XYLYLIC ACID, ETC. 841 



Barium mesitylate, (C 9 H 9 2 ) 2 Ba, crystallizes in 

 large, lustrous prisms, easily soluble in water. 



2. Xylylic acid, C 6 H 3 j g^ (1:2: 4) * is pro- 



duced by the simultaneous action of sodium and car- 

 bonic acid on monobrommeta-xylene ; and together with 

 para-xylylic acid by oxidation of pseudo-cumene. The 

 mixture of acids is purified by distilling off with water 

 vapor, and heating gently with tin and hydrochloric 

 acid ; and the two acids then separated by means of 

 partial crystallization of the calcium salts. Calcium 

 para-xylylate separates first, and afterward the xylylate. 

 The acids are precipitated from the solutions of their 

 salts by hydrochloric acid. Crystallizes from alcohol 

 in large, transparent, monoclinate prisms, from water 

 in fine needles. Fuses at 126. Very similar to mesity- 

 lenic acid. Distilled with lime, it, like mesitylenic acid, 

 yields meta-xylene, but is converted into xylidinic acid 

 by further oxidation. 



Calcium xylylate, (C 9 H 9 C>yCa + 2IPO, forms large, 

 hard, transparent, monoclinate prisms. 



3. Para-xylylic acid,C 6 H 3 j (1:3: 4).* In 



regard to the formation and preparation see Xylylic 

 Acid. Separates from boiling water in indistinctly 

 crystalline flocks, from alcohol in lanceolar prisms, con- 

 centrically grouped. Fusing point, 163. More easily 

 soluble in alcohol than xylylic acid. By further oxida- 

 tion it is converted, like xylylic acid, into xylidinic 

 acid, but yields ortho-xylene by distillation with lime. 



Calcium para-xylylate, (C 9 H 9 2 ) 2 Ca -f 3JH 2 0, forms 

 soft, untransparent, fascicular crystals. 



4. Ethyl-benzole acid (Para-), C 6 H 4 j QQQJJ is 

 obtained by the action of sodium and carbonic acid on 



* The position of the group CO. OH is designated by 1. 

 29* 



