Methylene chloride/pyridine solution

We recently have reported our initial studies on step-growth block copolymers containing segments of poly (aryl ethers) and poly (aryl carbonates) (9,10). The multiblock [ A-B ]n block copolymers were prepared by phosgenation in methylene chloride/pyridine solution either by what was termed an in situ or by a coupled oligomer technique (JO). The choice of polycarbonates and poly (aryl ethers) for initial studies was based on the several considerations. Copolymerization is feasible since the end groups in the two oligomers can be identical, as shown in Structures 1 and 2. Considerable information is available in the... 

A 100-mL, two-neck, round-bottom flask, equipped with two addition funnels was charged with pyridine (0.43 mL, 5.3 mmol) and 20 mL of methylene chloride. A solution of triflic anhydride (0.86 mL, 5.11 mmol) dissolved in 10 mL of methylene chloride was placed in one addition funnel. The sugar (2.55 mmol) dissolved in 10 mL of methylene chloride was placed in the other addition funnel. The flask was cooled to - 10°C in an ice-acetone bath, and the triflic anhydride solution added drop wise. A thick white precipitate began to form during die addition. After addition was complete, the suspension was allowed to stir for an additional 10 min. The sugar solution was added drop wise and stirring continued for an additional 1.5 h. The reaction mixture was poured into 50 mL of ice water, die layers were separated, and the aqueous layer was extracted with two 50-mL portions of methylene chloride. The combined extracts were dried over sodium sulfate, and the solvent was removed in vacuo. Hexane extraction, followed by in vacuo solvent removal, gave the Inflate ester [10]. 

A measured quantity of soil, sediment, or solid waste sample extracted with a measured volume of water, aqueous solution pH adjusted to >11 and serially extracted with methylene chloride pyridine partitions into the organic phase, which is then concentrated and analyzed as above. 

Finally, polymerization was completed by addition of 0.78 g (6.59 x 10 3 mol) hexamethylene diol that had been dissolved in pyridine and methylene chloride. This solution was dripped slowly into the reaction vessel over two hours the reaction was then stirred for 24 hours under nitrogen atmosphere. The resulting polymer (BP6L) was washed in 1 N HC1, precipitated in methanol, extracted in a Soxhlet extractor with methanol and vacuum dried. 

A 100-mL, two-nedc, loimd-bottom flask, eqvujqjed with two addition funnels was charged with pyridine (0.43 mL, S.S mmol) and 20 mL of methylene chloride. A solution of tiiflic anhydride (0.86 mL, 5.11 mmol) dissolved in 10 mL of methylene chloride was placed in one addition funnel. The sugar (2 mmol) dissolved in 10 mL of methylene dd de was... 

After a series of mechanical horror stories, attention was turned from transesterification to direct phosgenation. High molecular weight polymer was produced by passing phosgene into a stirred solution of bisphenol-A in a mixed methylene chloride/pyridine solvent. Excess pyridine and by-product pyridine hydrochloride was removed by water/acid washing. The polymer was recovered by addition of an anti-solvent such as alcohol or aliphatic hydrocarbon. This general process provided initial development quantities of polymer. 

Solubility and Solvent Resistance. The majority of polycarbonates are prepared in methylene chloride solution. Chloroform, i7j -l,2-dichloroethylene, yy -tetrachloroethane, and methylene chloride are the preferred solvents for polycarbonates. The polymer is soluble in chlorobenzene or o-dichlorobenzene when warm, but crystallization may occur at lower temperatures. Methylene chloride is most commonly used because of the high solubiUty of the polymer (350 g/L at 25°C), and because this solvent has low flammabiUty and toxicity. Nonhalogenated solvents include tetrahydrofuran, dioxane, pyridine, and cresols. Hydrocarbons (qv) and aUphatic alcohols, esters (see Esters, organic), or ketones (qv) do not dissolve polycarbonates. Acetone (qv) promotes rapid crystallization of the normally amorphous polymer, and causes catastrophic failure of stressed polycarbonate parts. 

Ji-Methoxy-ll, 11-ethylenedioxy-lS-methylestra-1,3,5(lO)-tnene. A solution of (+)3-methoxy-18-methylestra-l,3,5(10)-trien-17-one (5 g) dissolved in ethylene glycol (5 ml) and ethyl orthoformate (10 ml) containing />-toluenesulfonic acid (0.3 g) is heated under reflux for 2 hr in a nitrogen atmosphere. The resulting solution is diluted with methylene chloride and washed with dilute sodium bicarbonate and water. The organic phase is dried over sodium sulfate and evaporated to dryness in the presence of a trace of pyridine. Trituration of the residue with petroleum ether yields 4.7 g (82 %) of the pure ketal. 

A variety of media have been used for the Wallach fluorination reaction anhydrous hydrogen fluoride alone or with cosolvents such as methylene chloride, benzene, or tetrahydrofuran and hydrogen fluoride-pyridine alone or with co solvents such as benzene, glyme, or acetic acid [42,43, 46 50] Solutions of cesium fluoride, tetraethylammonium fluoride, or tetrabutylammonium fluoride in strong acids such as methanesulfonic acid or trifiuoroacetic acid with numerous cosolvents have also been studied [48, 49]... 

A 5% solution of chromium trioxide-pyridine complex in dry methylene chloride is prepared. The alcohol (0.01 mole) is dissolved in dry methylene chloride and is added in one portion to the magnetically stirred oxidizing solution (310 ml, a 6 1 mole ratio) at room temperature. The oxidation is complete in 5-15 minutes as indicated by the precipitation of the brownish black chromium reduction products. The mixture is filtered and the solvent is removed (rotary evaporator) leaving the crude product, which may be purified by distillation or recrystallization. Examples are given in Table 1.1. 

Thienylacetarnidocephalosporanic acid (7.0 g) was suspended in water (60 ml) and stirred with pyridine (7 ml) until the acid dissolved. The resulting solution (pH 5.9) was kept at 35°C for 3 days, then filtered and extracted with methylene chloride (4 x 60 ml). The methylene chloride extract was back-axtracted with a little water and the total aqueous solutions were then percolated through a column of Dowex 1x8 resin, (100 to 200 mesh, 150 g) in the acetate form at pH 4.3. The column was washed with water until the optical rotation of the eluate fell to zero and the eluate (500 ml) was freeze-dried. The residual white solid was dissolved in the minimum volume of methanol and after a few minutes the pyridine derivative crystallized this is the cephaloridine product. 

Esterification A solution of 500 mg of 6a,9a-difluoroprednisoione 17-butyrate in 2.5 cc of pyridine is treated with 1.25 cc of acetic anhydride and the reaction mixture permitted to stand overnight at 0°C. The reaction mixture is then poured into ice water and the crystaiiine precipitate formed is filtered off and recrystailized from a methylene chloride-ether-petroleum ether mixture to yield 494 mg of 6a,9a-difluoroprednisolone 17-butyrate, 21-acetate MP 191°-194°C. 

To a stirred suspension of p-(p-methoxvbenzyloxy)-phenylmalonic acid (125 mg) in methylene chloride (3 ml) are added triethylamine (55 All) and oxalyl chloride (26 AH) at -15°C, and the suspension is stirred for 40 minutes at 0°C. The mixture Is added to a solution of diphenylmethyl 7 -amino-7a-methoxy-3-(1 -methyltetrazol-5-yl)thiomethyl-1 -oxadethia-3-cephem-4methylene chloride (3 ml) and pyridine (63 AH), and the mixture is stirred for 30 minutes at 0°C. The reaction mixture is diluted with ethyl acetate, washed with aqueous 2 N-hydrochloric acid and water, dried over sodium sulfate, and concentrated to give crude product (212 mg), which Is chromatographed on silica gel (20 g) and... 

Step B A solution of the 3-tert-butylamino-2-oxopropanol in a mixture of pyridine hydrochloride and pyridine is treated with p-toluenesulfonylchloride. The mixture is stirred for /i hour at 25° to 30°C and then poured into cold water. The solution is treated with potassium carbonate and the pyridine evaporated in vacuo at a temperature between 55° and 60°C. The aqueous residue is treated with potassium carbonate and the mixture extracted with methylene chloride. Evaporation of the dried extract provides 1-toluene-sulfonyloxy-2-oxo-3-tert-butylaminopropane. 

Preparation of the acetate derivative Concentrate the aqueous mixture of saccharides to approximately 0.5 ml in a 20-50 ml container. Reduce the saccharides by adding 20 mg of sodium borohydride that has been dissolved carefully into 0.5 ml of water and let the reducing mixture stand at room temperature for at least 1 hour. Destroy the excess sodium borohydride by adding acetic acid until the gas evolution stops. Evaporate the solution to dryness with clean nitrogen. Add 10 ml of methanol and evaporate the solution to dryness. Acetylate with 0.5 ml (three parts acetic anhydride and two parts pyridine) overnight. Evaporate to a syrupy residue and add 1 ml of water. Evaporate again to dryness to remove the excess acetic anhydride. Dissolve the residue in 250 /d methylene chloride. 

Where B = pyridine, piperidine or 1-methylimidazole, in methylene chloride solution, but under normal conditions rapid irreversible autoxidation takes place 232) leading to the formation of the well characterised 247, 248) fi-oxo product, (TPP)Fe(IlI)—0—Fe(III) (TPP) and since the rate of oxidation decreases 249, 250) with increasing excess of axial base, B, it follows 232, 251) that a five co-ordinate species, Fe(II) (Base)TPP, is probably involved as an intermediate which can then undergo a bimolecular termination reaction with Fe(II) (Base)02TPP, followed by autoxidation. Firstly 251),... 

B. l-Eihyl-3-(3-dinuthylamino)propylcarbodiimide hydrochloride. A suspension of 34.6 g. (0.300 mole) of pyridine hydrochloride (Note 7) in 280 ml. of methylene chloride is prepared in a 1-1. Erlenmeyer flask. To this is slowly added 46.5 g. (0.300 mole) of l-ethyl-3-(3-dimethylamino)propylcarbodiimide. The resulting solution is diluted with anhydrous ether (Note 8) and stored at 0-5° for 16-20 hours. The crystalline product is collected by filtration in a dry atmosphere (Note 9), washed with a little anhydrous ether, and dried under reduced pressure over phosphorus pentoxide. The yield is 50.5-55.5 g. (88-96.5%), m.p. 104-109° (Notes 10 and 11). This material is sufficiently pure for most purposes. 

The amino indanol was placed in a 250 mL three-necked round-bottomed flask equipped with a magnetic stirrer bar under nitrogen. Dry methylene chloride (110mL) and triethylamine (6.7 mL) were then added. The reaction mixture was allowed to cool to 0°C before adding a solution of 2-chloro-sulfonyl pyridine (7.1 g in 50mL CH2C12) over 20 minutes. The mixture was stirred at this temperature for 1 hour. 

A freshly-prepared solution of phosgene (8 mmole) in 10 ml of methylene chloride was added dropwise to a stirred solution of 5 mmole of type II bisphenol in 2 ml of dry pyridine and 30 ml of methylene chloride. After the mixture was stirred for seven hours, the resulting solution was extracted with 50 ml of 10%... 

A solution of 6.5 g of isosafrole (or analog), 3.3 g of pyridine in 41 g of dry acetone is cooled to CP, Add 6.9 g of cold tetranitromethane over one min with good stirring. Stir for 2 more min and quench as above with 2.2 g of KOH in 40 ml of water, add a little more water and extract the nitropropene with dichloromethane. Evaporate after drying and recrystallize from methanol. This extracting with dichloromethane should be used in the above formula to get an additional amount of product from the filtrate. Follow the instructions immediately above. Dichloromethane is the same as methylene chloride. 

B. General Oxidation Procedure for Alcohols. A sufficient quantity of a 5% solution of dipyridine chromium (VI) oxide (Note 1) in anhydrous dichloromethane (Note 7) is prepared to provide a sixfold molar ratio of complex to alcohol. This excess is usually required for complete oxidation to the aldehyde. The freshly prepared, pure complex dissolves completely in dichloromethane at 25° at 5% concentration to give a deep red solution, but solutions usually contain small amounts of brown, insoluble material when prepared from crude complex (Note 8). The alcohol, either pure or as a solution in anhydrous methylene chloride, is added to the red solution in one portion with stirring at room temperature or lower. The oxidation of unhindered primary (and secondary) alcohols proceeds to completion within 5 minutes to 15 minutes at 25° with deposition of brownish-black, polymeric, reduced chromium-pyridine products (Note 9). When deposition of reduced chromium compounds is complete (monitoring the reaction by gas chromatography or thin-layer chromatography analysis is helpful), the supernatant liquid is decanted from the (usually tarry) precipitate and the precipitate is rinsed thoroughly with dichloromethane (Note 10). 

I. 4-methoxyacetophenone (30 //moles) was added as an internal standard. The reaction was stopped after 2 hours by partitioning the mixture between methylene chloride and saturated sodium bicarbonate solution. The aqueous layer was twice extracted with methylene chloride and the extracts combined. The products were analyzed by GC after acetylation with excess 1 1 acetic anhydride/pyridine for 24 hours at room temperature. The oxidations of anisyl alcohol, in the presence of veratryl alcohol or 1,4-dimethoxybenzene, were performed as indicated in Table III and IV in 6 ml of phosphate buffer (pH 3.0). Other conditions were the same as for the oxidation of veratryl alcohol described above. TDCSPPFeCl remaining after the reaction was estimated from its Soret band absorption before and after the reaction. For the decolorization of Poly B-411 (IV) by TDCSPPFeCl and mCPBA, 25 //moles of mCPBA were added to 25 ml 0.05% Poly B-411 containing 0.01 //moles TDCSPPFeCl, 25 //moles of manganese sulfate and 1.5 mmoles of lactic acid buffered at pH 4.5. The decolorization of Poly B-411 was followed by the decrease in absorption at 596 nm. For the electrochemical decolorization of Poly B-411 in the presence of veratryl alcohol, a two-compartment cell was used. A glassy carbon plate was used as the anode, a platinum plate as the auxiliary electrode, and a silver wire as the reference electrode. The potential was controlled at 0.900 V. Poly B-411 (50 ml, 0.005%) in pH 3 buffer was added to the anode compartment and pH 3 buffer was added to the cathode compartment to the same level. The decolorization of Poly B-411 was followed by the change in absorbance at 596 nm and the simultaneous oxidation of veratryl alcohol was followed at 310 nm. The same electrochemical apparatus was used for the decolorization of Poly B-411 adsorbed onto filter paper. Tetrabutylammonium perchlorate (TBAP) was used as supporting electrolyte when methylene chloride was the solvent. 

To a flask containing 11.6 gm (0.10 mole) of traws-cyclohexane-1,2-dioI and 18.6 gm (0.24 mole) of pyridine in 200 ml of methylene chloride is added drop-wise, over a 2 hr period at 0°C, 23 gm (0.19 mole) of thionyl chloride dissolved in 50 ml of methylene chloride. The pyridine hydrochloride is filtered and the methylene chloride solution is successively washed with 0.01 N hydrochloric... 

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