INDUSTRIAL AND ENGINEERING CHEMISTRY
APHIL, 1935
log K p X 106
=
3.444; K p X lo6 = 2806
On using 3.9 as the conventional chemical constant of hydrocyanic acid (Y),the following values are obtained: log Kp X I O 5 = 3.049; K p X lo6 = 1128
This value v a s approached frequently in the course of the precent m-ork as shown by the following figures on the constant of quilibrium at 6011” C. : Ratio NH3:CO 1:9 4 1: 10
Per Cent H C X 64 55
Loe
K p X lo5
2.7 2.09
Furtherniore, becaupe of the very small AH value of the reaction, the equilibrium shifts very little with the temperature. as shown by the following data: Temperature,
c.
575 600
700
Ratio
NHs:CO 1:10 1:lO 1:1(1
Yield, Per Cent 54.0 54.9 50.7
---Log Actual 2.67 2.68 2.70
K ~x, 105-
Theoretical 3.049 3,050 3.068
l k a l l y , in order to test the technical value of the results, a large-scale experiment was run. The apparatus used is represented in Figure 3. The large furnace contained a porcelain tube glazed on the inside, 69 mm. in diameter and 700 mm. in length. B y means of nichrome wire, 480 mm. of the tube were electrically heated. A current of 9 amperes
413
and 220 volts was used in heating it to 570” C. The bottom of the oven x a s made from asbestos disks cemented with a mixture of talcum and materglass. The top of the catalytic chamber was sealed by a water-cooled rubber stopper. One thousand grams of alumina splinters were placed upon a porcelain sieve plate cemented in the oven. The mixture of carbon monoxide and ammonia passed first through special large rotameters, then through a 10liter tower filled with soda lime, and finally through a preheater before entering the apparatus. In order to produce 100 grams of hydrocyanic acid, 1500 liters of gas per hour had to pass through the oven. The oven yielded 98 grams of hydrocyanic acid per hour.
Literature Cited (1) Anonymous, Chem. Em. Fett- Harz-Ind., 18,55 (19101. (2) Bredig, G . , a n d Elod, E., 2. Elekfrochem., 36, 1003, I 0 0 7 (1930); 37, 3 (1931); G e r m a n P a t e n t s 522,253 (Del:. S, 1922i, a n d 650,909 ( M a y 24, 1924). (3) I. G . Farbenindustrie=l.-G., Ibid., 449, 730 (1926’. (4) hlailhe a n d Godron. A n n . o h i m . . [SI 13, 1% f l W 0 1 : H u i ; S O ( ’ . chim.,[4] 27, 737 (1920,. ( 5 ) P a t r i c k , W. A , , dissertation, Goettinceii. 1911. (6) Simakof, J . Russ. Pit -Ci,em. Sx..61: 997 ‘19291. (7) T e i c h m a n , L., 2. EZet uchena.. 28. 202 ~ 1 9 2 2 ~ . (8) K a r t e n b e r g , H. \-,, Z. anorg. Chevz.. 52, 30s (19071 RECEIVEDOctober 10, 1934. The data i n thls p a p e r rorined a part oi tile doctor’s dissertation of €1. Yerbeek a t the Chemipcli-rechnisches Inatitut 01 the Technische Hochschule, A n c h e n .
Inhibitor Dves in Cracked Gasoline J
C. D. LOWRY, JR., GUSTAV EGLOFF, J. C. MORRELL, AND C. G. DRYER
Universal Oil Products Company, Riverside, Ill.
A number of dyes are shown to have antip r e s e n c e of alkyl or tertiary HE extensive use Of in oxidant ;iction in cracked gasoline. Reamino groups, Particularly when gasoline a n d in the ortho or para position. lationships are pointed out between strucThe effects of c h r o m o p h o r i c the successful application of inhibitors to the stabilization of ture and inhibiting effectiveness* The groups on i n h i b i t i n g potency cracked motor fuel suggested a fade when they act as inhibitors and SO give had not previously been deterstudy of compounds poqsessing an indication of their depletion. mined. both coloring and i n h i b i t i n g -Azo Dyes DroDerties. A number of azo dyes derived from intermediates of pro6illet (13) clainied a parallelism between the fastness of nounced inhibiting value mere prepared and tested. Their acid wool dyes and their possession of groupings nhich he effectiveness is expressed in the tables as “cyclohexene numbelieved conferred “antioxygenic” properties. Methyl rubber,” a reproducible means of inhibitor evaluation defined ber produced during the mar was dyed yellow to prevent de(8)as the calculated increase in the induction period of cycloterioration (16). Phenylazo-0-naphthylamine and azobenhexene produced by 0.002 per cent of an inhibitor, the cyclozene are reported b> Bondy (5) to protect rubbc,r exposed to hexene number being calculated from results obtained in a ultraviolet light by virtue of their specific light, absorption; reference gasoline whose response to a-naphthol bears a azo dyes derived from diphenylamine (14)also have protective power for rubber. During the progress of this work fordefinite relationship to that of cyclohexene. The data presented were obtained by adding 0.01 per cent of each inhibiteign patents were issued to the Standard Oil Development Company (1’7) relating to dyes as inhibitors in cracked gasoing substance t o a gasoline one-fifth as responsive to a-naphtho1 as cyclohexene, and determining the induction period by line. In a study (9) on the relationship of structure to inhibiting a previously described technic (9). Each sample was diseffectiveness, it was found that the presence of primary and solved in 5 cc. of benzene or hexone (methyl isobutyl ketone) ; secondary aromatic amino and aromatic hydroxyl groups these solvents have been found not to affect the induction usually conferred antioxidant power for cracked gasoline, period before addition to a 200-cc. sample of the gasoline. and that the effect of these structures was increased by the Data on azo dyes derived from a-naphthol are as follows:
INDUSTRIAL AND ENGINEERING CHEMISTRY
414
Cyclo-
(a-Na hthol) p-Hygoxyphenylazo-a-naphthol Phenylazo-a-naphthol o-Nitrophenylazo- a-naphthol p-Nitrophenylazo-u-naphthol
Solvent Kone Hexone Hexone Hexone Hexone
hexene No., Min.5 610
430
225 50
40
Color i n Gasoline Colorless Brown Red-brown Yellow Brown
Commercial Dyes Two commercially prepared azo dyes, which have been proposed for use in gasoline ( I O ) , and several dyes of other types from commercial sources were found to have inhibiting value: Cyrlo-
.4s the standard gasoline used had an induction period of 130 minutes,
the induction period produced by each inhibitor may be obtained by adding 130 to its cyclohexene number.
Comparison of the values for a-naphthol and phenylazo-anaphthol shows that the azo group is detrimental t o inhibiting action. An added hydroxyl, as in p- or o-hydroxyphenylazo-a-naphthol, is seen to increase inhibiting action, while a nitro group greatly reduces it. It is noteworthy that their effects are pronounced even though the groups introduced are quite distant from the original hydroxyl group of the naphthol. The following are azo dyes derived from monocyclic phenols: Cyclohexene No., Solvent
Min.
Color in Gasoline
VOL. 27, NO. 4
Oil Brown Azo dyes. oranee base Azine-dyes: Induline base B Nigrosine base N Triphenylmethane dye, Victoria Blue B base (Diphenylamine)
Color Index No. Solvent 73 Benzene 20 Hexone
hexene No. Color in Min: Gasoline 110 Red 220 Yellow
860 864
Benzene Hexone
550 160
Pink Red-violet
729
Hexone Hexone
125 80
Brown-red
.. .
.... . .
The effectiveness of the induline and nigrosine bases is probably due to the repeated diphenylamine groupings in their structures. Victoria Blue B base may owe its potency t o the same grouping or, if its structure is quinmoidal, it would appear, like Phenol Blue, to be an inhibitor of unusual type.
Use of Two Inhibitors Phenylazo-o-cresol p-Hydroxyavobenzene (Phenol)
Benzene Hexone Benzene
Yellow Yellow Yellow
65 0 10
The difference between catechol and phenylazocatechol shows again the harmful effect of the azo grouping, and the introduction of a nitro group produces a compound of still lower inhibiting value. I n contrast, phenylazohydroquinone has a higher cyclohexene number than hydroquinone. The zero value for hydroquinone does not indicate, however, that it is not an effective inhibitor for gasoline but, as shown in earlier work ( I 5 ) ,its value cannot be determined by the usual accelerated test, probably because it is directly oxidized under the severe conditions used. The higher number for the azo compound perhaps indicates a lessened tendency to direct oxidation but may not indicate superior inhibiting effectiveness when used a t room temperatures. p-Hydroxyazobenzene has no inhibiting power, the slight potency of phenol being lost by the introduction of the azo group, but the additional methyl group in phenylazo-0-cresol gives a substance of slight potency. Dyes were prepared by coupling benzidine and tolidine with a-naphthol and 1.5-dihydroxynaphthalene but, although they possessed definite inhibiting value, they were sparingly soluble in gasoline and are therefore not included.
Indophenol Dyes Two indophenol dyes were prepared, indophenol and Phenol Blue. Both were found to be effective antioxidants, the former ranking among the best inhibitors for gasoline. The corresponding leucoindophenols were even more potent than the dyes themselves:
Leucoindophenol
eolvent Hexone
Indophenol Leuco Phenol Blue
Hexone Hexone
Cyclohexene No., Min. 1415
1330 570
Color in Gasoline Nearly colorlesa Red Nearly
The characteristic grouping of the indophenols is favorable to inhibiting action, as shown by the great superiority of indophenol over phenol, and especially by the effectiveness of Phenol Blue, a compound containing neither a hydroxyl nor a primary or secondary amino group.
When gasoline containing inhibitor dye is exposed t o oxygen under the conditions of accelerated testing, the dye is oxidized and slowly fades during the time it protects the gasoline. The same change would probably occur in stored gasoline. The color imparted by the dye a t any time after the beginning of storage would be a measure of its concentration, and its fading a warning of inhibitor exhaustion. The nearly colorless leuco dyes, on acting as inhibitors, a t first form the dye and color the gasoline, and then again fade to nearly colorless. If both an inhibitor dye and a colorless inhibitor were used in gasoline, which might be desirable to avoid excessive coloration or reduce cost, the warning given by the fading of the dye would still be of value. Two inhibitors used in this way are oxidized during the period they are exerting their protective influence a t rates that are related to each other ( I ) . From the depth of color of the gasoline a t any time after addition of the inhibitors, it should be possible t o calculate the extent to which each substance had been oxidized. To test this effect, 0.005 per cent of phenylazo-a-naphthol and 0.0025 per cent of a-naphthol were added t o samples of refined Pennsylvania cracked gasoline, and induction periods were determined. Both inhibitors were then added in these concentrations to a third sample of the same gasoline, and induction period was redetermined. The induction periods (in minutes) are as follows: Gasoline alone Gasoline phenylazo-a-naphthol (0.005 per cent) Gasoline a-naphthol (0.0025 per cent) Gasoline both inhibitors
+ + +
45 205 255
410
Further samples, each containing both inhibitors, were then oxidized for 100 and 200 minutes. By colorimetric measurement the proportions of dye which had disappeared were determined, and by reaction with 2,6-dibromoquinone chloroimide, which gives a blue color with a-naphthol, the loss of this substance during the periods of oxidation was determined. The data showed that the inhibitors had been acted upon simultaneously. It was assumed that the inhibitors were used a t a uniform rate throughout the induction period (which probably is not strictly true) and that they were effective in combination in proportion to the increases in the induction period of the gasoline which they produced when used alone. Since the increases were 160 minutes for the dye and 210 minutes for a-naphthol, the substances were considered to have contributed 160/370 and 210/370 of the total induction period of 410 minutes. When, after 100 minutes, 20 per cent
APRIL, 1935
INDUSTRIAL AND ENGINEERING CHEMISTRY
of the dye had been used, it was assumed to have contributed 20 per cent of 177, or 35, minutes and t h a t sufficient anaphthol had been consumed in this time to furnish the remainder of the 100 minutes. The following table shows a comparison of the amounts of a-naphthol used during the periods of oxidation, as calculated in this way from the color of the dye remaining, compared with the actual loss of a-naphthol, determined by reaction with 2,6-diloromoquinone chloroimide. Oxidation Period
.
Min 100 Over 200
Loss of Phenylazo-or-naphthol
Consumption of a-Yaphthol Determined Calculated
%
%
%
20 Over 50
20 Over 60
23
415
nine cubic centimeters of a buffer solution (pH 9.24), containing 19.1 grams borax per liter, were mixed with 1 cc. of a 3 per cent alcoholic solution of 2,6-dibromoquinone chloroimide. Ten cubic centimeters of the gasoline containing a-naphthol were shaken for 5 minutes with this reagent. The mixture was allowed to settle, and the water layer, colored blue by the indophenol formed, was filtered and used for color comparison. Dye present in the gasoline remains in the gasoline layer and, unless it has a free hydrogen para to a hydroxyl group, does not interfere with the test. The method iva5 found t o remove about 80 per cent of the a-naphthol from the gasoline in the concentrations studied.
Acknowledgment
4’3
T h e agreement is close enough t o be of some utility. The discrepancy between the calculated and determined figures may indicate t h a t the inhibitors are not consumed uniformly but a t a n increasing rate during the induction period.
Experimental Procedure Phenylazo-a-naphthol was prepared according to Conant, Lutz, and Coreon ( 7 ) and recrystallized from benzene as directed by Bamberger (3). p-Hydroxyphenylazo-a-naphthol, first reported tiy Witt and Beintrock (18), was prepared by adding diazotized p-aminophenol to a solution of a-naphthol in caustic soda in the presence of sodium carbonate, The sample prepared here gave a blue color in sulfuric acid and dark red in alkalies as reported by the earlier investigator. o-Nitrophenylazo-a-naphthol was synthesized by rapidly diazotizing p-nitroaniline, coupling it with a solution of a-naphthol in caustic soda, and purifying by the method of Bamberger and Meimberg (4)who first prepared this compound. p-Nitrophenylazo-a-naphthol was similarly prepared (in poor yield) and was purified as directed by Bamberger (2). p-Hydroxyazobenzene and phenylazo-o-cresol were obtained from the Eastman Kodak Company and found to have melting points agreeing with the literature. Phenylazocatechol and pnitrophenylazocatechol were synthesized and purificd according to the directions of Witt and Mayer (20). The preparation of phenylazohydroquinone was by way of the benzoate, following Witt and Johnson (19). Phenolindophenol and its leuco derivatives were prepared and purified following Gibbs, Hall, and Clark (12). Phenol Blue and the leuco dye were synthesized according to the directions of Cohen and Phillips (6). The test for the determination of a-naphthol with 2,6-dibromoquinone chloroimide was based on work of Gibbs ( I I ) . Forty-
,** ri
The authors wish to thank R. Norris Shreve of Purdue University for suggestions concerning this work.
(1)
Literature Cited Alyea, H. N., and Backstrom, H. L. J., J. Am. Chem. Soc., 51,
90 (1929). (2) Bamberger, E., Ber., 28, 848 (1895). (3) Ibid., 28, 1218 (1895). (4) Bamberger, E., and Meimberg, F., Ibid., 28, 1888 (1895). ( 5 ) Bandy, H. F., Ibid., 66, 1618 (1931). (6) Cohen, B., and Phillips, M., Suppl. Pub. Health Repts., No. 74 (1929). (7) Conant, J. B., Lutz, R. E., and Corson, B. R., “Organic Syntheses,” Collective Vol. 1,p. 41 (1931). (8) Dryer, C. G., Lowry, C. D., Jr., Egloff, G., and Morrell, J. C., I N D . E N G . CHEM., 27, 315 (1935). (9) Egloff, G., Morrell, J. C., Lowry, C. D., Jr., and Dryer, C. G., Ibid., 24, 1375 (1932). (10) Egloff, G., Morrell, J. C., and Truesdell, P., Oil Gas J., 29 (42), 133 (1931). (11) Gibbs, H. D., J . B i d . Chem., 72, 649 (1927). (12) Gibbs, H. D., Hall, W. L., and Clark, W. M., Suppl. Pub. Health Repts., No. 69 (1928) (13) Gillett, Alfred, Compt. Tend., 176, 1402 (1923). (14) Ingram, J. R., U. S. Patent 1,889,331 (Nov. 29, 1932). (15) Lowry, C. D., Jr., Egloff, G., Morrell, J. C., and Dryer, C. G., I N D . ENO.CHEM., 25, 804 (1933). (16) Pummerer, R., 2. angew. Chem., 47, 117 (1934). (17) Standard Oil Development Co., French Patents 726,040 (Feb. 23, 1932); 733,994 (March 22, 1932). (18) Witt, 0. N., and Beintrock, A., Ber., 27, 2358 (1894). (19) Witt, 0. N., and Johnson, E. S., Ibid., 26, 1908 (1893). (20) Witt, 0. N., and Mayer, F., Ibid., 26, 1072 (1893). RECEIVED November 27, 1934. Presented before the Division of Organic Chemistry a t the 88th Meeting of the American Chemical Society, Cleveland, Ohio, Septemher 10 t o 14, 1934.
RESEARCHLABORATORIES UNIVERSALOIL PRODUCTS COMPANY
