An improved procedure for the syntheses of the two isomeric 8-chloro (4) and 11-chlorobenzanthrone (6) was devised and their condensation, by Ullmann reaction, to the corresponding dibenzanthronyls was achieved with the object of synthesizing violanthronyl derivatives. The product (mp 118°C) of reduction of 1-chloroanthraquinone (2) by Sn and glacial acetic acid which had been reported to be 4-chloro-9-anthrone (5), was found, by chromatographical separation, to be mixed crystals of two isomeric (5) (mp 137°C) and 1-chloro-9-anthrone (3) (mp 118°C), whose ratio was about 2 : 1. (5) was converted into pure (6) (mp 178°C) in 46% yield by the glycerol condensation. On the other hand, (4) (mp 182°C) obtained from (3) in this manner was the same product as the one obtained by the glycerol condensation of the reduction product of (2) in cone. H2SO4 with Al powder. (2) was converted into isomeric chlorobenzanthrones by a simultaneous reaction of reduction with aniline sulfate and condensation with glycerol. The product was separated by alumina chlomatography to (6) in 18% yield and (4) in 15% yield. Ullmann reaction of (4) and (6) was carried out in naphthalene, and 95% yield of 8, 8'-dibenzanthronyl was obtained from the former, while 11, 11'-dibenzanthronyl was obtained only in 7.8% yield from the latter.
The condensation product of benzanthrone (1) with 3-chloro or 3-bromo derivatives of (1) by sodium anilide was seperated by elution chromatography to give 3, 4'-dibenzanthronyl (5) mp. 3389°C, with 3-bromo-anilinobenzanthrone, and other by-products. By the same process as above, new 9-bromo (6) and 9-iodo derivative (7) of 4, 3'-dibenzanthronyl were synthesized from 3-bromobenzanthrone with corresponding 9-halogeno benzanthrone, while, 9-chloro (9) and 9-bromo-3, 4'-dibenzanthronyl (10), both new compounds too, were obtained from (1) and its 3, 9-dichloro or 3, 9 dibromo derivative.
It was found that a weak-acid mixture could be separated successfully by fractional extraction ; two immiscible solvent layers were diluted to a certain extent, and the substances separated were purified. This fractionation method consists in the combination of the stepwise extraction of each acid from their mixture in an organic solution (dilution 7-350) with successive, small portions of aqueous sodium hydroxide solution (dilution 5-30) and subsequent thin layer chromatographic tests on each of the acidified extracts. When an organic solvent suitable for separation can be found the fractional extraction is possible regardless of the difference in ionization constants.
Reactions of cyclohexene with aqueous sulfuric acid solution were carried out under varying reaction conditions. When 1 mol of cyclohexene reacted with 7 mol of 50% sulfuric acid at 70°C for 3 hrs., the products were cyclohexanol (yield 72 mol %) and its sulfate (yield 7.5 mol%) Furthermore, the optimum conditions for separation of the reaction mixture into organic layer and aqueous sulfuric acid layer were found. On the basis of these findings on the preparation of cyclohexanol from cyclohexene, the following process was proposed : After the reaction of cyclohexene with aqueous sulfuric acid solution is over, cyclohexanol is obtained from the organic layer which separated ; the separated aqueous sulfuric acid solution is used repeatedly.