Removal of dichloromethane

Removal of dichloromethane (CH2CI2) in the final step was performed by the checkers using a rotary evaporator. The pressure was monitored during evaporation and was not allowed to drop below 100 mm. In this fashion the same yield of material was obtained as reported. 

Volatile alkyl halogenides such as methyl iodide, methylene chloride etc., react quantitatively with the solid methylamine salt of 5-benzylidene- (39a) [32] and 5,5-diphenylthiohydantoin (37) to form the anticonvulsive solids 225 and 226 in quantitative yield [28] (Scheme 30). Unlike the solution reaction, only the S-alkylation occurs under gas-solid conditions. Furthermore, various dialkylamidodithiolate salts 228 react readily with dichloromethane at 80 °C. The salts with the quaternary cations react at room temperature and it is also possible to catalyze the reaction of the sodium salt by admixture of 10% of the corresponding phase transfer bromides [28]. These reactions have been tuned for removal of dichloromethane from loaded air streams [28]. 

Bis(pyrazol-l-yl)methanone (0.98 g, 6.3 mmol) and A-methylimidazole-2-alde-hyde (0.60 mL, 6.3 mmol) are added to a 50-mL Schlenk tube under nitrogen in an open system. A vigorous reaction commences immediately to produce a red-brown tar and carbon dioxide. The material thus obtained is dissolved in dichloromethane and chromatographed on a column (—2 x 15 cm Merck 60, 230/240-mesh silicagel 1 atm or medium pressure of nitrogen applied) with dichloromethane used as the eluent. A colorless solution of the product is obtained, as other product(s) are either not eluted or have low values. Addition of hexane (20 mL) to the dichloromethane eluent, followed by slow removal of dichloromethane under a vacuum at room temperature gives (pz)2(mhn)CH as white crystals (1.7 g, 49%). ... 

Galli, R. Leisinger, T. (1985). Specialized bacterial strains for the removal of dichloromethane from industrial waste. Conservation Recycling, 8, 91-100. 

The combined dichloromethane solutions may be washed with dilute hydrochloric acid, sodium bicarbonate solution, and water to remove excess traces of pyridine and chromium salts, or they may be filtered directly through a filter aid or passed through a chromatographic column. The product is obtained by removal of dichloromethane. any pyridine that remains can often bo removed under reduced pressure. 

Benzeneazophenyl Tellurium Tris[dithiocarbamates]2 To a stirred solution of 1.25 g (3.0 mmol) of 2-benzeneazophenyl tellurium trichloride in 200 ml dichloromethane under an atmosphere of nitrogen is added a solution of 10 mmol the sodium dialkyldithiocarbamate in 100 ml of dry methanol. The mixture is stirred for 0.5 h at 20°. The solvents are removed on a rotary film evaporator. The residue is treated with 200 ml dichloromethane. Insoluble sodium chloride is removed by filtration. Removal of dichloromethane from the filtrate and recrystallization of the residue from methanol produces purple crystals. 

The molar gas/solid imbibition ratios (from TGA experiments) and desorption temperatures were for 1 0.44 and 147 °C, for 2 0.93 and 117°C, for 3 1.43 and 125 °C and for 4 2.0 and 70 °C. Below the reported ratios the CH2CI2 gas was completely taken up within detection limits. Exhaust gases required column flow systems for removal of dichloromethane as the inclusion compound. 

After slow removal of dichloromethane from the inclusion co pounds of gossypol, a polymorph was formed with an ink-bottle-like empty space of an average diameter of 5... 

To a mixture of 100 ml of dry dichloromethane, 0.10 mol of propargyl alcohol and 0.11 mol of triethylamine was added a solution of 0.05 mol of Ph2PCl in 75 ml of dichloromethane in 3 min between -80 and -90°C. The cooling bath was removed, and when the temperature had reached 10°C, the reaction mixture was poured into a solution of 2.5 ml of 362 HCl in 100 ml of water. After vigorous shaking the lower layer was separated and the aqueous layer was extracted twice with 25-ml portions of dichloromethane. The combined solutions were washed twice with water, dried over magnesium sulfate and then concentrated in a water-pump vacuum, giving almost pure allenyl phosphine oxide as a white solid, m.p. 98-100 5, in almost 1002 yield. 

A mixture of 0.10 mol of the acetylenic alcohol, 0.12 mol of triethylamine and 200 ml of dichloromethane (note 1) was cooled to -50°C. Methanesulfinyl chloride (0.12 mol) (for its preparation from CH3SSCH3, (08300)30 and chlorine, see Ref. 73) was added in 10 min at -40 to -50°0. A white precipitate was formed immediately. After the addition the cooling bath was removed and the temperature was allowed to rise to -20°0, then the mixture was vigorously shaken or stirred with 100 ml of water. The lower layer was separated off and the aqueous layer was extracted twice with 10-ml portions of CH2CI2. The combined solutions were dried over magnesium sulfate and concentrated in a water-pump vacuum (note 2). The yields of the products, which are pure enough (usually 96%) for further conversions, are normally almost quantitative. 

A. 2-f2-Bmmoetkyl)-l,3-diozane (1), A 2-L, three-necked flask Is equipped with a mechanical stirrer, thermometer, and gas Inlet tube. In the flask are placed 750 ml of dichloromethane, 112 g (2.00 moll of acrolein (Note 1), and 0.10 g of didnnamalacetone Indicator (Note 2) under nitrogen. The yellow solution is cooled to 0-5°C with an Ice bath. Gaseous hydrogen bromide (Note 3) is bubbled Into the solution with stirring until the Indicator becomes deep red (Note 4). The Ice bath is removed and 1.0 g of p-toluene-sulfonic acid monohydrate and 152.2 g (2.00 mol, 144 mL) of 1,3-propanediol (Note 11 are added. The yellow solution is stirred at room temperature for 8... 

A-Fluoro-2,4,6-tnmethylpyndmium inflate (1 mmol) is added m several portions at room temperature to a tetrahydrofuran solution of sodium diethyl phenyl-malonate, obtained from 1 mmol of diethyl phenyl malonate and sodium hydnde at 0 C in tetrahydrofuran The reaction imxture is poured mto dilute hydrochlonc acid and extracted with ether The ether extract is washed with sodium bicarbonate and water and dned over magnesium sulfate The oily residue obtamed after removal of tihe ether is chromatographed on sihca gel (dichloromethane-hexane, 1 1) to give diethyl fluorophenylmalonate in 83% yield... 

A solution of 3 g of 2-amino-2 -(2-chlorobenzoyl)acetanilide in 50 ml of pyridine was refluxed for 24 hours after which time the pyridine was removed in vacuo. The residue was recrystallized from methanol and a mixture of dichloromethane and ether giving crystals of 5-(2-chlorophenyl)-3H-1,4-benzodiazepin-2( 1 H)-one melting at 212° to 213°C. 

The liberated crystalline substance is extracted twice with 50 ml of dichloromethane each time. After being separated, the dichloromethane layers are combined and washed once with 30 ml of water and dried over sodium sulfate. The solvent of the layer is removed by evaporation under reduced pressure to leave a crystalline residue (72.56 mg, 53% crude yield). 

The cooling bath is then replaced by a steam bath, and the reaction mixture is refluxed for 16 hours. It is then cooled, transferred to a one-necked, 1-1., round-bottomed flask, and concentrated to dryness on a rotary evaporator. The dark residue is dissolved in a mixture of 200 ml. of water, 200 ml. of dichloromethane, and 20 ml. of triethylamine, and the aqueous phase is separated and washed with two 200-ml. portions of dichloromethane. The organic phases are combined and washed with 300 ml. of saturated aqueous sodium chloride, dried over anhydrous magnesium sulfate, and filtered. Removal of the solvent on a rotary evaporator gives a red oil, which solidifies on storage at 0-5° (Note 5). Recrystallization of this solid from 40 ml. of absolute ethanol gives 7.6-8.4 g. (34-37%) of ethyl 4-amino-3-(methylthiomethyl)-benzoate, m.p. 83-85°. A second crop of l.l-2.5g. of crystalline material, m.p. 78-83°, may be obtained by concentration of the mother liquors (Note 6). 

B. Ethyl l-Amino-S-methylbenzoate. A 1-1., three-nocked, round-bottomed flask equipped with a mechanical stirrer, a condenser, and a nitrogen-inlet tube is charged with 11.25 g. (0.050 mole) of ethyl 4-amino-3-(methylthiomethyl)benzoate, 300 ml. of absolute ethanol, and 17 teaspoons (ca. 50 g.) of W-2 Raney nickel (Note 7). The reaction mixture is stirred at 25° for one hour, then stirring is discontinued, and the ethanolic solution is decanted from the catalyst (Note 8). The catalyst is then washed with one 300-ml. portion of absolute ethanol and one 500-ml. portion of dichloromethane, the solvent being removed... 

This material is dissolved in 500 ml. of ethanol, and the solution is transferred to a 2-1., round-bottomed flask. A solution of 200 g. of sodium hydroxide in 200 ml. of water is added, and the mixture is refluxed for 2 hours. Ethanol is then removed by distillation, and the residue is shaken with 500 ml. of water and 800 ml. of toluene. The toluene layer is separated, washed with two 200-ml. portions of water, and then vigorously shaken with 600 ml. of 2N aqueous hydrochloric acid. A portion of the 1-benzylisoquinoline hydrochloride precipitates at this point and is collected on a Buchner funnel and washed with 200 ml. portions of water and toluene. The filtrate is then transferred to a separatory funnel, the acidic layer is separated, and the crystals from the Buchner funnel are suspended in this layer. After basifying the suspension with 50% aqueous sodium hydroxide, the oil that separates is extracted with three 200-ml. portions of dichloromethane. The combined dichloromethane layers are dried over anhydrous potassium carbonate, filtered, and evaporated under reduced pressure to leave the crude product as a yellow oil. Distillation under reduced pressure then provides 49.8 g. (91%) of pure 1-benzylisoquinoline as a pale yellow oil, b.p. 145-150° (0.01 mm.). The product solidifies on standing and may be crystallized from chloroform-hexane to give colorless prisms, m.p. 54-55° (Note 12). 

---