Pony-tails

Looks like an alien, said the bartender who served it, wiggling his fingers like antennae on either side of Iris lanky hair. Are you a fan of Wylie s Mr. Dufresne, mutton-chopped and pony-tailed, was visible in the kitchen at the back, corralled like a quarterback by cooks, directing his food into the dining room. 

Table 4. The effect of salinity in growing medium on accumulation of Na", Cf, K", Ca ", Mg in dry matter of plants of. paniculatiis cv. Copper Moutain i Monarch, A. caudatus cv. Pony Tails. Data are mean SE, of 2 vegetations seasons with 3 replicates in each.

As discussed in the previous section, perfluorinated polyether pony-tails can be covalently grafted onto PPI dendrimers, and it has previously been shown that such materials are soluble in liquid CO2 [17]. HRTEM confirms that particles prepared within such dendrimer templates are nearly mono-disperse and are of a size that is consistent with the dendrimer template (Sect. 2.5.4). Such dendrimer-encapsulated metal particles are quite soluble in liquid and SC CO2. 

Preliminary results from a study of catalytic activation of the heterocoupling between arylhalides and alkenes using pony-tail-functionalized dendrimer-encapsulated Pd nanoparticles have shown promise. For example, the classic Pd-catalyzed Heck coupling between arylhalides and methacrylate yields predominately (> 97%) the trans-cinnimaldehyde product [176]. On the other hand, the C02-soluble dendrimer nanocomposite exclusively catalyzes the production of the highly unfavored 2-phenyl-acrylic acid methyl ester isomer at 5000 psi and 75 °C (Fig. 27] [177]. 

The fluorous biphase catalyst recovery concept was tested by performing nine consecutive reactions in a batch reactor. A total loss of 4.2% of rhodium was detected, and the decreasing 1 b ratio suggested some ligand leaching. The total turnover number reached with the system was 35,000 mole of aldehyde/mole rhodium, with a rhodium loss of 1.18 ppm per mole of aldehyde. Further optimization of this system, i.e. the use ofheavier fluorous solvents and longer pony tails, should decrease the amoimt of catalyst and fluorous solvent leaching. 

Quinine decorated with a fluorous pony-tail (326) has been developed as a catalyst for the Michael addition of a-fluoro-/ -ketoesters ArC0CHFC02Et to A-substituted maleimides. The resulting products with two vicinal chiral centres were obtained with <87% ee and >20 1 dr, and the catalyst was recycled by fluorous solid-phase extraction. ... 

Apart from the interaction between catalyst and substrate, halogen bonds can also be used in other aspects of organic synthesis. For example, Legros et al. employed a perfluorinated XB donor to facilitate the recycling of the actual organocatalyst of the reaction. This application was based on the concept to non-covalently tag the catalyst with perfluorinated alkane chains ( pony tailing ) [127], so that the resulting fluorophUic complex readily precipitates from some... 

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