Silicic acid aqueous methanolic solution

Figure 10. Si NMR spectra at 19.87 MHz of acid aqueous methanolic solution of silicic acids (1.5 M in Si), obtained from hydrolysis of Si(OMe)j,. Hydrochloric acid was incorporated to a concentration of 10 mol/dm. Times in minutes between hydrolysis and end of spectral accumulation are 32 (a), 64 (b), 395 (c). Accumulation times were 10,14, and 20 min respectively. Solution was maintained at —13 C throughout the experiment. Conditions are the same as Fig. 3. Irradiation frequency increases to the left.

The high preference of the crystalline silicic acids for methanol and ethanol from water is clearly expressed when the alcohol molar fraction in the adsorption layer, xi, is plotted against this fraction, xi, in the equilibrium solution (Fig. 27). Such a high preference for methanol and ethanol from aqueous solutions was also found for silicalite and ZSM-5 zeolites [171-174]. The parent compound K2Si2o04i XH2O also takes up high amounts of ethanol from dilute ethanol/ water mixtures [108]. 

Isolation of toxins. The digestive glands of shellfish were extracted with acetone at room temperature. After removal of the acetone by evaporation, the aqueous suspension was extracted with diethyl ether. The ether soluble residue was successively chromatographed twice over silicic acid columns with following solvents benzene to benzene-methanol (9 1), and diethyl ether to diethyl ether-methanol (1 1). To avoid degradation of dinophysistoxin-3 by contaminant acid, the silicic acid was washed with dilute sodium hydroxide solution and then with water prior to activation at 110 C. Toxic residue obtained in the second eluates was separated into two fractions... 

A suspension of 300 mg of adriamycin-14-valerate hydrochloride in 20 ml of ethyl acetate was treated with 0.45 ml of trifluoroacetic anhydride in small portions over a few minutes until all solids had dissolved. The solution was mixed immediately with equal portions of water and chloroform (total volume 100 ml). The chloroform layer was separated and washed once with water and twice with pH 7 aqueous buffer. The chloroform solution was dried over sodium sulfate and then was evaporated to dryness under reduced pressure. The residue was dissolved in 25 ml of methanol, and the resulting solution was heated at reflux for 5 minutes, then cooled and evaporated to dryness. The residue was redissolved in 4 ml of chloroform, and the crude product was precipitated by the addition of 20 ml of petroleum ether (b.p. 38°-49°C). The crude material was purified by chromatography on a silicic acid column. 

Tuber slices (338 kg) (1.5-2,0 mm thickness) of Ri cultivar Rishiri were inoculated with a zoospore suspension (250000-500000 zoospores/ml) of incompatible race of Phytophthora infestans (Mont.) de Bary, race 0 and incubated at 18-20°C for two days. The inoculated slices were stored in an ice-box (-30°C) for a week and then immersed in methanol (250 1) for a week. The supernatant was separated by decantation and the process was repeated twice with methanol (2 x 150 ml). The methanol extracts were combined and concentrated under reduced pressure below 30°C. The concentrate was extracted with chloroform and evaporated to yield oily residue from which a solid material was precipitated on treatment with acetone and was then removed by filtration. The filtrate w as c oncentrated to yield an o ily residue which w as treated with hexane. The hexane solution was concentrated, extracted with ether and washed with aqueous sodium carbonate (10%) and hydrochloric acid (0.1 M) to remove acidic and basic components. The ether extract was washed with water, dried and evaporated. The residue, which contained many c ompounds (by tlc) w as subjected toehromatographic p urification over silicic acid (Mallinckrodt, AR-100) and celite. Benzene ether (1 1 and 1 2) afforded crude rishitin which showed an almost single spot on tic. This was chromatographed over silica gel (Merck). Ether eluted pure rishitin (40) (3.9 g, from 338 Kg tuber slices), m.p. 65-67°C, [ai]-35.1°, max s, 3060,1640 and 890 cm 1 1HNMR 51.12 (3H, d, J=6 Hz), 3.12 (1H, t, J=9Hz),3.55 (lH,br,do,d, J=9and7 Hz), 4.18 (2H, br, s, 2 OH) C,3NMR 148.9 (Cn), 129.0 (C5), 124.9 (C10), 10.9 (C12), 79.2 (C8), 71.5 (C2), 41.6 (C7), 40.4 (C4), 38.3 (C8), 31.1 (C6), 29.7 (C9), 26.5 (C,), 21.0 (C13), 16.4 (Cm).22... 

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