Benzidine diazotized

Benzidine diazotized A 0.5% benzidine solution in 0.005% hydrochloric acid is mixed with an equal volume of 10% sodium nitrite solution in water the mixture is sprayed on the plate to yield a variety of colors. 

Difluorobiphenyl has been prepared from 4,4 -biphenyl-bis-diazonium piperidide (by diazotizing benzidine and coupling with piperidine) and concentrated hydrofluoric acid 1 by the action of sodium on -fluorobromobenzene in ether 2 from benzidine by tetrazotization and decomposing the biphenyl-bis-diazonium salt with concentrated hydrofluoric acid 3 by the above method in the presence of ferric chloride 4 and by the prolonged contact of the vapors of fluorobenzene with a red-hot wire.5 The method described here is the most satisfactory for... 

Figure 4.33 Benzidine can be diazotized with sodium nitrite and HC1 for reaction with proteins through their tyrosine, histidine, or lysine side-chain groups.

B/s-diazotized benzidine has been used to create active-hydrogen-reactive spacer arms on chromatographic matrices (Silman et al., 1966 Lowe and Dean, 1971). The compound may be used similarly to o-tolidine for the conjugation of active-hydrogen-containing molecules (see Section 9.1, this chapter, and Chapter 2, Section 6.1). 

Diazotization of 3,7-diaminodibenzothiophene 5,5-dioxide, which has the trivial name of benzidine sulfone, followed by coupling with phenols, anilines, or arylsulfonic acids gives bis-azo dyes varying in color from red-brown to blue. These dyes are useful for the coloring of plastics and cellulose. second class of compounds based on 3,7-diamino-... 

Example Diazotize 2,2,-dinitro benzidine, H2N.C0H3(NO2)-C6H3(NO2).NH2, also known as 2,2 -dinitrodiaminodiphenyl, by adding Na nitrite to its soln in cold H.C1. Filter, if necessary, and add to the filtrate an equivalent amount of Amm perchlorate dissolved in w. Filter off the precipitated orange-colored substance, wash it with w, followed by ale ether and then dry in tbe air. The dried material is much more sensitive than when wet. It explodes very violently at the slightest shock, or when heated Ref T.L. Davis E.H. Huntress, USP 1828960(1931)... 

Richfield-Fratz et al. (206) determined aniline, benzidine, 4-aminophenyl, and 4-amino-azobenzene in sunset yellow. The determination involved chloroform extraction followed by diazotization and coupling with the disodium salt of 3-hydroxy-2,7-naphthalenedisulfonic acid and analysis by reverse-phase HPLC. Using a similar system, Peiperl et al. (207) determined benzidine in sunset yellow. Dithionite was used to reduce any combined benzidine present. 

Prival et al. (213) determined combined benzidine in tartrazine. After reduction of combined benzidine with dithionite, benzidine was extracted, diazotized, coupled with pyrazolone-T, and analyzed by HPLC. 

Benzidine can be diazotized at each amino group. It can then couple with two equivalents of the aminosulfonic acid. Coupling occurs ortho to the amino group since the para position is blocked by the sulfonic acid group. 

Another polyquinone, which can be synthesized by addition polymerization of diazotized benzidine with benzoquinone 98) also appeared to be active. 

A similar procedure can be used in the diazotization of homologs and alkoxy derivatives of aniline, m-halogen derivatives of these, polynuclear bases such as benzidine, diaminodi- and -triphenylmethanes, di-aminodiphenylether, etc., and their derivatives, and, in general, for all amines of the benzene series whose hydrochlorides are not decomposed by water. Aminosulfonic and carboxylic acids can also be diazotized by the above procedure if they are sufficiently soluble in dilute hydrochloric acid. 

If the procedure is reversed, and the diamine is coupled first with the intei-mediate benzidine-salicyclic acid compound and then with diazotized sulfanilic acid, an isomeric dye, having the following structure, is formed ... 

Using this procedure, other diamines such as benzidine and dianisidine may be diazotized and coupled with other amino-naphthols, such as S acid (i-amino-8-naphthol-4-sulfonic acid), J add (2-amino-5-naphthol-7-sulfonic add). Gamma add (2-amino-8-naphthol-6-sulfonic add), and H add (i-amino-8-naphthol-3,6-disulfonic acid), or with simple naphthols such as NW add (i-naphthol-4-sulfonic add), Schaeffer s add (2-naph-thol-6-sulfonic acid), and R add (2-naphthol 3,6-disulfonic add). The procediue would be varied only in the manner of salting out the dyes, each of which would require a set of optimum cond tions... 

Bis-diazotized benzidine can be used as a bridging reagent between proteins and haptens containing aromatic groups that react with diazon-ium compounds. A conjugate of thyrotropin-releasing hormone (which contains a reactive histidine residue) was obtained in this way. ... 

The diazotization of benzidine yielding diazo and tetrazo compounds, the coupling of these with phenols and amines yielding azo compounds, which are the benzidine dyes, should be recalled here (p. 569). 

Congo Red.—When benzidine is diazotized a double diazo or tetrazo compound results (p. 575) from the diazotization of both of the amino groups. This diazonium or tetrazonium salt reacts with two molecules of naphthylamine sulphonic acid, naphthionic acid, forming a double azo or disazo compound. The sodium salt of this compound is Congo red. The reactions are ... 

Benzo purpurin.— Tolidine is di-methyl benzidine, that is it bears the same relation to toluene and ortho-toluidine that benzidine does to benzene and aniline. When this is diazotized and the tetrazonium salt coupled with sodium naphthionate the disazo compound resulting is a dye known as benzopmpurin 4B, which is also a substantive dye of a red color. 

B) Reduction of Benzidine to Biphenyl (Sm.). Place in a small beaker (150 ml) 2 g of benzidine hydrochloride, 10 ml of water, and 4 ml of concentrated hydrochloric acid. Cool to 0° and add 5 g of ice and a solution of 1.1 g of sodium nitrite dissolved in 5 ml of water. Stir until the diazotization is complete, that is, until all the material has dissolved, and a test with iodide paper shows presence of nitrous acid. Add 15 ml of ethyl alcohol, and sift in 5 g of zinc dust, in small portions over a period of 5 minutes, stirring after... 

Determinations of degradation of benzidine (10a) in wastewater have been undertaken with GC/MS231. This has been adapted to general studies of degradation of aromatic amines in water232. Diazotization provides a useful test for the presence of free aromatic amines in natural waters and waters destined for human consumption. Quantitative determination of the azo products is measured colorimetrically233. 

Alanyl-P-naphthylamide plus diazotized O-aminoazotoluene Benzidine plus hydrogen peroxide... 

---