Pressure reaction vessels

A somewhat different type of high pressure reaction vessel is illustrated in Figs. VI, 4, 3-5. This is designed for hydrogenation reactions at working pressures from 1 to 300 atmospheres (4,500 lb. per square inch) and at temperatures from atmospheric up to 400°. Fig. VI, 4, 3... 

In the intermolecular series, Diels-Alder cycloaddition of ethene to the pyrazi-none heterodiene led to the expected bicyclic cycloadduct (Scheme 6.95 b) [195], The details of this transformation, performed in pre-pressurized reaction vessels, are described in Section 4.3.2 [196], Similar cycloaddition reactions have also been studied on a solid phase (Scheme 7.58) [197]. 

Fig. 14.8 Simplified schematic diagram of a high-pressure digestion vessel with an EDL. A. plug and seal, B. quartz pressure reaction vessel with a sample solution, C. EDL with an antenna, D. vessel jacket with a screw cap, E. airflow. Adapted from Ref. [44],...

The step 1 product (10 mg) dissolved in 50 ml THF was placed in a high-pressure reaction vessel purged with nitrogen gas. Sodium methoxide in methanol was then added in 150 mol% excess and stirred while the reactor was purged with nitric oxide at 15 psi. Thereafter, the mixture stirred at ambient temperature for 24 hours and was then purged and the mixture precipitated in hexane. After filtering and drying, the product was isolated. 

Our next effort was to more accurately mimic the conditions that we were using for library optimization in the single-mode microwave, namely pressurized reaction vessels. It has been shown that the key to higher yields in microwave-assisted synthesis is not solely the direct heating but also the pressure effect—the ability to run reactions at higher... 

A complete methodology for the manipulation and reaction of air-sensitive solutions has evolved around cappable glass pressure bottles. Soft-drink bottles are sometimes used (hence these procedures are sometimes referred to as pop bottle techniques ) however, heavy-walled borosilicate glass pressure reaction vessels are superior. In contrast to the modified standard taper ware discussed above, this pressure apparatus offers advantages where modest pressures are necessary and where the centrifugation of precipitates is preferable to filtration. These techniques are especially popular in the preparative-scale study of catalytic reactions of small molecules, such as olefin polymerization. The pressure bottle is fitted with a cap containing two 1/8 in. holes and a rubber liner, which is secured by means of a hand-operated bottle capper (Fig. 1.31).18... 

In a cooled high-pressure reaction vessel there was placed a suspension of 30 g 2,5-dimethoxy-4-methylcinnamic acid in 150 mL liquid isobutene. This was treated dropwise with 0.6 mL concentrated I1 S04, then sealed and brought to room temperature. After 48 h shaking, the vessel was cooled again to -10 °C, opened, and poured into 200 mL of 10% Na2C03. This was extracted with hexane, the pooled extracts washed with H,0, and the solvent removed to yield 17.0 g of (t)-butyl 2,5-dimethoxy-4-methylcinnamate as an amber oil. Anal. (C16H2204) C,H. 

Reactions under pressurized conditions are not illustrated in this book, although there are a number of pressurized reaction vessels made of ceramic and plastic materials provided by the manufactures of microwave equipment (see Section 3.4). These vessels should not be replaced under any conditions with other vessels and cannot be switched between different type of microwave reactors either. 

A 0.750-g sample of solid benzoic acid, C7H6O2, was placed in a 0.500-L pressurized reaction vessel filled with 02 at 10.0 atm pressure and 25°C. The benzoic acid was burned completely to water and C02. What were the final mole fractions of C02 and H20 vapor in the resulting gas mixture brought to the initial temperature The vapor pressure of water at 25°C is 23.8 torr. Neglect both the volume occupied by nongaseous substances and the solubility of C02 in water. The water pressure in the gas phase cannot exceed the vapor pressure of water, so most of the water is condensed to the liquid. 

To a 5 liter Parr apparatus (special pressure reaction vessel commercially available) place 4400 milliliters of acetonitrile, 300 grams of 2,4,6,8,10,12-hexabenzyl-2,4,6,8,10,12-hexaazaisowurtzitane (prepared in step 1), 1000 milliliters of acetic anhydride, 75 grams of 20% palladium hydroxide on charcoal catalyst (commercially available), and 8.4 grams of bromobenzene. Then turn the machine on, and shake the mixture at 50 psi for 36 hours at 10 Celsius. After 36 hours, remove the reaction mixture from the Parr apparatus, and then filter to remove the precipitated product. The precipitated product also contains the charcoal catalyst (save the filtered reaction mixture). After filtration, mix the filtered-off solids with 10 liters of boiling chloroform, and then stir the mixture for 20 minutes. Then filter the mixture hot to remove insoluble impurities. After which, recrystallize the product from the chloroform, and then vacuum dry or air-dry the product. Next, add the dry product to 300 milliliters of acetonitrile, and then stir the mixture for ten minutes at room temperature. Afterwards, filter the mixture to collect the insoluble product, and then vacuum dry or air-dry the product. 

A pressure reaction vessel of about 300-ml. capacity capable of withstanding at least 250 p.s.i. at 125° (Note 1) is charged with 60.0 g. (0.51 mole) of 3-sulfolene (Note 2), 86.0 g. (82.0 ml., 0.50 mole) of diethyl fumarate (Note 3), and 1.0 g. of hydro-< uinone (Note 4). Commercial absolute ethanol (90 ml.) is added and the mixture stirred until most of the solid is dissolved. The vessel is sealed, heated slowly to 105-110° (Note 5), and maintained at that temperature 8-10 hours (Note 6). The vessel is then allowed to cool to room temperature, opened (Note 7), and the yellowish, fluid reaction mixture is poured into a 1-1. Erlenmeyer flask. 

Dichloropurine (20 g, 0.1 mol) and coned NH4OH (100 mL) were heated for 6h at 135°C in a high pressure reaction vessel. The ammoniacal solution was cooled and filtered to yield 12.0 g (68 %) of 11 which was above 95% pure as judged by UV absorption data. This product was best purified as the monohydrochloride. For this purpose a solution of 11 in dil KOH was adjusted carefully to pH 5 with HCl acid. The cooled solution was filtered and the salt recrystallized (H O). 

The reaction was effected in a suitable pressure reaction vessel having a capacity of about 6.2 liters and equipped with a thermometer, pressure gauge, expansion valve and an inlet tube by means of which the reactants could be introduced into the lower portion of said reaction vessel. 

Suppliers Cajon/Nupro/Swagelok/Whitey Swagelok Co., 29500 Solon Road, Solon, Ohio 44139 216-248-4600 Lab Crest Scientific/Fischer Porter Co., County Line Road, Warminster, Pennsylvania 18974 (OEM for pressure reaction vessels and couplings, selling only in minimum quantities of one dozen write for illustrated brochure describing vessel/shield options) 215-674-6610... 

Fig. 6.17 A high-pressure reaction vessel with a sampling valve.

Custom-built high-pressure reaction vessels (to about 1600 bar), optical cells (5 kbar), valves, tubing (6 kbar) and fittings, and liquid and gas pumps (to 4 kbar)... 

The decomposition of calcium carbonate (Eq. 13.2-3), or any other reaction in which the reaction products and reactants do not mix in the gas or liquid phase, represents a, fundamentally different situation from that just considered, and such a reaction may go to completion. To see why this occurs, consider the reaction of Eq. 13.2-3 in a constant temperature and constant pressure reaction vessel, and let Ncaco2,o md Nqo-,0 represent the number of moles of calcium carbonate and carbon dioxide, respectively, before the decomposition has started. Also, since none of the species in the reaction mixes with the others, we use pure component molar than partial molar Gibbs energies in the analysis. Then,... 

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