from the use of benzidine-based intermediates in making certain pigments, are mentioned later in this chapter. 

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