Amino azo benzene

Axial dispersion coefficient p-dimethyl amino azo benzene Domain antibodies... 

Azo Compounds.— The term azo is derived from the French word for nitrogen, viz., azote. Compounds designated by the name azo or some modification of it, e.g.y azo benzene, oxy azo benzene, amino azo benzene, hydrazo benzene, azoxy benzene, etc. represent a class of compounds in which two nitrogen atoms, each of which is linked to a separate benzene ring, are directly linked to each other by a double or single bond. 

Aminoazo Benzene from Nitroazo Benzene.— Another method of preparing aminoazo compounds is analogous to the preparation of aniline, i.e.f by the reduction of the corresponding nitro compound. When azo benzene is nitrated we obtain nitro azo benzene and this on reduction yields amino azo benzene. 

Constitution.— Both of these reactions of preparation establish the constitution of the amino azo compounds and also of the hydroxy azo compounds as we have represented them. While three isomers are possible in each case, depending on whether the azo group and the amino or hydroxyl group are in the ortho, meta or para positions in relation to each other, yet in fact only ortho and para compounds are known in most instances. The full constitution of the ortho and para amino azo benzene is then. 

Acid Yellow.—A mixture of the sodium salts of the mono- and di-sulphonic acid derivatives of amino azo benzene is a dye known as acid yellow or fast yellow, as above. 

Butter Yellow.—The di-methyl derivative of amino azo benzene which we have referred to in our discussion of the general method for the formation of amino azo compounds by the Griess reaction (p. 569), is also a dye known as butter yellow It is insoluble in water, but soluble in oils and, therefore, is used to color butter. 

Methyl Orange.— Another important dye compound related to the above is the well-known methyl orange which, though not used as a dye, is very widely used as an indicator. It is the mono-sulphonate derivative of di-methyl amino azo benzene. The alkali salts are orange yellow in color while the free acid is red violet, and these are the colors obtained when the indicator is used in acidimetric titrations. 

It is known also as helianthine and as tropaeolin D. It is not prepared by starting with amino azo benzene but with sulphanilic acid which is para-amino benzene sulphonic acid. This is diazotized and then coupled with di-methyl aniline yielding the azo compound. 

Bismarck Brown.—The dis-azo compound obtained meta-diamino benzene dis-azo benzene meta-di-amino benzene is a dye known as Bismark brown, though the dye is probably a mixture of the dis-azo compound and tri-amino azo benzene. With the exception of aniline yellow or amino azo benzene it was the first azo dye to be made. It was first prepared by Martins in 1864, and first made as a dye in 1866. 

Methyl yellow is also known as Tdpfer s indicator or dimethyl-amino-azo-benzene. It will be seen that some of the indicators have an... 

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