1188 



On saponifying the fraction boiling at 169° — J74°/l9 mna. with 

 a hot solution of potassium hydroxide the diol is formed, which had 

 already been obtained by Weiszgerber ; we got a better yield however 

 (58 '/, instead of 30 "/, of the theoretically possible one, calculated 

 from the diacetate). After sublimating in a vacuum and repeatedly 

 crystallising from toluene the trans-diol forms snow-white highly 

 lustrous leaflets, m.p. 159,8°— 160°. 



Though oui- analyses and our determinations of the molecular 

 weight in phenol ') pointed out, that the obtained substances were 

 the sought-for hydrindene diols, the possibility still existed that one 

 of the two might be an aequimolecular compound of cis- with trans- 

 hydriiidene diol. In fact H. Lkroux ") isolated siich compounds of the 

 naphtane-2.3.diols and of the naphtanetriene-2.3.diols: these compounds 

 preserved constant melting points throughout recryslallisations from 

 various solvents; in aqueous solution however — as appears from the 

 depression of the freezing point — they were dissociated into their 

 components. The isolation of the cis- and of the trans-isomer out of 

 the (cis -f- trans)-compound could only be brought about by acetylation, 

 from which a mixture of cis- and trans-diacetates results, which could 

 be separated by crystallising. 



If the occurrence of an inversion of cis into trans, or the reserve, 

 be excluded, it will be clear that never, in converting an aequimolecular 

 (cis -\- transj-compound into derivatives, the cis- or (he trans-derivative 

 can be obtained in a yield exceeding 50 % oi' the theoretical one. 

 So, having prepared from our hydrindene diols with the melting 

 point 107,5°— 108° and 159,8°— 160°, thee/.?- and trans-hydrindene-1.2. 

 diol-dibenzoates (melting respectively at 109,5° — 110,5° and at 

 76,5° — 77,5°), and the corresponding di-phenyhi)(fihnnes{\r\Q\\\u^\M'\[h. 

 strong decon» position at 205° and at 206,5°), in yields larger than 

 50 7o of the theoretically possible amounts, we have proved the unity 

 of each of our diols. 



On saponification by means of alcali the trans-derivatives directly 

 gave back the trans-diol; the cis-derivatives however, generally gave 

 rise to preparations, having indeed the appearance of the diol with 

 the m.p. 107,5°— 108°, but melting already at 100,5°— 101,5°, even 

 after recrystallising and sublimating. This new diol m.p. 100,5° — 

 101,5° is a polymorphic modijication of the cis-diol, as appears from 



1) The data, including those of the other substances to' be described, will be 

 given later in a full communication. 



») H. Leroux, Ann. de Ghim et de Phys. (8) 21, 536-47 (1910;^. 



