I-VDCSTRIAL A S D ESGIA-EERISG CHEMISTRY
July, 1925
721
The Preparation of 2-Aminoanthraquinone from Phthalic Anhydride and Chlorobenzene'.' By Max Phillips COLORL+BORATOhY, B L R E A LO F CHCVISTRY, V V A S H ~ ~ G T O D V C
In the preparation of chlorobenzoylbenzoic acid from The yield is practically quantitative-97 per cent of the phthalic anhydride, chlorobenzene, and aluminium theoretical. The various experiments on the preparation of 2chloride, the most favorable yield is obtained when the molal ratio of phthalic anhydride to aluminium chloride aminoanthraquinone from 2-chloroanthraquinone indiis 1:l. To carry out this preparation successfully an cate that the optimum experimental conditions are as excess of chlorobenzene should be used, about 4 to 5 follows: temperature, 220" C. ; reaction period, 6 hours; mols to 1 mol of phthalic anhydride. The optimum concentration of ammonia with respect to 2-chloroanreaction temperature is 100' C. The yield chloro- thraquinone, 20:1, although a 15:l ratio gave nearly as benzoylbenzoic acid is about 77 per cent of the theo- good results. The 2-aminoanthraquinone obtained under these conditions is 95 per cent pure and the yield is 91 per re tical. The conversion of chlorobenzoylbenzoic acid into 2- cent of the theoretical. The addition of catalysts such chloroanthraquinone may be brought about by heating as copper sulfate or copper powder to the reaction mixture it at 150' C. for 4 hours with sulfuric acid (sp. gr. 1.84). is undesirable.
. . .. .. .. X 1912 the Badische dnilin und Soda Fabrik obtained a patent3 on a process of making 2-aminoanthraquinone from 2-chloroanthraquinone. Two methods of preparing 2-aminoanthraquinone are described in the patent, one consisting in heating together in an autoclave 1 part of 2-chloroanthraquinone and 20 parts of 25 per cent aqueous ammonia a t 200" C. for 24 hours, and the other in heating in an autoclave 1 part of 2-~hloroanthraquinone,16 parts of ammonia, and 8 parts of copper sulfate a t 200" C. for 26 hours. The 2-aminoanthraquinone thus obtained is claimed to be pure and the yield nearly quantitative. A survey of the literature shows that no detailed study has been made of this process. Accordingly, it was undertaken in this labroatory with a view of ascertaining the optimum conditions for converting 2-chloroanthraquinone into 2aminoanthraquinone. This was subsequently extended to include also the preparation of 2-chloroanthraquinone from chlorobenzene and phthalic anhydride. The several reactions involved in the preparation of 2aminoanthraquinone from phthalic anhydride :tnd chlorobenzene may be represented by the following structural formulas :
I
0
0-J C o-\ II
13-CI
+
It
H/
0 Phthalic anhydride
chlorobenzoylbenzoic acid, a series of experiments was carried out in which the quantity of aluminium chloride added to the reaction mixture was the sole variable. I n all these experiments 5 mols of monochlorobenzene to 1 mol of phthalic anhydride was used, this optimum proportion having been determined through preliminary experiments. METHOD-Twenty-nine and six-tenth grams (0.2 mol) of finely ground phthalic anhydride and 112.5 grams of monochlorobenzene (1 mol) were placed in an Erlenmeyer flask provided with an inverted condenser a t the end of which was attached a calcium chloride tube. The requisite amount of powdered aluminium chloride was added and the flask containing the reaction mixture heated on the steam bath until no more hydrochloric acid was given off, which required about 8 hours. It was then allowed t o cool t o room temperature and ice water added t o it. This mixture was steam-distilled and the chlorobenzene that distilled over was collected and weighed. The residue remaining in the flask was filtered off, washed with hot water, and then repeatedly extracted with a 20 per cent sodium carbonate solution until free from chlorobenzoylbenzoic acid. The sodium carbonate solution was made acid with dilute sulfuric acid and the chlorobenzoylbenzoic acid separated out as colorless crystals, which were filtered off, and dried a t 110" C.
The chlorobenzoylbenzoic acid thus obtained (with the exception of that of Expt. 1, Table I) was pure, as indicated by chlorine determinations.
- o--Co--3" AIzCls
-COOH
T a b l e I-Effect of Amount of AIzCls on Yield of C h l o r o b e n z o y l b e n z o i c Acid Temperature,llOOO C.; molal ratio of phthalic anhydride t o chlorobenzene, 1 : 5 (29.6 grams phthalic anhydride a n d 112.5 grams chlorobenzene) Yield of Yield of CI in chlorobenhIolal ratio Chloroben- chloroben- chloroben- zoylbenof phthalic zene zoylbenzoylbenzoic acid anhydride recovered zoic acid zoic acid Per cent of Expt. to AlzClc Grams Grams Per centn theory 1 1:o.z 110 1.0 13.31 1.9 2 1:0.75 91 21.0 13.57 40.3 3 1:l 82 40.5 13.63 77.7 4 1:l.S 88 41.0 13.71 78.7 5 l:2 88 39.5 13.64 75,s aPer cent chlorine calculated for ClrHoOaCI, 13 60.
CrC0.-c" o-c0-.3"" Chlotobenzene
Chlorobenzoylbenzoic acid
",OH
HASO,
-co--
--f
-co---
__f
2-Chloroant hraqumone
2-Aminoanthraquinone
Experimental Chlorobenzoylbenzoic Acid
In order to determine the minimum amount of aluminium chloride (-41zC16)required to obtain the maximum yield of 1 Presented before the Division of Dye Chemistry a t the 68th Meeting of the American Chemical Society, Ithaca, N. Y., September b to 13, 1924. 2 Contribution No 103 from the Color Laboratory. 3 German P a t e n t 295,624.
It will be observed from Table I and Figure 1 that practically the maximum yield of chlorobenzoylbenzoic acid was obtained when the molal ratio of phthalic anhydride to aluminium chloride was 1:l. Heller,4 in studying the reaction between benzene, phthalic anhydride, and aluminium chloride, also found that the maximum yield of benzoylbenzoic 4
2. a n g e w Ciiem., 19, 869 (1906).
INDUSTRIAL A N D ENGINEERING CHEMISTRY
722
acid was obtained when the molal proportion of phthalic anhydride to aluminium chloride was 1 :1. Conversion of Chlorobenzoylbenzoic Acid into 2-Chloroanthraquinone
The chlorobenzoylbenzoic acid was prepared from phthalic anhydride and chlorobenzene using optimum conditione ascertained in the series of experiments described above. The product after one crystallization from benzene melted sharply a t 148' C. A chlorine determination on this product gave the following results: Substance 0.2506 0.2002 gram' AgCl 0.1420 0 1095 gram Calculated for Clrk~OaCl,13.60'per cent CI; fo'und, 13.53, 13.53per cent
In order to determine the necessary conditions for the conversion of chlorobenzoylbenzoic acid into Z-chloroanthraquinone, two series of experiments were conducted, one a t 100' C. and the other a t 150" C., in which the proportion of sulfuric acid (sp. gr. 1.84) to chlorobenzoylbeneoic acid was the only variable. 80 70
60 40 20
IO 0.75 I 1.5 2 Mols AIzC18 Figure 1-Amount of A l u m i n i u m Chloride Added t o Reaction Mixture a8 Related t o Yield of Chlorobeneoylbenzoic Acid
0.5
METHoD-Thirteen and three-hundredth grams (0.05mol) chlorobenzoylbenzoic acid and the requisite amount of sulfuric acid were placed in an Erlenmeyer flask and the mixture was heated in an oil bath at 150' C. for 4 hours. The reaction mixture was subsequently cooled t o room temperature and then poured into several times its volume of cold water. The precipitate of crude 2-chloroanthraquinone was filtered off, washed first with dilute sodium carbonate solution and then with water, and finally dried at 110' C. This product was extracted with benzene in a Soxhlet extraction apparatus and the r( sidue obtained on evaporation of the benzene was dried a t 110" C. and weighed.
Vol. 17, No. 7
Substance 0.2075 0.1889 gram. AgCl 0.1225 0.1114 gram Calculated for ClrHrO&I: 14.6iper ceht CI;fo'und, 14.60,14.58 percent
Ammonium Hydroxide. The ammonium hydroxide used in all the experiments was the ordinary C. P. article of 0.90 specific gravity. APPAmTuS-The apparatus5 used to study the reaction between 2-chloroanthraquinone and ammonia is shown in Figure 3. It consisted of a sheet-iron tank, A , which was surrounded by heat-insulatinp material, C, and the whole contained in wooden case B . Tank A was filled to the proper level with heavy cylinder oil, which was heated by electric heating coil D and kept in circulation by stirrer H . I t was also provided with two auxiliary electric heating coils E and E', which were used only to bring the bath rapidly up to the required temperature. The temperature of the bath was controlled by thermostat F operating a relay (not shown) which controlled the current passing through coil D. The temperature was indicated by a thermometer inserted in well G. The reaction was carried out in two specially constructed steel bombs, I and Z', consisting essentially of a steel chamber provided with a top, nut, and lead gasket. With this arrangement there was no difficulty in keeping the reaction chambers gastight. The steel bombs were held in place in carrier J by clamp K and screw L,and were rotated endwise by means of a train of gears driven by electric motor 5'. The carrier was. raised and lowered by racks M , M', and pinions N , N' opented through crank 0. It was held in position when either raised o r lowered by means of ratchet gear and stop P. The carrier revolved in bearings Q, Q'. and moved on guides R, R'. The stirrer H was operated by motor S through gears V , W , and T . Throughout the experiments it was possible to keep within one degree of the desired temperature.
METHODS-In working out the most favorable conditions for the conversion of 2-chloroanthraquinone into 2-aminoanthraquinone, it was necessary to determine experimentally the following factors: (1) proper reaction temperature, (2) proper reaction period, (3) ratio of ammonium hydroxide to 2-chloroanthraquinone, and (4) the effect of various catalysts. With the apparatus used, the effect upon the yield of 2aminoanthraquinone of each of these factors could be very conveniently studied. The first series of experiments, t h e determination of optimum reaction period, was conducted a t 200' C. With the ratio of 2-chloroanthraquinone t o ammonium hydroxide constant-namely, 1 : 20 (5 grams of 2-chloroanthraquinone to 100 grams of ammonia)-experiments were performed in which the time of reaction was t h e only variable. Similar experiments were conducted a t 220" 100
Table 11-Effect of Varying Q u a n t i t y of Sulfuric Acld Temperature, 150" C . ; 0.05 mol chlorobenzoylhenzoic acid (13.03 grams) ; reaction Deriod. . .4 hours YIELD OF 2-CHLOROANTHRA2-ChloroRatio of chloroQUINONE anthraquinone henzoylbenroic Crude Pure Per cent yield Erpt. acid to H2S0, Grams Grams of theory
I
90 80 70
50 6o
11 111111111111 I 2 3 4 5 6 7 8 9 l o l l 12
PAR75 Hz 5 0, Table I1 and Figure 2 show that practically the maximum yield of 2-chloroanthraquinone was obtained when the ratio of chlorobenzoylbenzoic acid to the sulfuric acid was 1:6 . Thc product obtained in Expt. 1 was considerably darker than that obtained in the other experiments. A similar series of experiments conducted at 100' C. yielded only small amounts of 2-chloroanthraquinone. Conversion of 2-Chloroanthraquinone to 2-Aminoanthraquinone About 300 grams of this MaTE~1a~s--2-~k~oroanthraguinone. compound were prepared using the optimum conditions as determined from the preceding experiments. The product was crystallized twice from benzene and dried at 120' C. It melted sharply a t 204' C. A chlorine determination made on this material gave the following results:
Figure 2-Amount of Sulfuric Acld Added to Reaction Mixture a8 Related to Yield of 2-Chioroanthraquinone
and 180' C., and from the results thus obtained the optimum reaction period and temperature were deduced. Experiments were subsequently conducted a t M O O , 200', and 220' C., where the reaction period remained constant but where the ratio of 2-chloroanthraquinone to ammonia varied, and from these experiments the optimum concentration of ammonia with respect to 2-chloroanthraquinone was ascertained. In the same manner the effect of various catalysts was studied. Isolation and Analysis of the Reaction Product At the end of each experiment the steel bombs were cooled by immersion in cold water. They were subsequently opened 6
Constructed by R . Hellbach, of the mechanical staff of this laboratory.
July, 1925
I N D U S T R I A L A N D ENGINEERING CHEAIIISTRY
I//
~
Figure 3-Apparatus
for Studying Reaction between 2-Chloroanthraquinone and Ammonia
723
ISDCSTRIAL ASD ESGIiY'EERISG CHEMISTRY
724
and the reaction mass was carefully transferred to a beaker. The crystalline product, consisting principally of 2-aminoanthraquinone, and in some of the experiments also unconverted 2-~hloroanthraquinone,was filtered off , washed with water, dried, and its weight determined. This was analyzed for 2-aminoanthraquinone and for 2-chloroanthraquinone by methods described elsewhere in this paper. The ammoniacal filtrate, which in most of the experiments was violet in color,
Vol. 17, No. 7
time of reaction was the only variable. All experiments on the conversion of 2-chloroanthraquinone into 2-aminoanthraquinone were performed in duplicate and are recorded in the tables as ( a ) and ( b ) . Table 111-A indicates that the yield of 2-aminoanthraquinone increases with increase in the time of reaction, reaching the maximum practically a t the end of 10 hours. Following the same procedure, two series of experiments were conducted a t 220" and 180' C., respectively. It will be observed from Table 111and Figure 4 that greater yields of 2-aminoanthraquinone were obtained a t 220 " C. than a t 200" C., and that the reaction proceeds much more rapidly, reaching very nearly the maximum a t the end of 4 hours. Attention is also called to the purity of the product, particularly in Expts. 3 and 4. At 180" C. the reaction proceeded very slowly and the yields were decidedly low. From the results 220" C. seems to be the optimum temperature for the conversion of 2-chloroanthraquinone into 2-aminoanthraquinone. Effect of Amount of Ammonia on Yield of 2-Aminoanthraquinone
Curve 1-200' Curve 2-220' Curve 3-180'
To determine the optimum concentration of ammonia with respect to 2-chloroanthraquinone, two series of experiments were carried out, one a t 200" C. and the other a t 220" C., keeping the time of reaction constant (6 hours) but varying the amount of ammonia. The results in Table IV indicate that a t 220" C. practically the same yield of 2-aminoanthraquinone was obtained when 1.5parts of ammonia to 1 part of 2-chloroanthraquinone were used as when 20 parts of ammonia were used. At 200" C.,
C. C. C.
was acidified with nitric acid, the red flocculent precipitate filtered off, and the filtrate made up t o a definite volume and analyzed for chlorine (present as chloride) by the Volhard method. From the results thus obtained the precentage of 2-chloroanthraquinone used up in the reaction was computed. This is recorded in the tables in the column headed "2Chloroanthraquinone Consumed, Per cent ." This calculation was based on the assumption that in the reaction between chloroanthraquinone and ammonia one mol of ammonium chloride results for every mol of chloroanthraquinone converted into 2-aminoanthraquinone1 as represented by the following equation:
co
/ \
C6H4
co
C6Hs.Cl
\
'CO
/
/
+ 2 SHdOH = CnHd\
\
CsHs.NH2
'co'
/
+ NHdC1 f 2 HzO
DETERMIN.4TION O F 2-CHLOROA4NTHRAQUINONE I N THE REACTION PRoDucT-This was accomplished by analyzing the product for chlorine and from this calculating the percentage of 2-chloroanthraquinone. DETERMINATION OF ~ - A M I N ~ A N T H R A Q U I N O N E - T ~ was ~S determined by the du Pont official method,6 which consists in estimating the amount of standard sodium nitrite solution required for the diazotization of the 2-aminoanthraquinone.
Experimental Data Effect of Time and Temperature on Yield of 2-Aminoanthraquinone
Csing the same amount of 2-chloroanthraquinone and ammonia in each case ( 5 grams of 2-chloroanthraquinone and 100 grams of ammonia) and keeping the temperature constant a t 200" C., experiments were conducted in which the e The writer is indebted t o E. K Bolton for a detailed description of the official du Pont method for determination of 2-aminoanthraquinone.
when the ratio of 2-chloroanthraquinone to ammonia was either 1:IO or 1:15, the yields of 2-aminoanthraquinone were decidedly low and the product was impure. Effect of Addition of Catalysts
In the Badische patent3 it is claimed that nearly quantitative yields of 2-aminoanthraquinone are obtained when catalysts such as copper sulfate or copper powder are added to the reaction mixture. Accordingly, experiments were conducted a t various temperatures-namely, 180°, 200", and
ISDCSTRIAL A S D ESGIiVEERISG CHEMISTRY
July, 1925
T a b l e 111-Effect
725
of V a r y i n g Time of R e a c t i o n 1: 20 ( 5 grams t o 100 grams)
Ratio of 2-chloroant.hraquinone t o h"4OH,
Time of reaction Hours
Expt.
2-Chloroanthraquinone consumed Per cent
4
4.4119 4.4366 4,449s 4.5332 4.3751 4.3713 4.2761 4.2615 4.3511 4,3354
(,
5 10 12
I
4 6
b
1
6
2
8
2-Chloroanthraquinone CI in in reaction reaction product (calcd. product from 70C1) Per cent Per cent .4-Temperalure, ZOO' C 38.10 37.90 15.76 15.97 8.96 8.61 6.70 5,SS 3.46 2.05 B-Temperalure, 220' C 2.59 17.70 2.31 15.80 0.27 1.84 0.30 2.0.5 0.09 0.81
Weight of reaction product Grams
86.2 (bj 86.2 (a) 99.6 (b) 99.2 (u) 99.6 (b) 99.4 (a) 99.8 (b) 99.8 ((1)
22.2 ( b ) 22.2 (n) 26.4 (b) 25.9
(Q)
4.4i5S
4.4865 4.4240 4.4133 4.4149 4.4474
0.34 0..
O.Ob
.
o...
4,4045
4.3904
O... C-Temperature, 11,7 5 11.87 11.40 11.51
4.696i 4.6535 4.7458 4 . 7445 T a b l e IV-Effect
0..,
2 Aminoanthraquinone in reaction product Grams Per cent
2-Aminoanthraquinone Per cent yield of theory
58.7 59.1 51.8 81.6 86.2 86.0 92.8 91.2 93.0 92.6
18.0
3,5895 3.6610 4.1054 4.1354 4.2073 4.1983 4.1974 4 1006
80.2 81.6 92.8 93.7 95.3 94 4 95.3 93 4
79.5 89.2 89.9 91.4 91.2 91.2 89.1
0.8594 0.8236 0.9254 0.9156
18.3 17.7 19.5 19.3
18.6 17.9 20.1 19.9
180' C.
80.4 81.2 78.0 78.7
of V a r y i n g the A m o u n t of A m m o n i a
Reaction period, 6 hours
Expt
Ratio of 2-chloro2-Chloroanthraanthraquinone quinone consumed to ammonia P e r cent
1
1:13
la) 62.9 (b) 62.3
2
1:10
( a ) 29.80
( b ) 29.80
1
1:l5
2
1:lO
( a ) 99.4
(bj 9 9 . 2 ( u ) 89.85 ( b ) 90.39
2-Chloroanthraquinone in Weight of CI in reaction reaction product reaction product product (calcd from % C1J Grams Per cent Per cent .=-Temperature, 200' C . 4 , 135.3 5.20 35.60 4.0053 5.15 35.22 4,6932 10.58 72.37 4.643s 10,66 72.92 E-Temperature, 220' C . 4.3462 0.15 1.02 4.374:3 0.07 0.47 4 ,448.; l.i4 11.90 4,422'7 1.61 11.01 T a b l e V-Effect
Expt.
Time of reaction Hours
1
6
2
6
3
4
4
4
5
2
6
2
2-ilminoanthraquinone in reaction product Grams Per cent 2,5018 2.3875 1.1263 1.1470
60.5 59.6 24.C-l 24.J
4.0941 4.0899 3.7011 3.6883
94.2 93.5 83.2 83.4
2- Aminoanthraquinone Per cent yield of theory
of C a t a l y s i s
Ratio of 2-chloroanthraquinone t o NH-OH, 1: 20 ( 5 grams t o 100 grams); 0.5 gram catalyst used in each experiment 2-Chloroan2-Amino2-Amino2-Chlorothraquinone anthraanthra: anthralyeight of Cl in in reaction quinone quinone in quinone reaction reaction product (calcd.) reaction reaction product ' product consumed product product from % CI) Catalyst Per cent Grams Per cent Per cent Grams Per cent Temperalure, 180' C. 10.39 71.07 1.1899 25.9 CuSO4.5HzO ( a ) 32.13 4.5945 ( b j 31.82 4,6088 10.1s 69.64 1.2936 25.9 C!u powder (a) 60.73 6.89 47.13 2.0478 47.7 4.2932 ( b ) 59.86 4.3920 6.96 47.61 2.0642 47.0 Tempcrature, 200' C. CuSOi.5H.O ( a ) 67. 92 4,3600 5.27 36.03 2.6988 61.9 ( b ) 66.56 4.3620 5.40 36.94 2.6477 60.7 Cu powder (a) 93,62 3 9269 0.83 5.67 3.2750 83.4 ( b ) 95.00 3.9231 0.76 5.20 3.2914 83.9 Temperalure, 220' C. CUSOL~H~O (a) 91.10 4.3963 1.63 11.15 3.7368 85.0 ( b ) 91.10 4.4328 1.61 11.01 3.7630 84.8 C u powder (a) 98.77 4.1126 0.25 1.71 3.4299 83.4 ( b ) 99.45 0.21 1.43 3.40i5 83.4 4.0858
220O-to ascertain the effect of these catalysts' on the yield of 2-aminoanthraquinone. In comparing the results obtained in these experiments (Table V) with those in which no catalyst was used, it is seen that in most of the experiments the catalytic effect of copper sulfate was not very pronounced and was generally inferior to that of copper powder. Although these catalysts when added to the reaction mixture tend to give greater yields of 2-aminoanthraquinone, the yield in proportion to the 2chloroanthraquinone used up in the reaction is actually less. T h e copper powder used for these experiments was prepared according t o t h e method of Gatterman a s modified by Ullmann a n d Ihelecki, Ber , 34, 2175 (1901).
89.0 88.9 80.4 80.1
2-Amino. an,thraquinone Per cent yield of theory
2 j .8 28.1 41.5 44.6 58.6 57.5 71.2 71.5
81.2 81.8 24.5 (4.0
This is because copper powder and, to a lesser extent, copper sulfate bring about another reaction, resulting in the formation of a substance which remains dissolved in the ammoniacal liquors and is apparently hydroxyanthraquinone. Thus in Expts. 6 (a) and ( b ) , although practically all the chloroanthraquinone was used up in the reaction, nevertheless, the yield of 2-aminoanthraquinone was only about 74 per cent. In this experiment, in addition to the 2-aminoanthraquinone, 0.60 gram (or 12 per cent of the weight of the 2-chloroanthraquinone used in this experiment) of ammonia-soluble material was obtained. It would seem, therefore, that, taking all factors into consideration, the addition of either copper sulfate or copper powder to the reaction mixture is undesirable.
