USRE4320E - Improvement in the manufacture of alizarine - Google Patents

Description

UNITED STATES PATENT OFFICE.

IMPROVEMENT IN THE MANUFACTURE OF ALIZARINE.

Specification forming part of Letters Patent No. 95,465, dated Octoberfi, 1869; Reissue No. 4,320, dated April 4, 1871. v

DIVISION A.

To all whom it may concern:

Be it known that we, CHARLES GRAEBE, of Frankfort-on-the-Main, and CHARLES LIE- BERMANN, of Berlin, in the Kingdom of Prussia, have invented a Process for Preparing Alizarine from Anthracene; and we do hereby declare the following to be a full, clear, and exact description thereof, which will enable those skilled in the art to make and use the same.

We first change the anthracene into anthrakinon, (oxanthracene,) a substance known to the chemists bythe investigations of Anderson. For this purpose we take one part, by weight, of anthracene, two and one-half parts, by weight, of bichromate of potash, and ten or fifteen parts,by weight, of concentrated acetic acid, and we heat these substances together in a vessel, either of glass or clay, to about 100 centigrade to 120 centigrade, till nearly all of the bichromate of the potash is dissolved, and the liquid. has acquired a deepgreen color. We then recover the acetic acid not consumed in the reaction by distillation, and treat the residuum with water, to remove the chromic acetate. From the insoluble mass we obtain the anthrakinon in a pure state by distilling the whole from a retort of glass or iron. In the place of the acetic acid, sulphuric acid, diluted with one or two parts of Water, may be employed.

Instead of the method just described, we also employ the following one: We heat anthracene in a vessel of glass or of clay, with ten parts of concentrated acetic acid, to about 100 centigrade, or a little higher, and we add nitric acid of about 1.3 specific gravity in small portions, till the violent reaction ceases. After distillation of the acetic acid we purify. We then convert the anthrakinon, prepared by one of the methods described, into bibromanthrakinon. For this purpose we take three parts of anthrakinon and five parts of bromine, and we heat these substances for ten or twelve hours, or until nearly the whole of the bromine has disappeared, to a temperature, by preference, of about 100 centigrade, in a suitable close vessel, either of glass or enameled or glazed iron, which is capable of sustaining the pressure generated by the reaction. The apparatus is then allowed to cool; it is opened in order to permit the escape of bromic acid, which can be recovered by absorption either in water or in alkaline solution. We purify the bibromanthrakinon remaining in the vessel, as a solid substance, by

crystallization from benzole.

Instead of the method above described for preparing bibromanthrakinon, we also employ the following: We convert first the anthracene into a bromine derivative, into the tetrabromanthracene, known to chemists by the investigations of Anderson. We take one part of this tetrabromanthracene, and we heat it in a retort of glass or clay, with about five parts of nitric acid of about 1.3 specific gravity, to 100 centigrade, as long as vapors of bromine are evolved. We distill off the greater portion of the nitric acid, wash the residuum with water, and purify it by crystallization from benzole. We thus receive the bibromanthrakinon, as before, in the form of a yellow solid mass. We then convert the bibromanthrakinon into alizarine. For this purpose we take one part of bibromanthrakinon, two to three parts of caustic potash or soda, and so much water as is necessary to dissolve the alkali, and we heat the same in an open vessel of glass, glazed or enameled iron, or silver, to about 180 to 260 centigrade, for one hour, or till the mass has acquired a deep-blue color. We then dissolve it in water, and filter the violent solution, from which we precipitate the alizarine by an inorganic acid.- We collect the yellow flocks of alizarine thus obtained on a filter, and wash them with water.

By these methods we receive the alizarine 2 I p p p in a form in which it can be employed in the same manner as the different preparations from madder.

In the place of bromine, chlorine also may be employed, but not so conveniently, as the reactions above described are more difficult to accomplish With chlorine than with bromine.

What we claim as new, and desire to secure by Letters Patent, is-

The within-described process for the production of alizarine, by first preparing bibromanthrakinon or bichloranthrakinon, "and then converting these substances into aliza rine, substantially as above set forth.

This specification signed by us this 30th day of November, 1870.

CHARLES GRAEBE. CHARLES LIEBERMANN.

Witnesses as to the signature of Charles Liebermann:

K. KREISMANN, G. MARAssE.

Witnesses:

OTTO PETZKE, R0131. PREUSS.