INDUSTRIAL AND ENGINEERING CHEMISTRY
April, 1927
I n a recent paper Lewis and Riesl* have attempted a n analysis of Knietsch's data and have reached the conclusion t h a t the reaction velocity equation must be stoichiometric. Since the results of the calculations on which this conclusion is based are given for only one temperature, at which the constancy of the calculated velocity constant is less complete than could be desired, it is difficult t o judge whether the third o r d e r equation is really satisfactory. Such a n equation is not necessarily a n impossibility theoretically for a catalyzed reaction, but i t is very improbable, as is shown by the considerations advanced in the first part of this paper. By means of their equation Lewis and Ries found t h a t the third order velocity c o n s t a n t passes through a maximum at about 525" C. 1 2 3 4 and decreases rap1/F idly a t higher temFigure +-Data of Knietsch on Contqct p e r a t u r e s . This Sulfuric Acid Reaction appeared necessary t o account for the fact, noted b y Knietsch, that, although the conversion obtained a t about 500" C. was always a large fraction of the equilibrium value? the actual equilibrium value was not reached even a t temperatures several hundred degrees higher. Unfortunately, the method of temperature measurement is not stated in Knietsch's paper; nevertheless, i t appears 11
THISJOURNAL, 17, 593 (1925).
497
certain that equilibrium was obtained at all temperatures above about 550" C., but owing t o the large heat evolution in the reaction the actual equilibrium reached corresponded t o a catalyst temperature as much as 50 or more degrees higher than that of its surroundings. A similar behavior, though less pronounced, was noted by Unger in the experiments on ammonia synthesis previously cited. Effect of Quantity and Shape of Catalyst
It may be noted that when the reaction product is strongly adsorbed the percentage of this product in the exit gases (100 X) is nearly proportional to the square root of S and, therefore, to the square root of the amount of catalyst. For this reason most of the reaction occurs a t the entrance end of the catalyst, the remainder being progressively poisoned by the product toward the exit end. Apparently the only hope of avoiding this waste of catalyst in practice is to use several converters in series and remove the product formed in each converter before the gases pass on to the next. Such an arrangement would also tend to minimize the undesirable effects of the "hot spot" which is always present in exothermic reactions, but which must be especially pronounced when the reaction is largely localized at the entrance end of the catalyst. In any reaction, whether or not the products are adsorbed, and irrespective of the presence or absence of the reverse reaction, the percentage of product in the exit gases is always a function of the quantity of catalyst (as represented by S) divided by the flow rate-i. e., a function of the space velocity. Therefore, doubling the amount of catalyst produces the same change in X as halving the rate of flow, regardless of the shape of the catalyst mass. Only when the conditions are not uniform over any given cross section of the catalyst a t right angles to the direction of flow would a shape factor be expected to intrude.
A Proposed New Food Dye' By H. Johnson and P. Staub COLOR
LABORATORY, WARNSR
T
HERE are a t present two green dyes on the list of
certified colors which are permitted to be used for coloring foodstuffs and beverages under rulings issued by the United States Department of Agriculture. Officials of the Bureau of Chemistry in charge of the division covering the use of food colors are now considering the admission of a third green dye to the permitted list. This is a new substance and has been named Fast Green F. C. F. It has passed the physiological tests required by the Department of Agriculture of coal-tar bodies to be used as coloring in foods. Fast Green F. C. F. belongs to the triphenylmethane group of acid dyes and is similar in general composition to Light Green S. F. Yellowish and Guinea Green B, the two green colors already on the permitted list. The leuco bases of all three dyes result from the condensation of two molecules of ethylbenzylaniline monosulfonic acid with, respectively, one molecule of benzaldehyde or a derivative of benzaldehyde-thus, Guinea Green B Benzaldehyde Light Green S. F. Yellowish Benzaldehyde +sulfonic acid p-Hydroxybenzaldeh yde Fast Green F. C . F. o-sulfonic acid
,Investigation has shown that Fast Green F. C. F. is a fast, non-fading dye when used in foodstuffs and beverages, where1
Received February 18, 1927.
JSNKINSON
C O . , ST.
LOUIS,MO.
as under the same conditions Light Green and Guinea Green are subject to rapid and sometimes complete decolorization. The new dye is also more intense than the other two greens, and the manufacturer can therefore use much less of it when coloring a food product or beverage-a decided advantage. Manufacturing Process The process commonly used for Guinea Green B is applicable to the manufacture of Fast Green F. C. F. by substituting p-hydroxybenzaldehyde o-sulfonic acid for benzaldehyde. It consists in the condensation of one molecule of p-hydroxybenzaldehyde o-sulfonic acid, with two molecules of ethylbenzylaniline monosulfonic acid, followed by oxidation of the leuco substance obtained with lead peroxide in the presence of dilute sulfuric acid.2 The insoluble lead sulfate is filtered off and the color separated by salting out. The preparation of p-hydroxybenzaldehyde o-sulfonic acid is conveniently accomplished by starting from p-nitrotoluene o-sulfonic acid. Direct methods have been proposed for oxidizing the methyl group to the aldehyde, but the writers prefer the indirect method of first oxidizing p-nitrotoluene o-sulfonic acid to the corresponding stilbene compound in alkaline hypochlorite solution.3 * Actiengesellschaft fur Anilinfabnkation, German Patent 50,782 (1889). a Clayton Aniline C o . , English Patent 5351 (1897); Levinstein, Ltd., German Patent 106,961 (1897).
INDUSTRIAL AND ENGINEERING CHEMISTRY
498 ,CHs 2C6H3-SO3Na
N ' O2
(1) (2)
/
CH
-
CH
+ C6H3-SO3Na
\ / 0zN
NaOa+c6H3
\NO2
(4)
This provides the sodium salt of dinitrostilbene disulfonic acid in a practically chemically pure condition, which can be converted quantitatively into two molecules of the sodium salt of p-nitrobenzaldehyde o-sulfonic acid by oxidation with potassium permanganate in alkaline solution.4 /CH
CsHa-SOsNa 'NO1
PHO
=CH (1) \ N ~ O ~ S - C ~ H ~ + ~ C C H ~ - S O ~ N(2) ~
OziT/
\NO,
(4)
Reduction of the p-nitro to the p-amino aldehyde is effected in the usual way by reduction with ferrous carbonate paste. The amino aldehyde thus obtained is diazotized with sodium nitrite, the resulting diazonium salt being converted into 4
Levinstein, Ltd., German Patent 115,410 (1897).
Vol. 19, No. 4
p-hydroxyaldehyde o-sulfonic acid by warming to 80-90" C., with dilute sulfuric acid. The writers have also tried out the method of condensing two molecules of ethylbenzylaniline monosulfonic acid with the aldehyde taken as described above to the amino stage. The resulting p-amino leuco substance is then diazotized and hydrolyzed to the p-hydroxy compound. The method presents several disadvantages, however. The amino leuco acid substance is relatively insoluble in water, so that diazotization must be performed in very dilute sohtion. Furthermore, the hydrolysis of the diazonium salt of the leuco substance does not proceed smoothly, nor is the theoretical amount of nitrogen evolved. Bright red bodies are formed that cannot be separated from the leuco base. These red substances are partially destroyed and decolorized by oxidation with lead peroxide, but their decomposition products cannot be separated from the color. The writers therefore advise against this method of making Fast Green F. C. F.
The Ash of Hard Spring Wheat and Its Products' By Betty Sullivan and Cleo Near RUSSELL-MILLER MILLINGC o . , MINNEAPOLIS, MI".
Experimental Procedure 0 COMPLETE analyses of the ash of strong northwestern wheat and its mill products have been pubThe wheat used was a typical dark northern hard spring lished. Since the ash of flours milled from these wheats differs markedly in physical character and chemical Marquis wheat, grown in North Dakota. This wheat was composition from the flours milled from softer varieties, it thoroughly washed and dried before being milled by a long, five-break, intensive middlings purification system. The was thought best to make complete ash analyses as well as percentage yield of its products is given in Table I. The a general study of the ash of wheats and flours. ashes on all the samples were obtained by the hydrogen No small amount of data can be found in the literature concerning the ash components of flour-mill products of peroxide method and ignition a t 620" C. for 16 hours as described in a previous article.' different wheats. Much of the information, however, is incomplete or erroneous. For example, in a frequently Table I-Analyses of Selected Marquis W h e a t a n d I t s Mill Products quoted nutrition publication2 the mineral constituents of (Figures in per cent, calculated to dry basis) a patent flour are based on an ultimate ash analysis where TOTAL CONLow MILL-RUN the total ash of the patent is reported as 0.165 (13.92per cent STITUENT W H E A T PATENT CLEAR G R A D E M I D D L I N G S BRAN GBRM moisture). Such a low ash is highly improbable and any Yield 58.00 12.00 2.60 14.41 12.99 ..." excalculation of mineral components of flours based upon such Ether tract 2.53 1.41 2.35 3.75 6.57 6.40 11.94 3.40 1.62 2.64 4 23 8.14 6.67 11.25 a low ash is inaccurate. I n the same publication it is in- Lipoid Crude fiber 7.00 8.27 2.90 correctly stated that "in everyday life the one deficiency Dry aluten 14.97 14.49 18.16 G i1;t.e n of white flour which is most likely to make itself apparent is Good Very good Good quality 17.76 15.09 14.13 17.76 18.47 18.55 29.20 Protein its lack of magnesium, this deficiency causing its constipating Ash 1.462 6.748 5.041 4.762 2.05 0.482 0.804 0.4546 0.1327 0.7160 0.3801 character." Complete data as to the percentage yield of Magnesium 0.1898 0.0308 0.0624 0.0452 0.0180 0.0227 0.0376 0.1115 0.1158 0.0692 Calcium flours, system of milling, and the methods of analyses are Phosphorus 0.4440 0.1162 0.1910 0.3511 1,0446 1.5208 1.2533 frequently lacking, making it impossible to interpret the Potassium 0.2370 0.0552 0.0875 0.1533 0.5633 0.7098 0.5542 The germ, which would have a percentage yield of less than one results adequately. D e m p ~ o l f , TellerJ4 ~ and Grossfeld5 per cent, was diverted to the middlings and the bran and is included there. have shown that the percentage of magnesium oxide increases The separate sample of germ whose analysis is glven here was taken from the spouts before its arrival to the bran and mlddlings. and the percentage of calcium oxide decreases in going from higher to lower grades of flour. In many of these analyses I n order to ascertain if there was any loss of phosphorus the phosphorous pentoxide increases slightly m-ith diminishing refinement. McHarguea has reported that some of the by ashing according to this method, a sample of germ of high content, higher than is usually found in wheat rarer elements occurring in wheat-namely, copper, iron, phosphorus products, was taken for the test. Two grams of germ were zinc, and manganese-are found in much smaller concenweighed into a Kjeldahl flask and 10 GO. concentrated sulfuric tration in the endosperm than in the bran or germ. acid, 20 cc. concentrated nitric acid, and 20 cc. 5 per cent C. P. hydrogen peroxide were added. The mixture was heated 1 Received September 17, 1926. 2 Ohio Agr. Expt. Sta., BuZl. 266, 229 (1913). over an electric heater until the destruction of organic matter 8 Ann. Chem. Pharm., 149, 343 (1869). was complete and the liquid clear. Phosphorus was then 4 Ark. Agr. Expt. Sta., Bull. 42, Pt. 2 (1896). determined by the gravimetric pyrophosphate method (I). 5 Z. ges. Gefreidew., 1'2, 73 (1920). e Paper presented before the Division of Agricultural and Food ChemPhosphorus determinations were likewise made on samples
N
1
(I
istry at the 68th Meeting of the American Chemical Society, Ithaca, N. Y., September 8 t o 13, 1924.
7
Sullivan and Near, 1.Am. Chem. SOC.,49, 467 (1927).
