Syringe pump Subject

To a solution of alcohol 2a-h (3.0 mmol) in THF (2.0 mL) was added 10% Pd/C (0.015 g) followed by a solution of le (2.0 mmol) in THF (2.0 mL), slowly added over a 1 h period via a syringe pump. After the addition, the reaction was allowed to stir at room temperature for another 1 h after which pentane (20 mL) was added and the reaction was filtered through Celite. The volatile components were removed under reduced pressure to give a colorless liquid which was subjected to flash column chromatography on silica gel eluting with hexane (100 mL) followed by hexane ethyl acetate (30 1) to give the pure product as a colorless liquid. The yields and characteristic data for 3a-h are presented below. 

The scope of the reaction was evaluated by variations in both the radical and the radical acceptor. In the presence of ZnCb, the propionaldehyde N acylhydrazone 8a was subjected to radical additions of various organic iodides (Table 2.3, entries 1 4). Reaction conditions entailed addition of Bu3SnH (5 equiv) and O2 (7 ml/mmol) by syringe pump to a mixture of iPrI (10 equiv), 136 (10 equiv), and Lewis acid (2 equiv) in 2 1 CH2Cl2/ether at 78 °C, gradually bringing the mixture to ambient temper ature after the addition. Under these conditions, ethyl radical (from the triethylbor ane) can compete for the radical acceptor, and as a result, the separable ethyl radical adduct 17 (Scheme 2.2) was observed (<10% yield) in all cases. With simple secondary and tertiary alkyl iodides as radical precursors (entries 1 4), additions to 8a occurred with moderate yields to afford N acylhydrazines. Radical reactivity is... 

Methods available to control non-Newtonian flows are the same as for Newtonian flows, including pressure-driven flows via syringe pumps, capillary-driven flows, and electrokinetic flows. These methods and others are covered in more detail in other entries. In many cases the behavior of polymer solutions subject to a driving force is similar to that of the corresponding Newtonian solvent as long as the characteristic strain rate remains below the coil-stretch transition or De <2- Above this critical value, shear thinning and elasticity are important. 

So far, the only 0,CCA that includes a skin compartment is that developed by Brand et al. (2000). Dorsal skin from male hairless mice was used in a perfusion system that contained a chamber with Hep-G2 liver cells in a compartment downstream of the skin compartment. The system was operated with a syringe pump and subjected to paroxovanadium [V0(02)21,10 phenanthroUne] bpV(phen). A net 22% increase in glucose consumption was measured in the Hep-G2 cells, demonstrating that the system is capable of simulating the uptake of the compound through skin. The authors also show that the system can be used with Caco-2 cell to construct a model of the intestinal epithelium (Brand et al. 2000). 

Charge a two-necked, round-bottomed flask (50 mL) with copper(l) cyanide (0.1 g, 1.1 mmol), lithium bromide (0.11 g, 1.3 mmol), and a stirring bar. Fit the flask with a gas adapter (with stopcock) and a septum. Connect the flask to a vacuum/inert atmosphere manifold, and subject it to three pump/refill cycles. Add dry, distilled THF (15 mL) to the flask by use of a dry, glass syringe. Stir this mixture, and then cool it in an ice-bath. 

In a case of synthesis of PBA homopolymer, the polymerization was carried out at 70 °C. DMDBrHD (56.6 pL, 0.26 mmol), PMDETA (54.4 pL, 0.26 mmol), BA (11 mL, 78 mmol), and anisole (1.1 rtiL) were added to a 25-mL Schlenk flask eqtripped with a magnetic stir bar. The flask was sealed, and the resulting solution was subjected to three freeze-pump-thaw cycles. After equilibration at room temperatrrre, CuBr (37.3 mg, 0.26 mmol) was added to the solution tmder nitrogen flow and the flask was placed in preheated oil bath. Aliquots were removed by syringe in order to monitor molectrlar weight evolution. After a predetermined time, the flask was removed from the oil bath and opened to expose the catalyst to air. The polymerization solution was diluted with CHCI3 and passed over an alumina (activated neutral) coltrrrm to remove the catalyst. Solvent was removed by rotary evaporation, and the polymer was isolated by precipitation into cold methanol. 

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