35 



aqueous solutions) gives a heuntifully oivstallizing and only siiglitiy 

 soluble conipouiid, to wliicii the following formula must be assigned 

 as a result of analysis and examination of properties: 



(f^u ) -— Q f) C H B 



"^ \ Calculated 53,16 9,17 6,90 



^**'\ yBOH Yonnii 53,10 9,07 6,80 



(CH,), = C — 53,27 9.12 6,95 



Tlie compound has an exceedingly great crystallizing power, melts 

 not entirely sharply at 100 — 102°, is somewiiat volatile, and lias 

 a pleasant odour strongly reminiscent of saffron. It is, however, 

 by no means a strong acid, and like boric acid it hardly colours 

 blue litmuspaper red, and in accordance with this the said diol 

 (which is readily soluble in water) does not bring about any increase 

 of conductivity of the boric acid, as was to be expected from such 

 a 1.3 diol according to the data collected by BöesekeiN up till now. 

 As a result of this I believed that the really stronger acid boro- 

 complexes must possess another structure than had been assumed 

 so far, and this was soon confirmed. I succeeded, though only after 

 some more difticulties, in isolating analogous and likewise only 

 exceedingly weakly acid boron-compounds of 2. 4. dimethyl hexane 

 2.4.diol, 2.4:.pentane diol, and pinacone, likewise diols which do not 

 appreciably intluence the conductivity of boric acid. In the case of 

 tri-methylene glycol, ordinary glycol, and cis-1 .2.cyclo hexane diol 

 the existence of compounds could be shown, but attempts to isolate 

 them in a pure state failed'). It is probable tiiat all the 1.2 and 

 1.3 diols are able to form such compounds with boric acid, that in 

 many cases, however, they can be separated only with great difficulty, 

 if at all, in consequence of unfa\ourable solubility conditions and 

 similar difficulties. In aqueous solution they are partially split up 

 into their components. The compound described first, at 0° in 0,1 

 normal solution for 75 " ,. The readiness with which this compound 

 is obtained, is owing to its slight solubility in water (4,46 g. in 

 100 cc. solution at 25°), which is still smaller than that of boric 

 acid. It dissolves in diluted alkalies, pi-obably accompanied by 

 formation of a potassium salt, which is, however, also dissociated, 

 as pure diol is withdrawn from the solution by ether. The liquid 

 free diol is salted out by strong potassium hydroxide ; the potassium 

 salt itself could not be isolated as yet. In the cis. 1.2 cyclo hexane 

 diol, however, the corresponding potassium salt is slightl}' soluble 

 in an excess of strong potassium hydroxide, and cx'ystallizes out. 



' ) I hope to discuss tlie details of tlie preparation in my doctor's dissertation. 



3* 



