Liebig's 1831 paper that describes a new apparatus for the analysis of organic compounds and the results of several analyses using the apparatus is a justly famous contribution to the evolution of modern chemistry. In this paper, I look at the three separate components of Liebig's combustion apparatus that collect the water, carbon dioxide and nitrogen released by the combustion of six alkaloids. Gravimetric data included in the paper reveal that very accurate results could be obtained for water by absorption in a calcium chloride tube, and even better results for carbon dioxide resulted from use of the Kaliapparat. Volumetric measurement of nitrogen gave very poor results despite Liebig's efforts to improve it. Inaccuracies in nitrogen measurement made consistent construction of accurate molecular formulae for nitrogenous substances impossible, and only fortuitous decisions intended to bring molecular formulae into agreement with measured combining weights gave formulae in agreement with modern ones, as in the case for quinine.
The synthesis of 3,6-dimethyl-6-n-butyl-5,6-dihydropyridazine, the first 5,6-dihydropyridazine, is described. On heating it undergoes a [1,5] sigmatropic hydrogen rearrangement to give the corresponding 1,6-dihydropyridazine.
Using M.O. calculations, a correlation is estab-wavelength.1 The Frank-Condon maximum of (4) occurs lished between the angle subtended by an azo-group and a t 435 nm, about 100 nm to the red as compared with that the energy of the l(n,v*) transition.found for the five-membered ring analogue ( 5 ) or that for the unconjugated six-membered ring system (1). The only azo-compound with an absorption energy comparable to RECENTLY the conjugated azo-compound (4) was syn-that for (4) is the sterically strained cis-azo-2-methyl-2thesized and found to exhibit its low energy absorption, a propane (8), which suggested that the variation in transition presumed l(n,v*) transition, a t an unexpectedly long energy might be steric in origin.
The structure of the dimer formed from acetonylacetone and hydrazine has been re-examined. On the basis of chemical and spectroscopic data, a covalent tricyclic structure is proposed.La structure du dim2re formt B partir de I'acetylacttone et de I'hydrazine a t t t reexaminee. Sur la base de donntes chimiques et spectroscopiques, une structure covalente tricyclique est proposte.
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