DAINS ET AL.: ARYL ISOTHIOCYANATES. 9 



LARGER-SCALE PRODUCTION. 



Tlic preparation of the mustard oil was carried out in a number 

 of experiments, using from five to ten times the amount of the 

 reagents listed above, with corresponding dilution. The percentage 

 yields, however, were not so great as with smaller amounts. For 

 instance, 280 gms. of aniline gave 232 gms. of product, and 560 gms. 

 of aniline yielded 435 gms. of pure redistilled phenyl isothiocyanate. 

 The low results were due in part to difficulties in properly mixing 

 the reagents. If much free nitric acid was formed it decomposed 

 the ammonium phenyl dithiocarbamate, thus preventing the for- 

 mation of the lead phenyl dithiocarbamate. Other by-products 

 that occurred were ammonium thiocyanate, diphenyl thiourea, 

 triphenyl guanidine, which appeared as the nitrate, and monophenyl 

 thiourea, where any excess of ammonia was present. In addition 

 a strong current of steam is needed to separate the oil from the 

 mass of lead sulphide formed. 



ACTION OF LEAD NITRATE ON OTHER SALTS OF THE PHENYL 



DITHIOCARBAMIC ACID. 



It seemed worth while to try the desulphurization of other than 

 the ammonimn salts, since in the absence of that reagent certain 

 side reactions might be prevented. 



Sodium Salt. C,H,NHCSSNa. 



Aniline 28 . gms. 



Carbon bisulphide 27.0 gms. 



Sodium hydroxide 13. 1 in 50 cc. water. 



Lead nitrate 100.0 in 300 cc. water. 



The sodium salt which formed on mixing the reagents was so 

 thick that the stirrer was stopped. Alcohol, 22 cc, was therefore 

 added, and the stirring continued for one-half hour. After standing 

 for an hour the orange-colored mixture was dissolved in 300 cc. of 

 water and treated with the lead nitrate solution. Only a 30.2 per 

 cent yield of the mustard oil was obtained, the greater portion of the 

 aniline having been converted into thiocarbanilide. 



Barium Salt. (C6H3NHCSS)3a. 



Aniline 28 gms. 



Carbon bisulphide 30 gms. 



Crys. barium hydroxide 47.5 gms. in 110 cc. of water. 



Zinc chloride 42. 1 gms. in 42 cc. of water. 



Sodium hydroxide 9.6 gms. in 18 cc. of water. 



The aniline was slowly added to the mixture of barium hydroxide 



