. Currents in biochemical research. Biochemistry -- Research; Biochemistry; Research. LEONOR MICHAELIS in extremely alkaline solution can be written as formula XI and which O -O OH i k CH3—/N—CHs CH3— / \ —CH3 CH3— Y 0 X —CH3 CH3 \ -CHs. —CH3 —CH3 -o XI in less alkaline solution would add first one, then another, proton to form XII. This is the customary bivalent reduction. The inter- mediate, brown substance is the result of a univalent reduction; and it can be shown by various methods, to be described later on (see pages 215 and 217), that it has the same molecular size as XI and differs fro
. Currents in biochemical research. Biochemistry -- Research; Biochemistry; Research. LEONOR MICHAELIS in extremely alkaline solution can be written as formula XI and which O -O OH i k CH3—/N—CHs CH3— / \ —CH3 CH3— Y 0 X —CH3 CH3 \ -CHs. —CH3 —CH3 -o XI in less alkaline solution would add first one, then another, proton to form XII. This is the customary bivalent reduction. The inter- mediate, brown substance is the result of a univalent reduction; and it can be shown by various methods, to be described later on (see pages 215 and 217), that it has the same molecular size as XI and differs from it only in so far as one oxygen atom is negatively charged and not the other. This brown substance is a free radical. One might say that one oxygen atom is bivalent and the other uni- valent, as in XIII. The same molecular species, in a more acid solu- tion, would have formula XIV. O O GHj CH, ^. -CH3 -CH3 CH3 CH3 ,-V^-CH3 -GHs o- XIII OH XIV Let us consider first the reaction in a strongly alkaline solution. When the solution of the quinone is mixed with increasing amounts of a reducing agent, there will always be, except for the very begin- ning and the end of the oxidation, a mixture of the quinone, the hydro- quinone, and the intermediate free radical which we shall call semi- quinone; and an equilibrium is established between these forms. It is important to emphasize that the equilibrium is established instan- taneously, and that there is no sluggishness in its formation, as is usually the case in the formation of equilibria with organic compounds (except acidic ionizations). The activation energy of this reaction leading to equilibrium is extremely small. So, in the solution, the intermediate free radical is never present without being in mixture with the quinone 214. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfect
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