Diethyl ether, atmosphere

Bromoethane was used in sterilisation equipment to make diethyl ether atmospheres fireproof. This method is inefficient since 31 % brominated derivative should be used. Inflammability data regarding bromoethane vary from one author to the next. It is most often agreed that this compound has very narrow inflammability limits (13.5-14.5%). The range is more critical under pressure and is thought to reach 8.6-20%. 

Butadiene is a noncorrosive, colorless, flammable gas at room temperature and atmospheric pressure. It has a mildly aromatic odor. It is sparingly soluble in water, slightly soluble in methanol and ethanol, and soluble in organic solvents like diethyl ether, ben2ene, and carbon tetrachloride. Its important physical properties are summarized in Table 1 (see also references 11, 12). 1,2-Butadiene is much less studied. It is a flammable gas at ambient conditions. Some of its properties are summarized in Table 2. 

Because phenols are weak acids, they can be freed from neutral impurities by dissolution in aqueous N sodium hydroxide and extraction with a solvent such as diethyl ether, or by steam distillation to remove the non-acidic material. The phenol is recovered by acidification of the aqueous phase with 2N sulfuric acid, and either extracted with ether or steam distilled. In the second case the phenol is extracted from the steam distillate after saturating it with sodium chloride (salting out). A solvent is necessary when large quantities of liquid phenols are purified. The phenol is fractionated by distillation under reduced pressure, preferably in an atmosphere of nitrogen to minimise oxidation. Solid phenols can be crystallised from toluene, petroleum ether or a mixture of these solvents, and can be sublimed under vacuum. Purification can also be effected by fractional crystallisation or zone refining. For further purification of phenols via their acetyl or benzoyl derivatives (vide supra). 

These compounds are odourless, rather unstable compounds, and should be distilled under vacuum in an inert atmosphere. They are water-soluble but can be extracted from aqueous solution with a solvent such as diethyl ether. 

MeOH (copper-coloured prisms) or from diethyl ether by adding MeOH. Also purified by chromatography on columns of magnesia or calcium hydroxide, and crystd from CS2/EtOH. May be purified via the dipalmitate ester. Stored in the dark, in an inert atmosphere. 

Physalien (all trans /J-carotene-3,3 -diol dipalmitate) [144-67-2] M 1044, m 98.5-99.5°, A (Xmax) 1410 (449nm), 1255 (478nm) in hexane. Purified by chromatography on water-deactivated alumina, using hexane/diethyl ether (19 1) to develop the column. Crystd from benzene/EtOH. Stored in the dark, in inert atmosphere, at 0°. 

This reaction is the cause of a widely recognized laboratory hazard. The peroxides formed from several commonly used ethers, such as diethyl ether and tetrahydrofuran, are explosive. Appreciable amounts of such peroxides can build up in ether samples that have been exposed to the atmosphere. Because the hydroperoxides are less volatile than the ethers, they are concentrated by evaporation or distillation, and the concentrated peroxide solutions may explode. For this reason, extended storage of ethers that have been exposed to oxygen is extremely hazardous. 

Ethers — (R-O-R) are low on the scale of chemical reactivity. Aliphatic ethers are generally volatile, flammable liquids with low boiling points and low flashpoints. Well known hazardous ethers include diethyl ether, dimethyl ether, tetrahydrofuran. Beyond their flammability, ethers present an additional hazard they react with atmospheric oxygen in the presence of light to form organic peroxides. 

A mixture consisting of 2 grams of 2-hydroxy-3-(N,N-diethylcarboxamido)-9,10-dimethoxy-1,2,3,4,6,7-hexahydro-1 Ib-H-benzopyridocoline (OH-axial) hydrochloride (prepared by treating the base with hydrogen chloride gas in absolute ether) dissolved in 7 ml of acetic anhydride containing 3 ml of pyridine was heated at 100°C for 2 hours under a nitrogen atmosphere. At the end of this period, a crystalline precipitate had formed and the resultant mixture was subsequently diluted with an equal volume of diethyl ether and filtered. 

Aluminium can be deposited from complex organic solutions if sufficient precautions are taken, and such coatings are now being produced commercially in North America. Two of the systems on record are (1) aluminium trichloride and lithium aluminium hydride dissolved in diethyl ether used at 40°C and 50A/m, and (2) aluminium chloride, n-butylamine and diethyl ether used at 20°C and 970 A/m. Deposits of 0-010 mm can be obtained on mild steel or copper at 20°C and 970 A/m using aluminium-wire anodes and nitrogen or argon atmospheres. 

To a stirred solution of 2.0 mmol of LDA in 3.3 mL of a 60 40 mixture of THF/hexane at — 78 °C under a nitrogen atmosphere is added 264 mg (2.0 mmol) of tert-butyl propanoatc in 2 mL of THF. After 30 min stirring a solution of 168 mg (1.5 mmol) of ethyl (t)-2-butenoalein 1.5 mL of THE is added and the mixture is stirred for an additional hour at — 78 °C. The reaction is quenched by addition of sat. NH4C1. Extraction with diethyl ether, drying over NiiCl followed by evaporation of the solvent and short path distillation gives the adduct yield 378 mg (1.2 mmol, 84%). 

To a stirred solution of 5 mmol of LDA in 4 mL of THF at — 78 °C is added under an argon atmosphere 0.97 g (5 mmol) of a-ethoxyethoxybenzeneacetonitrile. The mixture is stirred for 0.5 h and subsequently 0.75 g (5 mmol) of hexahydro-2(177)-naphthalenone are added followed by stirring at — 78 °C for 1 h. After this period the mixture is allowed to warm to 0°C and stirred at that temperature for an additional hour. 20 mL of sat. aq NH4C1 are added and the resulting mixture is extracted three times with 30 mL of diethyl ether. The combined ether layers are washed with water until neutral and dried over MgSO . The solvent is evaporated and the remaining solid material is recrystallized from ethanol to afford the adduct yield 1.55 g (90%) mp 168-169 C. 

To a stirred slurry of 35 mg (0.87 mmol) of sodium hydride in 5 mL of THF under a nitrogen atmosphere at OX is added 225 mg (0.80 mmol) of ethyl [4-oxo-1-(2-propenyl)-2-cyclohexenyl]methylpropanedioatein 3 mL of THF. After the evolution of hydrogen ceases the cooling bath is removed and the mixture is stirred for 2.5 h at 25 °C. The mixture is poured into cold 0.1 N aq HCI and then extracted three times with 10 mL of CH2n2. The combined extracts are washed with aq NaHCO, and water. After drying and evaporation of the solvent the crude product is recrystallized yield 197 mg (87%) mp 83-84 C (diethyl ether). 

To a stirred solution of 0.74 g (4 mmol) of (S)-2,5-dihydro-2-isopropyl-3,6-dimethoxypyrazine in 20 mL of THF under a nitrogen atmosphere are added at — 70 °C, 2.6 mL (4 mmol, 1.55 N in hexane) of butyllithium and stirring is continued for 10 min. Then, a solution of 0.97 g (6 mmol) of methyl (/f)-3-phenylpropenoate in 10 mL of THF is added. After 2 3 h a solution of 0.24 g (4 mmol) of acetic acid in 2 mL of THF is added and the mixture is allowed to warm to 25 rC. The solvent is removed in vacuo, the residual product dissolved in 10 mL of diethyl ether, then shaken with 10 mL of water, and the water layer extracted twice with 10 mL of diethyl ether. The combined diethyl ether extracts are dried over MgS04 and the diethyl ether is evaporated. The crude product is purified by bulb-to-bulb distillation to give the adduct yield 1.28 g (92%). 

To a stirred suspension of 2.3 mmol LDA in 20 mL of THF arc added at — 80 X under a nitrogen atmosphere 253 mg (1 mmol) of methyl 2-(2-hydroxy-2,6,6-trimethylbicyclo[3.1.1]hept-3-ylideneamino)propanoate and the mixture is stirred for a further 30 min. After the addition of 114 mg (1 mmol) of ethyl ( )-2-butenoate the mixture is stirred at — 80 °C until the reaction is complete (followed by TLC on silica gel). The mixture is poured into 70 mL of sat. aq NH4C1 and subsequently extracted three times with diethyl ether. The combined ether layers arc dried over Na2S04 and the solvent is evaporated. The crude adduct is purified by chromatography (silica gel. diethyl ether/hexane 66 34) yield 330 mg (90%). 

Reverse-phase evaporation in a nitrogen atmosphere was used to prepare lipids. A lipid film previously formed was redissolved in diethyl ether and an aqueous phase containing the dyebath components added to the phospholipid solution. The resulting two-phase system was sonicated at 70 W and 5 °C for 3 minutes to obtain an emulsion. The solvent was removed at 20 °C by rotary evaporation under vacuum, the material forming a viscous gel and then an aqueous solution. The vesicle suspension was extruded through a polycarbonate membrane to obtain a uniform size distribution (400 nm). 

The simple distillation is accomplished by using a rotary evaporator at atmospheric pressure and bath temperature 50°C. The last traces of solvent are removed under reduced pressure with an ambient temperature bath. Caution the product is volatile and will be lost by evaporation it care is not taken. If water should be present, the compound can be dissolved in diethyl ether, dried again over MgSC>4, filtered and distilled. 

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