Acetone, water uptake

A solution of 20 g of desoxycorticosterone in 190 ml of absolute ethanol was stirred in an atmosphere of hydrogen in the presence of 1.68 g of 25% palladium on calcium carbonate catalyst. After 20 hours, approximately 1 molar equivalent of hydrogen had been absorbed and hydrogen uptake had ceased. The catalyst was removed by filtration and the filtrate evaporated in vacuo to yield 20 g of nearly pure product, MP 135°C to 140°C. The crude product was demonstrated to be free of starting material by paper chromatography. A highly purified product was obtained by recrystallization from acetone-water with cooling in an ice bath, yield 14.5 g, MP 152°C to 154°C. The product was characterized by analysis and by absence of ultraviolet absorption. 

Water is often a major impurity in deuterated solvents, especially in polar solvents. For example, commercial acetone- contains 150-250 ppm of water even immediately after opening the bottle. The water content in acetone-sample tube with a plastic cap increases lOOppm/day in the chemical laboratory. When the sample in the NMR tube is kept in an effectively air-conditioned room (NMR laboratory), the water uptake rate decreases to 40ppm/day. Sealing with Parafilm is not effective in reducing the rate of water uptake. Sealing with shrinkable tube made of polyethylene effectively decreases the rate to ca. lOppm/day, even in the chemical laboratory. When the tube with plastic cap is... 

Figure 7. SEM and XRMA microphotographs of palladium catalysts supported on the amphiphilic resin made by DMAA, MTEA, MBAA (cross-linker) [30]. Microphotographs (a) and (b) show an image and the radial palladium distribution after uptake of [Pd(OAc)2] from water/acetone the precursor diffuses only into the outer layer of the relatively little swollen CFP after reduction the nanoclusters remain close to the edge of the catalyst beads. Microphotographs (c) and (d) show the radial distribution of sulfur and palladium, respectively, after uptake of [PdCU] from water after reduction palladium is homogenously distributed throughout the catalyst particles. This indicates that under these conditions the CFP was swollen enough to allow the metal precursor to readily penetrate the whole of polymeric mass. (Reprinted from Ref. [30], 2005, with permission from Elsevier.)...

Similarly, the uptake of acetone into sulfuric acid-water solutions has been reported (Duncan et al., 1998), with the formation of 4-methyl-3-penten-2-one and trimethylbenzene at temperatures above 200 K and 75 wt% H2S04. 

The observation of inhibition of the H/D exchange reaction by CO and CH3CN implicates coordinatively unsaturated intermediates in the H2 capture process. As a part of this manuscript we report evidence for the existence of an acetone derivative of the (p-H)(Fen)2 complex, as suggested by theory. As it has obvious ramifications for technical development of such H2-uptake catalysts, the possibility that water might similarly compete for the open site and serve both as a required reagent and a catalyst inhibitor deserves a future detailed study. 

Cocaine binds and inhibits the dopamine uptake carrier (Wink, 1993). This alkaloid currently is a drug of abuse in many countries. The widespread method for illicit extraction/processing of cocaine is an interesting example of alkaloid isolation and properties. Leaves of the coca plant are dried and then soaked in a mixture of water and kerosene. The resulting paste is then mixed, in turn, with dilute sulfuric acid, lime, potassium permanganate, and more kerosene. Finally the crude alkaloidal paste is extracted with ether and acetone to remove impurities (Anon., 1985 Boucher, 1991). 

Additional tools can help to break down perceived barriers to the usage of some of the more unfamiliar solvents. Building on the frequent use made of lists of peaks arising from trace residual solvents in common deuterated NMR solvents, NMR guides emphasising the peaks of some of the less familiar and potentially greener solvents in common deuterated NMR solvents (chloroform, DMSO, methanol, water, acetone and acetonitrile), can help act as a reminder of different options and help remove some of the barriers to their uptake. 

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