Medium pressure apparatus

A medium-pressure apparatus is assembled from a stainless steel bomb, standard parts, valves, unions and copper or stainless steel tubing according to Fig. 4. 

When using gas chromatography at normal pressures it is necessary to estimate Bxc values to obtain accurate thermodynamic data. Cruickshank and colleagues have described a medium-pressure apparatus for obtaining B c as well as chemical potentials at infinite dilution. 

Synthetic chiral adsorbents are usually prepared by tethering a chiral molecule to a silica surface. The attachment to the silica is through alkylsiloxy bonds. A study which demonstrates the technique reports the resolution of a number of aromatic compoimds on a 1- to 8-g scale. The adsorbent is a silica that has been derivatized with a chiral reagent. Specifically, hydroxyl groups on the silica surface are covalently boimd to a derivative of f -phenylglycine. A medium-pressure chromatography apparatus is used. The racemic mixture is passed through the column, and, when resolution is successful, the separated enantiomers are isolated as completely resolved fiactions. Scheme 2.5 shows some other examples of chiral stationary phases. 

A process for the depolymerisation of Nylon 6 carpet fibre in the presenee of steam under medium pressure (800 to 1500 KpA, 100 to 200 psig) is described. The feasibility of the seheme was demonstrated using a small laboratory apparatus and the best run produced a 95% yield of crude eaprolaetam. The data obtained were used to construct a computer model of the process for both batch and continuous flow stirred reactors. 6 refs. 

The apparatus is dried in an oven at 140° overnight and cooled under nitrogen or argon prior to the irradiation. A Vycor filter sleeve and a 450-watt medium-pressure mercury lamp are placed in the immersion well. The Vycor filter, the quartz immersion well (catlog No. 19434), the 450-watt mercury lamp (catalog No. 679A36), and the requisite transformer are all available from Hanovia Lamp Division, Canrad-Hanovia Inc., 100 Chestnut Street, Newark, New Jersey 07105. 

The biscarbamate 5a and carbamate 3a were dissolved in acetonitrile (Fischer - ACS grade) and photolyzed with a 200-Watt medium pressure, Hanovla lamp in a typical preparative photolysis apparatus with pyrex sleeve. Integrated proton NMR data for the resultant solutions were made on a Jeol 4H-100 NMR. 

The photooxidation was carried out in a commercial weathero-meter (Q-UV, Q-panel Co., Cleveland, Ohio). This apparatus uses medium pressure mercury fluorescent UV lamps (Sunlamps F5-40, Westinghouse Electric Corp.) which emit UV light in the 273-378 nm range with a maximum intensity at 310 nm. 

Fig. 16.17 Representative plot of the behavior of sulfa drugs obtained from photolysis on a turntable apparatus, under four Pyrex-filtered 175-W medium-pressure Hg-vapor lamps. Photodegradation of sulfamethazine in deionized H O ( ) and enhanced photodegradation in natural lake water ( ). Reprinted with permission from Boreen AL, Arnold WA, McNeil K (2005) Triplet-sensitized photodegradation of sulfa drugs containing six-membered heterocyclic groups identification of an S02 extrusion photoproduct. Environ Sci Technol 39 3630-3638. Copyright 2005 American Chemical Society...

Pcntacarbonyl[(methoxy)(methyl)carbene]chromium(0) (16, R1 = R2 = Me 475 mg, 1.9 mmol) and the chiral ene carbamate (see above equation) (718 mg, 3.8 mmol) in CH2Ci2 (20 mL) were placed in a Fischer Porter pressure tube and saturated with CO (3 eycles to 6.33 atm of CO) and then irradiated (450-W Conrad-Hanovia 7825 medium-pressure lamp, Pyrex well) under 6.33 atm CO overnight. The yellow-green solution was filtered through a pad of Cclitc, and the solvent evaporated. The crude mixture was placed in a sublimation apparatus and heated at 30-50°C (1 Torr) until no further Cr(CO)6 could be obtained. The residue was preabsorbed on silica gel and flash chromatographed yield 319 mg (61 %) mp 133-134"C. 

A suspension of NaHCO, (1.6 g, 19 mmol) and crude 7-diazotrieyclo[3,2.1.12 4]nonan-6-one (70 mg, 0.47 mmol) in dioxane (60 mL) and H20 (15 mL) was irradiated with a medium-pressure Hg lamp in a Pyrex apparatus at 0 nC and the remaining alkaline solution extracted with Et20. The alkaline phase was acidified and extracted with Et20 giving the carboxylic acid as a viscous oil yield 30 mg (45%). 

Figure 6. Block drawing of the pilot installation for the production of trichloromethyl chloroformate by exhaustive photochlorination [39] 1 Dryer for gaseous Cl2 (H2S04 cone.). 2 Safety tank. 3 Thermoregulated immersion-type photochemical reactor. 4 Raschig column. 5 Cl2 detection system (1,2,4-trichlorobenzene). 6 Neutralization tank (20% NaOH). 7 Reservoir of 20% NaOH. 8 Buffer to atmospheric pressure (20% NaOH). 9 Active carbon filter. 10 Reservoir of crude trichloromethyl chloroformate. 11 Buffer to normal atmosphere via CaCl2 filter and direct entry for trichloromethyl chloroformate to be distilled. 12 Distillation flask with Vigreux column. 13 Exit to vacuum pump. 14 Solid NaOH filter before pump. 15 Cooling water alarm linked to power supply of the light source. 16 Medium pressure mercury arc. 17 Heater for distillation apparatus. 18 Magnetic stirrers. /T thermometer /P manometer.

CAMPHOS = l,2,2-trimethyl-l,3-bis(diphenylphosphinomethyl)cyclopentane. All reactions were carried out in a medium-pressure Parr apparatus for 24 hr at 300 psi hydrogen at 60°C in 200 ml 1 1 (v/v) deoxygenated ethanol-benzene with a substrate-to-triethylamine mole ratio of 6.25. 

From the practical point of view these electrolyzers can be divided into apparatuses producing hydrogen and oxygen at a medium pressure (8 to 10 atm.), and apparatuses operating at a high pressure of 150 to 200 atm. 

Apparatus. Contact angle measurements were made on a Model A-100 Rame-Hart version of the NRL Contact Angle Goniometer. Exposures were carried out in a forced-draft hood with the unfiltered radiation from a General Electric UA-3 medium-pressure mercury lamp. Spectra were recorded on a Perkin-Elmer Model 350 ultraviolet spectrophotometer, a Beckman IR-12 infrared spectrophotometer with a Wilks Model 7 internal reflectance attachment, and an Aminco-Bowman Spec-trofluorometer with a 1P28 photocell. 

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