Dry Ice condenser

A dry 1-L, three-necked, round-bottomed flask equipped with a large Teflon-covered magnetic stirring bar, a thermometer, and a dry ice condenser (Note 1) is flushed with argon (Note 2), then capped with a serun stopper and subsequently maintained under a positive pressure of argon (Note 3). A 30 dispersion of lithium metal (in mineral oil) containing 1% sodium (13.9 g, 2.00 g-atom of lithium) (Note 4) is rapidly weighed and transferred to the flask. 

The dry ice condenser used with the apparatus should have sufficient condensing capacity to prevent the loss of significant amounts of methyl... 

A slight positive pressure of argon was maintained in the vessel throughout the reaction by using an argon line connected to both a bubbler containing Nujol and the inlet on the dry ice condenser. 

B. 3,3-Dimethoxycyclopropene. A 500-ml., three-necked, round-bottomed flask is equipped with a magnetic stirrer, a gas-inlet tube, a thermometer, and an acetone-dry ice condenser charged with acetone-... 

A 1-1., three-necked, round-bottomed fiask is equipped with an efficient dry-ice condenser (Note 1), a mechanical stirrer, and a gas-inlet tube. The fiask is immersed in an acetone-dry ice bath and 600 ml. of anhydrous ammonia is introduced. After replacing the inlet tube with a... 

A gas bunbling device is attached to the dry-ice condenser. A simple apparatus consists of two 500-ml. filtering flasks equipped with... 

An apparatus resembling that pictured by Schlatter is assembled in a good hood. Two 5-1. three-necked flasks are mounted side by side about 10 cm. apart and about 10 cm. above the bench top or stand base. These arc referred to as the left and right flasks. Kach flask is provided with a dry ice condenser in the outermost neck, and each condenser is [imlected from the... 

Deuterioammonia (about 5 ml) is generated by adding deuterium oxide (14 ml) to a stirred suspension of magnesium nitride (20 g) in mineral oil (30 ml). Tlie deuterioammonia is collected directly in the reaction flask (equipped with a dry ice condenser) at —79° after passing through a trap which is kept at 0°. 

To a solution of 14.5 g of 2-bromo-2 -(2-chlorobenzoyl)acetanilide in 100 ml of tetrahy-drofuran, an excess of liquid ammonia (ca 150 ml) was added. The ammonia was kept refluxing with a dry-ice condenser for 3 hours after which time the ammonia was allowed to evaporate and the solution was poured into water. Crystals of 2-amino-2 -(2-chloro-benzoyOacetanilide were collected, which after recrystallization from ethanol melted at 162° to 164 C. 

Acetylene was passed into a stirred solution of 3.05 grams (0.44 mol) of lithium in 300 ml of liquid ammonia until the blue color exhibited by the mixture had disappeared. Ethyl /3-chlorovinyl ketone (47.4 grams 0.40 mol) dissolved in 50 ml dry ether was then added to the resulting solution of lithium acetylide over a period of 20 minutes, during which the color deepened through yellow to reddish-brown. The mixture was stirred under reflux maintained with a Dry Ice condenser for 2 hours. Thereafter, dry ether (200 ml) was added and the ammonia was permitted to evaporate with stirring overnight. 

The checkers used a dry ice condenser during the introduction of ammonia to the reaction flask and replaced it with an air condenser before the addition of sodium. 

To minimize loss of volatile products such as benzene, it is advisable to employ a dry ice condenser on top of the conventional condenser. 

A solution of 5 (20 mmol) in CH2C12 (100 mL) was treated with liquid NH3 (100 mL) and while the NH3 was refluxing the mixture was stirred for 5h in a flask fitted with a dry-ice condenser. The NH, was then allowed to evaporate at rt and the CH2C12 solution was washed with H20, dried and evaporated in vacuo to leave the 2-(aininoacetamido)benzophenone 6. 

Propanone, l-chloro-l,l,3,3,3-pentafluoro-] (b.p. 7.8° available from PCR, Inc. or Allied Chemical Corp.) are combined in a flask fitted with a dry ice condenser and a magnetic stirring bar. The refluxing mixture is stirred for 4-0 hours and then allowed to warm gradually to room temperature. The contents of the flask are extracted three times with anhydrous ether, and the combined extracts are distilled at atmospheric pressure. After the ether has been removed, continued distillation gives 22.8-28.5 g. (55-69%) of l,l,l-trichloro-3,3,3-trifluoroacetone, b.p. 83.5-84.5°, infrared (film) 1790 cm. - This compound is stored at room temperature in a tightly stoppered bottle. In the absence of reliable toxicity data, it should be handled with normal precautions. 

A water pump purchased from Little Giant Pump Company, Oklahoma City, Oklahoma, was used by the submitters to circulate ice-water through the condenser. The checkers used a dry ice condenser. 

The reaction is exothermic. The checkers found that the yield of the final product was raised from 57% in the first run to 71% in the second and third runs when the triethylamine was added at 30-34° with slight cooling. Another procedural change made by the checkers in Part A in these last two runs was that the dry ice condenser was kept in place for more than 8 hours after the... 

A 3-1. three-necked flask, equipped with a Dry Ice condenser (Note 1), a sealed Hershberg-type stirrer, and an inlet tube, is set up in a hood and charged with 108 g. (0.75 mole) of a-naphthol (Note 2). The stirrer is started, and to the rapidly stirred flask contents (Note 3) is added 11. of liquid ammonia as rapidly as possible (about 5 minutes). When the naphthol has gone into solution (about 10 minutes), 20.8 g. (3.0 g. atoms) of lithium metal (Note 4) is added in small pieces and at such a rate as to prevent the ammonia from refluxing too violently (Note 5). After the addition of the lithium has been completed (about 45 minutes), the solution is stirred for an additional 20 minutes and is then treated with 170 ml. (3.0 moles) of absolute ethanol which is added dropwise over a period of 30-45 minutes (Note 6). The condenser is removed, stirring is continued, and the ammonia is evaporated in a stream of air introduced through the inlet tube. The residue is dissolved in 1 1. of water, and, after the solution has been extracted with two 100-ml. portions of ether, it is carefully acidified with concentrated hydrochloric acid. The product formed is taken into ether with three 250-ml. extractions, and then the ether extract is washed with water and dried over anhydrous sodium sulfate. The ether is removed... 

A 2-1. three-necked flask is thoroughly dried and fitted with a large dry-ice condenser, a mechanical stirrer, a nitrogen inlet, and a powder funnel in an efficient hood. With nitrogen flowing through the system, 62.5 g. (1.60 moles) of commercial sodium amide (Note 1) is added rapidly. (Caution Sodium amide is corrosive and readily decomposes in the presence of moisture.) The funnel is replaced by a gas-inlet tube, the condenser is filled with a mixture of dry ice and acetone, and ca. 400 ml. of liquid... 

A 2-1. three-necked flask is fitted with a sealed mechanical stirrer, a gas-inlet tube, and a dry ice condenser protected from the air by a soda-lime drying tube (Note 1). The system is flushed thoroughly with dry ammonia, and 32.8 g. (0.84 mole) of sodium amide (Note 2) is added to the flask. The system is again flushed with ammonia, the condenser is provided with dry ice covered by acetone, and 1.2 1. of liquid ammonia is condensed... 

It is necessary to use a dry ice condenser in order to shorten the time required to condense the. ammonia (4 hours compared with 6 hours without the condenser). The ammonia tank was warmed with an... 

A. 1,2-Dimethyl-l,4-cyclohexadiene. Caution This step should he conducted in a hood to avoid exposure to ammonia fumes. A 5-1. three-necked flask, cooled in a dry ice-isopropyl alcohol bath, is fitted with an efficient stirrer and a dry ice condenser. The flask is charged with approximately 2.5 1. of liquid ammonia, the stirrer is started, and 450 g. of anhydrous diethyl ether, 400 g. (10 moles) of absolute ethanol, and 318.5 g. (3.0 moles) of u-xylene (Note 1) are added slowly in that order (Note 2). I hen 207 g. (9.0 g. atoms) of sodium is added in small jtieees over a 5-hoiir... 

The flask containing the crude product is equipped with a capillary tube and distilling head and surrounded by a water bath, which may be heated by a hot plate or steam cone. A water-cooled condenser connects the distilling head with the center neck of a two-necked receiver which is surrounded by a Dry Ice bath. The outer neck of the receiver is fitted with a Dry Ice condenser arranged in such a way that vapors which... 

The experimental setup is shown in Fig. 3. The NO generator consists of a 100-mL T14/20 three-necked flask fitted with septa on the two outside necks. The central neck is connected to a dry-ice condenser that is filled with dry ice/ ethanol during the synthesis. The condenser is connected to the NO line via clear tubing. The NO fine consists of three drying tubes connected together in a line by... 

Figure 3. Experimental design for ONOO s3mthesis. The dry-ice condenser of the NO generator is used to trap any water that may evolve after addition of iron sulfate. The three drying tubes of the NO line trap any remaining water before it reaches the reaction vessel.

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