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CHEMISTRY: JOHNSON AND TICKNOR 
been coupled with carbon-bisulphide in this manner. Fischer attempted 
to convert this salt into ethyl isothiocyanacetate by digestion in aqueous 
solution with silver and mercury salts (Hoffmann's mustard oil reaction). 
He found that it underwent decomposition by such treatment giving 
solutions having the odor of a mustard oil, but ethyl isothiocyanacetate 
was not isolated by him. 
We now find that this dithio carbamic acid salt I of Fischer's can be 
transformed easily and almost quantitatively into ethyl isothiocyanace- 
tate by application of an unique reaction discovered by Andreasch.^ 
This investigator has shown that simple amine salts of the above type 
interact with ethyl chloroformate at ordinary temperature giving 
smoothly isothiocyanates with evolution of carbonoxysulphide and ethyl- 
alcohol. The reaction is expressed by the following general equation: 
R.NH.CSSH.NHzR. + CICOOC2H5 = RNCS COS + C2H5OH + 
R.NH2.HCI 
Fischer's glycocoll-dithiocarbamic acid salt I also interacts with ethyl- 
chloroformate according to the above expression giving an intermediate 
thiolester having the Formula 11. Therefore the first phase of this trans- 
formation may be expressed by the following equation: 
NHCH2COOC2H5 
I 
CSSH.NH2.CH2COOC2H5 + CI.COOC2H5 = 
(Fischer's Salt) 
NH.CH2COOC2H5 + C2H5OOC.CH2NH2.HCI 
I 
CSS.COOC2H5 (II) 
This thiolester displays greater stability than combinations of this t3^e, 
which have hitherto been described. Below 100° the ester II is quite 
stable. If heated above this temperature in a vacuum, it undergoes a 
smooth decomposition . Carbonoxysulphide is copiously evolved together 
with alcohol, and nearly a theoretical yield of ethyl isothiocyanacetate 
is produced. The mustard oil agrees in all its properties with the iso- 
thiocyanate prepared by the thiophosgene method, and boils at 102-104° 
at 10 mm. pressure. The second phase of this interesting reaction is 
expressed by the following equation: 
NHCH2COOC2H5 
I COS -f C2H5OH + SCN • CH2COOC2H5 
CSSCOOC2H5 
