6-7 + 2 -* 8 electrocyclic reactions probably amounts to at least 18-20 kcal/mol, a figure substantially larger than the previously suggested minimum value of 11-12 kcal/mol.5•25 (25) It is possible that the transformation to the "nonallowed" system (ref 5) actually occurs via allowed hydrogen shifts from all-cis-2,4,6,8-decatetraene. We acknowledge a stimulating discussion with Professor W. R. Roth concerning this point.

Novel electrochemical methods have been developed for determination of total hemoglobin, hematocrit, and detection of hemolysis in whole blood. Hemoglobin is measured through its peroxidase activity, a fluoride ion-selective electrode being used to monitor the rate of fluoride ion production from the oxidation of an organofluorine compound. Results agree well with those obtained with the cyanmethemoglobin method (r = 0.970). Hematocrit is determined from the ratio of the sodium ion concentrations measured with an ion-selective electrode before and after lysis of the erythrocytes. Results by this and the microhematocrit method correlated well (r = 0.987). Hemolysis in a whole-blood sample is detected by using an oxygen electrode to measure the oxygen released when hemoglobin in plasma is oxidized.

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Ein Gemisch aus Li‐alanat und Pyridin im Überschuß wird 24 Stunden bei Raumtemperatur gerührt (Bildung von Li‐tetrakis‐[1,2‐dihydro‐pyridyl‐(1)]‐ aluminat) und anschließend mit Methyl‐ oder Äthyljodid, Benzylchlorid oder Brom versetzt.