Pressure for nitrogen

Attempts to increase the yield of l//-l-benzazepines by carrying out the reactions under high nitrogen pressure were only marginally successful. For example, in dichloromethane solution and 10 kbar nitrogen pressure for seven days, the yield of dimethyl 1-methyl-l //-benzazepine-3,4-dicarboxylate is increased to only 20%.144... 

Add the supernatant see Note 4). Place the cell on a magnetic stirring table, and pressurize the system to the recommended nitrogen pressure for a given membrane (usually about 55 psi). 

The following results refer to the adsorption of nitrogen on a graphitised sample of carbon black, and give the ratio of the nitrogen pressures for temperatures of 90 K and 77 K which are required to achieve a given amount of adsorption ... 

Recombination reactions are highly exothermic and are inefficient at low pressures because the molecule, as initially formed, contains all of the vibrational energy required for redissociation. Addition of an inert gas increases chemiluminescence by removing excess vibrational energy by coUision (192,193). Thus in the nitrogen afterglow chemiluminescence efficiency increases proportionally with nitrogen pressure at low pressures up to about 33 Pa (0.25 torr) (194). However, inert gas also quenches the excited product and above about 66 Pa (0.5 torr) the two effects offset each other, so that chemiluminescence intensity becomes independent of pressure (192,195). 

Ethylene oxide storage tanks ate pressurized with inert gas to keep the vapor space in a nonexplosive region and prevent the potential for decomposition of the ethylene oxide vapor. The total pressure that should be maintained in a storage tank increases with Hquid temperature, since the partial pressure of ethylene oxide will also increase. Figure 5 shows the recommended minimum storage pressures for Hquid ethylene oxide under nitrogen or methane blanketing gas. 

Fig. 5. Recommended safe storage pressures for liquid ethylene oxide under nitrogen (—) or methane ( ) blanketiag (9). To convert kPa to psi, multiply...

The mixture is cooled to room temperature, then filtered. The solvent is removed under reduced pressure, leaving the tribromide (47) as a foam. The foam is mixed with sodium iodide (9.55 g, 0.064 mole) and acetone (74 ml) and heated under reflux in a nitrogen atmosphere for 3.5 hr. The acetone is removed under reduced pressure and the residue is treated with chloroform and aqueous sodium thiosulfate solution. The chloroform layer is separated and washed with sodium thiosulfate solution until it is free from iodine, then dried over magnesium sulfate, filtered and evaporated to dryness under reduced pressure. The crude product (48) is obtained as a brown sohd (4.85 g) which is chromatographed over alumina (122 g, Merck acid-washed). The column is developed with hexane, benzene and ethyl acetate mixtures. The product (3.43 g) is eluted by benzene and benzene-ethyl acetate (10 1). Recrystallization from acetone yields purified 3jS-acetoxy-pregna-5,14,16-trien-20-one (48), 3.25 g, mp 158-159° 309 m/ (e 10,700). 

To obtain the free base, 34 g (0.256 mol) of N-ethyl-3-piperidinol and 20 g (0.22 mol) of diphenylacetyl chloride were mixed in 80 cc of isopropanol and the solution was refluxed for 2 hours. The isopropanol was evaporated in vacuo at 30 mm pressure, the residue was dissolved in 150 cc of water and the aqueous solution was extracted several times with ether. The aqueous solution was then neutralized with potassium carbonate and extracted with ether. The ethereal solution was dried over anhydrous potassium carbonate and the ether removed by distillation. The product was then distilled at its boiling point 180° to 181°C at 0.13 mm of mercury whereby 14 g of a clear yellow, viscous liquid was obtained. The nitrogen content for CjiHjjNOj was calculated as 4.33% and the nitrogen content found was 4.21%. 

A) Preparation of 1-Methyl-2-Picolinium Chloride 98 ml of cx-picoline is dissolved in 200 ml of methanol, cooled and 85 ml (at -68°C) of methyl chloride is added. The solution is charged to an autoclave, sealed and the nitrogen pressure of 300 psig is established. The mixture is heated at 120° to 130°C for 2 hours, cooled and opened. The resulting solution is then evaporated to dryness in vacuo, yielding a residue of 110 g. This residue is then dissolved in 50 ml of water and extracted with two 50 ml portions of ether. The aqueous phase is then diluted to 150 ml with water and an assay for ionic chloride is performed which indicates the presence of chloride ion equivalent to 721 mg/ml of 1-methyl-2-picolinium chloride. 

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