Chemistry. — " Provisiondl Communication on Boric Acid Com- 

 pounds of some Oiyanic Substances containing more than one 

 Hydroxijl-Groui). Boron as a Pentavalent Element." By 

 F. II. Hkrmans. (Communicated by Prof. J. BOeseken). 



(Communicated at the meeting of December 30, 1922). 



The l)eliavi()iir of l>()ric acid towards Iiydroxyl-containing organic 

 substances is striking in many respects. The extra-ordinary ease 

 and rapidity with wliich it forms esters of the type of B(OR), with 

 the ordinary saturated alcohols, also when a catalyst is absent, is a 

 totally' unexpected property for a weak, and for liie rest mono-basic 

 acid such as boric acid, and in this respect it is unequalled. 



Siill more interesting is the action of boric acid on the aqueous 

 solutions of mulli-valent alcohols and other substances rich in 

 hydro.xyl, such as some sugars. It has been known for a long time 

 that these mixed solutions sometimes present a much greater hydrogen 

 ion concentration than a solution of boric acid only. The alkaline 

 reaction of a borax solution can even become an acid one by addition 

 of substances such as mannite'). Also the influence of boric acid 

 or Iwrales on the optical rotatory power of such sidjstances rich in 

 hydroxyl, was early observed. Undoubtedly these phenomena point 

 to compounds which boric acid forms with the substances mentioned 

 above. -Several investigators have expressed their opinion about the 

 nature of these compounds'). Mostly it is assumed that acid boric 

 acid esters are formed which possess a highei' degi'ee of acidity than 

 free boric acid. Systematic attempts to tind out more about these 

 compounds through their isolation, have seldom been made, at least 

 they have not l)een very successful. 



In 1869 Duve') described a series of salts of different boro-tartaric 

 acids, which however present the apparance of glassy, non-crystallizing 

 masses or amorphous precipitates, the individuality of which is open 

 to doubt. The same principle applies to most of the boro-citric acid 



1) We will postpone the older and more recent literature on this subject to a 

 following publication. 



S) Vierteljahrsschr. pr. Pharm. XVIll, 321. 



