Die gegenüber den entsprechenden Kohlenwasserstoffen und strukturgleichen Ethem reaktionsfreudigeren Amine wie z.B. Triethylamin, Triethylendiamin, Pyrrolidin und tert‐Butylamin liefern Geschwindigkeitskonstanten zwischen 3.3 ‐ 10°C ‐4.4‐ 109 /M‐s für die Titelreaktionen.

. Can. J. Chem. 58,803 (1980). Two spin traps. 4-(N-methy1pyridinium)tert-butyl nitrone (4-MePyBN) and 5,5-dimethyl-1-pyrroline-1-oxide (DMPO) were examined for their effectiveness at trapping hydroxyl in water. At pH 6 and 22"C, rate constants for trapping hydroxyl were found to be 0.5 x 109 M-I s-I (4-MePyBN) and 2.0 x lo9 1M-I s-l (DMPO). The hydroxyl adduct of DMPO decayed by a firqt order process with a half-life of 870 s. This was at least three times greater than that of the 4-MePyBN adduct. These and other results suggest that DMPO is the superior trap for this particular application and is well suited for use in biological systems. PAUL R. MARRIOTT, M. JOHN PERKINS et DAVID GRILLER. Can. J. Chem. 58,803 (1980). On a examine deux pieges a spin la ("V-methy1pyridiniun1)-4 tert-butyl nitrose (MePy-4BN) et l'oxyde-l de dimethyl-5.5 pyrroline-1 (ODMP), pour leur efficacite dans la capture du groupe hydroxyle dans I'eau. On a trouve, a 22°C e t a un pH = 6. que les constantes de vitesse de la capture du groupe hydroxyle dans I'eau sont de: 0.5 x 109 M L s L (MePy-4BN) et 2.0 x lo9 M-I 5 -I (ODMP). L'adduit hydroxyle du ODMP se decompose selon une reaction du premier ordre avec une demi-vie de 870 s. Cette periode est au moins trois fois plus elevee que celle de I'adduit du MePy-4BN. Ces resultats ainsi que d'autres suggerent que le ODMP est le piege ideal dans cette application particuliere et il est indique pour ktre utilise dans les systemes biologiques.[Traduit par le journal]

The isotropic 13Cα and proton hyperfine interactions of the ethyl radical have been measured in the temperature range 112–313 K in the liquid solvents propane and 2,2,4-trimethylpentane. The data are entirely consistent with a value of 500 cm−1 for the out-of-plane bending frequency and with the assumption of a harmonic potential well for the vibration. Calculations show that the accuracy of vibrational analysis by EPR spectroscopy is limited by the quality of the experimental data rather than by the assumption of a harmonic potential function. The 13Cα hyperfine splittings for simple alkyls in their ’’planar’’ configuration are calculated to be 37.1 G [⋅CH(CH3)2]; 34.8 G(⋅CH2CH3); 33.1 G (⋅CD3) and 31.9 G (⋅CH3). These results show that hyperfine splittings which are uncorrected for vibrational contributions are not a reliable guide to spin densities.

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E.s.r. spectroscopy has been employed to study the reactions of a variety of organic compounds with ammoniumyl (N H,+') generated in a flow system from the titanium( Ill)-hydroxylamine couple. Radicals resulting from hydrogenatom abstraction from certain substrates ( e . g . alkanols) have been detected and it is concluded that NH,+* is an electrophilic species with a greater degree of selectivity than hydroxyl. A pseudo steady-state analysis for radicals in the cavity is shown to be appropiiate and values have been obtained for the rate constant for the initiating reaction [k(TiIII + NH,OH) ca. 6 x 105 I mo1-I s-l at pH 21 and for the relative rates of attack of NH,+' on different substrates. YO1 5DDIT is generally accepted that the titanium(II1)-hydroxylamine redox couple is an effective source of *NH2-or, depending on the pH, NH3+*-as shown in reactions (i) and (ii) . For example, synthetic applications involving