Heating methods water bath

Method of Preparation Add 0.5 mL of H2SO4 to a mixture of 5 g of salicylic acid and 5 mL acetic anhydride in a 100 mL flask. Continue stirring and heat on water bath for 15 min, keeping the temperature between 50°C and 60°C. Pour the mixture in about 80 mL of ice cold water, filter and crystallize with a mixture of equal volumes of acetic acid and water. 

Waste water 1986 (chromium(VI)) Sample mixed with a masking agent and cetyltri methyl-ammonium bromide solution at pH 47-6.6, heated in water bath at 50 C for 10 minutes Spectrophotometry at 583 nm Lower than diphenylcarbazone method No data Qi and Zhu 1986... 

Sample preparation followed the method described by Ryoto (13). One gram SPE or dry deoiled lecithin was dissolved in 100 g of oil and heated to 60-80°C for complete dispersion of the emulsifier. Ethanol-insoluble lecithin was added at a level of 1 mg/100 g oil and any residual to the ethanol was removed by heating a water bath. Samples with 0.5 and 0.25% SPE or dry lecithin were prepared by diluting the original sample with oil. Deoiling and fractionation of lecithin were done with acetone and ethanol, respectively, as reported by Ziegelitz (15). Turbidity test was conducted on 70 mL oil in a 100-mL tube at different concentrations of DK F-10 (0.0,0.5, and 1.0%) at several temperatures. 

B) Preparation of Benzoyl Chloride (Sm.). Use the same apparatus and method described in section (A). Place 5 g of benzoic acid and 5 ml of thionyl chloride in the tube. Heat at 60° for 30 minutes. Then change the condenser, and insert the thermometer and a new receiving tube. Heat the water bath to boiling. The liquid that distills over is unchanged thionyl chloride, which boils at 78-80°. Re-... 

The yield is reported to be improved by the following modification of the method described. In a 3-I. three-necked flask provided with a stirrer, reflux condenser, and dropping fuimel, set in asbestos-sodium silicate stoppers (5, 9), are placed 1900 cc. of 50 per cent nitric acid (1262 cc. of nitric acid, sp. gr. 1.42, diluted to 1900 cc.) and i g. of ammonium vanadate. The flask is surrounded by a water bath heated to 50-60°, and, while the mixture is stirred, 357 g. (3.5 moles) of commercial cyclohexanol is added very slowly so that the temperature of the bath is maintained at 50-60°. This requires about six to eight hours. The reaction is completed by heating the water bath to boiling until the evolution of nitrogen oxides has ceased (about one hour). The hot reaction mixture is siphoned off and allowed to cool. The yield of crude adipic acid is 372 g. (72 per cent of the theoretical amount). 

Various heating methods, including conventional heating in water bath, pressure cooker, steamer, and... 

L 2N HCl, decant and wash the aqueous phase three times with CHCI3 dry, evaporate in vacuum (can chromatograph as for (III)) to get about 11 g 4,5,6,7-tetrahydro-4-indolone (IV). 7.35 g (IV), 5 g 10% palladium-carbon, 700 ml mesitylene and reflux eight hours or more. Filter hot, wash precipitate with methanol, cool and evaporate in vacuum (can chromatograph as for (III)) to get 5 g 4-OH-indole (V) (recrystallize from petroleum ether), which can be converted to the diakyltryptamine by any of the methods described here or as follows (the first step leading to (VI) may not be necessary). 5 g (V), 20 ml pyridine, 10 ml acetic anhydride and heat in water bath 10 minutes. Pour on ice, stir and add NaHCOs. After one-half hour extract with ethyl acetate, wash... 

Use approximately 0 5 ml. of glycerol, and cork the flask A securely when weighing the glycerol by difference, owing to the very hygroscopic nature of the latter. Heat on the water-bath for 60 minutes instead of 30 minutes. Excellent results are obtained by this method if a freshly opened sample of anhydrous glycerol is available a sample which has been exposed to the air for even a short period will absorb sufficient water to give inaccurate results. 

Ether. The most satisfactory method for the removal of (diethyl) ether is either on a steam bath fed from an external steam supply or by means of an electrically-heated, constant-level water bath (Fig. 77, 5, 1). If neither of these is available, a water bath containing hot water may be used. The hot water should be brought from another part of the laboratory under no circumstances should there be a free flame under the water bath. It caimot be too strongly emphasised that no flame whatsoever may be present in the vicinity of the distillation apparatus a flame 10 feet away may ignite diethyl ether if a continuous bench top lies between the flame and the still and a gentle draught happens to be blowing in the direction of the flame. 

Method 1. Mix 1 0 g. of 3 5-dinitrobenzoic acid (Section IV,168) with 4 ml. of thionyl chloride in a dry 50 ml. conical flask fit a reflux condenser, carrying a plug of cotton wool at the upper end, into the flask and heat on a water bath for 15-30 minutes. Remove the condenser and heat the flask in a boiling water bath FUME CUPBOARD 1) until the excess of thionyl chloride has evaporated. Use the resulting 3 5-dinitrobenzoyl chloride (about 10 g.) immediately. 

Method 2 (from hydrazobenzene). Prepare a solution of sodium hypobromite by adding 10 g. (3-2 ml.) of bromine dropwise to a cold solution of 6-0 g. of sodium hydroxide in 75 ml. of water immersed in an ice bath. Dissolve 9-5 g. of hydrazobenzene (Section IV,87) in 60 ml. of ether contained in a separatory funnel, and add the cold sodimn hypobromite solution in small portions. Shake for 10 minutes, preferably mechanically. Separate the ether layer, pour it into a 100 ml. distilling flask, and distil off the ether by warming gently on a water bath. Dissolve the warm liquid residue in about 30 ml. of alcohol, transfer to a small beaker, heat to boiling on a water bath, add water dropwise to the hot solution until the azobenzene just commences to separate, render the solution clear again with a few drops of alcohol, and cool in ice water. Filter the orange crystals at the pump, and wash with a little 50 per cent, alcohol. Dry in the air. The yield is 8 g. 

Method 1. Place 20 g. of crude benzoin (preceding Section) and 100 ml. of concentrated nitric acid in a 250 ml. round-bottomed flask. Heat on a boiling water bath (in the fume cupboard) with occasional shaking until the evolution of oxides of nitrogen has ceased (about 1 -5 hours). Pour the reaction mixture into 300-400 ml. of cold water contained in a beaker, stir well until the oil crystallises completely as a yellow solid. Filter the crude benzil at the pump, and wash it thoroughly with water to remove the nitric acid. RecrystaUise from alcohol or methylated spirit (about 2-5 ml. per gram). The yield of pure benzil, m.p. 94-96°, is 19 g. 

Method 2. Into a 500 ml. round-bottomed flask place 120 ml. of dry A.R. benzene, and 35 g. (29 ml.) of redistilled benzoyl chloride. Weigh out 30 g. of finely-powdered, anhydrous aluminium chloride into a dry corked test-tube, and add the solid, with frequent shaking, during 10 minutes to the contents of the flask. Fit a reflux condenser to the flask, and heat on a water bath for 3 hours or until hydrogen chloride is no longer evolved. Pour the contents of the flask wliile still warm into a mixture of 200 g. of crushed ice and 100 ml. of concentrated hydrochloric acid. Separate the upper benzene layer (filter first, if necessary), wash it with 50 ml. of 5 per cent, sodium hydroxide solution, then with water, and dry with anhydrous magnesium sulphate. Isolate the benzophenone as in Method 1. The yield is 30 g. 

An alternative method of removing the aniline is to add 30 ml. of concentrated sulphuric acid carefully to the steam distillate, cool the solution to 0-5°, and add a concentrated solution of sodium nitrite until a drop of the reaction mixture colours potassium iodide - starch paper a deep blue instantly. As the diazotisation approaches completion, the reaction becomes slow it will therefore be necessary to teat for excess of nitrous acid after an interval of 5 minutes, stirring all the whUe. About 12 g. of sodium nitrite are usually required. The diazotised solution is then heated on a boiling water bath for an hour (or until active evolution of nitrogen ceases), treated with a solution of 60 g. of sodium hydroxide in 200 ml. of water, the mixture steam-distilled, and the quinoline isolated from the distillate by extrsM-tion with ether as above. 

Method 2. Place 48 g. (41 -5 ml.) of freshly-distilled furfural, 52 g. of dry malonic acid (1), and 24 ml. of dry pyridine (2) in a 500 ml. round-bottomed flask, fitted with a reflux condenser. Heat the flask on a boiling water bath for 2 hours, cool the reaction mixture and dilute with 50 ml. of water. Dissolve the acid by the addition of concentrated ammonia solution, filter the solution and wash the filter paper with a... 

Method 1. Dissolve 76 g. of thiourea in 200 ml. of warm water in a 750 ml. or 1 litre round-bottomed flask. Dilute the solution with 135 ml. of rectified spirit and add 126-5 g. of benzyl chloride. Heat the mixture under reflux on a water bath until the benzyl chloride dissolves (about 15 minutes) and for a further 30 minutes taking care that the mixture is well shaken from time to time. Cool the mixture in ice there is a tendency to supersaturation so that it is advisable to stir (or shake) the cold solution vigorously, when the substance crystallises suddenly. Filter off the sohd at the pump. Evaporate the filtrate to about half bulk in order to recover a further small quantity of product. Dry the compound upon filter paper in the air. The yield of hydrochloric acid filter off the sohd which separates on cooling. Concentrate the filtrate to recover a further small quantity. The yield of recrystalhsed salt, m.p. 175° is 185 g. some of the dimorphic form, m.p. 150°, may also separate. 

Method 2. Ethyl p-nitrobenzoate. Place 21 g. of p-nitrobenzoic acid (Section IV,154), 11-5 g. of absolute ethyl alcohol, 3 8 g. of concentrated sulphuric acid, and 30 ml. of sodium-dried A.R. benzene in a 250 ml. round-bottomed flask, fit a reflux condenser, and heat the mixture under reflux for 16 hours. Add 50 ml. of ether to the cold reaction mixture, wash the extract successively with sodium bicarbonate soiution and water, dry with anhydrous magnesium sulphate or calcium chloride, and distil off the solvent on a water bath. Remove the last traces of benzene either by heating in an open evaporating dish on a water bath or in a bath at 100-110°. The residual ethyl p-nitrobenzoate (21 g.) solidifies completely on cooling and melts at 56°. 

N,N -Diethylbenzidine has been prepared by heating ethyl iodide, benzidine, and ethanol in a pressure tube at water-bath temperature, and by the reaction of diethylzinc on benzene-diazonium chloride. The method described here is a modification of that of Shah, Tilak, and Venkataraman. ... 

In the pickling process, use countercurrent flow of rinse water use indirect methods for heating and pickling baths. 

Methylated spirit contains, in addition to ethyl and methyl alcohols, water, fusel-oil, acetaldehyde, and acetone. It may be freed from aldehyde by boiling with a—3 per cent, solid caustic potash on the water-bath with an upright condenser for one hour, or if larger quantities are employed, a tin bottle is preferable, which is heated directly over a small flame (see Fig. 38). It is then distilled with the apparatus shown in Fig. 39. The bottle is here surmounted with a T-piece holding a thermometer. The distillation is stopped when most of the spirit has distilled and the thermometer indicates 80°. A further purification may be effected by adding a little powdered permanganate of potash and by a second distillation, but this is rarely necessary. The same method of purification may be applied to over-proof spirit, which will henceforth be called spirit as distinguished from the purified product or absolute alcohol. 

Naphthyl methyl ether.—Dissolve 3-6grams(3-naphthnl in I3 5 c.c. 10 per cent, caustic soda solution, add 3 c.c. meth l sulphate, warm the liquid gently and shake vigorously. In. i short time the naphthyl methyl ether separates as a solid mass. The product is heated for ten minutes on the water-bath, a little water is added, and the naphthyl ether filtered and washed with water. It is crystallised from alcohol and deposits in lustrous plates m. p. 70—72°. The yield is theoretical. It may be used for analysis by Zeisel s method. 

Neuberg and Tiemann propose the following method, depending on the fact that most aldehydes form a compound with thiosemi-car-bazide. The oil containing aldehyde is heated in alcoholic solution on a water-bath, with thiosemi-carbazide. Various salts of the heavy metals will form insoluble precipitates with the thiosemi-carbazone formed, and such precipitate is dissolved in alcohol, and a current of hydrogen sulphide passed through until the metal is precipitated, leaving the thiosemi-carbazone dissolved in the alcohol. 

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