Benzene, diazo hydroxide diazonium chloride

Benzene diazo- and diazonium derivs 2 B54—B58 chemistry, definition and history 2 B54—B55 benzene diazonium chloride 2 BS5 benzenediazonium hydroxide and derivs 2 B55—BS6... 

Kekule Formula.—These facts led Kekule to suggest a second formula in which the nitrogen atoms are both trivalent and in the same relationship to each other and the ring as they are in azo benzene. The formula is CeHs—N=N—Cl, benzene diazonium chloride. For some time this was the accepted formula for, if we put it in the reactions which we have written for the formation of diazo compounds and for their conversion into azo compounds and into hydrazines, we find that it is satisfactory. It does not agree, however, with the true salt character of benzene diazonium chloride nor the strongly basic nature of the hydroxide compound, the free diazo benzene. In every respect the neutral salts, e.g., benzene diazonium chloride and the free diazo... 

Such a reaction agrees perfectly with the new formula which has been generally accepted as expressing the constitution of the free diazo base and the salts. The base thus takes the name benzene diazonium hydroxide and the salts, e.g., the chloride, benzene diazonium chloride signifying their ammonium character. The new formula does not, however, fit the reactions by which diazo. compounds are converted into azo or amino azo compounds nor the reduction of diazo benzene to phenyl hydrazine. Thus we have two formulas neither of which... 

Acids, Alkali Salts.—The free diazo benzene base which will always be spoken of now as benzene diazonium hydroxide and which necessitates the introduction of the pentavalent nitrogen formula is formed by the action of silver hydroxide upon benzene diazonium chloride. By the action of acids the diazonium hydroxide is converted into salts and these salts are neutral. If, however, the diazonium chloride is treated with alkalies, like potassium hydroxide, we obtain alkali metal salts of the diazo compound. 

Bases, Neutral Salts.— As a base it forms salts, in which form the diazo compound is obtained by diazotization, and which though also unstable has been isolated in small quantities and the composition and properties determined. Of the three salts, the sulphate, chloride and nitrate, the first is the most stable and the last is the least stable. They are colorless crystalline neutral compounds soluble in water, difficultly soluble in alcohol and insoluble in ether. After being prepared by the ordinary diazo reaction, with sodium nitrite in cold acid water solution, they may be precipitated in crystalline form by the addition of alcohol and ether. If the diazotization is effected in alcohol solution by means of amyl nitrite or ethyl nitrite the crystals of the diazonium salt separate at once. These salts of diazo benzene all show true salt characteristics, e.g., they lower the freezing point of solutions. The diazo radical, (CeHs—N2—) is thus basic toward strong acids, and the hydroxide, the non-isolated hypothetical diazo benzene, CeHs—N2—OH, is the free base. It may be considered as the simplest aromatic diazo compound and the mother substance of all other members of the class. 

---

See also in sourсe #XX -- [ , , ]

---