Scavenger technique

Immobilized Reagents and Scavenging Techniques in Library Synthesis... 

For scavenger techniques refer to refs. 4 and 5 and particularly to J.J. Parlow, R.V. Devraj, M.S. South, Curr. Opin. Chem. Biol 1999, 3, 320-336. 

When a strong electron acceptor (electron scavenger) is added in the irradiated system, some of the electrons will react with the scavenger before they recombine with their parent cations. Therefore the measurement of the yield of the scavenging products as a function of the scavenger concentration can be used to monitor the geminate recombination, and the electron scavenging technique has proved to be an important tool in experimental studies. 

Dallinger, D., Gorobets, N.Y. and Kappe, C.O., High-throughput synthesis of N3-acylated dihydropyrimidines combining microwave-assisted synthesis and scavenging techniques, Org. Lett., 2003, 5, 1205. 

Why is it necessary to use scavenge techniques for the removal of barium (by barium chromate) and plutonium (by ferric hydroxide precipitation) ... 

The kinetics of these pyrolysis reactions were followed by several complementary methods under conditions as close to the product studies as possible. The most frequently-used ampule technique14 17) with gc analysis of 5 and the scavenger technique, with chloranil or Koelsch radical as scavenger 18), for very labile compounds 5 were complemented by the DSC method, in which the heat flow under conditions of linear temperature increase is analysed. It proved to be a particularly convenient and reliable technique 18- 21). Rates were followed over a temperature span of at least 40 °C with temperature control of 0.1-0.2 °C. All rate data and activation parameters were subjected to a thorough statistical analysis including statistical weights of errors. The maximum statistical errors in k were 3%, in AH 1 kcal mol-1 in AS 513 e.u. and in AG (at the temperature of measurement) g0.5 kcal mol-1. 

F.L. Tabares, D. Tafalla, I. Tanarro, V.J. Herrero, A. Islyaikin, C. Maffiotte Suppresion of hydrogenated carbon film deposition by scavenger techniques and their application to the tritium inventory control in fusion devices. Plas. Phys. Contr. Fusion 44, L37 (2002)... 

Microwave-assisted fluorous Ugi reactions were presented where the reaction times and convenient separation techniques appeared more attractive than the corresponding room temperature methods with traditional scavenging techniques. ... 

The kinetics of these pyrolysis reactions were followed by several complementary methods under conditions as close to the product studies as possible. The most frequently-used ampule technique with gc analysis of 5 and the scavenger technique,... 

In the last two decades there has been a substantial progress in understanding the nature and reactions of biologically relevant free radicals, and the development of new antioxidants. Both biochemical methods and free radical scavenging techniques have been widely employed. Fast reaction kinetic techniques have been found to be very useful in directly probing the reactions of antioxidants with free... 

MacCoss, R N, Brennan, P E, Ley, S V, Synthesis of carhohydrate derivatives using solid-phase work-up and scavenging techniques, Org. Biomol. Chem., 1, 2029-2031, 2003. 

The use of pulse radiolysis and scavenging techniques has identified the electron in liquid hydrocarbons [116]. In these non-polar media, interaction between the electron and the solvent is, of course, very small and it is doubtful whether such electrons can properly be described as solvated. The pulse radiolysis of hexane or 3-methyl hexane gave rise to a short lived transient species absorbing at Xm ax = 1500 nm. Rate coefficients for reaction in hydrocarbon solutions at 193°K are given in Table 10. Baxendale et al. [117] have studied the pulse radiolysis of liquid methylcyclohexane and obtained rate coefficients for the reactions of the electron with carbon tetrachloride and pyrene at 293° K. Relative rate coefficients have been obtained by irradiation of hydrocarbons containing two electron scavengers [118]. 

In recent years this approach has been extensively employed and there is substantial evidence for the production of e aq. When steady state ultraviolet light sources were used, hydrated electrons were detected by competitive scavenging techniques (9, 21, 22, 51, 63, 71). When flash photolysis techniques were employed, e q was identified by its absorption spectrum and its reactivity followed spectrophotometrically (28, 38, 60). 

The microwave-induced N3-acylation of the dihydropyrimidine (DHPM) Bigi-nelli scaffold using different anhydrides has been discussed in a comprehensive report [130] (Scheme 16.85). The process included purification of the reaction mixture by means of a microwave-assisted scavenging technique. Several scavenging reagents with different loadings of amino functionalities have been used to sequester excess benzoic anhydride (BZ2O) from the reaction mixture [130, 139, 140]. 

Reactivity of CI2 Toward Hot Atoms. A C -scavenging technique has been used to determine the thermalized atom fractions, t, in recoil F experiments with SFe and C2F6 (1,6,15). 

---