Diethyl ether, purification

Halogenated acyl derivatives of steroids have been applied in order to increase sensitivity of the analysis. It follows from a comparison of the ECD responses of haloacetates of steroids that the highest sensitivity can be obtained with the aid of monochloro-acetates [351]. Brownie et al. [352] applied them in the analysis of testosterone in blood. The method involves the extraction of blood plasma with diethyl ether, purification by TLC and derivatization. GC analysis is performed only after a preliminary separation on a thin layer. Preparation of the derivatives is carried out by treating a dried extract with... 

A sample of 2-ethylnaphthalene was reacted with HFA in the presence of catalytic amounts of AICI3 at 60 °C for 48 h. Volatiles were removed and the products extracted with diethyl ether. Purification of the crude reaction mixture by column chromatography (Si02) with a gradient of acetone (0-30%) in... 

In both cases, analytically pure material can be obtained by recrystallization of the crude product from ethanol-diethyl ether. Purification 1 recrystaUization from toluene. 2 recrystallization from ethanol-diethyl ether. 

A solution of 0.60 mol of ethyllithium (note 1) in about 400 ml of diethyl ether (see Chapter II, Exp. 1) was added in 30 min to a mixture of 0.25 mol of 1,4-diethoxy-2-butyne (see Chapter VIII-6, Exp. 8) and 100 ml of dry diethyl ether. The temperature of the reaction mixture was kept between -40 and -45°C. Fifteen minutes after the addition had been completed, 0.5 mol of methyl iodide was added at -40 C, then 100 ml of dry HMPT (for the purification see ref. 1) were added dropwise in 15 min while keeping the temperature at about -40°C. Thirty minutes after this addition the cooling bath was removed, the temperature was allowed to rise and stirring was continued for 3 h. The mixture was... 

One can readily appreciate the usefulness of pK value in purification procedures, e.g. as when purifying acetic acid. If acetic acid is placed in aqueous solution and the pH adjusted to 7.76 [AcOH]/[AcO ] with a ratio of 0.1/99.9], and extracted with say diethyl ether, neutral impurities will be extracted into diethyl ether leaving almost all the acetic acid in the form of AcO in the aqueous solution. If then the pH of the solution is adjusted to 1.67 where the acid is almost all in the form AcOH, almost all of it will be extracted into diethyl ether. 

For materials with very low melting points it is sometimes convenient to use dilute solutions in acetone, methanol, pentane, diethyl ether or CHCI3-CCI4. The solutions are cooled to -78° in a dry-ice/acetone bath, to give a slurry which is filtered off through a precooled Buchner funnel. Experimental details, as applied to the purification of nitromethane, are given by Parrett and Sun [J Chem Educ 54 448 7977]. 

Cellulose for chromatography is purified by sequential washing with chloroform, ethanol, water, ethanol, chloroform and acetone. More extensive purification uses aqueous ammonia, water, hydrochloric acid, water, acetone and diethyl ether, followed by drying in a vacuum. Trace metals can be removed from filter paper by washing for several hours with O.IM oxalic or citric acid, followed by repeated washing with distilled water. 

Common impurities found in aldehydes are the corresponding alcohols, aldols and water from selfcondensation, and the corresponding acids formed by autoxidation. Acids can be removed by shaking with aqueous 10% sodium bicarbonate solution. The organic liquid is then washed with water. It is dried with anhydrous sodium sulfate or magnesium sulfate and then fractionally distilled. Water soluble aldehydes must be dissolved in a suitable solvent such as diethyl ether before being washed in this way. Further purification can be effected via the bisulfite derivative (see pp. 57 and 59) or the Schiff base formed with aniline or benzidine. Solid aldehydes can be dissolved in diethyl ether and purified as above. Alternatively, they can be steam distilled, then sublimed and crystallised from toluene or petroleum ether. 

The purification of diethyl ether (see Chapter 4) is typical of liquid ethers. The most common contaminants are the alcohols or hydroxy compounds from which the ethers are prepared, their oxidation products (e.g. aldehydes), peroxides and water. Peroxides, aldehydes and alcohols can be removed by shaking with alkaline potassium permanganate solution for several hours, followed by washing with water, concentrated sulfuric acid [CARE], then water. After drying with calcium chloride, the ether is distilled. It is then dried with sodium or with lithium aluminium hydride, redistilled and given a final fractional distillation. The drying process should be repeated if necessary. 

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). 

Dimethylphenol [95-65-8] M 122.2, m 65°, b 225°/757mm, pK 10.36. Heated with an equal weight of cone H2SO4 at 103-105° for 2-3h, then diluted with four volumes of water, refluxed for Ih, and either steam distd or extracted repeatedly with diethyl ether after cooling to room temperature. The steam distillate was also extracted and evaporated to dryness. (The purification process depends on the much slower sulfonation of 3,5-dimethylphenol than most of its likely contaminants.). It can also be crystd from water, hexane or pet ether, and vacuum sublimed. [Kester Ind Eng Chem (Anal Ed) 24 770 1932 Bernasconi and Paschalis J Am Chem Soc 108 29691986.]... 

The present method offers several advantages over earlier methods. The use of carbon tetrachloride instead of diethyl ether as solvent avoids the intrusion of certain radical-chain reactions with solvent which are observed with bromine and to a lesser degree with chlorine. In addition, the potassium bromide has a reduced solubility in carbon tetrachloride compared to diethyl ether, thus providing additional driving force for the reaction and ease of purification of product. The selection of bro-... 

A mixture of 2.0 mmol of a 1.6 N solution of butyllithium in hexane and 0.47 g (2.0 mmol) of(-)-spartcinc in 10 mL of diethyl ether is stirred for 15 min at — 78 rC then 0.26 g (2.0 mmol) of 1-methyl-l//-indene in 2 mL of diethyl ether are added. Stirring is continued for 30 inin at 20 °C, the mixture is cooled to — 70 CC and 2.5 mmol of the acid chloride in 2 mL of diethyl ether are added. After stirring for 4h the usual aqueous workup was accomplished by addition of 10 mL of diethyl ether and successive washing with 10 mL of 2 N aq HC1. water and sat. aq NtiCl, respectively, followed by chromatographic purification on silica gel with diethyl cthcr/pentane. 

Pure di-2-propenylzinc2,8,9 10, bis(2-methyl-2-propenyl)zinc11 or di-2-butenylzinc11 are best prepared by the metal exchange between dimethylzinc and the appropriate triallylborane, which is produced in situ from the Grignard reagent and boron trifluoride-diethyl ether complex. The purification is accomplished by distillation, for experimental procedure, see ref 2, p619. 

A solution of 1 equivalent of the oxazolidinone in diethyl ether is cooled to —78 C. To the resultant suspension are added 1.4 equivalents of triethylamine. followed by 1.1 equivalents of dibutylboryl triflate. The cooling bath is removed and the reaction mixture is stirred at 25 °C for 1.5 h. The resultant two-phase mixture is cooled to — 78 "C with vigorous stirring. After 1 equivalent of aldehyde is added, the reaction is stirred at —78 °C Tor 0.5 h, and 0 "C for 1 to 2 h. The solution is diluted with diethyl ether, washed with 1 N aq sodium bisulfate, and concentrated. Following oxidation with 30% aq hydrogen peroxide (10 equivalents, 1 1 methanol/water, 0 C. 1 h), extractive workup and chromatographic purification, the aldol adduct is obtained with >99% diastcrcomeric purity. 

A -( 1-Chloro- or bromoalkyl)amides are generally moisture-sensitive, unstable compounds, which are often directly used without further purification. Standard Lewis acids such as boron trifluoride-diethyl ether, aluminum(lll) chloride, zinc(II) chloride, tin(IV) chloride and titani-um(IV) chloride are used to generate the /V-acyliminium ion, although sometimes a catalyst is not necessary. 

The dinitrophenylhydrazones were separated from the reaction mixture by thin-layer chromatography (silica gel G developed with benzene) and further purified by thin-layer chromatography on aluminum oxide G (petroleum ether-diethyl ether (96 to 4), silica gel G (chloroform), and silica gel G (diethyl ether)). In all cases, the specific activities of the dinitrophenylhydrazones remained constant over the course of the last two purifications. 

The submitters purified the product by the following procedure. The residual pale yellow solid is dissolved in 50 ml of diethyl ether and the remaining solid is filtered off (Note 16). The filtrate is concentrated to a volume of ca. 25 mL, and the solution is allowed to crystallize at 0°C. Once crystallization begins, 50 mL of petroleum ether is added in two portions over 10 hr, and then crystallization is allowed to proceed overnight at 0°C. The white solid is collected by filtration and washed with a mixture of 3 1 petroleum ether-diethyl ether to afford 3.8 g of 4. Chromatographic purification of the mother liquor (5.5 x 18 cm of DSH silica gel 40-63 mm, elution with 1 L of petroleum ether/ethyl acetate 4 1 followed by 1.5 L of 3 1 petroleum ether-ethyl acetate) gives 2.5 g of 4 as a pale yellow solid. All the material is combined and recrystallized from diethyl ether/petrol as above to yield 5.2 g (47%) of 4 in two crops. 

Sulfuric acid 96% (technical quality) and diethyl ether (technical quality) were purchased from Bie Bemtsen A/S, Sandbaekvej 7, DK-2610 Roedovre, Denmark and used without further purification. Isoquinoline (97%) and potassium nitrate (99%) were purchased from Aldrich Chemical Company, Inc. and used without further purification. 

The alkanephosphonic acid dichlorides obtained by these methods are converted with amines, with all reactions carried out in solvents such as acetone, benzene, or diethyl ether at 10°C with triethylamine as HC1 captor. The conversion runs quantitatively followed by a purification with the help of column chromatography with chloroform/methanol in a ratio of 9 1 as mobile phase. The alkanephosphonic acid bisdiethanolamides could be obtained as pure substances with alkane residues of C8, C10, C12, and Ci4. The N-(2-hydroxyethane) alkanephosphonic acid 0,0-diethanolamide esters were also prepared in high purity. The obtained surfactants are generally stable up to 100°C. Only the alkanephosphonic acid bismonomethylamides are decomposed beneath this temperature forming cyclic compounds. 

PLC separations (Figure 16.13) started with toluene-ethyl acetate (95 + 5 v/v) as the mobile phase, whereas the final purification was achieved with cyclohexane-diethyl ether (80 -i- 20 v/v). The isolated and extracted compound matched the GC-MS of 24-norursa-3,12-dien-ll-one (compound 11) and is confirmed as an oxidized pyrolyzed boswelhc add. 

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