. and their homologues lose, under the influ- U NITED STATES PATENT OFFIcE.

BENNO HOMOLKA, OF FRANKFORT, AND AUGUST STOCK, OF HOOHST- ON-THE-MAIN, GERMANSI, ASSIGNORS TO THE FARBWERKE, VORMALS MEISTER, LUOIUS 85 BRUNING, OF HOOHST-ON-Tl-IE-MAIN, GERMANY.

NITROBENZYLIDEN SULFONIC ACID AND PROCESS OF MAKING SAME.

SPECIFICATION forming part of Letters Patent No. 622,854, dated April 1 1, 1899.

V, Application filedrDecember 15, I897- Serial No. 662,029. (SpecimensJ' V v .To all whom it may concern.-

Be it known that we, BENNO HoMoLKA, doctor of philosophy, a citizen of theEmpire of Austria-Hungary, residing at Frankforton-the-Main, and AUGUST STOCK, doctor of philosophy, a citizen of the Empire of Germany, residing at Hochst-on-the-Main, Germany, have invented certain new and useful Improvements in the Manufacture of Orthoand Para- Nitrobenzylidenanilinsulfonic Acids and Their Homologues, of Which the following is a description.

This invention relates to the production of orthoand paranitrobenzylanilin and its homologues.

We have found that the nitrobenzylanilinsulfonic acids, described in our American application, dated December 15, 1897, Serial No. 662,028, of the general formula Nitro- Benzyl Anilin Sulfonic acid ence of oxidizing agents, two atoms of hydrogen and are transformed into the nitrobenzylidenanilin sulfonic acids or their homologues according to the following equations:

2 e'. e., ortho-nitrobenzyliden anilinsulfonate Anilin sulfonic acid.

saltv vhere M represents a monovalent metal atom-for instance, Na, K, NH &c.

Thefree acids do not exist, but decompose completely, in presence of Water, into nitrobenzaldehyde and aromatic aminsulfonic acid according to the equations:

(1)OH=N.O H,SO H C l-I, I ,+H O:

2 Ortho=nitrobenzy1iden anilin sulfonic acid (1)COH 6 h 2 Ortho=nitrobenza1dehyd (1)CH':N.C H SO H V 0 7 4 2 (4:)NO Para-nitrobenzyliden-toluidin sulfonic acid (1)0OH Y 0 H H N. (3 H S0 11 Para-nitrobenzaldehyd Toluidin sulfonic acid. The nitrobenzylidenanilin sulfonic acids and their honiologues therefore form a particularly suitable material for the manufacture of orthoand paranitrobenzaldehyde.

We illustrate the practical application of our invention, for instance, as follows: Thirtythree kilograms of orthoor paranitrobenzylidenanilinsnlfonate of sodium (or the equivalent quantity of the salt of an orthoor paranitrobenzyliden-toluidin-sulfonic acid of an orthoor paranitrobenzyliden-Xylidin sulfonic acid, or of an orthoorparanitrobenzylnaphthylamin' sulfonic acid) are dissolved in water, whereupon a concentrated solution of 10.5 kilograms potassium permanganate (KMnO is slowly introduced While cooling and stirring rapidly. Instead of potassium permanganate the equivalent quantities of other oxidizing agents may be emp1oyed-for instance, salts of alkali and alkaline earths of the manganic acid or permanganic acid, manganese dioxid, (MnO leadperoxid, (PbO ferric chlorid, (Fe Gh ferric sulfate, Fe (SO,) ferricyanid of potassium, ammonium persulfate, &c. It is of advantage to introduce carbonic acid or to add mangnesium sulfate. As soon as the violet color of the potassium permanganate has disappeared the oxidation is completed. Filtration is done from the precipitated manganese dioxid, and a clear yellow solution of the nitrobenzylidenanilinsulfonate salt or of a salt of the nitrobenzyliden-toluidin sulfonic acid, the nitrobenzyliden or Xylidin sulfonic acid, or the nitrobenzyliden-naphthylamin sulfonic acid remains behind. From this solution are obtained the solid salts either by salting out with chlorid of sodium or by evaporation. The salts thus obtained are yellowish powders, soluble in water, insoluble in the other usual mineral solvents. The free sulfuric acids isolated in the usual way from these salts decompose, as already said above, into nitrobenzaldehyd and anilin sulfoacid 0r toluidin-sulfonic acid, Xylidin sulfonic acid, or naphthylamin-sulfonic acid.

Having now described our invention, what we claim is 1. The herein-described process for the mancomposition With diluted minerals acids, ni-

trobenzaldehyde, substantially as set forth.

In testimony that we claim the foregoing as our invention we have signed our names in presence of two subscribing witnesses.

BENNO HOMOLKA. AUGUST STOCK.

Witnesses:

HEINRICH HAHN, ALFRED BRISBISS.