Five isomers of benzene tetrachloride, synthesized by the iodine-catalyzed photochlorination of benzene, have been isolated by vacuum rectification and partition chromatography, purified and characterized by melting point and infrared spectrophotometry. The steric structures of these isomers have been established by chlorination to benzene hexachloride. On the basis of the products thereby formed and of the structural relationships of the tetra-and hexachlorides, it has been possible to confirm chemically the reported configurations of the benzene hexachlorides and to assign the following structures to the benzene tetrachlorides: a, eepp; ß, peep; 7, eeep; S, eeee; e, eepe. The photocatalytic addition of chlorine to the cycloolefinic double bond has been shown to proceed by two cis and two trans mechanisms, yielding products in which the chlorine substituents thus introduced are oriented ep or pe, and ee or pp, respectively. Chemical evidence was obtained for ring conversion. B.p., 15 ram., Isomer °c.
Separation of nickel from seven times its weight of antimony, arsenic, barium, cadmium, calcium, magnesium, potassium, sodium, strontium, and zinc was obtained by precipitation with dimethylglyoxime. The precipitates were spectrographically free from these elements. Aluminum, chromium, copper, and manganese were definitely coprecipitated. The error introduced into the weight of precipitate by the chromium and manganese is insignificant.
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