Cooling with Ice

In the past, ice was often used as a coolant, poured directly into the medium that needed to be cooled. This is obviously only possible when the chemistry is compatible with water, since the medium soon becomes diluted by molten ice. Ice acts by releasing it latent heat by melting AH meu = 320kjkg 1. The amount of ice used must be taken into account during this process. Ice cooling may be interesting as an emergency coolant. 

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Equip a 500 ml. three-necked flask with a dropping funnel, a mechanical stirrer and a reflux condenser. Place a solution of 72 g. (65 ml.) of redistilled phenylhydrazine (Section IV,89) CAUTION poisonous) in 300 ml. of ether in the flask, stir vigorously, and add 33 g. (26 ml.) of A.R. carbon disulphide slowly during about 30 minutes. A precipitate is formed immediately upon the addition of the carbon disulphide, the mixture becomes warm and the temperature soon approaches the boiling point maintain the temperature just below the b.p. by cooling with ice water if necessary. When the addition is complete, stir for a further 30 minutes, then filter the precipitate at the pump, wash it with about 25 ml. of ether, and spread it upon filter paper for 20 minutes to permit of the evaporation of the ether. The yield of the salt (I) is 92 g. 

It is liquefied by conducting the gas through a condenser cooled with ice water. Where difficult to obtain, it may be prepared by passing chlorine gas through a stirred suspension of sodium tetrakis(cyano-C)zincate prepared in situ from sodium cyanide and zinc sulfate. ... 

Carefully add 8 ml cone, sulfuric acid and 0.5 ml anisaldehyde under cooling with ice to a mixture of 85 ml methanol and 10 ml glacial acetic acid [1, 4, 8, 11,16]. 

Dipping solution Add 10 ml sulfuric acid (95 — 97%) cautiously to 85 ml water while cooling with ice and add 5 ml methanol after mixing thoroughly. 

A suspension of lithium aluminum deuteride (1.6 g) in dry tetrahydrofuran (60 ml) is added dropwise to a stirred and cooled (with ice-salt bath) solution of 5a-androst-l4-ene-3j3,17j3-diol (179, 1.6 g) and boron trifluoride-etherate (13.3 g) in dry tetrahydrofuran (60 ml). The addition is carried out in a dry nitrogen atmosphere, over a period of 30 min. After an additional 30 min of cooling the stirring is continued at room temperature for 2 hr. The cooling is resumed in a dry ice-acetone bath and the excess deuteriodiborane is destroyed by the cautious addition of propionic acid. The tetrahydrofuran is then evaporated and the residue is dissolved in propionic acid and heated under reflux in a nitrogen atmosphere for 8 hr. After cooling, water is added and the product extracted with ether. The ether... 

In the preparation of the nitrosochloride, Wallach proposed to use pinene in glacial acetic acid and amyl nitrite. Ehestadt has recently proposed the following method, which is very simple and yields excellent results The pinene (or oil of turpentine) is diluted with its own volume of ether, the solution cooled with ice, and the gas generated hy dropping a saturated solution of sodium nitrite into concentrated hydrochloric acid passed through the solution. Fine crystals of pinene-nitrosochloride soon commence to separate out. Schimmel Co. obtained the following yields of nitrosochloride by the methods quoted —... 

Five parts of the terpene, 7 of amyl nitrite, and 12 of glacial acetic acid are mixed and cooled with ice and salt, and a mixture of 6 parts of hydrochloric acid and 6 parts of glacial acetic acid added in small quantities at a time. Five parts of alcohol are then added and the mixture allowed to stand in a freezing mixture for a itime. A mass of crystals separates, which consists of the crude nitrosochlorides. This is filtered off and washed with alcohol. When perfectly dry 100 grams of the crystals are digested with 200 c.c. of chloroform for a few moments and at once filtered. The chloroform dissolves a-nitrosochloride, which is precipitated by the addition of excess of methyl alcohol. The crude compound is filtered off, dried and digested with anhydrous ether for... 

To a solution of 16.35 grams of estradiol in 75 ml of dry pyridine, 21.00 grams of the abovementioned chloroformyl-bis()3-chloroethyl)amine are added while stirring and cooling with ice-water. 

The product is dissolved in 134 ml of 96% ethanol whereupon 26.8 ml of concentrated hydrochloric acid and 201 ml of water are added while cooling with ice-water. The pre-... 

The temperature is again lowered to 20°C to 25°C and maintained at this value by cooling with ice while 500 ml methanol are added drop by drop. The resulting solution is admixed drop by drop to a suspension of 240 g powdered caustic soda in 800 ml methanol at 20°C to 25°C. After mixing is completed, stirring is continued for 30 minutes at room temperature. The solution now contains inorganic salts and /3-dlmethylamino-a-methoxyethoxyacroleln. 

Preparation of w-Phenyl-tert-Butylamine 24 grams of the urea derivative obtained as indicated above, were well mixed with 96 grams of calcium hydroxide in a flask immersed in an air bath and provided with a dropping funnel the stem of which reached the bottom of the flask. The mixture was heated to 240°-260°C (inside temperature) for 7 hours during which time 86 cc of water was slowly added. The vapors were collected in a receiver cooled with ice. After extraction with ether and distillation, the product was obtained as a colorless liquid boiling from 80°-84 C at 9 mm according to U.S. Patent 2,590,079. 

Parts of pyrazine-2,3-dicarboxamide (1 mol) is slurried in 1,000 parts of 1 N aqueous sodium hydroxide. The reaction mixture is heated at 95°C to 98°C until a clear solution results. Thereupon the mixture is cooled with ice to about 5°C and acidified to approximately a pH of 1. The cold reaction mixture is allowed to stand until precipitation of the pyrazlne-2arboxylic acid is substantially complete whereupon it Is recovered by filtration end dried at 50°C to 60°C. 

To a solution of 60 g of potassium xanthogenate in 240 cc of water there is added dropwise, while being cooled with ice, a solution of 42 g of 3,4-bis-bromomethyl-4-hydroxy-5-methyl-pyridinium-bromide In 1 liter of water so that the temperature remains between 2°C and 5°C. After stirring for 1 hour at the same temperature, the water is decanted off and the residue is triturated with acetone. Yield 25 g of 4-hydroxymethyl-5-hydroxy-6-methyl-pyridyl-(3)-methy I xanthogenate melting point 170°C to 171°C (alcohol, decomposition). 

The aqueous alkaline extract is heated to ioo° to remove ether and volatile impurities. The solution is then cooled with ice and acidified with 25 per cent sulfuric acid, and the organic acid separated. The water layer is distilled from a 2-1. flask until no more oily solution comes over, The distillate is saturated with salt and the acid layer is separated. This water layer together with the low boiling fraction from distillation of the crude trimethylacetic acid is distilled and the distillate salted out as before. 

Spray solution 1 Mix equal volumes of nitric acid (65 Vo) and methanol while cooling with ice. The reagent solution may be kept for several weeks. 

A, trans-2,4-Pentatiienoic acid. A 1-1., three-necked, round-bottomed ilask is equipped with a mechanical stirrer, a condenser cooled with ice-cold water (Note 1) and bearing a calcium chloride drying tube, and a powder funnel. The flask is charged with 206 g. (210 ml., 2.6 moles) of pyridine (Note 2), vigorous stirring is... 

Me3SiCl 14 (2.5 mb) is added to a solution of 2 g /9-ketoester 1412 in 20 mb dry CHCI3. The solution is cooled with ice-water and HCl gas introduced until saturation occurs. After 16 h at room temperature the volatile constituents are removed in vacuo and the residue distilled in a Kugelrohr apparatus to give 1.7 g (93%) 1413 as a slightly yellowish oil, b.p. 95 °C/0.2 Torr [4] (Scheme 9.49). 

It had been decided to purify N,N-dimethylaniline by mixing acetic anhydride, water and hydrochloric acid following a published operating method. However, a slight modification was made that consisted in using the double amount of reagents. The medium was cooled with ice. When hydrochloric acid was introduced, the anhydride hydrolysis was so violent that it caused the apparatus to detonate. 

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