Patented Dec. 21, 1937 2,102,737

UNITED STATES PATENT OFFICE 2,102,737 PREPARATION OF ANTMONY CHLORDES Ferdinand W. Peck, Penns Grove, N.J., and Wii liam R. Waldron, Wilmington, Del, assignors to E. I. du Pont de Neneurs & Company, Wil mington, Del, a corporation of Delaware No Drawing. Application February 28, 1934 Seria No. 13,400 10 Claims. (C. 23-98) This invention relates to , move arsenic. It is also possible to produce anti more particularly , and a mony trichloride by reacting together metallic proceSS for the production thereof. It further antimony and , but such relates to the preparation of antimony a process is hazardous Since the reaction occurs 5 Solvent mixtures and to the production of flavan with almost explosive violence. throne from Such mixtures by condensation with One of the objects of this invention is the pro beta-amino-anthraquinone. vision of a new and improved process for the It is known that flavanthrone may be formed production of antimony trichloride from metallic by heating beta-amino-anthraquinone with anti antimony in an organic solvent. Another object O hony pentachloride. One such method involves is the production of antimony trichloride by a 10 heating the beta-amino-anthraquinone with process which is substantially non-corrosive, antimony pentachloride in nitrobenzene. An which avoids the formation of the antimony oxy other method involves the preparation of flavan chloride as a by-product, and in which the yields throne by heating beta-amino-anthraquinone of antimony trichloride are high. A further ob With antimony pentachloride to 160° C. Whereby ject is the preparation of solvent mixtures of an addition compound of the color with antimony antimony trichloride and antimony pentachloride penta chloride is formed, and then decomposing suitable for the production of flavanthrone in this addition compound to the color compound. high yields. A still further object is to provide The method of preparing the antimony penta a new and improved route to flavanthrone start chloride to be used in this condensation is an in ing with metallic antimony as one of the raw 20 portant factor, Since the yields of flavanthrone materials. Other objects will appear hereinafter. may vary Widely with different methods of pre These objects are accomplished by the follow paring the antimony pentachloride, either due to ing invention. Finely ground metallic antimony contamination by impurities or, in Some cases, is suspended in an organic solvent and while stir probably due to the lack of certainingredients ring to keep the antimony in suspension, 25 in the condensation process. is introduced until a large percentage of the me A number of processes have heretofore been tallic antimony is chlorinated to the trichloride. proposed for making antimony chlorides. One of After the desired amount of metallic antimony these processes consists in burning antimony in has been converted, the antimony chloride-solvent chorine, in this Way forming the penta, chloride mixture is preferably heated in the presence of: 30 30 directly. When the pentachloride is thus pro the excess of metallic antimony over that theo duced, however, it contains the chlorine addition retically required to convert any antimony penta product which is disastrous to a high yield of chloride Which may have been formed back to fia Vanthrone. the trichloride. Usually, the amount of anti Antimony trichloride may be prepared by treat mony pentachloride present is Small and is caused ing antimony With chlorine While maintaining by local over-chlorination. After the Small an excess of antimony at all times. It may be amount of pentachloride has been removed by prepared, also, by dissolving antimony oxide in this treatment, the liquid portion of the mixture, a large excess of concentrated , comprising Substantially the solvent. With the antimony trichloride dissolved therein, is sepa 40 40 but in doing this the oxychloride is always formed. On distillation, considerable proportions of the rated from the metallic antimony in any suit -trichloride distill with the Water and acid, and able manner, for example, by filtration or by there is also obtained an Oxychloride residue. decantation, and the liquid then purified, prefer This reaction is very corrosive and it is difficult ably by distillation either at atmospheric or at to find materials suitable for plant equipment. reduced pressures. Antimony trichloride may also be formed by If desired, the antimony trichloride may be the action of aqua, regia, on the metal. This proc recovered as such at this point, in which case ess has been modified by chlorinating a suspen it is most convenient to carry out the chlorina sion of antimony in 20% to 25% hydrochloric tion of the metallic antimony in a solvent, which acid. Another process for the preparation of has a boiling point relatively remote from that 50 50 antimony trichloride involves the reaction of of the antimony trichloride. Where it is desired antimony sulfide with chlorine gas. The anti to produce antimony penta, chloride, however, the mony sulfide is diluted with an inert material such chlorination of the metallic antimony is most as sand and the trichloride, after its formation, conveniently effected in a solvent such as nitro 55 55 is treated with additional antimony sulfide to re benzene which has a boiling point not far re 2 2,102,787 moved from that of the antimony trichloride. from metallic antimony to flavanthrone. As ex By distilling the crude antimony trichloride-sol amples of solvents which may be used in the for vent mixture, an antimony trichloride-solvent mation of the antimony trichloride may be men mixture is obtained which may be further chlo tioned benzene, toluene, solvent naphtha, carbon 5 rinated with very satisfactory results. The re tetrachloride, ortho-dichlorobenzene, nitroben 5 Sultant antimony pentachloride-containing mix Zene, Ortho-nitrochlorobenzene and para-nitro ture may then be reacted with beta-amino-an chlorobenzene. The nitrobenzene employed may thraquinone to produce flavanthrone in good be prepared by the nitration of benzene with ni yield. tric acid produced from metal nitrates such as The invention will be further illustrated, but is Sodium nitrate, or with synthetic nitric acid such () not limited, by the following example, in which as may be obtained by the oxidation of ammonia. the parts are by weight. It will be recognized that the results with all Sol EacGimple vents are not comparable. Benzene and ortho dichlorobenzene have given as good resultS aS Suspend 356 parts of finely ground metallic nitrobenzene in the formation of the antimony antimony in 1500 parts of nitrobenzene and, under trichloride. efficient agitation sufficient to keep the metallic In the formation of the antimony pentachlo antimony in suspension, introduce 258 parts of ride, it is desirable, although not essential, to en chlorine over the course of six to eight hours at a ploy a solvent which may also be used in the fla temperature of approximately 35° C. or lower. wanthrone condensation. For this purpose high- : The addition of chlorine may be regulated by the boiling solvents such as, for example, nitroben increase in weight or by an analysis to show the Zene, ortho-nitrochlorobenzene and para-nitro percentage of antimony trichloride in the nitro chlorobenzene may be mentioned. Nitrobenzene benzene solution. This should show the pres is especially desirable for use in the production of ence of 25% to 27% antimony trichloride. At antimony pentachloride and in the production of the end of the chlorination there should be ap flavanthrone, on account of the ease with which proximately 60 to 65 parts of unreacted antimony, the reactions proceed and the good yields ob Which amounts to approximately 18% excess of tained. In the formation of antimony penta metal. chloride-solvent mixtures and in the Subsequent Heat, the chlorination charge to 90° C. and hold condensation of such mixtures with beta-amino three hours so that any antimony penta, chloride anthraquinone, better results are obtained with Which is formed in Small amounts may be trans nitrobenzene than with Solvents Such as Ortho formed to trichloride by reacting with the excess nitrochlorobenzene and para-nitrochlorobenzene. of metal. This reaction may be shown to be The chlorination of the metallic antimony to complete when there is no increase in the forma antimony trichloride has been carried out with tion of trichloride as ShoWn by analysis. Remove very satisfactory results without the addition of the nitrobenzene-antimony trichloride mixture a catalyst. from the excess of antimony by decantation or The temperature employed in chlorinating the filtration, and distill either at atmospheric or re metallic antimony may vary within relatively 40 duced pressure, the distillation at reduced pres wide limits. A low chlorination temperature 40 sure being preferable. seems to give the best results, though chlorina Chlorinate the distilled nitrobenzene-antimony tions at a temperature as high as 85° C. have trichloride mixture by the introduction of chlo been made and give satisfactory results with the rine through a tube leading to the botton. Of the solvent, only slightly chlorinated. 45 vessel while maintaining the temperature at 15 In the formation of antimony trichloride, the 45 C. to 25° C. rate of chlorination may be increased over that To the resultant antimony penta, chloride-con given in the example but, in doing this, the taining mixture add beta-amino-anthraquinone amount of antimony pentachloride formed is in With continued agitation and condense to flavan creased. The excess of metallic antimony en throne by any suitable method. ployed in the antimony trichloride formation : In practising the invention, it has been found may be as low as 3% to 5%. This residual an that the presence of iron of antimony Sulfide does timony may be left in the chlorination vessel not injure the chlorination to the trichloride. and the amount Subtracted from the annount of The chlorination innay, therefore, be carried out in antimony used in the next charge. The yield of 5 5 a vessel made of iron materials of construction, antimony trichloride, according to the example, 5. i. e., iron, steel, the stainless steels and Similar is 98% to 99% of the antimony consumed. naterials. - The chlorination proceeds as Well with more or The state of subdivision of the metallic anti less solvent than the quantity stated in the ex mony may vary within relatively wide limits. ample. In fact, solutions with an antimony tri 60 Antimony metal ground as coarse as 40-mesh has chloride content as high as 45% have been made. been used satisfactorily. The antimony particles As already indicated, in carrying out the prep may be larger but, in general, the more finely aration of the antimony trichloride in nitro ground metal chlorinates more easily. Fast agi benzene with the object in view of preparing fla tation is desirable to keep the metal in Suspension. vanthrone, it is desirable to convert any antimony 65 The organic solvent employed in any given pentachloride present in the reaction mixture (55 step of the process should preferably be Substan obtainable by reacting chlorine with the metallic tially inert under the conditions of reaction. The antimony back to the trichloride prior to distill solvent used in the formation of the antimony lation. Unless the pentachloride is removed, in trichloride may or may not be the Sane as the the Subsequent distillation the pentachloride at 70 solvent used in the formation of the penta-chlo tacks solvents such as nitrobenzene with a re 70 ride. The same is true with respect to the Sol placement of the nitro group by chlorine and an vent used in the flavanthrone condensation. It evolution of nitrogen oxides. is usually advantageous, however, to keep the By preparing the antimony trichloride in a same solvent when going from one step to the solvent and distilling it just before use, it is ex next or, for that matter, in going all the Way ceptionally pure and free from contamination 2,102,787 3 from the containers which is brought about by mixture during the reaction, and then heating the corrosive action of the trichloride per Se. the reaction mixture containing the excess me Further, the yield of antimony trichloride in ac tallic antimony to a temperature higher than the Cordance with the present invention is high, no chlorination temperature to reconvert by-prod oxychloride is formed, and after distillation the lucts. 5 material is exceptionally pure provided the me 6. The process which comprises reacting chlo tallic antimony is free from arsenic and bismuth rine with metallic antimony suspended in a state or other metals which have volatile chlorides. of Subdivision in nitrobenzene at a temperature There is a decided cost advantage by this proc not higher than about 85°C., heating the result ess over other methods of preparing antimony ant chlorination reaction mixture to a tempera 0 trichloride, antimony pentachloride and flavan ture higher than the chlorination temperature throne. With excess metallic antimony over that required As many apparently widely different embodi to convert any antimony, pentachloride present ments of this invention may be made Without to antimony trichloride, and subjecting the re departing from the Spirit and scope thereof, it is Sultant antimony trichloride-nitrobenzene mix to be understood that we do not limit OurSelves ture to distillation. to the specific embodiments thereof except as 7. The process which comprises suspending defined in the following claims. about 356 parts of metallic antimony in a state We claim: of Subdivision not substantially larger than 40 1. The process which comprises subjecting me mesh in 1500 parts of nitrobenzene in an iron 20 tallic antimony in a state of Subdivision to chlo Vessel, reacting therewith, while agitating the rination in a substantially inert organic solvent mixture, about 258 parts of chlorine introduced at a temperature not higher than about 85°C., Over the course of six to eight hours, maintaining and heating the resultant chlorination reaction the chlorination temperature not substantially mixture to a higher temperature with exceSS me higher than 35 C., then heating to about 90° C. 25 2. 5 tallic antimony over that theoretically required for about three hours, separating the nitroben to convert any antimony pentachloride present Zene-antimony trichloride mixture from the solid to antimony trichloride. residue, Subjecting the separated nitrobenzene 2. The process which comprises subjecting antimony trichloride mixture to distillation, and metallic antimony in a state of Subdivision to reacting the distilled nitrobenzene-antimony tri 30 30 chlorination in a substantially inert organic Sol chloride mixture with chlorine. vent at a temperature not higher than about 8. The process of preparing antimony trichlo 85° C., heating the resultant chlorination re ride which comprises suspending metallic anti action mixture to a higher temperature with ex mony in a state of subdivision not substantially cess metallic antimony over that theoretically larger than 40 mesh in nitrobenzene, adding 35 required to convert any antimony pentachloride chlorine at a temperature not substantially high present to antimony trichloride, and distilling er than 35° C. While maintaining an excess of the antimony trichloride prior to further chlorin the metallic antimony, and then heating the re ation. Sultant chlorination reaction mixture contain 3. The process of producing antimony trichlo ing the excess metallic antimony to a tempera 40 ride which comprises reacting metallic antimony ture of about 90° C. to reconvert by-products. 40 in a state of subdivision with chlorine in an 9. The process of preparing antimony chloride aromatic solvent for antimony trichloride at a which comprises reacting chlorine with metallic temperature not higher than about 85 C., the antimony Suspended in a state of subdivision in amount of chlorine being less than the propor an aromatic solvent for antimony chloride at a 45 tions theoretically required to convert all of the temperature not higher than about 85° C., while antimony to antimony trichloride. maintaining an excess of metallic antimony in 4. The process of producing antimony trichlo the chlorination reaction mixture during the ride which comprises reacting metallic antimony reaction. in a state of subdivision with chlorine in a Sub 10. The process of producing antimony trichlo stantially inert organic solvent at a temperature ride which comprises reacting metallic antimony 50 not substantially above 35° C. Whereby antimony in a state of Subdivision. With chlorine in a high trichloride and small amounts of antimony pen boiling aromatic solvent for antimony chloride tachloride are formed, and heating the resultant of the class consisting of nitrobenzene, ortho mixture with excess metallic antimony at a high nitrochlorobenzene and para-nitrochlorobenzene 5 5 er temperature. at a temperature not higher than about 85° C., 55 5. The process of producing antimony trichlo while maintaining an excess of metallic anti ride which comprises reacting chlorine With me mony in the chlorination reaction mixture dur tallic antimony suspended in a state of Subdivi ing the reaction. sion in nitrobenzene, at a temperature not higher FERDINAND W. PECK. 60 than about 85° C. while maintaining an exceSS WILLIAM R, WALDRON. 60 of metallic antimony in the chlorination reaction