Лако-красочные материалы — производство

Alkali fusion brings about the replacement of a sulfo group in an aromatic nucleus by hydroxyl, and thus affords a synthesis for numerous technically important phenols and phenol derivatives. Particularly in the naphthalene series, alkali fusion ts one of the most frequently used operations, along with sulfonation, nitration, and reduction. There are two essentially different […]

Like halogenation and nitration, sulfonation is of the greatest importance in dye manufacture. Most of the water soluble dyes owe their solubility to the presence of sulfonic acid groups. In addition, sulfonic acids are extremely important intermediates in the preparation of phenols, especially those of the naphthalene series. The majority of sulfonation reactions are effected […]

The reduction method described above, using iron in the presence of a small amount of acid, was originated by Bechamp and Brimmeyr and is the most widely used technical reduction method. In general it runs very smoothly, pro­vided that the following conditions are adhered to: 1. The reaction vessel must be metal. Only wrought iron […]

The Lunge nitrometer provides a simple and very useful means for controlling nitrations carried out in concentrated sulfuric acid solu­tion. Its usefulness for the determination of the oxyacids of nitrogen, especially nitric and nitrous acids, depends on the fact that these acids (and their salts and esters) are quantitatively and rapidly reduced to NO by […]

Nitration of aromatic compounds is carried out industrially, in most cases, using a mixture of nitric and sulfuric acids (mixed acid or nitrating acid). The sulfuric acid serves to take up both the water formed in the nitration reaction and that originally present in the nitric acid; in this way a sufficiently high concentration of […]

Chlorination is almost always carried out technically by the direct action of gaseous chlorine. Substances which are liquid at the reaction temperature are usually treated, without dilution, with chlorine gas, as described above forbenzene. Solid substances, on the other hand, must usually be dissolved or sus­pended in a suitable liquid. For this purpose, of course, […]

1. Chlorobenzene Cl Benzene undergoes a substitution reaction with chlorine only in the presence of halogen carriers. An addition reaction takes place in the absence of a carrier, leading to the formation of benzene hexa — chloride. Iron is the only halogen carrier used extensively in industry, a suitable form being fine iron powder. Chlorination […]

Carbazole behaves on substitution like a derivative of diphenyl — amine, i. e., it is attacked first in the positions which are ortho or para to the imino group. Introduction of a substituent in the position meta to the nitrogen can only be accomplished indirectly. Thus, stronglydirecting Class 1 groups may be introduced into both […]

In the naphthalene series, two isomers, a and /3, are possible wuen only one substituent is present. Nitration and halogenation of naph­thalene give practically only the a compound. On the other hand, sulfonation with concentrated sulfuric acid always gives a mixture of the two isomers (pure a-naphthalenesulfonic acid can be obtained by sulfonation with chlorosulfonic […]

Monosubstitution products of benzene exist in only one form, but when a second substituent is introduced into the molecule, any one of three isomers may be formed: ortho, meta and para. Which of the three isomers will be formed in any particular case depends, to a small degree, on the nature of the entering group […]