Diisopropyl ether, purification

After flashing the propylene, the aqueous solution from the separator is sent to the purification section where the catalyst is separated by a2eotropic distillation 88 wt % isopropyl alcohol is obtained overhead. The bottoms containing aqueous catalyst solution are recycled to the reactor, and the light ends are stripped of low boiling impurities, eg, diisopropyl ether and acetone. A2eotropic distillation yields dry isopropyl alcohol, and the final distillation column yields a product of more than 99.99% purity. 

The crude product is purified by decolorization with charcoal and recrystallization from 100-150 ml. of diisopropyl ether to give about 19-21 g. (27-30%) of colorless needles, m.p. 70-72°. This material is sufficiently pure for most purposes. Further purification may be achieved by further recrystaUization from diisopropyl ether and/or sublimation at 60° (0.1 mm.) onto a cold-finger condenser to give material melting at 73-74° (Note 9). 

There is a long history of laboratory and plant fires and explosions involving the very high flammability and/or tendency to peroxide formation in these widely used solvents, diisopropyl ether being the most notorious. Methods of controlling peroxide hazards in the use of ethers have been reviewed [1], and information on storage, handling, purification [2,3] and disposal [4] have been detailed. 

The use of these asymmetric hydrogenation catalysts gives the C-2 chiral center in about 80% optical purity. The same value would apply also to the chiral methyl. For further purification, a crystallization process was used. The optically impure lactic acid (an oil) was dissolved in an approximately equal volume of boiling diethylether diisopropyl ether, 1 1 on standing at 5°C large, colorless, crystals of optically pure chiral methyl chiral lactic acid, 162, were deposited. The recovery of the purified material was 60%. Because of the inherent relationship between the two chiral centers, optical purity at C-2 guarantees optical purity at C-3. 

Purification of MTBE (b.p. 55°C) for general solvent use is by distillation. Its use in general solvent applications is still small. However, since MTBE has no secondary or tertiary hydrogens it is very resistant to oxidation and peroxide formation. This makes it an attractive replacement for the more traditional diethyl, and diisopropyl ethers. 

A new process that converts propylene and water to diisopropyl ether (DIPE) was developed by Mobil Research Development Corp. DIPE is a high-octane gasoline blending agent which, unlike other ethers, utilizes propylene in its synthesis. The DIPE reaction takes place in a fixed-bed catalytic reactor via a series of reaction steps. Isopropyl alcohol (IPA) is an intermediate which is recycled within the process. A propane/propylene splitter is included in the feed purification section to increase the concentration of propylene in the feed and maximize the DIPE production. DIPE utilizes propylene from the refinery and does not depend on an outside supply of alcohol. DIPE has similar octane blending values of RON and MON as other ethers like MTBE and TAME. DIPE also has a lower Reid vapor pressure than that of MTBE. DIPE is virtually nontoxic and has not caused adverse systemic effects or tissue toxicity [66]. 

Isolation and purification In the case of sohd nitriles, the solid precipitate is collected by filtration, washed with water, air-dried, and recrystallized from diisopropyl ether to afford an analytically pure product. 

Phosphoric acid and phosphate salts are produced either by oxidation of elemental phosphorous or by extraction of the phosphate mineral Ca3(P04)2 (apatite) with sulfuric acid. Production from elemental phosphorous is energetically more demanding and therefore capacities are increasingly shifting towards the extraction process. However, the production of food grade phosphoric acid from the natural mineral apatite requires additional separation and purification steps to remove heavy metals (such as e.g., Cu or As) from the crude phosphoric acid. Precipitation techniques and countercurrent extraction with organic solvents, such as n-butanol or diisopropyl ether, are applied for this purpose. 

A solution of dibromodifluoromethane (5.05 g. 24 mmol) in anhyd hexane (10 mL) was added dropwise over 30 min to a solution of sodium diisopropyl phosphite (1 9.03 g, 48 mmol) in anhyd hexane under N2 at — 78 C. The solution was stirred at this temperature for 3 h then filtered through a bed of Celite 545. Evaporation of the solvent under vacuum left a colorless oil, which was distilled to yield a fraction distilling above 75 C at 0.8 mbar. Purification of this fraction by flash chromatography (silica gel. acetone/ petroleum ether 1 15) yielded the bisphosphonate 2 yield 3.6 g (40%). 

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