1120 
Chem. Soc. 91, (1907), 1641) has again attacked the same reaction 
and has found out that the reaction is unimolecular with respect to 
hypophosphorous acid, but it is catalytically accelerated by hydrogen 
ions. Nobody has examined the action of light on this reaction. 
lt has now been found out that the action of iodine on the acid 
as well as its salts is eatalytically accelerated by sunlight as will 
be evident from the following tables, though Luruer and PLorNikorr 
(Zeit. Phys. Chem. 61, 524 (1907)) have shown that light is without 
any influence on the action of iodine on phosphorous acid. (See p. 1119). 
Evidently light markedly accelerates the action of iodine on hypo- 
phosphorous acid as well as hypophosphites. Here light plays the 
same part as hydrogen ions do in these oxidations. 
Dawson and his pupils (Trans. Chem. Soc. (1909), 95, 1860; 
(1913) 108, 2135) have shown that iodine acts slowly on an aqueous 
solution of acetone and that the action is catalytically accelerated 
by hydrogen ions. According to the above authors the reaction takes 
place according to the following scheme 
[CHE COCH, = CHe: € (OH) CH, 
Il CH,:C(OH)CH, + I, > CH, Cigar OH, 
Il CH,.i¢ con CH, > CH,ICOCH, + HI. 
Now it has been found out tbat light acts as a positive catalysor 
in the above reaction. In the absence of an acid, the interaction 
between iodine and aqueous acetone proceeds very slowly ; so at 
the beginning an equal amount of acid was added to each of the bottles 
in order to accelerate the reaction. 
Acetone and iodine. 
EA | 3 | 
: . Time of | Amount of | Unchanged » : 
Quality of light | exposure iodine ae RTE Volume of solution 
| 
1) Sunlight 360’ 0.00635 0.00145) 5 cc. zog iodine and 5 cc. 
Darkness | 360’ Do | 0.00248 | acetone and 5 c.c. 5 HCI 
2) Sunlight | 420 | Do |- | 0.00121 | 
Darkness | 420° Do | 0.00225 | 
3) Diffused light 365’ Do | 0.00197 
Darkness 365’. | __Do ‚ | 0.00242 | a 
4) Diffused light | 425/ | Do 0.00162 | 3 
Darkness | 425/ Do 0.00219 | 
