Hydrogenation autoclaves

In a hydrogenation autoclave are introduced 92 g of 2-hydroxy-4-nitrophenylbenzoate preceded by 200 cc of ethyl acetate Raney nickel, obtained from 30 g of alloy, is added with 300 cc of ethyl acetate. Hydrogenation under pressure (100 to 120 kg) at ordinary temperature is carried out during a period of about 12 hours. The nickel is filtered off and the ethyl acetate is removed by distillation on the water bath under a vacuum of 300 mm. There is thus obtained 80 g of crude damp 2-hydroxy-4-aminophenylbenzoate which after recrystallization from isopropyl alcohol melts at 153°C. 

Ignition of hydrogen leaking from a hydrogenation autoclave stirrer gland was... 

B. l-Carbethoxymethyl-4-carbethoxypiperidine. Fifteen grams of 10% palladium on charcoal2 is added to the solution of the pyridinium bromide. The mixture is placed in an agitated 2-1. hydrogenation autoclave and hydrogenated at 90° under an initial pressure of 100 atm. (Note 4). Slightly more than the calcu-... 

Harak, J., Stud. Sur. Sci. Catal., 1986, 27 (Catal. Hydrog.), 579-511 A comprehensive discussion of parameters and methods necessary for effective control of laboratory and industrial scale hydrogenation autoclaves, and the need for early recognition of hazardous situations is available. 

High-pressure hydrogenation requires rather sophisticated (and expensive) hydrogenation autoclaves which withstand pressures up to about 350 atm and which can be heated and rocked to insure mixing (Fig. 3). For medium-... 

See other UNIT OPERATION OR UNIT PROCESS INCIDENTS See also CATALYTIC HYDROGENATION AUTOCLAVES... 

The first one is a hydrogenation autoclave for 250 bars and 350 °C with a completely encapsulated agitator, the second one a vessel for tobacco expansion with nitrogen, designed for a minimum of 140,000 cycles at 825 bars and 100 °C. 

Figure 2. HP-hydrogenation autoclave Figure 3. HP-tobacco expansion vessel...

After the hydrogenation autoclave is cleaned it is best to carry out one or two ester hydrogenolyses with copper chromite in order to remove the last traces of poison. The bomb may then be used for hydrogenations. 

See other unit operation or unit process incidents See also catalytic hydrogenation autoclaves... 

A hydrogenation autoclave must be fitted with a manometer, a safety valve, and a valve through which additional hydrogen can be pressed in during an experiment. The temperature must be measured in the interior of the autoclave, either by a built in thermoelement or by a thermometer placed in a sheath that reaches into the interior. 

The hydrogenation reactions were carried out in the liquid phase (373 and 398 K) in a BERGHOF BAR 845 hydrogenation autoclave under constant hydrogen pressure (70 atm) in ethanol as solvent. In eveiy case 50 mg of catalyst and 100 mg of substrate were used. 2,2,4,4-Tetramethyl-l,3-cyclobutanedione, 5-hexen-2-one and (-)-verbenone (2,6,6-trimethylbicyclo[3.1.1]hept-2-en-4-one) were purchased from Aldrich Chemical Co. 

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