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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