I,VDUSTRlAL , 4 5 0 ENGIXEERING CHEMISTRY
December, 1929
bly does not affect their significance for comparative purposes, however. At all temperatures there is a rapid drop in acidity during the first 8 hours of tanning. This probably reflects the displacement of sulfuric acid from combination with collagen by chromi-complexes. The higher the temperature, the more rapidly does the acidity decrease, up to 30" C. Above 30" C. temperature has practically no effect on the acidity of the chromium salt. After the apparent acidity has fallen to about 0.46 it remains practically constant throughout the remainder of the tanning period. At temperatures of 30" C. or over this equilibrium acidity is reached in 24 hours, but a t lower temperatures it was not reached up to 120 hours. After 24 hours the acidity of a leather tanned a t 20" C. is about 33
1227
per cent higher than that of leather tanned a t 30" or higher, while the acidity of leather tanned a t 10" C. is 100 per cent higher. After tanning for only 4 hours the leather tanned at 50" C. almost stood the boiling test; that is, it showed only a slight contraction and remained soft and supple. The leathers tanned a t 40" and a t 50" C. stood the boiling test after an 8hour tannage; that tanned at 30" C. after 24 hours; and those tanned a t 10" and 20" C. after 48 hours. That a leather is produced a t all at 50" C. shows that the tannage at that temperature must be very rapid, as raw skin is rapidly converted into gelatin on exposure to a solution of p H 3 a t that temperature.
Studies in Liquid Partial Oxidation-I'z' E. P. King, Sherlock Swann, Jr., and D. B. Keyes I i N I V E R s I T Y O F I L L I N O I S , U R B A N A , ILL.
The catalytic oxidation of ethylbenzene and acetalo r g a n i c liquids. It is also HE partial oxidation of dehyde in the liquid phase has been studied. Catalysts necessary that the catalyst for organic compounds usused for the vapor-phase oxidation of hydrocarbons have liquid phase oxidation shall ing air as the oxidizing been tried as catalysts for the oxidation of ethylbenoperate a t a much lower temagent, and in the presence of zene. The oxidation of acetaldehyde was carried out perature than is customary a c a t a l y s t , h a s been the in aqueous solution and substances capable of changing for the vapor phase in order foundation of several successvalence were used as catalysts. The effect of obtaining ful commercial r e a c t i o n s . that the reaction may go withbetter contact between gas and liquid phases by means Oxygen may be substituted out the use of pressure. This of a high-speed stirrer was studied for both oxidations. for hydrogen in a hydrocarnecessitates the development The conversion of ethyl alcohol to acetic acid in two bon. for example. bv a mocof a special type of catalyst. ess ilivolving s e v e r a l s t e p s steps was also carried out. There are many processes and utilizing relatively costly involving the oxidation of an oxidizing agents. It is apparently difficult to make the sub- organic liquid by means of air, some of which are commercial stitution directly. Examples of such a reaction are the well- and others which might well become commercial processes known partial oxidation of naphthalene to phthalic anhy- if the general problem of bringing the two phases into contact dride and the partial oxidation of anthracene to anthra- efficiently were solved. The oxidation of acetaldehyde to quinone ( 5 ) . In these cases specially prepared catalysts are acetic acid is an example of such a reaction which is already used and the reactions are carried out in the vapor phase. carried out on a commercial scale. The importance and use Since all oxidations are exothermic, it is necessary to main- of acetic acid is ever increasing with the growth of industrial tain very precise temperature control. Otherwise the oxi- organic chemistry. Acetic acid is used in the manufacture dation would continue and only the end products of the of lacquers, cellulose acetate, and various solvents. Anreaction be obtained-namely, carbon dioxide and water. other example is the oxidation of ethylbenzene to acetoExperience has shown that temperature control is an ex- phenone. Acetophenone is now prepared by the Friedelceedingly important factor in this type of reaction. Crafts reaction, which is quite expensive. The use of acetoIf such a reaction is carried out in the vapor phase with a phenone in the manufacture of resins and as a reagent in solid catalyst, the heat is, presumably, liberated a t the sur- the preparation of various organic compounds is increasing. face of the catalyst, because this is where the reaction is It was the object of this investigation, therefore, to study supposed to take place. The heat is transmitted to the the effects of different catalysts on the oxidation of ethyl walls of the reaction tube by means of the gases, the solid benzene and acetaldehyde, and also to show the effect of catalyst, or both. Since the heat capacity of the reacting increase in the efficiencyof contact between the gas and liquid gases is small, usually an inert, diluting gas is added to make phases on the products of these reactions. The conversion up for this deficiency. Steam is often used because of its of alcohol to acetic acid was tried in a continuous process relatively high specific heat. The solid catalyst, though it involving two steps. may have a fairly high heat capacity, is often a poor conductor Historical of heat, and as it is usually stationary is of little value. On the other hand, if the reaction could be run in the There has been a great deal of investigation on oxidation liquid phase, the higher heat capacity and better heat conductivity might make the matter of temperature control in the liquid phase by means of air. Stephens (11) has more simple. However, it is difficult to obtain good contact done some notable work on the oxidation of liquid aromatic between a gas and a liquid, especially when that gas is not hydrocarbons, including the oxidation of ethylbenzene in very soluble in the reacting liquid, as in the case of air and the liquid state. Many investigators have studied the oxidation of alcohol Presented by D. B. Keyes before the Division of Industrial and Ento acetic acid by means of air, and a great number of methods gineering Chemistry at the 78th Meeting of the American Chemical Society, for carrying out the reaction have been suggested, as well Minneapo!is, Minn , September 9 to 13, 1929. as many catalysts for hastening the reaction. Although some Published by permission of the director of the Engineering Experiment Station, Uni\ersity of Illinois investigators have obtained acetic acid in the direct oxida-
'T
1
-
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INDUSTRIAL AND ENGINEERING CHEMISTRY
tion of alcohol by means of air in the presence of various catalysts in one step (9), nevertheless it seems to be generally granted that the direct oxidation of alcohol to acetic acid is difficult of accomplishment. Judging from the patent literature, the immediate source of acetic acid is acetaldehyde, using oxygen or air as the oxidizing agents, and various salts of cerium (8), manganese (d), iron ( I ) , vanadium (2), and other metals as catalysts in the liquid phase. Glacial acetic acid alone also catalyzes the oxidation of acetaldehyde.
Vol. 21, KO.12
In the presence of a substance such as acetic anhydride, the rate of oxidation was increased. As was stated before, it was believed that the slowness of the rate of oxidation was due partially to lack of intimacy of contact between the liquid and oxygen. Hence it was believed that the rate of reaction would be accelerated by stirring and by the presence of a catalyst. The catalysts tried were substances that had been found active for the vapor-phase oxidation of hydrocarbons. It should be remembered that, though a liquid phase is present in these experiments, it does not necessarily mean that the reaction takes place in the liquid phase. A probable place would be a t the gas-liquid interface in the gas film, as well as the liquid film. Experimental
Figure 1-Apparatus for Catalyst Testing
There are various sources of acetaldehyde. One source is the hydration of acetylene in the presence of a mercury salt. The vapor-phase oxidation of ethyl alcohol with various metal catalysts yields as high as 66 ( 7 ) to 78 per cent (10) conversions to acetaldehyde, depending upon the catalyst used, with losses as low as 5 per cent. Recently another possible source of acetaldehyde has been suggested in the partial oxidation products of natural gas and petroleum gases. Theoretical
It has been shown in the electrolytic oxidations of organic compounds that certain substances, such as cerium sulfate, which are capable of changing valence will act as oxygen carriers or catalysts. The mechanism of their behavior is that in their state of maximum valence they cause the oxidation of the organic compound and are themselves reduced. They are then re-oxidized by the anodic oxygen. Such a substance would therefore be a suitable carrier for the air oxidation of acetaldehyde to acetic acid, if it should have an oxidation potential high enough to bring about the oxidation of acetaldehyde and would be capable of re-oxidation by air. The rate of oxidation would then be determined by the slower of these tnw processes. Creighton and Fink (3) list the normal oxidation potentials of several metallic ions in acid solution. According to their table the ion having the highest oxidation potential was the cobaltic ion. It was thought that this ion might be the most active accelerator, and that manganic, ceric, ferric, and chromic ions w o u l d follow in the order mentioned. With this in mind the acetates of these metals and others were tried as accelerators in the oxidation of acetaldehyde to acetic acid by means of air or oxygen. Ethylbenzene (11) has been found to be oxidized by air or oxygen very slowly to acetophenone without a catalyst.
APPARATus-Since a very corrosive mixture was used in making most of the tests in this investigation, a glass container with a high-speed stirrer made of illium (12) was used, (Figure 1) It was found to be entirely unattacked by any concentration of acetic acid in the presence of oxygen. The oxidation of ethylbenzene was carried out with the illium stirrer in a closed system. The container used was a 250-cc. Pyrex beaker just large enough for the stirrer and the tube introducing the oxygen. An air turbine rotated the stirrer a t a rate of 5000 r. p. m. The beaker was fitted with a stopper of rubber covered with latex with a central opening for the stirrer. A bearing, with graphited asbestos cord packing, closed the opening about the stirrer practically gas-tight under the pressure maintained in the apparatus. The stopper was also fitted with openings for a filling funnel, a reflux condenser, the oxygen tube, a siphoning tube, and a thermometer which was bent to fit under the turbine, and then calibrated. The oxygen came from a cylinder equipped with a Hoke reducing valve, and was measured by an accurate flowmeter. The reaction beaker was heated with a steam bath. The tests using various catalysts in the oxidation of acetaldehyde to acetic acid in water-acetic acid solution were carried out in a liter beaker 19 em. tall and 10 em. in diameter. This beaker was supported inside a 1.5-liter beaker by means
Figure 2-Apparatus
for Alcohol Oxidation
of flat pieces of rubber stopper. The outside beaker was fitted with an inlet for steam and another for cold water and an overflow. The inner beaker was fitted with a large rubber stopper through which openings were cut for the bearing which closed around the stirrer, the filling funnel, the oxygen tube, the thermometer bent as described above,
December] 1929
INDUSTRIAL A N D ENGINEERING CHEMISTRY
and the siphon for emptying. There was also an opening for the condenser which led into wash bottles. The apparatus for the continuous oxidation of alcohol consisted of a copper catalyst for the dehydrogenation of the alcohol connected with the unit for the conversion of acetaldehyde to acetic acid. (Figure 2) PROCEDURE-Oxidation of Ethylbenrene. o n e hundred grams of ethylbenzene were placed in the reaction beaker with or without the catalyst, The oxygen was passed in a t a rate calculated to oxidize all the ethylbenzene in 24 hours. The stirrer was run a t a rate of about 5000 r. p. m., and the reaction was allowed to go continuously for 24 hours. At the end of this time the products were removed and 10 cc. tested for acetophenone with phenylhydrazine and semicarbazine. Tests with Catalysts for Oxidation of Acetaldehyde. Sufficient catalytic material was always made up so that the catalyst for each run in a series would have the s a m e composition. The concentration of catalyst present in each test was from 1 to 2 per cent by w e i g h t . F o u r h u n d r e d cubic c e n t i m e t e r s of t h e acetic a c i d s o l u t i o n were placed in the reaction vessel and kept a t a temperature of 70" C. About 30 grams of a c e t a l d e h y d e were added, and the stirrer per cen/ c t e f ~ AC/b ~u weqbf Figure 3 was started. The flow of oxygen was regulated by means of a Hoke valve, so that as the absorption capacity of the solution increased more oxygen would be released. As the oxidation proceeded the acetic acid concentration was kept constant by dilution with water to within 1 per cent by weight and the acetaldehyde concentration kept between 1.5 and 1.75 molal. The test was run for a t least an hour after the oxygen absorption had become constant. It was necessary to keep the temperature constant to within one degree; otherwise there would be an expansion of the gas in the system causing the Hoke valve to close or a contraction causing more gas to flow than was really being used, in either case making the reading on the flowmeter fluctuate. The problem of comparing rates of oxidation is discussed by Job (6). After the absorption had remained reasonably constant for an hour, the stirrer was stopped and an analysis made of the products of the reaction. After all the data had been obtained on the preceding test, the solution was diluted to a lower acid concentration and a similar test made. This was repeated until the acid Concentration was so low that the absorption was scarcely detectable. These data were then checked and the curve plotted. Oxidation of Alcohol to Acetic Acid. Two tests were made on the continuous oxidation of alcohol to acetic acid in two steps. (Figure 2) The procedure was identical in both tests, except that manganese acetate was used as the catalyst in the acetaldehyde to acetic acid section of the process in one test and cobalt acetate was used in the other. Air was caused to pass into a flask containing the 96 per cent (by volume) alcohol a t a rate of 80 liters per hour. The temperature of this alcohol was kept between 50" and 53" C. by means of a hot plate in order to maintain a ratio of about 5 mols of air to 1 mol of 96 per cent alcohol. The
1229
alcohol-air mixture then passed into the catalyst tube filled with highly activated copper gauze, which was kept a t 310" &IOoC. Forty to fifty per cent conversion of the alcohol to acetaldehyde took place in the catalyst tube, as was found by preliminary tests on this part of the process. The reaction products then passed into a large flask, where most of the alcohol and water condensed out with some of the acetaldehyde. Most of the acetaldehyde and the unused air passed on into the gas tube leading into the acetaldehyde-acetic acid solution, where about twice the calculated amount of oxygen was added from the oxygen cylinder. The acetaldehyde remaining in the alcohol-water solution, after being transferred to a distilling flask, was distilled over into the acetaldehyde-acetic acid system. The purity of the acetaldehyde distilled over was controlled by watching the temperature of the vapor coming over from the air-cooled bead column. The concentration of this acetic acid used in the acetaldehyde oxidation was maintained a t about 90 per cent. This was necessary to keep the rate of oxidation fast enough to prevent an accumulation of acetaldehyde in the acetic acid solution when manganese acetate was used as the catalyst. A run of 6 hours was made for each test. Discussion of Results O X I D ~ T I O NOF ETHYLBENZENE-The oxidation of ethylbenzene with oxygen has been carried out by means of the stirring apparatus a t 102-104" C. without a catalyst, and also the effects of several substances as catalysts have been tried. Runs of 24 hours each were made. The most significant data are given in Table I. Table I-Oxidation
of Ethylbenzene YIELD
ETHYLBENZENS
CATALYST
IN
Grams None
Acetic anhydride Manganese acetate Cerium oxide
100 3 3
CHARGE Grams 150 100 150
150
ETHYL-
OF
BENZENE
PHENONE
RATED
Grams
Grams
2.5 18.0 31.0 3.0
27 30 35 32
ACETO-
EVAPO-
Comparing the results of Stephens (11) with those of Table I, it seems that the stirrer did not increase the efficiency of the oxidation very much without the presence of a catalyst. Stephens obtained 9.5 grams of acetophenone from 50 grams of ethylbenzene in 24 days. Referring to Table I, the oxidation in one day without a catalyst was about 1.67 per cent. Stephens obtained a yield of 19 per cent in 24 days or less than 1 per cent per day. It might appear that the result without a catalyst in Table I was better than that of Stephens] but it is reasonable to believe that the oxidation is more rapid a t first owing to the absence of water, which is an inhibitor. However, the difference in yield per day is large enough to assume that tthe stirrer accelerated the rate of reaction a t least slightly. Comparison of the results with acetic anhydride shown in Table I with those of Stephens gives a better indication of the efficiency of the stirrer. According to Table I the yield using acetic anhydride was 18 per cent per day, while Stephens' yield was 36 per cent for 11 days or about 3l/? per cent per day. This indicates clearly that the absorption of oxygen was facilitated by the stirrer. It appears, too, that the more reactive the substance is toward oxygen, the more the stirrer facilitates the absorption of the oxygen. Manganese acetate was found to act as an accelerator, giving a yield of acetophenone of 20.6 per cent in 24 hours. This is better than in the case of acetic anhydride. Since only about 2 per cent manganese acetate was used, it seems that the effect of the manganese acetate was more that of a true catalyst than that of removing the inhibitor, water.
ISDUSTRIAL AND ENGIA-EERI-VG CHEMISTRY
1230
Various oxides mere tried as accelerators. Ceric oxide showed the best activity, which was little better than no catalyst a t all. Other acetates than that of manganese were tried but with little success. OXIDATIOK OF ACETALDEHYDE USINGVARIOUSCATALYSTSThe tests on the various substances used as catalysts for the oxidation of acetaldehyde to acetic acid were run under as nearly identical conditions as possible. There were some losses due to leakage of the apparatus a t the bearing, around the stirrer. However, this loss was between 1 and 3 per cent and was quite constant. The percentage yield of acetic acid, based on the acetaldehyde used, varied from 95 to 98 per cent depending upon the rate of oxidation in the solution. The more rapid the oxidation of acetaldehyde the higher was the yield of acetic acid and the lower the yield of carbon dioxide. The yields of carbon dioxide varied from 1 to 3 per cent. The results of the catalyst tests are given in Table I1 and Figure 3. Table 11-Oxidation CATALYST
Acetate of cobalt
Acetate of nickel
Acetate of manganese
Acetate of vanadium (brown)
of Acetaldehyde b y Oxygen ACETIC ALDEHYDE ACID CONVERTEDOXYGEN IN TOACETIC ABSORPCHARGE ACID TION Per cent b y wt. Per cent Liters Der hour 98.0 25.0 93 97.5 88 15.0 97.0 6.0 81 97.0 4.0 77.5 97.0 2.0 70 97.0 0.5 60 12.0 97.0 93 10.0 97.0 86 97.0 7.0 77 97.0 3.4 70 0.5 97.0 67 8.4 97.5 93 97.5 91 7.0 97.0 4.6 86 96.0 2.4 81 96.0 0.5 75 97.0 7.0 93 97.0 90 6.2 97.5 86 5.2 4.0 80 97.0 70 96.0 2.4 60 96.0 0.7
Acetate of cerium
93 90 83 70 60
97.5 97.5 97.0 97.0 96.0
5.0 4.2 3.0 1.0 0.4
Acetate of vanadium (green)
93 90 83 75
96.0 96.0 95.0 95,o
4.0 3.6 1.0 0.4
Acetates of iron and chromium
93 90 85 80 93 91 84
95.0 95.0 94.0 94.0 95.0 95.5 95.0
3.0 1.6 1.0 0.5 2.0 1.0 0.2
Glacial acetic acid
The rate of oxidation was found to decrease with a decrease in concentration of acetic acid in the solution in every series of tests. The decrease in rate of oxidation with the decrease in acetic acid concentration in the presence of cobalt, manganese, and nickel was very great. On the other hand, the decrease in rate of oxidation with decrease in acetic acid concentration in the presence of cerium and vanadium salts was not nearly so great. This general decrease in rate of oxidation with decrease in acetic acid concentration seems t o agree with Wieland’s results (IS). Cobalt ion was found to be the greatest accelerator of the oxidation of acetaldehyde to acetic acid, with nickel second, and manganese third. The activity of cobalt was demonstrated by the fact that the solution became brown in the presence of an excess of oxygen, but if only a deficiency of oxygen were added, for instance by decreasing the flow of oxygen into the stirring apparatus, the solution became lighter rapidly and finally was a light pink, the color of the
Vol. 21, s o . 12
cobaltous ion. The absorption under these conditions was about one-half the rate of absorption when the brown color mas evident. In the presence of manganese the absorption was not so rapid as in the presence of cobalt, but the same color changes were evident, which indicates that manganese acts in the same way that cobalt does in the acceleration of the reaction. The activity of cerium and vanadium salts did not decrease as rapidly with decreasing acid concentration as the actirities of the other catalysts. KO color changes were evident in the cerium solutions. A brown acetate of vanadium was obtained if the solution was treated with oxygen before acetaldehyde was added. The solution then stayed brown throughout the test. If an excess of acetaldehyde was added and then treated with oxygen, the solution would stay green and the rate of oxidation was consistently less than the rate of oxidation of the brown solution. Iron and chromium showed slightly better activities than glacial acetic acid alone. Various combinations of catalysts were tried, but in no case did any combination show an activity greater than the most active one of the group. Other substances, such as turpentine, xylene, oxides of nitrogen. Fehling’s solution, and various insoluble oxides, were tried, but either they had little effect or else the effect was too small compared with the complications involved in their use, so that they were not practical as accelerators for the reaction. Various substances were found to have an inhibitive effect. Iron decreased the effect of manganese and cerium. Substances dissolved by acetic acid splashing up on the rubber stopper had a poisoning effect upon the catalyst. This was remedied by covering the stopper with a layer of latex, letting it dry, and then treating it with acetic acid. Also care was taken to keep the solution from splashing up to the stopper. Tests on the oxidation of acetaldehyde to acetic acid in the presence of the various catalysts were made using air. The general shape of the curves was the same. However, the yields of acetic acid were slightly lower, and the yield of carbon dioxide higher due to acetaldehyde being carried over by the excess air and the probable vapor phase oxidation of the aldehyde taking place. Tests using manganese acetate and cobalt acetate are typical. The runs were always one hour. T a b l e 111-Oxidation of Acetaldehyde b y Air ACETIC ALDEHYDE ALDEHYDE ACETALACID CONVERTEDCONVERTEDDEHYDE CATALYST IN TOACETIC TO CARRIED CHARGE ACID COZ OVER Per cent b y w l . Per cent Per cent Per cent Manganese acetate 93 94.0 5.0 21 90 93.5 5.0 20 80 93.0 5.5 18 93 95.0 4.5 20 Cobalt acetate 88 94.5 5.0 18 81 94.0 5.0 16
The percentage of the acetaldehyde carried over decreased slightly with the decrease in acetic acid concentration, being held in solution by the high percentage of water. THE COKTINUOUS OXIDATIONOF ALCOHOLTO ACETIC AcID-Tests were made using cobalt acetate and manganese acetate as the catalysts for the acetaldehyde to acetic acid step. The tests were made for 6 hours. The most successful results are given in Table IV. T a b l e IV-Oxidation of Alcohol to Acetic Acid ALCOHOL CONVERTED RECOVERED ALCOHOL YIELD TO ACID COZ AS ALDEHYDEUNACC. FOR USED Per cent Per cent Per rent Per cenl Mol per hour Per cent COBALT ACETATE IN 9OPER CENT ACETIC ACID SOLUTION
0 72
621
7 8
278
2 3
89.9
MANGANESE ACETATE I N ~ O P E R CENT ACETIC ACID SOLUTION
0 57
502
8 2
382
3 4
88 4
IXDUSTRIAL AAVD ENGINEERING CHEMISTRY
December, 1929
The percentage yield is calculated on the basis of recoTered product's. These results shorn that it is possible to oxidize alcohol continuously to acetic acid in two steps with a yield of 90 per cent by weight. With the present stage of development' of non-corroding metals, the necessary equipment for such a process on an industrial scale seems possible. Literature Cited (1) Behrens, German Patent 287,360 (1913); C. d.,10, 212: (1916). 12) Chem. Fabrik Griesheim-Elektron, British Patent 17,424 (July 31, 1911); C . . A , , 7, 399 (1913).
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(3) Creighton and Fink, "Principles and Applications of Electrochemistry," Vol. I, p. 229. (4) Galitzenetein a n d Mugdon, U. S. Patent 1,179,420; C. 4 . , 10, 1878 (1916). ( 5 ) Jaeger, IND. END.CHEX.,20, 1330 (1928). (6) Job, Compt. r e n d . , 142, 1413 (1906). (7) Orloff, J . Russ. Phys. Chem. S O L ,40, 203 (1938). ( 8 ) Meister, Lucius, and Bruning, British Patent 10,377 (April 27, 1914) ; J . SOC.Chem. I n d . , 33, 961 (1914). (9) Naumann, Moeser, and Lindenbaum, J . prabt. Chem., 76, 146 (1907). (10) Simington a n d Adkins, J . Am. Chem. Soc., SO, 1449 (1928). (11) Stephens, I b i d . , 48, 1824, 2920 (1926); 60, 2523 (1928). (12) University of Illinois Eng. Expt. Sta., Circ. 19. (13) Wieland, Be?., 46, 2606 (1912).
1 -Amino-2,4-Dichloroanthraquinone'
,
A few of these substitu' The preparation of l-amino-2,4-dichloroanthraquin- derivative bytheexhaustively tion products are described chlorohyhere to illustrate the Fide drate of l - a n i i n o a n t h r a j one here described is a remarkable illustration of the utility of compounds of this preparation of an anthraquinone body through a quinone and finally, through t y p e . when 1-amino-2,4ti ng Of the anthrabenzoylbenzoic acid synthesis after many attempts to dibromoanthraquinone is prepare it directly from aminoanthraquinone had quinone ring, a ketonic acid. condensed with aniline or After a continued study we concluded that l-amino-2,4one of its homologs alizarin dyestuff bases are dichloroanthraauinone formed. More specifically, could be more economically when p-toluidine is condensed with this compound and the prepared through a benzoylbenzoic acid synthesis than from condensation product sulfonated, alizarin blue, an acid wool 1-aminoanthraquinone. dye, is obtained. If l-methylamino-2,4-dibromoanthraquinThe synthesis thereupon planned resulted in a successfuI one is condensed with an aromatic amine and the product method of preparing l-amino-2,4-dichloroanthraquinonein sulfonated, another acid wool dye is obtained. If the alizarin practically a pure state. m-Dichlorobenzene is treated with blue base is condensed in a suitable diluent in the presence phthalic anhydride and aluminum chloride as in preparing of copper and sodium acetate, a ditolylamidoinclanthrene is other benzoyl-0-benzoic acids. The resulting product is then is acety- nitrated and the nitrodichlorobenzoyl-o-benzoic acid is reduced obtained. When l-amino-2,4-dibromoanthraquinone lated and the resulting product condensed a member of the to the amino body. The amino body is condensed to the anthrapyridone series is obtained. When the amine group is anthraquinone by the use of known condensing agents, prefdiazotized and then transformed into the hydrazine group erably sulfuric acid monohydrate. The yield in each step of and the latter body condensed, dyestuffs of the pyrazole the process is high. Because of the number of steps in the anthrone yellow series are obtained. Similarly, other group- process, however, the yield of final product from the m-diings important in vat dyestuff synthesis may be introduced chlorobenzene amounts to only about 70 per cent of theory. into the anthraquinone molecule by the use of this compound. Theoretical It occurred to us that for many purposes, especially the A theoretical study of the original material, the subsequent preparation of dyestuffs in which the original halogen of the anthraquinone molecule does not appear in the final dyestuff, substitution products, and the ring closing of the aminobut is eliminated from the molecule in the various condensing dichlorobenzoylbenzoic acid suggests that the chemical strucreactions to produce the dyestuffs, the corresponding l-amino- tures of the compounds are well adapted for the above syn2,4-dichloroanthraquinone should be equivalent to the corre- thesis. I n the preliminary condensation of m-dichlorosponding bromo compound and should have the advantage of benzene the chlorine atoms, being meta to one another, being cheaper, bromine being replaced in the original material mutually and collectively exert a para-ortho directing influence on an entering group. I t is known that the di-ortho by the less expensive chlorine. We made a study of the literature, but were unable to find position between meta substituents is a rather less reactive a method for preparing l-amino-2,4-dichloroanthraquinone. position. The entrance of the benzoylcarboxylic acid radical Our first attempts therefore were based upon analogous is therefore restricted to practically one position; that is, para to one chlorine atom and ortho to the other. In a similar 1 Presented before t h e Division of Dye Chemistry a t t h e 78th Meettreatment of either 0- or p-dichlorobenzene the reported yields ing of t h e American Chemical Society, Minneapolis, Minn., September 9 are substantially lower than we have experienced in this isot o 13, 1929.
1
