Column evacuation

The drying agent was filtered off on a sintered-glass funnel and rinsed with some THF. The solution was transferred into a 500-ml wide-necked flask and concentrated in a water-pump vacuum. In order to remove the last traces of THF and some water the flask was connected directly (without a column) to a condenser and a receiver, cooled at -190°. The flask was evacuated by means of a mercury pump (p < 0.1 mmHg) and heated for 1.5 h at 85°C. The greater part of the mono-... 

To a mixture of O.BB mol of anhydrous lithium chloride and 100 ml of OMSO was added a solution of 0.40 mol of the acetylenic tosylate (for a general procedure concerning the preparation of acetylenic tosylates, see Chapter VllI-3, Exp. 3) in IBO ml of DMSO. The flask was equipped for vacuum distillation (see Fig. 5). Between the receiver, which was cooled at -75°C, and the water-pump was placed a tube filled with KOH pellets. The apparatus was evacuated (10-20 mmHg) and the flask gradually heated until DMSO began to reflux in the column. The contents of... 

The fluid plasticizer (solvent) consists of an energetic compound, eg, nitroglycerin, an inert carrier, and a stabilizer. The system is evacuated to remove volatiles, moisture, and air, and the plasticizer is then pressurized and passed slowly upward through the powder bed while the powder is held stationary by a pressure plate on the powder column. Casting solvent may also be added from the top of the mold. 

In preparing any of the above for use in columns, the dry powder is evacuated, then mixed under reduced pressure with water or the appropriate buffer solution. Alternatively it is stirred gently with the solution until all air bubbles are removed. Because some of the wet powders change volumes reversibly with alteration of pH or ionic strength (see above), it is imperative to make allowances when packing columns (see above) in order to avoid overflowing of packing when the pH or salt concentrations are altered. 

Step 2. Go to the left-hand column in table, final Suction Pressure (hs). Read across to find evacuation time equal to or less than that determined in Step 1. Read to the top of table and note unit number. See Table 6-15. 

A mixture of Nd(OAc)3 (0.21 g, 1 mmol) and 4-/er/-hutylphthalonitriIe (7 1.47 g, 8 mmol) was fused in an evacuated glass ampule with gradual raising of the temperature to 290 JC and this temperature was then maintained for 2 h. The cooled melt was ground and purified by column chromatography (alumina, benzene) to ohtain a blue powder yield 1.03 g (60%). 

The second column of Table 3-1 contains f0 values corresponding to the five voltage settings. These zq values were calculated from the output currents for hydrogen (third column) because a measurement of i0 on the evacuated cell could not be risked with the plastic windows. In this calculation, which was done by Equation 3-14, /uh = 1-00 was used, this arbitrary procedure being permissible because hydrogen is almost transparent. 

The system is evacuated to a pressure of 5-10 mm., and the tube is heated to 700°, measured at the center of the heated zone. 2-Chloro-2,3,3-trifluorocycIobutyl acetate is admitted at the rate of 10-20 g. per hour. From 70 g. (0.35 mole) of the cyclobutyl acetate there is obtained 62-68 g. of mixed solid and liquid condensate (Note 10). Fractionation through a 30-cm. column packed with glass helices affords 30-35 g. (60-70%) of 1-chloro-1,4,4-trifluorobutadiene (Note 11), b.p. 50-51°, 1-3870 18-22... 

Hydrolytic Kinetic Resolution (HKR) of epichlorohydrin. The HKR reaction was performed by the standard procedure as reported by us earlier (17, 22). After the completion of the HKR reaction, all of the reaction products were removed by evacuation (epoxide was removed at room temperature ( 300 K) and diol was removed at a temperature of 323-329 K). The recovered catalyst was then recycled up to three times in the HKR reaction. For flow experiments, a mixture of racemic epichlorohydrin (600 mmol), water (0.7 eq., 7.56 ml) and chlorobenzene (7.2 ml) in isopropyl alcohol (600 mmol) as the co-solvent was pumped across a 12 cm long stainless steel fixed bed reactor containing SBA-15 Co-OAc salen catalyst (B) bed ( 297 mg) via syringe pump at a flow rate of 35 p,l/min. Approximately 10 cm of the reactor inlet was filled with glass beads and a 2 pm stainless steel frit was installed at the outlet of the reactor. Reaction products were analyzed by gas chromatography using ChiralDex GTA capillary column and an FID detector. 

Metal-modified silicas were exposed to excess BuOOH vapor in order to generate the supported feri-butylperoxide complexes, followed by evacuation to remove PrOH and unreacted BuOOH. Reaction kinetics were monitored as the uptake of cyclohexene from the gas phase, using a ThermoNicolet Nexus FTIR spectrometer to measure the intensity of the o(C=C) mode. In situ spectra were recorded in custom-made glass reactors under vacuum. Formation of cyclohexene oxide was confirmed by GC/MS on an HP 6890 equipped with a DBI capillary column (J W Scientific). 

The distilling flask, collection flask, and column are continuously evacuated with a high-vacuum system. When the bulk of the pentane and residual hexane have distilled away, the temperature of a silicone oil bath surrounding the distillation flask is raised from room temperature to 125° over about a one-hour period. When the distillation rate diminishes appreciably, the temperature is slowly raised to 150° and maintained there until no more liquid is obtained. The distillation flask is cooled to room temperature before air is admitted to the system. The distilled product weighs 86.5 g. (89% yield checkers report 89 %t) and melts at 32 to 32.5°. In this state of purity, (bromomethyl)-carborane is suitable for most uses, but it may be further purified by crystallization from pentane or methanol. For example, crystals obtained by chilling a solution of 86.5 g. of the car-... 

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