322 PROCEEDINGS OF THH AMERICAN ACADEMY 



chloride ; but by distillation of ethyl pyromucic tetrachloride, of the 

 tetrachloride of j)yroinucyl chloride, or of ethyl 8 chlorpyromucic tetra- 

 chloride, the fS8 dic'hlorpyromucic acid melting at 155-156'^ may be 

 obtained, and in the first two cases a third dichlorpyromucic acid melt- 

 ing at 197-198° is also formed. By careful reduction of the fSd or 

 the /3y dichlorpyromucic acids, the )8 chlorpyromucic acid melting at 

 145-146° is formed. 



Ethyi. Pyromucic Tetrachloride, 



The ethyl pyromucate which we have used in the course of our 

 investigations we have made by warming a solution of pyromucic acid 

 (3 parts) in absolute alcohol (5 parts) with concentrated sulphuric 

 acid (3 parts acid, Sp. Gr. 1.84). After heating for four hours on the 

 water bath, the mixture was allowed to cool, precipitated with water, 

 and the ether washed with a dilute solution of sodic carbonate. The 

 crude ether was then dried by exposure to the air and distilled. The 

 yield of pure distilled ether which is thus obtained amounts to about 

 85 per cent of the weight of the acid taken. This is somewhat less 

 than that which may be obtained by means of hydrochloric acid, but 

 the method is much more expeditious and convenient. 



When dry chlorine is passed over ethyl pyromucate we found that 

 the ether was rapidly liquefied with the evolution of heat, and that the 

 formation of the addition product proceeds as described by Malaguti 

 until the ether has increased in weight very nearly the amount re- 

 quired by the addition of four atoms of chlorine. We soon found, 

 however, that, no matter how carefully the chlorine was dried, hydro- 

 chloric acid escaped, showing the formation of a substitution product, 

 and that the amount of hydrochloric acid formed depended largely 

 upon the rapidity of the stream of chlorine and the consequent eleva- 

 tion of temperature. Even when the ether was carefully cooled to 0° 

 during the whole of the treatment with chlorine, the formation of 

 hydrochloric acid could not wholly be avoided. In this respect our 

 experience agrees with that of Hill and Sanger,* who were unable to 

 form the ethyl pyromucic tetrabromide without the simultaneous for- 

 mation of substitution products. While the statements of Malaguti 

 seemed to leave no room for doubt that the ethyl pyromucic tetrachlo- 

 ride was completely carbonized by heat, experiments made with bro- 

 mine in this laboratory had shown that substitution products could 

 readily be formed from the ethyl pyromucic tetrabromide by heat, 



* These Proceedings, xxi. 155. 



