INDUSTRIAL AKD EKGINEERING
1030
are so numerous that he is almost certain to overlook some one of them. He is apt to think, for instance, if he is unfamiliar with the field, that, if he gives the name of the dye, he has described it sufficiently minutely. As a matter of fact, this is not so, because dyes are not found in commerce as chemically pure substances. Also, while I am a great believer in the value of academic research and of its being untrammeled by any effort to make it practical, yet it seems foolish not to make academic work fit into the practical use of products if we can do so without causing the academic work t o suffer. For in-
Vol. 25, No. 9
CHEMISTRY
stance, I do not see any advantage in a study of lake formation using dyestuffs that are not sufficiently adapted to the production of commercial lakes to rank as lake colors. The idea of synthesizing valuable dyestuffs in the course of anything but long continued and specialized work in the field is bound to be disappointing. Synthetic work having for its object the production of useful dyes I would regard as the least promising of all fields for the academic worker. RECEIVED April 15, 1933.
Preparation of 1,2- and 2,3Diaminoanthraquinones P. H. GROGGINSAND H. P. NEWTOK,Bureau of Chemistry and Soils, Washington, D. C . I n the preparation of 3’,4’-dichloro-2-benzoylbenzoic acid, a study of the eflect of time, temperature, solvent ratio, and agitation on yield and purity of the product is reported. The m a x i m u m yield is 80 per cent. Cyclization of the keto acid by means of concentrated sulfuric acid gires in all instances a mixture of the isomeric dichloroanfhraquinones. Differ-
T
HIS report deals nith the utilization of 1,2-dichlorobenzene as a raw material for the preparation of 1,2and 2,3-diaminoanthraquinones. These isomeric conipounds have been previously prepared by more complex methods. Briefly, the procedure employed in this case was the condensation of phthalic anhydride with 1,2-dichlorobenzene, in the presence of anhydrous aluminum chloride, to yield 3’,4’-dichloro-2-benzoylbenzoicacid, which was cyclized to a mixture of the isomeric 1,2- and 2,3-dichloroanthraquinones. Conditions were found under which the separated isomers were aminated to the corresponding diaminoanthraquinones. A critical examination of the available technical 1,2-dichlorobenzene indicated the presence in practically all cases of varying quantities of 1,4dichlorobenzene, chlorobenzene, and traces of polychlorinated benzenes. By means of refrigeration and distillation, a relatively pure 1,2-dichlorobenzene was obtained, which contained as the only impurity a trace of 1,4dichlorobenzene. Carswell (3) reports the boiling point of pure 1,2-dichlorobenzene to be 180.3’ C. It was possible to secure for this work a special product which gave a distillation range of 179.5’ to 180.5’ C. PREPARATION
O F 3’,4’-DICHLORO-2-BENZOYLBENZOICACID
Senn (8), Phillips ( B ) , and later M. and N. Tanaka (9) reported the preparation of 3’,4’-dichloro-2-benzoylbenzoic acid by the condensation of phthalic anhydride with 1,2dichlorobenzene in the presence of anhydrous aluminum chloride. In the present investigation a study was made of the effect of time, temperature, solvent ratio, and agitation, in an attempt to improve the purity and yield of the keto acid. The equipment employed is shown in Figure 1. Tables 1-111 illustrate the effect of the variables listed. The phthalic anhydride, anhydrous aluminum chloride, and 1,Zdichlorobenzene were mixed together and treated under the conditions
ence i n solubility of each isomer in sulfuric acid and also in ethanol indicates the quantitative relationship of 13 per cent 1,2-dichloroanthraquinoneto 87 per cent 2,3-dichloroanthraquinone. Ammonolysis of the corresponding dihalogenoanthraquinones, in the presence of copper, a n oxidant, and ammonium nitrate, results in the complete removal of chlorine. indicated in the tables. After the reaction was completed, the mass was hydrolyzed with cold dilute mineral acid, the excess of l,>dichlorobenzene was removed by steam distillation, and the aluminum was removed as a salt in solution. The soluble ammonium salt of the keto acid was obtained by treating the residue nith aqueous ammonia. This was passed through a filter to remove insoluble impurities, and the keto acid was reprecipitated by the addition of mineral acid. The 3’,4’-dichloro->benzoylbenzoic acid was then collected on a filter, washed, dried, and weighed. TABLEI. EFFECTOF SOLVEKT RATIOON PREPARATION OF 3‘,4’-DICHLORO-2-BENZOYLBEh’ZOICACID Phthalic anhydride 0.5 mole = 74.0 grams 10% = 147.8 grams Anhydrous AlClr, {mole l,2-Dichlorobenzene = 0.5 mole X ratio Solvent = excess 1,2-dichlorobenzene Theoretical yield = 147.5 grams Reaction time = 8 hours 90’ C. Reaction temp. M. p. of pure keto acid = 192.5’ C. M.p. of crude keto acid, all runs 190-191’ C.
+
-
-
SOLVENT TYPEOF EXPT. PHTHALIC ANHYDRIDE AQITATION Moles None 1 None 2 None 3 None 4 None 5 Continuous 1-A Continuous 2-A Continuous 3-.1 Continuous 4-A Continuous 5-.1
YIELD yo of theory 24.0 35.4 64.4 95.0 65.4 96.5 66.4 98.0 67.1 99.0 62.6 92.3 65.2 96.2 68.6 101.2 70.5 104.0 71.8 106.0
Grams
PREPARATION AKD SEPARATIOK OF ISOMERIC DICHLOROAKTHRAQUINONES
Penn (8) reported 87 per cent of 2,3-dichloroanthraquinone and 13 per cent of 1,2-dichloroanthraquinonefrom the cyclization of 3’,4’-dichloro-2-benzoylbenzoicacid. He made the cyclization with concentrated sulfuric acid and effected a separation of the isomers by the difference in their solubility
i n tiic r e d u a l acid. M. and S. Tanaka (8) state that tiicy olhained 2&dichloroanthraquinone in the condensation of 1 , Z - d i e h l o r o b e n z c n e wit11 piitlialic a n h y d r i d e in the presenec of nluriiinuni clikiride at 130" to 150" C. As might liave been e x p e c t e d , neitlicr the yield nor tlie purity of the product \%'as satisfactory. Xone of tlie various dehyd r a t i n g a ~ e n t stried ware as satisfactory for this cyclization as sulfuric acid. I'rcliminary cxperirncnts in ring closure indicated tlic p r c s e n c o of both tlie 1,2- a n d 2,%dichloroant.liraquinones. In an effort to increase the quant,it.y of the ni o r e v a1u it111e 1,2-isomer, cyclizations were made with the fc~ll~wing varial~les: time, acid ratio. acid coiiccntration. and teiiiperaturc. A h i g h e r temperature, above 150' C., iirdicated tlieformalion of slightly more of the 2,3-isoiuer at the expense of the 1,2-isorrrer. In all cases both anthraquinones were found. Practically tireoretical yii:lds were ohtained under the following miditions: temperature, 135' C.; time, 7.5 hours; and a ratiu of 8 part.s of 95 per cent sulfuric acid to m e part of keto arid.
cate that prnctir:ally pure 2,3dichloroantliraquinorie may lie o h t a i n e d directly f r o m tlic cyclization mixture, consisting of 92 per cent sulfuric acid, \yit!i a net yield of 82.5 per cent of 2,3-dichloroanthraquinone. With a rcsidual acidity of 89.75 per cent s u l f u r i c acid, a less pure 2,%deriua.tive of 87 per cent yield was isolated. The purc 1 , 2 - d i c li I o r o R n t h r a quinone could not be isolated in the manner described aborc. O n e recrystallizat,ion of tlie product from tlie filtrate of experiment 7, Table IV, from ethanol, yielded 1,2-dichloroanthraquinone with 5 melting point of 193" to 194' C. Repeated recrystallizations from tohiene, glacial a c e t i c acid, or ethanol (in any order) zave in all cases the follonina melting points (corrected): fo'i 1,3-diclilon,antlir~i~uinone. 194.5' C . : for 2.3-dichloroanthra-
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