Reaction methods rotary evaporator

Note. (1) The steam distillation may be omitted, if desired, by utilising the following method of purification. Allow the reaction mixture to cool, decant the aqueous layer and dissolve the residue in about 150 ml of toluene. Wash the toluene solution with water, 1 per cent sodium hydroxide solution and finally with water dry with magnesium sulphate, distil off the toluene on a water bath (rotary evaporator) and distil the residue under diminished pressure. 

The checkers prepared this ester on a 0.7-mol scale by a modification of the previously published method.2 The modification was effected as follows. The ethereal extract from the formaldehyde-diethyl malonate reaction, after drying over sodium sulfate for 3 hr, was concentrated in a rotary evaporator and the residue was stored in a refrigerator overnight. The crude ester was obtained as white crystals, mp 47-50°C yield 85.6%. The checkers found that the ester prepared in this manner gave superior yields of the acrylic acid. 

A(A -Bis(3-aminopiopyl)ethylenediamme is prepared by the method of E. K. Barefield. Six moles of 1,3-propanediamine is dissolved in 1.4 L of absolute ethanol and the solution is cooled to 5° in an ice bath. To this solution is added 0.75 mole of 1,2-di-bromoethane from a dropping funnel with vigorous stirring. After the addition is complete, the reaction is heated to reflux temperature for I A hours.. Potassium hydroxide, 150 g, is added and the mixture is refluxed for a further 1 hour. The reaction mixture is cooled to room temperature and filtered to remove the solids. The filtrate is evaporated to a sludge on a rotary evaporator and the semisolid is extracted several times with diethyl ether. The ether solution is evaporated until a viscous liquid remains. The liquid is distilled in vacuo (b.p. 138-148°/2 ton) and stored over potassium hydroxide pellets in a bottle protected from light. The yield is 64 g. 

Citric Acid Method (CA) Ce and Zr nitrate (Ce(N03)3 6H20 and Zr0(N03)2 6H20) precursors were dissolved in methanol (ratio of methanol/nitrate solution = 2 1 (v/v)) and excess citric acid was added (molar ratio of N03 /acid = 6 1.15). The resulting solution was stirred at room temperature for at least 12 hours. The solvent and the reaction products were eliminated using a rotary evaporator at room temperature. The most important step in... 

Preparative Method conveniently prepared by the reaction of di-isopropylsilane in carbon tetrachloride with palladium(II) chloride at 140 °C for 8 h in a steel bomb. Washing the residue with ether and removing the ether by rotary evaporation yields the product which is purified by distillation to yield a clear colorless oil. 

The extracts from the reaction are combined and shaken up with a little anhydrous magnesium sulfate (120 grams) and filtered. The filtrate is evaporated to dryness in the rotary vacuum evaporator, care being taken not to heat the extracts or the residual syrup above 55° C. A good mechanical vacuum pump and effective cold traps in the line are necessary to remove the residual dimethylformamide from the residue. A brown to black bubbly residue should remain when evaporation is complete. This residue contains the amide product and considerable impurities. A general method of purifying the amide follows. 

Gas Chromatography-Mass Spectrometry Negative-ion chemical ionisation mass spectrom-etry is the best method to identify a wide range of synthetic corticosteroids in horse urine (E. Houghton et at, Biomed. Mass Spectrom., 1982, 9, 459-465). Method. Extract 10 ml of urine with 25 ml of methylene chloride, separate the solvent layer, dry over anhydrous sodium sulphate, and evaporate to dryness in a rotary film evaporator at 30° to 40°. Heat the residue with 100 p.1 of an 8% solution of methoxyamine hychochloride in dry pyridine in a reaction tube at 80° for 30 minutes, add 50 pi of trimeOiylsilylimidazole, [Pg.98]

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