174-P.] 



THIOCYANIC ACID 



269 



Arch., 69, 354; Gscheidlen, Pfliiger's 

 Arch. 14, 401 : in saliva, submaxillary 

 and sublingual, Gscheidlen, loc. cit.; 

 Oehl, Canstatt's Jahresber. d. Med. 1, 

 I2O; Kriiger, Zeit. Biol. 37, 6; Ch. 

 Centr. 1899, 1, 53; Grober, Ch. Centr. 

 1901, 1, 839 : in gastric juice, Kehling, 

 Zeit. physiol. Ch. 18, 397; Nencki, 

 Ber. 28, 1318; Nencki and Sieber, 

 Zeit. physiol. Ch. 32, 291 : in nasal and 

 conjunctival secretions, Muck, Ch. Centr. 

 1900, 2, 1157 : for method of identifi- 

 cation in urine, blood, bile, &c., see 

 Bruylants, Journ. Pharm. [5] 18, 104 ; 



SYNTHETICAL PROCESSES. 



[A.] From carbon through cyanogen 

 (see under hydrogen cyanide [172 ; A]). 

 Cyanogen passed over heated potassium 

 polysulphide gives thiocyanate ( Wohler, 

 Pogg. Ann. 3, 181). Nitrogen passed 

 over a strongly ignited mixture of 

 potassium carbonate (containing sul- 

 phate) and charcoal gives a trace of 

 potassium thiocyanate (Erdmann and 

 Marchand, Journ. pr. Ch. 26, 414). 

 Or cyanogen chloride interacts with 

 ammonia to form cyanamide (Cloez and 

 Cannizzaro, Ann. 78, 229), which can 

 be treated as below under E. Nitro- 

 genous organic matter (such as urea) 

 fused with potassium polysulphide gives 

 potassium thiocyanate (Aufschliiger, 

 Zeit. anal. Ch. 35, 315). 



Or carbon dioxide passed over heated 

 sodamide gives cyanamide (Beilstein 

 and Geuther, Ann. 108, 93 ; Drechsel, 

 Journ. pr. Ch. [2] 16, 203). Ammonium 

 carbonate or carbamate heated with 

 sodium also yields cyanamide (Fenton, 

 Trans. Ch. Soc. 41, 263). Subsequent 

 steps as below under E. 



Ammonium thiocyanate is produced 

 by the electrolysis of a solution of 

 ammonium hydrosulphide with gas- 

 retort carbon electrodes (Millot, Comp. 

 Rend. 103, 153; Bull. Soc. [2] 46, 

 246). 



[B.] From hydrogen cyanide [172] by 



combination . with ammonium polysul- 

 phide (Liebig, Ann. 61, 126). Or 

 metallic cyanides or ferrocyanides [172 ; 

 A] give thiocyanates on heating with 

 sulphur or alkaline sulphides (Porret, 

 Gilb. Ann. 53, 184; Berzelius, Berz. 

 Jahresber. 1, 48 ; Wiggers, Ann. 29, 

 319 ; Liebig, Ann. 50, 349 ; 51, 288 ; 

 61, 126; Henneberg, Ann. 73, 230; 

 Lowe, Jahresber. 1853, 407 ; Babcock, 

 Zeit. [2] 2, 666 ; Frohde, Pogg. Ann. 

 119, 317 : for production of potassium 

 thiocyanate by the fusion of carbon, 

 sulphur, and ammonium sulphate with 

 potassium hydroxide see Fleck, Ding. 

 poly. Journ. 169, 209 : for production 

 of potassium thiocyanate by the inter- 

 action of potassium thiosulphate and 

 cyanide see Dobbin, Ch. News, 77, 



[C.] From carbon disulphide [160] 

 and ammonia as under hydrogen cyanide 

 [172; B]. 



[D.] From ethyl alcohol [14] and 

 nitric acid, &c., through mercury ful- 

 minate (see under benzoic aldehyde 

 [114 ; A]). The latter gives ammonium 

 thiocyanate when acted upon by sul- 

 phuretted hydrogen (Ber. 8, 1 1 7 8). 



[E.] Urea [Vol. II] on heating with 

 sodium or by distillation with quick- 

 lime gives cyanamide (Fenton, Trans. 

 Ch. Soc. 41, 262 ; Emich, Monats. 1O, 

 332). The latter on treatment with 

 sulphuretted hydrogen or (better) am- 

 monium sulphide yields thiourea (Bau- 

 mann, Ber. 6, 1375 ; 8, 26), and this 

 on heating with water at 140 or per se 

 at 160-170 becomes converted into 

 ammonium thiocyanate (Haller, Bull. 

 Soc. [2] 45, 706). 



[F.] Guanidine [Vol. II] is converted 

 into the nitroso-derivative (Thiele, Ann. 

 273, 133). The latter on heating with 

 water gives cyanamide (Ibid. 136), 

 which can be treated as above under E. 



NOTE : For the liberation of free thiocyanie 

 acid from its salts see WOhler, Gilbert's Ann. 

 69, 271 ; Hermes, Zeit. [2] 2, 417 ; Journ. pr. 

 Ch. 97, 465 ; Zimmermann, Ann. 199, I ; 

 Klason, Journ. pr. Ch. [2] 35, 403. 



