Excessive cooling

The N,N -dibenzyl-N,N -bis-[2-(3, 4 -dihydroxyphenyl)-2-oxoethyl] -hexamethylene-diamine-dichlorohydrate-monohydrate used as the starting material was prepared as follows 2 mols of chloroaceto pyrocatechin were dissolved in 2,000 cc of acetone and heated to boiling with 2 mols of N,N -dibenzylhexamethylene-diamine for 12 hours, almost the theoretical quantity of N,N -dibenzylhexamethylene-diamine-dichlorohydrate being precipitated and removed by suction after cooling. Excess HCI was added to the filtrate, approximately 66% of the theoretically possible quantity of crude dichlorohydrate of the N,N -dibenzyl-N,N -bis-[2-(3, 4 -dihydroxyphenyl)-2-oxoethyl] -hexamethylene-diamine being precipitated. The product was cleaned by recrystallization from water with the addition of animal charcoal. After drying the substance contained water of crystallization at ambient temperature, MP 206° to 209.5°C. 

A solution of the piperidino-diol (9 grams) in acetic anhydride (18 ml) was heated at 90°C for 1 hour, the solution cooled, excess acetic anhydride destroyed by the careful addition of water, and the resulting solution carefully made alkaline with 2N caustic soda solution to precipitate a solid product. The soiid was dried, extracted with n-hexane and the solution filtered free of insoluble material before percolation down a column (4x1" diameter) of alumina. Eiution with n-hexane gave a fraction (4.2 grams) which was crystallized twice from ether to give the diacetate, MP 176°-180°C. 

If the internal temperature is too low the reaction stops therefore the mixture should not be cooled excessively. A buildup of unreacted (A)-l-chloropropene in the reaction flask can result in an uncontrollable exotherm when the reaction temperature again increases. 

With diethyl ether, dichloroacetylene forms an azeotrope that contains 55.4% of dichloroacetylene, which is not explosive and is stable in air. If this solution is cooled excessively, the chlorinated derivative separates by forming a second liquid layer that can detonate when the compound is stirred or when the cap that seals the bottle is turned. The same thing happens when the homogeneous mixture is stirred with water. It is prepared safely by adding a catalytic quantity of methanoi to a mixture of trichloroethylene and potassium hydride in tetrahydrofuran. 

Liberation of methanol during decomposition of 1-methoxy-heptyl-l-hydroperoxide was demonstrated by holding a hot copper wire in the vapor. The odor of formaldehyde was detected. From the solution, the oxime of heptaldehyde was obtained (m.p., 54-55.5°C.) undepressed in admixture with an authentic sample. (Found C, 65.16 H, 11.55 N, 10.83%. C7Hi5ON requires C, 65.07 H, 11.70 N, 10.84%.) Another sample of the hydroperoxide (0.73 gram) was boiled for a few minutes with dilute H2S04. The solution was cooled, excess of sodium hydroxide was added, and the mixture was boiled under reflux for 1.5 hours, then acidified and steam-distilled. The ether extract of the distillate was separated into neutral and acid (0.071-gram) fractions. From the latter, the amide of heptoic acid (m.p. 92-94°C.) was obtained. 

To 3-chlorotetracyclo[3.3.0.02 8.03,6]octan-4-one dimethyl acetal (6 g. 30 mmol) and r-BuOH (33 g, 0.44 mo ) in THF (160 mL) was added Na (5 g, 0.22 mol) in small pieces. The mixture was heated to reflux for 8 h. After cooling, excess Na was destroyed by adding MeOH and the mixture was poured into ice H20 (700 mL). The aqueous phase was saturated with NaCI and extracted several times with Et20. Drying, evaporation and distillation at 0.01 Torr gave the title compound yield 4.1 g (82%). 

Ferric Pyroarsenite, FCj(As205)3.7HoO, has been described 7 as a yellow substance obtained by adding ferric hydroxide to a hot saturated solution of arsenious oxide in concentrated sodium hydroxide. On cooling, excess of arsenious oxide separates, and after keeping for 24 hours a yellow precipitate of the above composition is formed. The existence of the pyroarsenite has not been confirmed, however. 

A solution of the piperidino-diol (9 grams) in acetic anhydride (18 ml) was heated at 90°C for 1 hour, the solution cooled, excess acetic anhydride... 

A one gallon reactor was charged with the polyolefin Neodene (319 g) dissolved in 750 ml of THF. The reaction mixture was then treated with dimethylamine (222 g) and a solution of Rh(CO)2(acac) (3.7 g) and tris(2,4-di-t-butylphenyl)phosphite (46.2 g) dissolved in 400 ml of THF so that the final rhodium concentration was 900 ppm by weight. The mixture was heated to 80°C and pressurized to 600 psi with syngas and then stirred under these conditions for 7 hours. The reactor was cooled, excess... 

A solution of 387 g. (3.0 moles) of isoquinoline in 350 ml. of 48% hydrobromic acid is evaporated to near dryness, and 480 g. (3.0 moles) of bromine is added slowly. (Hood.) The resulting mixture is heated under an air reflux condenser at 180-190° for 7 hours, during which evolution of hydrogen bromide is complete. After cooling, excess sodium hydroxide solution is added and the mixture is steam-distilled. Water is decanted from the distillate until approximately 5 1. remains, and nitric acid is added to the hot mixture until the bromoisoquinoline is in solution. Upon cooling the nitrate salt precipitates and is filtered off and redissolved in hot water. Addition of excess ammonium hydroxide precipitates the 4-bromoisoquinoline which upon recrystallization from ether melts at 39-40°. The yield varies between 45% and 74%. 

The dihydro base obtained above was dissolved in glacial HOAc (50 mL) and coned HNO, (8.0 mL) was added dropwise with cooling. Excess chopped ice was added and the mixture was made distinctly alkaline by addition of NaHCOj. The crystalline precipitate was separated and washed with EtOH yield 5.5 g (64%) deep red solid mp 222 C (dec.). 

Blocking Inadequate cooling Excessive winding tension Excessive pressure on nip rolls Bad resin Use better cooling method Adjust tension Adjust pressure Check resin... 

The circulation tank operates at the pressure of the cell-room hydrogen header. When the rectifiers stop for any reason, nitrogen enters the vapor space of the tank to prevent development of an explosive environment or a vacuum due to vapor cooling. Excess gas vents through the hydrogen seal pot. The tank may be vertical, as shown, or horizontal. 

Stereospecific reduction. NaBH4 added with stirring at 25° to a soln. of 9a-fluoro -16a- methyl -17,20 20,21- bis (methylenedioxy) -11- oxopregn -4- eno [3,2-c] -pyrazole in dimethylformamide containing water, after 4 hrs. ice-cooled, excess reagent decomposed with N HCl, and the product converted to its hydrochloride 9a-fluoro-ll) -hydroxy-16a-methyl-17,20 20,21-bis (methylenedioxy)-pregn-4-eno[3,2-c] pyrazole hydrochloride. Y 86.2%. R. Hirschmann et al., J. Med. Chem. 7, 352 (1964) aminoalcohols s. T. Chiemprasert, H.-J. Rimek, and F. Zymalkowski, A. 685, 141 (1965) stereospecific reduction of a-aminoketones s. A. Ichihara et al.. Bull. Chem. Soc. Japan 38, 1158 (1965). 

On the day of the Chernobyl accident, operators disabled the safety system on the reactor while they proceeded with an experimental test of the reactor. During the test, the reactor cooled excessively and threatened to shut down. If... 

Information must be available to determifie the individual reactivity contribution of xenon, graphite heating and cooling, metal heating and cooling, excess at shutdown in horizontal rods, and the effects of metal and poison discharge. The s um. of these separate reactivity items can be used to calculate the pile reactivity at. any time. 

Coke-oven gas flora the exhauster, at a tenqterature of 45 -55 C (113 -131 F), is cooled in the secondary cooler to about 28 C (82°F)> then enters the absorption section of the vessel. A portion of the rich solution from the absorber is cooled and recycled over the bottom packed section to remove the heat of reaction and provide a high liquid flow rate in this zone. Cooled excess flushing liquor, which is a dilute solution of ammonia, is fed into the column in the lower third of the vessel. Water flora the free ammonia stripper is fed into the top of the absorber. This water still contains fixed ammonia, but since this form of ammonia has a negligible ammonia vapor pressure, it does not significantly affect the gas purity attainable. According to Svoboda and Diemer (1990), this type of washer typically reduces the ammonia content of coke-oven gas fiom 200-500 g/100 scf to 2-7 g/100 scf. 

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