Experiments with highly carriers

Experiments With Highly Purified Ammo Acid Carrier... 

Experiments With Highly Purified Amino Acid Carrier Preparations... 

Lactams were obtained in 80-95% conversion with high trans-selectivity (de >95%) but only moderate enantioselectivity ee ca. 30%). The stereoinduction results from the relatively remote stereocentres located at the linker units. For support recovery the authors performed nanofiltration experiments and it was found that the recovered dendrimers could be easily reused as substrate carriers. 

The choice of an ionic liquid was shown to be critical in experiments with [NBuJBr (TBAB, m.p. 110°C) as a catalyst carrier to isolate a cyclometallated complex homogeneous catalyst, tra .s-di(ri-acetato)-bis[o-(di-o-tolylphosphino) benzyl] dipalladium (II) (Scheme 26), which was used for the Heck reaction of styrene with aryl bromides and electron-deficient aryl chlorides. The [NBu4]Br displayed excellent stability for the reaction. The recycling of 1 mol% of palladium in [NBu4]Br after the reaction of bromobenzene with styrene was achieved by distillation of the reactants and products from the solvent and catalyst in vacuo. Sodium bromide, a stoichiometric salt byproduct, was left in the solvent-catalyst system. High catalytic activity was maintained even after the formation of visible palladium black after a fourth run and after the catalyst phase had turned more viscous after the sixth run. The decomposition of the catalyst and the formation of palladium... 

The ability of PolyHIPE materials to absorb liquids has been exploited in experiments on their potential use as carrier materials for the safe transport of hazardous or flammable liquids [128]. A poly(styrene/DVB) sample was able to absorb twenty times its own weight of liquid paraffin, simply by immersing the material in the liquid. However, the problem in this application is the subsequent removal of the liquid from the polymer. This can only be achieved by vacuum distillation, which is very difficult with high boiling liquids. 

Ammonium nitrate is the most readily available and cheapest salt of nitric acid, now manufactured wholly from synthetic ammonia and from nitric acid obtained by oxidation of ammonia. Ammonium nitrate was prepared for the first time as early as in 1659 by Glauber. The original experiments with it as a component of explosive mixtures began in the second half of the nineteenth century. Ammonium nitrate is the most widely used oxygen carrier, since it is an ingredient of the commonest group of high explosives. The reasons for this are to be seen in its properties and those of its explosive mixtures appreciable chemical stability, and low sensitiveness to friction and to shock. 

Before injecting the pulses into the reactor, the reactor is supplied with the carrier gas nitrogen and allowed to reach steady state. For the high-temperature experiments, the reactor was heated for at least one hour and the steady state observed with a temperature sensor on the reaction plate. The reactor temperature was mostly 450 °C, at close to atmospheric pressure. 

Yoshida et a/.110 concluded from experiments with copper vanadate that the NO reduction on a pre-reduced catalyst proceeds by a mechanism involving adsorbed NO, adsorbed NH3, and adsorbed 02. Shikada et al.nl have shown that by using a complex Si02 —Ti02 oxide as carrier a very active and stable catalyst is obtained which is highly resistant to S02 for long periods. 

The active transport aspect of siderophore iron utilization remains largely unexplored, although such a process probably exists—in addition to facilitated diffusion—in view of the high affinity of the cells for siderophores and the likely participation of an energized state of the membrane in their transport. Experiments with whole cells must perforce be performed with mutants lacking the ability to make these carrier molecules. 

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