14 THE UNIVERSITY SCIENCE BULLETIN. 



/ 



RESUME OF RESULTS. 



Aryl Per cent yields based 



isothiocyanates. « on amines used. 



■ Phenyl 76.8 



o-Tolyl 73.2 



m-Tolyl 74.7 



p-Tolyl 72. 1 



1, 3, 4,-Xylyl 52.0 



Pseudocumyl 50. 7 



Alpha-naphthyl 68.0 



Beta-naphthyl 00.0 



o-Anisyl 70.7 



p-Anisyl 68 . 6 



p-Phenetidyl 72.7 



m-Bromophenyl , 37 . 4 



p-Bromophenyl 39 . 6 



p-Chlorophenyl 59 . 3 



p-Iodophenyl 53 . 3 



p-Nitrophenyl 00.0 



From the consideration of the foregoing results, it is evident that 

 the success of the method is dependent upon at least three factors: 

 First, the completeness of the formation of the ammonium aryl 

 dithiocarbamate, RNHCSSNH^. Second, the ease and completeness 

 of separation from the sulphide precipitate. Third, the avoidance 

 of side reactions leading to the formation of free aryl dithiocarbamic 

 acid, aniline, etc. The low yield in the case of the xylyl, cumyl and 

 alpha-naphthyl derivatives would seem to be due to their slight 

 volatility with steam and the difficulty of extracting the oils from 

 the mass of lead sulphide. 



The cause of the failure with beta-naphthylamine must be de- 

 termined by further investigation. 



With the halogen substituted anilines which are less basic than 

 the aniline, toluidine, etc., there is probably incomplete salt forma- 

 tion, which would thus account for the lower yields. 



SUMMARY. 



The paper describes a method for the preparation of aryl isothio- 

 cyanates which is relatively simple and inexpensive and which gives 

 yields greater than any which require the intermediate formation of 

 the diaryl thioureas. 



D 



