Precipitates product isolation

Thionyl chloride (354 mmol) was added dropwise at 30 °C to a suspension of the product from Step 1 (177 mmol) in 500 ml CH2CI2 and the mixture stirred at 40 °C 1 hour. The mixture was treated with NaHCOj and after COj evolution stopped, it was cooled to room temperature, and the precipitated product isolated in 96% yield. 

The product from Step 4 was cooled to 14 °C and treated with lithium t-amylate (504mmol) followed by the addition of 16.7ml (S)-l,2-chloropropanediol over 45 minutes. The temperature was maintained between 28 and 32 °C 2 hours, quenched using 37.5 ml HOAc and 225 ml water, and the pH adjusted to 6 to 9 using NH4OH. Solka floe (53.74 g) was added and the mixture heated to 75 °C. Thereafter, the solids were removed, washed with 805 ml THF, and the filtrate concentrated. The mixture was cooled to -10 °C and the precipitated product isolated by filtration, mp = 194-197 °C. H-NMR and MS data supplied. 

The oxygen is then replaced by nitrogen and a solution of sodium hydroxide (5 g) in methanol (100 ml) and water (50 ml) is added. After agitation for 70 min at ambient temperature, followed by the addition of acetic acid (10 ml), the mixture is poured into water (4 liters). The precipitate is isolated by filtration, washed with water and dried in an air draft at 100° to yield 47 g of crude product. This material is dissolved in methanol (1.5 liters) and ethyl acetate (500 ml) and the solution concentrated to half its initial volume. Ethyl acetate (500 ml) is added and the solution is cooled to yield 29.4 g (63%) of 3, 17a-dihydroxy-16f -methyl-5a-pregnan-20-one mp 255-260° [ajp 45.6° (diox.). 

The charged group introduced into products by the aldol donors (phosphate, carboxylate) facilitates product isolation and purification by salt precipitation and ion exchange techniques. Although many aldehydic substrates of interest for organic synthesis have low water solubility, at present only limited data is available on the stability of aldolases in organic cosolvents, thus in individual cases the optimal conditions must be chosen carefully. 

On several occasions the product isolated by the submitters was contaminated with L-cystine dihydrochloride, which was not easily removed by recrystallization. In this event the product was converted to the zwitterionic form and recrystallized in the following manner. The pH of a solution of the product in water was adjusted to 6 with aqueous 2.5N potassium hydroxide. The neutralized solution was evaporated to dryness under reduced pressure at ca. 40°. The residue was dissolved in a minimum amount of hot water, and two volumes of 95% ethanol were added to precipitate S-acetamidomethyl-L-cysteine monohydrate, dec. 187°, [a] 9 — 42.5° (c = 1, water). 

Polysaccharide formation may be endocellular, exocellular or capsular. The polysaccharide is usually a normal metabolic product, frequently a major product. Isolation and purification of a bacterial polysaccharide generally involve continued precipitations from a buffered solution, together with electrodialysis or ultrafiltration. 

Precipitate the CDI-activated Tween 20 by the addition of ethyl ether, and then isolate the precipitate using centrifugation or filtration. Redissolve the precipitated product in DMSO and repeat the precipitation process two more times to insure removal of excess reactants and reaction by-products. After the final precipitation, dry the isolated precipitate overnight in vacuo to remove remaining solvent. 

C02 as adjustable-solvent In this case, the reaction is carried out in scCOz under truly monophasic conditions and the catalyst is selectively precipitated through a change in temperature and/or pressure. Again, product isolation is achieved by SCF extraction. 

Method A. Chlorination TMBA-IC14 (22.7 g, 54 mmol) is added to the alkylbenzene (54 mmol) and AIBN (0.89 g, 5.4 mmol) in CC14 (300 ml) and the solution is refluxed. Precipitated TMBA-ICl, is removed from the cooled solution and the filtrate is concentrated. n-C6H 4 (30 ml) is added to the concentrate and the chlorinated products isolated by chromatography from silica. 

Products from peroxydisulftiric acid oxidations are usually isolated in high yield and high purity with potential by-products such as azo, azoxy and nitroso compounds usually absent. Product isolation is usually facile the product either precipitates from solution or can be extracted, with any unreacted amine remaining in the acid liquors. Peroxydisulfuric acid is, however, a very strong oxidant and some substrates are rapidly destroyed, which is the case for polynitrophenylenediamines. The reactivity of such substrates can be moderated by prior... 

This thermally reversible precipitation suggested potential applications to the technology of reaction product isolation. It could be used as a tool to allow isolation of a specific product from a totally soluble reaction by raising the temperature. 

Solubilised enzyme preparations are well suited for many ftmdamental studies, for example spectroscopic investigations reqtriring transparent solutiorrs. When the solubilised preparatiorrs are used as catalysts it is an advantage that mass trarrsfer limitations are normally absent, but product isolation and ertzyme recovery are usirally more difficult than with solid enzyme preparations. Methods used to separate the enzyme from the product solution include precipitation of the enzyme, and the use of membranes which retain the enzyme but not the product. 

Poly(4-vinylpyridine) (10 mmol) having an Mn 300,000 Da was dried and then treated with l,l,l,2,2,3,3,4,4,5,5,6,6-tridecafluoro-8-iodooctane (12mmol) and the mixture reacted for 48 hours at 80°C in 50 ml N,N -dimethyIformamide. The solution was precipitated by pouring into ethyl acetate and then washed with petroleum ether. The material was dried under vacuum for 24 hours at 60°C and the product isolated in 90% yield. 

A mixture consisting of the step 1 product and 2,2 -azobisisobutyronitrile was heated to 70°C for 18 hours. The transparent amber ionic liquid polymer salt was purified by dissolving in acetone and precipitating in cold diethyl ether. The precipitate was collected by cold suction filtration and the product isolated as a tacky transparent yellow liquid that had a Tg of 49°C and an intrinsic viscosity value of 0.3. 

A round-bottom flask was charged with 15 ml of a toluene and water, 2 1, respectively, phenyltrimethoxysilane (0.02 mol), p-chloromethylphenyltrimethoxysilane (0.02 mol), and methanesulfonic acid (5 mol%) and then stirred at ambient temperature for 12 hours. The organic layer was isolated, concentrated, and then added dropwise to a large quantity of -hexane. The precipitated solid was filtered, dried, and the product isolated in 93 % yield having an Mn of 1300 Da with a poly dispersity index (PDI) of 1.25. 

A 50-ml Schlenk tube containing a stirrer bar was charged with 3.4 ml of toluene, vinyl acetate (71 mmol), tris(2,2,2-trifluorethyl) phosphite (0.36 mmol), and dibenzoyl peroxide (0.18 mmol) successively at 60°C. The reaction mixture was then stirred in the closed Schlenk tube at 70°C for 2 hours and then treated with bis(ally-loxy)methane (3.56 mmol) and stirred at 70°C for 20 hours. All volatile components were then removed using an oil pump vacuum. The polymer was dissolved in acetone and then precipitated in heptane and 1.78 g product isolated as a white powder. 

A mixture consisting of the step 2 product (40 g), potassium bicarbonate (48.7 g), tetra-butylammonium iodide (8.0 g), 2,6-di-ter -butyl-4-mcthylphcnol (1.74 g), and 500 ml THF was treated with acrylic acid (11.2 g) and then refluxed for 6.5 hours and stirred at ambient temperature for 16 hours. Thereafter it was diluted with diethyl ether, washed with water, dried, filtered, concentrated, and then dissolved in hot isopropyl alcohol. Upon cooling solids precipitated from the solution and the product isolated after filtering, mp = 50°C. 

A reactor was charged with the step 4 product (0.96 g), 2,2 -bipyridyl (0.55 g), and THF (80 g). After deaeration, bis(l,5-cyclooctadiene)nickel(0) (1.05 g) was added and the mixture heated to 60°C for 1.5 hours and then cooled and precipitated in 300 ml of ion exchange water. The precipitate was isolated and then dissolved in chloroform, filtered, and purified by passing through a column filled with alumina. The polymer was reprecipitated in methanol, reisolated, dried, and 0.5 g of product isolated having an Mn of 7.3 x 10s Da. 

Form T2,2, 5/,2"-terthiophene (349 pmol) and 3,3 -di-n-butyl-4,4 -dimethyl-2,2 -dipyrrylmethane (349 pmol) were dissolved in 35 ml CH2C12 at ambient temperature and then treated with 26.9 jjlL of trifluoroacetic acid. At the first sign of baseline material by thin-layer chromatography (TLC) using silica gel and CH2CI2, the reaction was quenched by adding 52.2 p,L of DBU and p-chloranil (873 pmol) and the solution stirred for 4 hours at ambient temperature. The mixture was then treated with 36p,L of triethylamine and stirred for 1 hour. Excess triethylamine (5.190 mmol) was then added and mixture stirred for 15 minutes. The reaction mixture was then precipitated in methanol and 76.9 mg product isolated as a brownish-purple solid. 

A reaction flask was charged with methacrylic acid (6.9 g) dissolved in 200 ml THF containing triethylamine (8.0 g) at ambient temperature and then treated with the drop wise addition of 2-adamanthyl chloromethyl ether dissolved in 100 ml of THF. The solution was stirred for 12 hours and then filtered to remove the precipitated salt. It was then concentrated and the residue dissolved in 200 ml of ethyl acetate. The solution was washed once with water, reconcentrated, and the product isolated as a white solid. 

The step 1 product (20.0 g), y-butyolactone methacrylate (13.6 g), and tricyclodecyl methacrylate (8.8 g) were dissolved in 200 ml of THF and treated with 2,2 -azobisiso-butyronitrile and refluxed for 12 hours. The resin was precipitated by pouring the solution into 2 liters of -heptane. It was then isolated and dried under reduced pressure and the product isolated as a powder having a Mw of 10,800 Da, polydispersity of 2.14, and molar ratio composition of 40 40 20 of adamantoxy methacrylate, y-butyolactone methacrylate, and tricyclodecyl methacrylate, respectively. 

The step 1 product (0.412 g) was dissolved in 10 ml of chlorobenzene and treated with iron(III) chloride (0.46 g) in 10 ml of chlorobenzene and then heated to 65°C for 48 hours. After cooling to ambient temperature 15 ml of chlorobenzene was added and the solution poured into 200 ml methanol where it was ultrasonicated for 2 minutes. After being stirred at ambient temperature for 1 hour, a precipitate was isolated that was added to a mixture of 200 ml of methanol and 50 ml 12 M ammonium hydroxide solution. The mixture was then ultrasonicated for 30 minutes and a dark red solid precipitated. The solid was purified by Soxhlet extraction using methanol for 3 hours, hexane for 24 hours, heptane for 24 hours, and then chlorobenzene for 24 hours. After filtration 0.12 g of product was isolated as a dark red solid having an M = 16,550 Da, Mw = 65,300 Da, with a polydispersity of 3.95. 

The step 7 monomer (0.61 mmol) and bis(trimethylstenyl)bithiophene (0.61) were dissolved in anhydrous DMF with gentle heating and then treated with tetrakis(triphe-nylphosphine) palladium(O) (about 10 mol% based on the total amount of reagents) and the mixture reacted at 85°C for 6 hours. The solution was cooled to ambient temperature, filtered, and the polymer isolated. It was then successively washed twice with hydrochloric acid/chloroform, twice with ammonia solution /CHC13, and twice with water/CHCl3. The polymer was then precipitated in methanol, dried, and 0.38 g of product isolated as a red polymer having an Mn of 25,000 Da. 

Poly(hydroxymaleimide-co-hydroxystyrene) (5.60 mmol) was dissolved in 20 ml of /V-mcthylpyrralidonc and then cooled to 0°C. The solution was then treated with tri-ethylamine (20.16 mmol) and stirred for 60 minutes and then further treated with the step 4 product (0.656 g) and octanoyl chloride (4.03 mmol). The mixture was heated to ambient temperature and stirred for 24 hours and then precipitated by pouring in methanol and water. It was filtered, extracted with methanol, and 5.3 g product isolated. 

To a stirred solution of the step 2 product (4.12 mmol) dissolved in 20 ml THF was added a solution of the lithium salt of (2,2-dimethyl-[l,3]-dioxolan-4-yl)-methanol in 10 ml THF and the mixture refluxed for 18 hours. Upon cooling to ambient temperature, THF was partically removed and a concentrated solution/suspension of the crude product added dropwise to water. The aqueous mixture was then acidified to pH 5-6 and the precipitated polymer isolated. The polymer was redissolved in 50 ml 2 1 and then dried in vacuo at 50°C for several hours. The organic solution was extracted twice with 30 ml saturated sodium chloride solution and once with 30 ml of water. The material was dried using MgSO filtered, concentrated, and redissolved in a minimum amount of acetone and then precipitated into 100 ml hexane. Hexane was decanted, dried in vacuo, and the product isolated as a pale yellow viscous liquid in 60-90% yield. 

A reactor containing 5 ml of 95% nitric acid was cooled to between 0 and 5°C in an ice/water bath and then treated with the step 3 product (200 mg) and the mixture stirred for 15 minutes while maintaining the temperature below 5°C. The solution was then added dropwise to 60 ml of water, cooled, and the nitrated product isolated as a white, oily solid precipitate. Water was decanted, the precipitate washed with water, and in vacuo at 50°C for 2-3 hours, and the product isolated as a pale yellow viscous liquid in 80-90% yield. 

A Schlenk flask was charged with cetyltrimethylammonium bromide (8.3 mg) and bis(tii-/-butyl-phosphinc)palladium(0) (23.4 mg) and then treated with the step 3 product (2.28 mmol) and 1,4-dibromobenzene (2.28 mmol) dissolved in 15 ml toluene. The mixture was then treated with 45 wt% KOH solution in water (0.8528 g) and heated to 90°C for 48 hours. The contents of the vessel were filtered, concentrated, and a reddish oil isolated. The residue was dissolved in chloroform, filtered through Celite, and reconcentrated. The solid was placed into a Soxhlet thimble and extracted for 20 hours with acetone. The polymer was redissolved in chloroform and then precipitated in hexanes and 1.567 g of product isolated. 

V,V-dimethylamino)pyridinc (400 mg). The mixture was cooled in an ice bath for 20 minutes and then treated with dropwise addition of M/V-dicyclohexyl carbodiimide (34 mmol) dissolved in 50 ml CH2C12 over a period of 60 minutes. It was then stirred for 60 minutes in an ice bath and then at ambient temperature overnight. A precipitate that formed was removed by vacuum filtration using a Buchner funnel and the filtration aid Celite and then washed with 100 ml 0.1 M HC1,100 ml 5% NaOH, and with 100 ml water. The organic layer was dried and concentrated to give a slightly cloudy viscous liquid and 11.4 g of product isolated. 2... 

A 25-ml Schlenk tube was charged with the step 2 product mixture (1.76 or 2.00 g) dissolved in 2 or 9 ml of either THF or toluene. All samples were free radically initiated using either 2,2 -azobis(isobutyrylnitrile) (Vazo 64) or l,l -azobis(cyclo-hexanecarbonitrile) (Vazo 88). Each tube was then sealed with a rubber septum and then degassed by three cycles of freeze-thaw pumping and then heated to 60°C for selected times. After cooling to ambient temperature, the mixture was precipitated in 20 ml petroleum ether and then isolated and washed with cold petroleum ether and the product isolated. 

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