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Students are given a solution of some ion not covered in the regular identification scheme and asked to identify the ion, adopt or devise a scheme of analysis for an unknown containing the usual scheme of ions plus the one extra ion, and to analyze a couple of rather simple general unknowns that may or may not contain the extra ion.

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RECEIVED FEBRITARY 11, 1R57-1 new synthesis of dioxanes inrolving the condensation of a diene, a mercuric salt and a glycol has bcen developed. The product from butadiene, mercuric nitrate and ethylene glycol, after precipitation as the halide and replacement of the halomercuri group with iodine, yielded a mixture of cis-and trans-2,3-bis-(iodomethyl) -p-dioxanes. Nitric acid oxidation of the trans-bis-(iodomethyl) compound produced the trans-dicarboxylic acid in good yields and without isomerization. The anhydride of the trans-acid was converted to the cis-anhydride by extended refluxing in acetic anhydride, and hydrolysis of tht: cis-anhydride yielded the cis-diacid. The facts that trans-diacid could be partially resolved, but that cir-diacid could not, were used for definite assignment of configuration. Oxidation of the cis-2,8-bis-(iodomethvl) -p-dioxane failed t o protluce a diacid but did produce cis-3-hydroxymethyl-2-p-dioxanecarboxylic lactone. When cis-2,3-bis-( p-toluenesulfr~nat~mctli~l) -pdioxane, which had been formed from the glycol obtained by the reduction of dimethyl cis-2,3-p-dioxanedicarhos\..late, was treated with sodium iodide, the cis-bis-(iodomethy1)-p-dioxane mas obtained, thus relating the latter to the cis-diacid I n the original synthesis, equilibration conditions produced predominantly the trens compound, indicating it to be more stahlc than the cis isomer.

An alkyl substituted dioxadiene has been made for the first time. When iraws-2,5-bis-(iodomethyl)-;£>-dioxane was treated with hot base, the elimination of the elements of hydrogen iodide produced a diolefin, 2,5-bis-(exomethylene)-£dioxane. This substance was isomerized by means of a palladium-on-charcoal catalyst to a stable diolefin, 2,5-dimethyl-£dioxadiene. Treatment of either diolefin with methanol in the presence of a trace of acid produced the dimethoxyacetal of dimeric hydroxyacetone, thus supporting a dioxane structure for that compound.