INDUSTRIAL A N D ENGINEERING CHEMISTRY
532
Vol. 18, No. 5
Researches on Thiazoles'Bz XI-Syn thesis of 2- ( p -Aminophenyl) -5-Methylhenzothiazole and Incidental Compounds : Isomers of Dehydrothio-p-Toluidine and of Chloramine Yellow By Marston Taylor Bogert and Roger William Allen COLUMBIA UNIVBRSITY, NEWYORK, N. Y.
I
N THE prosecution of their investigation of the connection
between color and constitution in the case of the thiazole dyes, the writers have prepared an isomer of dehydrothiop-toluidine, in which the methyl group is in position 5, and from this the corresponding isomer of the well-known chloramine yellow NN, or Columbia yellow (Color Index No. 814). The synthesis may be outlined as follows: , ~ H(4)Z
(1) CHs.CsHs
/I
CHa.CsHs
-C
\NOz(3)
/+)*+
* (CHs.CsH3
N ' O2
\NO2
(1)
/+)*
(CHsCsHa
(11)
/%C.C~,H~.NOZ
Zn + CHsCsHs
+
\N/ (111)
The product formed bright yellow needles, m. p. 175.5' C. (cor.); yield, 60 per cent. Analysis. Calculated for C I I H ~ ~ O ~ C, & :49.98; H, 3.57 per cent. Found: C, 49.82; H, 3.67 per cent. 2-Amino-4-Methylphenyl Mercaptan (11)
The zinc salt was obtained by reducing the nitro disulfide in glacial acetic solution with zinc dust, as recommended by Bogert and Snell,a except that it was found preferable to add the zinc dust directly to the boiling solution. When 3 grams of the nitro derivative were added to 350 cc. of boiling glacial acetic acid, they dissolved immediately. The zinc dust (5 to 6 grams) was then added gradually (during 2 minutes), a t such a rate that the solution boiled gently. Rapid reduction ensued, and the solution became colorless in about 1 minute. The hot solution was filtered immediately (with suction) into 2 volumes of water, and the zinc salt separated as this solution cooled; yield, 2.9 grams or 97 per cent. Analysis. Calculated for ClrHlgN&Zn: C, 49.26; H, 4.75 per cent. Found: C, 49.56; H, 4.86 per cent. 2-(p-Nitrophenyl)-5-Methylbenzothiazole (111)
whose sodium sulfonate was oxidized by sodium hypochlorite to the isomer of chloramine yellow. The thioflavine from this new dehydrothio-p-toluidine isomer is also under investigation and will be described in a later communication. The various steps in the synthesis were accomplished by methods similar to those described in previous papers from these l a b o r a t ~ r i e s . ~ ~ ~ Like dehydrothio-p-toluidine, alcoholic solutions of its isomer exhibit a beautiful violet fluorescence. The chloramine yellow dye obtained as the final product was scarcely distinguishable from chloramine yellow itself in physical, chemical, or tinctorial properties. 2-Nitro-4-Methylphenyl Disulfide (I)
An intimate mixture of 3.4 grams of the above zinc salt and 3.7 grams of p-nitrobenzoyl chloride was heated a t 100" C. for an hour, after which the pulverized melt was extracted with warm N sodium hydroxide, and the residue decolorized and crystallized from alcohol.3.' Light yellow needles resulted, m. p. 182.5" C. (cor.); yield, 3.5 grams or 64 per cent. Analysis. Calculated for C14HloOzNzS: C, 62.22; H, 3.70 per cent. Found: C, 62.37; H, 3.82 per cent. 2- ( p -Aminophenyl) -5-Methylbenzothiazole (IV)
A mixture of 3 grams of the nitro thiazole, 10 cc. of concentrated hydrochloric acid, 90 cc. of water, and 10 grams of granular tin was boiled gently for 3 hours. Vigorous boiling appeared to cause some decomposition. The mixture was filtered hot, the cooled filtrate made strongly alkaline with 4 N sodium hydroxide, the solution kept warm for an hour, then cooled, and the separated crude product filtered When this was decolorized and crystallized from 50 per cent alcohol it gave beautiful, pale yellow needles, m. p. 218" C: (cor.), whose alcoholic solution exhibited a violet fluorescence; yield, 2.1 grams or 80 per cent. Analysis. Calculated for C14H12N&: C, 70.0; H, 5.0 per cent. Found: C, 70.46; H, 5.06 per cent.
From 3-nitro-4-aminotoluene (m. p., 116" C.), the 3-nitro4-iodotoluene was prepared by the usual diazo reaction following the method of Willgerodt and S i m o n i ~ . ~The product formed colorless long, flat needles, m. p. 55" C., in agreement with the literature; yield, 80 per cent. This iodo derivative was converted into the nitro disulfide by digesting it in hot alcoholic solution with sodium disulfide, washing the crude product with water, to remove sodium iodide, and with alcohol to free it from any unchanged iodo derivative, and crystallizing the residue from glacial acetic Sulfo Acid , ~(p-Aminophenyl)-5-Methylbenzothiazole acid in the presence of a suitable decolorizing c a r b ~ n . ~ , ~2A solution of .5 grams of the amino thiazole in 20 cc. of 1 Presented in abstract under the title "The Synthesis of Another Isomer of Dehydrothio-#-Toluidine, 2-(p-Aminophenyl)-5-Methylbenzothiaconcentrated sulfuric acid at 25" C. was treated gradually iole," at the 69th Meeting of the American Chemical Society, Baltimore, with 15 cc. of fuming sulfuric acid (containing 50 per cent free Md., April 6 to 10, 1925. Received December 24, 1925. SOs) a t such a rate that the temperature of the solution re2 Contribution No. 501 from the Chemical Laboratories of Columbia mained below 50" C. The mixture, after being kept for 8 University. a Bogert and Snell, J . Am. Ckem. Soc., 46, 1308 (1924). hours longer a t 40" to 50" C., was poured upon ice and the 4 Bogert and Bergeim, Proc. Nul. A c a d . Sci., 10,318 (1924);Color Trade sulfo acid separated as a bright yellow ~ o l i d . ~ ~ ~ J . , 16, 83 (1924).
Ber., 59, 269 (1906). ( a ) Blanksma, Rcc. trau. chim., 20, 121 (1901); and ( 6 ) Wohlfahrt, J . prakt. Chem., [ 2 ] 66, 551 (1902). 6
a Compare
Compare Hofmann, Ber., 12, 2362, 2365 (1879). Compare Green, J . Chem. Soc. ( L o n d o n ) , 55, 229 (1889); Ber., 22 968 (1889). I
8
INDUSTRIAL A N D ENGINEERING CHEMISTRY
May, 1926
Isomer of Chloramine Yellow NN, Columbia Yellow, or Direct Fast Yellow (Color Index No. 814)
The sulfo acid was dissolved in sodium carbonate solution and subjected to the action of a freshly prepared sodium hypochlorite solution for 24 hours at 10" to 15' C. The original colorless solution slowly changed to a deep yellowish red.4ng The dye was salted out, washed thoroughly with salt solution, and dried. As so prepared, it formed a brown powder, easily soluble in water, and dyed cotton directly a yellow shade scarcely distinguishable from that obtained with chloramine yellow NN in solutions of similar strength. When subjected to the usual tests4 for fastness to acids, alkalies, light, etc., its behavior was practically identical with 9
Compare Farbenfabr. vorm. F. Bayer, German Patent 65,402; Fried. Winlher, 8 , 1922.
lacndn, 8 , 752;
533
that of chloramine yellow NN. Tinctorially, therefore, it seems to make little difference in these dyes whether the methyl group is in position 5 or 6. Summary
1-By starting with m-nitro-p-toluidine, an isomer of dehydrothio-p-toluidine has been prepared carrying the methyl group in position 5. 2-From this new base a dyestuff has been obtained isomeric with chloramine yellow NN (Color Index No. 814), of similar properties and dyeing similar shades. 3-Other new compounds prepared in the course of the investigation were the 2-nitro4methylphenyI disulfide, 2amino-4-methylphenyl mercaptan (zinc salt), and 2-(pnitrophenyl)-5-methylbenzothiazole.
Corrosion of Steels in the Atmosphere' By W. G. Whitman and E. L. Chappell DEPARTMENT OF CHEMICAL ENGINEERING, MASSACHUSETTS INSTITUTE OF TECHNOLOGY, CAMBRIDGE, MASS,
M
ETHODS of estimating the resistance of steels to at-
mospheric corrosion are of practical interest to both the user and manufacturer of the material. The most conclusive tests yet devised are those of long-time exposure to service conditions, but the time and expense required by such tests seriously limit their general application and emphasize the necessity for an atmospheric test which will give a reliable index of corrosion resistance within a short time. Many mistakes in rapid testing for atmospheric corrosion have been recorded because some accelerating factor was introduced into the test which was not present under normal conditions. In the simple method described in this paper the primary accelerating influence is m o i s t u r e 4 e., the steel is kept wet during a larger fraction of the time than obtains in service. The validity of this method of hastening corrosion is evidenced by the fact that the results compare satisfactorily with the results of long-time service tests on the same steel specimens.
almost entirely on the volume of the cylinder H and the water rate of the spray. The spray period in the tests described here was 15 minutes, while the drying period was varied from 30 minutes to 23 hours and 45 minutes. Samples
Most of the tests were run with specimens of steel supplied by the Bureau of Standards from a reserve stock of American Society for Testing Materials test steels. Other samples of these same materials had been exposed in long-time tests in the atmosphere at Pittsburgh, Annapolis, and Fort Sheridan, Ill., and their relative resistances to corrosion under service conditions were therefore well established. 2
Testing Equipment
The testing equipment is shown diagrammatically in Figure 1. T is a galvanized box, coated inside with metalin-oil paint. The steel test specimens, 2 X 6 inches, are held a t an angle of 30 degrees from the horizontal by paraffined wooden clothespins attached to horizontal supporting rods. A spray nozzle operates intermittently for 15-minute intervals, the cycle of operation being automatically regulated by the system shown at the right of the figure. Water drained from the spray in the test box flows through pipe A , going partly into the cylinder H , and partly into the waste line through valve B. The rate of inflow through the spray nozzle is greater than the rate of draining a t B, so that after 15 minutes the float, F , moves the lever system from position 2 to 1, closing valve C on the water line. The shutting o f f of the spray stops the flow through pipe A so that the cylinder H slowly drains through valve B. When the float reaches the lower check, L1,the water valve C is reopened, starting another period of spraying. The length of the drying time may be varied greatly by changing the rate of drainage at B. The length of the spray period, although slightly influenced by the rate of flow a t B, depends I
Received January 7, 1926.
-
WASTE
Figure 1-Rapid
Atmospheric Corrosion Tester
A set of specimens of irons in which the chromium content had been varied was furnished by Mr. Speller, of the National Tube Company. Duplicate test pieces (2 X 6 inches) were cut from all these specimens and exposed in the spray box as described. The samples were prepared for testing by a preliminary corrosion in the test box, after which the rust was cleaned off with 0.1 N hydrochloric acid, steel wool, and a towel, and the steels were washed thoroughly with warm water, alcohol, and ether. The samples were then weighed with an accuracy of 0.0005 gram. After exposure in the test box the cleaning and weighing were repeated. The average 2
Proc. A m . SOC. Testing Materials, Comm. A-6, 1921-4.
