June, 1926
INDUSTRIAL AND ENGINEERING CHEMISTRY
No. 1 2 3 4 5 6 7 8 9 10
11
12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
Production a n d Value of S o m e Important Dyes Produced i n t h e United States i n 1924 , SALES Production Quantity Value No. of Units of ' Units of Units of Price NAME Schultz No. mfrs. 100,000 Ibs. 100,000 Ibs. $50,000 per Ib. 3 199.9 78.3 0.22 874 179.8 Indigo, 20% paste 5 42.6 0 . I9 117.3 111.9 720 Sulfur black 37.6 0.38 54.7 49.5 9 462 Direct deep black E W 16.5 3.30 4 858 ... 2.5 Alizarin saphirol B 15.1 0.64 217 12.7 1L.8 13 Agalma black 10B 12.1 1.13 5.4 8 5.4 515 Methyl violet 12.1 1.52 4.0 Auramine 5 3.9 493 ~-. 0.48 11.8 6 12.3 12.4 700 Nigrosine W. S. 10.8 0.38 14.1 14 14.0 Sulfur brown 1.26 9.0 3.6 3 4.1 659 Methylene blue 0.65 9.0 7.7 6.9 9 Oxamine black 333 8.4 0.48 7.7 13 8.8 181 Salicine black U 8.0 0.49 8.3 8.2 476 10 Benzamine brown G 0.33 8.0 12.2 11.6 8 145 Orange I1 7.5 0.84 4.5 5.1 5 304 Chrysophenine G 6 . 8 1.26 2 . 7 2 . 4 5 424 Chicago blue 6B 2.56 6.5 1.3 1.2 8 536 Alkali blue 1.91 6 . 3 1 . 7 1 . 9 4 279 Benzo fast scarlet A.. 9 0.73 . 4.5 4.0 6 363 Benzopurpurine 4B 6 . 8 0.66 4 . 4 4 . 5 8 Direct yellow R 5.7 0.72 3.9 3.3 6 134 Metanil yellow 5.6 1.85 1.5 1.3 4 587 Eosine 5.6 5.5 0.49 5.6 9 33 Chrysoidine 1.70 1.8 5.5 4 1.6 495 Malachite green 5.4 0.51 5.6 10 5.4 284 Bismarck brown 2R 5.4 2.77 5 1.0 1.0 168 Amaranth (food) 0.37 5.1 12 7.0 6.9 337 Benzo blue 2B 4.7 0.89 2.7 2.7 4 257 Sulfoncvanine G 4.7 2.64 0.9 0.9 5 19 Fast light yellow 4.7 0.79 2.9 9 3.0 163 Azo rubine
give dyeings of a very red shade and obviously contain a considerable amount of a red impurity. The B t h sample gives a dull dyeing and is distinctly not the same quality as the remaining samples. It is of interest to note that over half of the samples have a dye content between 55 and 65 per cent, indicating that for most manufacturers the compliance with a definite standard such as 60 per cent would not be difficult. Conclusions It appears that neither the spectrophotometric nor the titanous chloride method is entirely satisfactory for the
629 Per cent total value 11.2 6.1 5.4 2.4 2.2 1.7 1.7 1.7 1.5 1.3 1.3 1.2
1.1 1.1 1.1 1.0 0.9 0.9 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.7 0.7
0.7
0.7
evaluation of commercial samples of agalma black 10B in respect to strength. However, a combination of the two methods seems to give a satisfactory means of specifying a standard commercial type, since where the two methods agree the result is that obtained by the usual dyeing test. Over half of the twenty-three samples examined satisfy this requirement. A standard of 60 per cent purity by titanous chloride and spectrophotometer would necessitate but slight shift in the strength of the standards of a majority of manufacturers.
Preparation of Cyanamide Hydrochloride' By L. A. Pinck and H. C. Hetherington FIXEDNITROGEN &SEARCH
LABORATORY, %'ASHINOTON, D. C.
YANAMIDE, H2CN2, possesses considerable interest as the natural starting point in a large number of organic syntheses, and although at present it has little or no commercial value, it is by no means certain that uses would not soon be found for it were it not for its extremely hygroscopic nature and its tendency to polymerize, even in the solid state and at room temperature. For these reasons the salt cyanamide hydrochloride, H2CN2.2HCIJ which is known to be far less hygroscopic and more stable than cyanamide itself, should be of greater interest. Cyanamide hydrochloride is a white crystalline compound, stable at ordinary temperature when dry but hydrolyzing readily in aqueous solution. It may be heated safely to 7Oo-8O0 C., but decomposes rapidly when heated above 100' C., yielding hydrogen chloride and mellon. Two methods have previously been proposed for the preparation of cyanamide hydrochloride. The earlier2 of these consists in passing dry hydrogen chloride gas into an absolute ether solution of cyanamide. The success of the preparation depends upon the complete absence of moisture, for in the presence of even a very slight amount of water the hydrochloride forms a sticky mass which is difficult to dry and which invariably clogs the gas inlet. The other recorded method3 consists in dissolving cyana-
C
1
Received March 19, 1926.
* Dreschel, J. prakf. Chem., [Z] 11, 315 (1875).
* Hantsch and Vagt, Ann., 314, 366
(1901).
mide in concentrated hydrochloric acid and evaporating the solution in a vacuum desiccator. This method is open to several objections, chief of which is the difficulty of obtaining a dry product, free from uncombined hydrogen chloride. Moreover, there is considerable danger of contamination of the product with urea formed by hydrolysis of cyanamide in the aqueous solution of hydrogen chloride. Since the elimination of water is the principal difficulty in the foregoing methods, it was believed that the preparation might be more satisfactorily carried out in solvents such as ethyl alcohol, methanol, or acetone, which through their miscibility with water would prevent the salt from taking up all the moisture in the system. Qualitative experiments were first made to determine whether or not ethyl alcohol would itself react with the other constituents. That such a reaction might occur was indicated by the reported preparation of alkyl isourea from cyanamide and alcoholic hydrogen ~ h l o r i d e . ~It was found, however, that this reaction is too slow to take place to a measurable extent during the preparation of cyanamide hydrochloride. A somewhat similar behavior was observed in the case of acetone. While no side reactions occurred when cyanamide hydrochloride was prepared in this solvent, a compound corresponding to tri-isopropyl diurea or triacetony1 diurea was formed when a solution of cyanamide 4
Stieglitz and McKee, Bey.. 33, 807 (1900).
1iydror:iiluride in :wetone *-as allowed to stand for several weeks. Experiments were made to determine the yield and quality of product obtainable when cyanamide was added to an alcoholic solution of varying hydrogen chloride and water cont,rnt. It was found, as would be expected, that the solubility of H2CN,.21CI in alcohol was materially reduced by the presence of a slight excess of hydrogen chloride, and that the salt could sati5factorily he prepared in alcohol containing as much as 10 per cent of water. Yields of 98 to d9 per cent., based on the cyananiide used, are obtsinable by the method finally adopted when the salt is made in several lots and the mother liquor from the first lot ip used for tlinse succeeding, but when one preparation only is made the solubility of the salt reduces the yield to nbmL 94 pur cent. Although nicthnuol and acetone were found to be fairly satisfactory, the higher solubility of cyanamide hydrochloride in these solvents materially reduced the yields as compared wi1.h those obt,ained from ethyl alcohol. Method Adopted
Dry hydrogen chloride is passed. into ethyl alcohol (95 per cent) until the solution contains about 40 per cent HCI.
To this solution solid cyanamide is gradualiy added in quantity suiticient to react with about 95 per cent of the hydrogen chloride. Proper cooling is supplied so as to keep the ternperature at 45" C. or less, thus preventing the escape of hydrogen chloride and alcohol. The reacting mixture is agitated for a short time (5 to 10 minutes), filtered, and washed, preferably with a saturated alcoholic solution of cyanamide hydrochloride or ether, to remove the excess hydrogen chloride. The salt can be safely dried at 80" C. The mother liquor, if no ether has been used, is made up to the original volume with the required amount of fresh alcoholic hydrogen chloride, and hydrogen chloride is further added until the required concentration (approximately 40 per cent) is obtained. Cyanamide is then added to the soliition as in the first cycle of operation. The yield is thus made practically theoretical and the process may be continued irr this manner until the volume of water introduced with the cyanamide and that due to absorption from the atmosphere has risen to a point where difficulty is experienced in obtaining a dry product. The percentage of water may rise to about 10 per cent without interfering with the isolation of the hydrochloride in practically pure and dry condition. From the nature of the preparation, it will be seen that there is no limitation to the scale on which i t may be carried out.
Apparatus for Wet Ashing' By William A. Turner BURBIG
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