the case. She : same dahon solution is formed 
re hydrocoumarinic sulphonate. Potassium hydrocoumarinic sulphonate 4 
sodium salt. The barium salt separates when a solution of barium acetate is a 
to a strong solution of the sodium salt. 
‘sulphite solution and evaporates to about half the volume; he then adds a 50 per cent. 
10 g. from 10 g. of coumarin. 
by degrees and forms hydrocoumarinic sulphonate. 
‘heating 1-thiocoumarin with phosphorus pentasulphide; the product, when isolated — 
warming coumarin with potassium bisulphite solution; it is less soluble 
e ; Sih 
Coumaric acid is formed by splitting off the sulpho group from | the sodium s om 
of the hydrocoumarinic sulphonate. Dodge heats coumarin with a 25 per cent. sodium ¥ 
" 
potassium hydroxide solution and evaporates to dryness on the water- bath. The — 
strong hydrochloric acid, when coumaric acid is precipitated. The yield is “about 
Coumarin may be recovered from the hydrocoumaric sulphonate. For this nine 
the sulphonate solution from 2 g. of coumarin was evaporated to dryness, pulverized = 
and mixed with 5 cc. of acetic anhydride. On standing the mixture becomes solid ee 
a 
Be 
We have, then, here the following er of reactions: Coumarin <_, ; Hydro ae 4 
sulphonate *—, Hydrocoumaric sulphonate <—, Coumaric acid. a 
Recovery of coumarin from the hydrosulplanate presents some difficulty; decompo- \E 
sition with barium hydroxide gave the best results. The hydrosulphonate when heated — 
at 130 to 160°, splits into coumarin, sodium sulphite, sulphur dioxide and water: — 4q 
® 
¢ 
53 
. 
2 CgH;O2NaSO; == 2 CyoHe O2 oe Naz:SOz; a SO, -- H,O : 
Limettin, also known as “citroptene”, reacts with bisulphite solution when the 
sulphonate is formed, but the reaction takes more time than with coumarin. ACen R 
to prepare limettic acid were unsuccessful. ie 
In conclusion Dodge deals with the hydrolysis of coumarin which he considers 3 
to be a suitable subject for a careful physico-chemical study. . ee 
Three sulphuretted analogues of coumarin are possible, according to whether in 
the molecule but: one of the two atoms of oxygen has been replaced by sulphur 
(formula I and II), or both (Ill). The CS-thiocoumarin (thione-coumarin) has been 
known for some time and is readily prepared by the reaction of phosphorus penta- 
sulphide on coumarin; unless purified by special method, it possesses an unpleasant, 
fecal-like odour. 1-Thiocoumarin (thiol-coumarin) (II) was prepared a few years ago 
by Chmelewsky and Friedlinder') from o-mercapto-cinnamic acid by intramolecular 
CH: CH-CO.H / CH: CH 
<sH. Sig CoH 6 co 
possess the nasty smell of the thione- ge ae on the contrary its odour is- rather i 
pleasant, resembling coumarin. ae 
According to H. Simonis and A. Elias*) 1.2-dithiocoumarin (III) is obtained by 4 
dehydration: CgH, This preparation does not 
from the reaction mass by boiling with benzene, cristallizes to beautiful deep red a 
prisms and needles, m. p. 104°. Its fecal odour, which resembles that of 2-thio 
coumarin, may be somewhat weakened by boiling with copper powder in benzen 
melts at 237 to 239°, the aurichloride compound at 208 to 210°. 1-Thiocouma 
*) Berl. Berichte 46 (1913), 1906. -—- *) Berl. Berichte 49 (1916), 763. 
