OP ARTS AND SCIENCES. 327 



Mucoxychloric Acid. 



W. Z. Bennett* and one of us several years ago studied the ac- 

 tion of baric hydrate upon mucochloric acid. It was found that the 

 acid was decomposed by a large excess of baric hydrate, and that 

 a /3 dichloracrylic and formic acids were formed in nearly theoretical 

 quantities. When the baric hydrate is carefully added, so that the 

 solution is at no time very strongly alkaline, the reaction follows an 

 entirely different course, and mucoxychloric acid is found in abun- 

 dance. Since the a /3 dichloracrylic acid had already been shown to 

 be more stable than the corresponding dibromacrylic acid, we were 

 led to study mucoxychloric acid more in detail, with the hope that its 

 derivatives would also prove more stable and more manageable than 

 those of mucoxybromic acid. In the preparation of mucoxychloric 

 acid we followed precisely the same method wiiich we had found ad- 

 vantageous with the bromine compound. Mucochloric acid t was 



* These Proceed! ncrs, Vol. XVI. p. 206. 



t Altliough W. Z. Bennett and I had succeeded in obtaining a fairly satis- 

 factory yield of mucochloric acid, the method which we used was troublesome 

 and tedious in the extreme when large quantities of material were involved, 

 and necessitated the prolonged treatment of large quantities of liquid at 0° 

 with chlorine gas. The slightest want of care also frequently diminished the 

 yield most seriously. I therefore made many fruitless attempts to find some 

 more advantageous method for its preparation. I at last hit upon an extremely 

 convenient and simple method, which allows the preparation of any quantity of 

 mucochloric acid desired in the course of a few hours. The yield is also quite 

 satisfactory, and falls not far short of that which is attainable by the old method. 

 Pyromucic acid is suspended in 142- times its weight of common strong hydro- 

 chloric acid (Sp. Gr. 1.16), and somewhat more tlian four molecules of finely 

 powdered manganic dioxide is then gradually added. At first the mixture is 

 kept cold (ice cooling is unnecessary). The temperature is then allowed to 

 rise, and finally the solution is heated and boiled gently for twenty minutes. 

 Since it is difficult to filter the hot strongly acid liquid from the impurities con- 

 tained in the manganic dioxide, the solution is allowed to cool, and the muco- 

 chloric acid which separates collected upon a filter of coarse cloth. It is then 

 dissolved in hot water, and the filtered solution concentrated by evaporation if 

 necessary. Prom 100 grm. of pyromucic acid suspended in 1250 cc. of 

 ordinary hydrocliloric acid and 380 grm. of manganese dioxide (83% MnO.,), 50 

 grm. of pure mucochloric acid are readily obtained, and the mother liquors 

 yield 2-3 grm. of a somewhat dark-colored acid. Bennett and I obtained by 

 the much more laborious method, as the result of many separate operations, 

 129 grm. of mucochloric acid from 202 grm. pyromucic acid. This method ac- 

 cordingly yields in a short time about 83 per cent of the amount attainable by 

 the more tedious method. — H. B. H. 



