34 



f.ions were fulfilled. The aoooin|)aiijing formnla was the simplest, 

 and was used 113' different investigators (see e.g. Abkgg's Handboek 111 

 pg. 43), and also served Bohskkk.n as a working-.scheme. According to 

 \p „ this assumption one molecule of di-oxy-compound, 



X I Np Qii therefore, combines with one molecule of boric 



\/-, q/ acid with loss of water to a cyclic compound, 



/ which would have stronger acid properties. 



Different investigators have supposed other relations as to the number 

 of molecnies combining than these to account for the physico-chemical 

 behaviour of the mi.ved boric acid-polyoxyderivative-solutions, but the 

 giounds on which these suppositions were based, are generally uncertain, 

 and often conflicting. Up till now nothing could be said with certainty 

 about the general type on which t!ie acid complexes are based. The 

 observations agree with each other only in so far that these com- 

 pound.s are almost con)|)letely dissociated in aqueous solution, and that 

 their formation is favoured by increase of the concentration of the 

 componenls. It further appeared from diffeient invesligations that in 

 some cases (a.o. with substances like mannite and dulcite); seveial 

 compounds of different composition must be present in the solution, 

 of which however, it can, not be ascertained which are the typically 

 acid ones. 



In 1911 Fox and Gaugk') described the first compound of boric 

 acid with a multi-valent alcohol which is well crystallized. From 

 an alcoholic solution they obtained a mannito boric acid CjHijOgB. 

 They do not however, say, anything about the constitution. A second 

 compound was described by Dkrx'), viz. the crysiallized cis-cyclo 

 heptane diol boric acid. He determined the boron content by tilration 



and gave the following formula based on that C.Hj, : \BOH,H,0. 

 We might consider the mannito boric acid in an analogous way as 

 C.H,,0, : \bOH, H.O. Both alcohols increase the conductivily of 



the boric acid in a high degree. There were, as we see, reasons to 

 look upon these compounds as being the strong complex acids that 

 bring about these phenomena. The impetus for making a new attempt 

 to ascertain the nature of the strongly acid boric acid compounds 

 was given by the following accidental discovery. The 2.4. dimethyl 

 peniane 2.4. diol') when reacting on boric acid (even in very diluted 



1) Soc. 99. 1075. 



2) Recueil 41, 340 (1922). 



') Obtained from GHgMgJ and diacetone alcohol. Mr. Langeduk drew my 

 attention to a new method of preparation, vvliich renders this latter substance 

 very easily accessible. (Adams, Organic Syntheses 1921, p. 45). 



