Rotary vacuum evaporator

The crude ketal from the Birch reduction is dissolved in a mixture of 700 ml ethyl acetate, 1260 ml absolute ethanol and 31.5 ml water. To this solution is added 198 ml of 0.01 Mp-toluenesulfonic acid in absolute ethanol. (Methanol cannot be substituted for the ethanol nor can denatured ethanol containing methanol be used. In the presence of methanol, the diethyl ketal forms the mixed methyl ethyl ketal at C-17 and this mixed ketal hydrolyzes at a much slower rate than does the diethyl ketal.) The mixture is stirred at room temperature under nitrogen for 10 min and 56 ml of 10% potassium bicarbonate solution is added to neutralize the toluenesulfonic acid. The organic solvents are removed in a rotary vacuum evaporator and water is added as the organic solvents distill. When all of the organic solvents have been distilled, the granular precipitate of 1,4-dihydroestrone 3- methyl ether is collected on a filter and washed well with cold water. The solid is sucked dry and is dissolved in 800 ml of methyl ethyl ketone. To this solution is added 1600 ml of 1 1 methanol-water mixture and the resulting mixture is cooled in an ice bath for 1 hr. The solid is collected, rinsed with cold methanol-water (1 1), air-dried, and finally dried in a vacuum oven at 60° yield, 71.5 g (81 % based on estrone methyl ether actually carried into the Birch reduction as the ketal) mp 139-141°, reported mp 141-141.5°. The material has an enol ether assay of 99%, a residual aromatics content of 0.6% and a 19-norandrost-5(10)-ene-3,17-dione content of 0.5% (from hydrolysis of the 3-enol ether). It contains less than 0.1 % of 17-ol and only a trace of ketal formed by addition of ethanol to the 3-enol ether. 

The reaction mixture is diluted with 250 ml of water, the mixture is transferred to a 2 liter flask using methanol as a wash liquid, and the organic solvents are distilled at 20-25 mm using a rotary vacuum evaporator. The product separates as a solid and distillation is continued until most of the residual toluene has been removed. The solid is collected on a 90 cm, medium porosity, fritted glass Buchner funnel and washed well with cold water. After the material has been sucked dry, it is covered with a little cold methanol, the mixture is stirred to break up lumps, and the slurry is kept for 5 min. The vacuum is reapplied, the solid is rinsed with a little methanol followed by ether, and the material is air-dried to give 9.1 g (85%), mp 207-213° after sintering at ca. 198°. Reported mp 212-213°. The crude material contains 1.0-1.5% of unreduced starting material as shown by the UV spectrum. Further purification may be effected by crystallization from methanol. 

In a 250 ml Erlenmeyer flask covered with aluminum foil, 14.3 g (0.0381 mole) of 17a-acetoxy-3j5-hydroxypregn-5-en-20-one is mixed with 50 ml of tetra-hydrofuran, 7 ml ca. 0.076 mole) of dihydropyran, and 0.15 g of p-toluene-sulfonic acid monohydrate. The mixture is warmed to 40 + 5° where upon the steroid dissolves rapidly. The mixture is kept for 45 min and 1 ml of tetra-methylguanidine is added to neutralize the catalyst. Water (100 ml) is added and the organic solvent is removed using a rotary vacuum evaporator. The solid is taken up in ether, the solution is washed with water and saturated salt solution, dried over sodium sulfate, and then treated with Darco and filtered. Removal of the solvent followed by drying at 0.2 mm for 1 hr affords 18.4 g (theory is 17.5 g) of solid having an odor of dihydropyran. The infrared spectrum contains no hydroxyl bands and the crude material is not further purified. This compound has not been described in the literature. 

The resulting solutions ixom above experiments were saturated with sodium chloride and then diethyl ether was added to extract 3-methyl-2-cyclopentenone from aqueous NaOH solution. The diethyl ether in the oiganic phase was then removed by a rotary vacuum evaporator. The heavy cut residue was separated by a simple distillation. The collected 3-methyl-2-cydopentenone was dried over solid anhydrous MgS04 and filtered. 

Round-bottom flasks, 1-L, 500-mL and 50-mL with ground joints Rotary vacuum evaporator, 40 °C bath temperature Separatory funnel, 300-mL Funnel, 10-mm diameter... 

Rotary vacuum evaporator with 40 °C water-bath Ultrasonic water-bath... 

Rotary vacuum evaporator, 40 °C bath temperature Separatory funnel, 300-mL... 

Rotary vacuum evaporator, water-bath temperature 40 °C... 

Round-bottom flasks, 50-, 100- and 300-mL Rotary vacuum evaporator, bath temperature 40 °C Separatory funnels, 100- and 200-mL... 

SPE cartridge column Mega Bond Elut Cig, lO-g/60-mL (Varian). The SPE cartridge column is rinsed with 100 mL of methanol and 100 mL of distilled water Rotary vacuum evaporator, 40 °C bath temperature Water-bath, electrically heated, temperature 80 °C Mechanical shaker (universal shaker)... 

Erlenmeyer flask, 500-mL Round-bottom flasks, 300-mL Rotary vacuum evaporator Stainless-steel centrifuge tube, 250-mL Ultracentrifuge pH meter... 

ORBO-42 tube A sampling cartridge filled with two portions (100-mg front bed and 50-mg backup bed) of adsorbent (porous styrene-divinylbenzene copolymer), 8-mm i.d., 100-mm length Rotary vacuum evaporator, 35 °C bath temperature Separatory funnel, 500-mL... 

Nitroacetone (237 g) was generated in dichloromethane-ethyl acetate solution by treating its dicyclohexylamine aci-salt with sulfuric acid. Towards the end of concentration of the solution by rotary vacuum evaporation at 40-50°C, a small explosion occurred. Extreme caution and small scale handling of a-nitroketones are urged [1], If exact neutralisation of the dicyclohexylamine salt had not been achieved, presence of excess sulfuric acid (or of some undecomposed aci-salt) may have reduced the stability of the nitroacetone [2],... 

Evaporate 2pmol of total homogenized lipid in chloroform using a stream of nitrogen or a rotary vacuum evaporator. 

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. 

The mother liquors and the two washes containing methanol are collected and combined. A one normal solution of potassium hydroxide in methanol is added in approximately equal volume to the combined washes and mother liquors. The solution is then filtered and the filter washed with a few ml of methanol. The filtrates are allowed to stand at room temperature for two to three hours to reequilibrate the iso-lysergic acid amides from the mother liquors. About 500 ml of water is then added and the mixture extracted with 2.5 liters of methylene chloride in divided portions in a separatory funnel. The combined extracts are shaken with 25 grams of anhydrous magnesium sulfate and filtered. The filtrate is taken to dryness on the rotary vacuum evaporator, care taken not to heat above 55° C. The material is purified in the same manner as that from the original reaction mixture using approximately one fourth the quantities of solvents and alumina as for the original. 

M potassium phosphate buffer pH 8.0 (1000 mL) hydrochloric acid (cone.) (100 mL) distilled water (1000 mL) fermentor/ bioreactor (1.5 L capacity) rotary vacuum evaporator/oven ice... 

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