Di- chloromethane

Bis(3,4-diethyl-2-pyrrolylmethyl)-3,4-dietliyl-l//-pyrrole (2), prepared in situ from the di-t-butylester of the 5,5 -dicarboxylic acid (/), reacts with 4//-1,2,4-triazole-3,5-dialdehyde (3) in di-chloromethane in the presence of trifluoroacetic acid and 2,3-dichloro-5,6-dicyano-/)-benzoquino-ne as an oxidation reagent. Dark blue crystals are obtained after chromatographic purification. The dark violet chloroform solution fluoresces purple at 360 nm and gives the NMR experiments 39. Which compound and which tautomer of it has been formed ... 

Meanwhile a stirred suspension of phosphorus pentachloride (14.99 g, 0.072 mol) in dry di-chloromethane (150 ml) was cooled to 0°C, and N,N-dimethylacetamide (27.5 ml) was added. The resulting solution was recooled to -10°C and 2-fur-2-yl)-2-methoxyiminoaceticacid (syn-isomer) (12.17 g, 0.072 mol) was added. The mixture was stirred at -10°C for 15 minutes and crushed ice (35 g) was added. The mixture was stirred at 0°C for 10 minutes, whereafter the lower dichloromethane phase was added over 10 minutes to the cephalosporin solution prepared above, cooled to -10°C so that the reaction temperature rose steadily to 0°C. The mixture was stirred at 0°C to 2°C for 1 hour, whereafter the cooling bath was removed and the reaction temperature allowed to rise to 20°C over 1 hour. The reaction mixture was then added slowly to 2 N hydrochloric acid (100 ml) diluted with cold water (1.15 C) at 5°C. The pH of the two-phase mixture was adjusted to below 2 with 2 N hydrochloric acid (10 ml), and the mixture was stirred and recooled to 5°C. The solid which precipitated was filtered, washed with dichloromethane (100 ml) and water (250 ml), and dried in vacuo at 40°C overnight to give the title compound (22.04 g, 86.6%). 

Kinetic isotope effects have also been measured in trifluoroacetic acid-di-chloromethane and are discussed under (d) below. 

General procedure microgel (1 g) was dissolved in di-chloromethane (80 mL) under an inert atmosphere. 

Hexafluoroantimonate catalysts are formed from the corresponding chloride complexes. LigandCuCl2 complexes are formed by stirring the two reagents in di-chloromethane until the largely insoluble CuCl2 is completely dissolved (typically... 

Fuchigami and co-workers showed that a-fluoroallenyl sulfide 302 can be smoothly converted into ( )-configured vinyl iodide 320 by addition of iodine in di-chloromethane at ambient temperature (Scheme 8.87) [166]. Ma et al. [176] treated... 

This enzyme [EC 4.5.1.3] catalyzes the hydrolysis of di-chloromethane to generate formaldehyde and two HCl. Glutathione is required as a cofactor. 

Electrochemical oxidation of cadmium in a solution of ](4-methylphenyl)sulfonyl]-2-pyridylamine] (HL) in acetonitrile/di chloromethane mixtures resulted in CdL2 complex formation [149]. The electrochemical oxidation of cadmium amalgam in nonaqueous solvents CH2CI2, 1,2-C2H4CI2, and PC was also used for the preparation of cadmium complexes with 18-membered macromonocyclic ligands, 18-06, 18-S6, I8-N2O4, and 18-N6 [150]. The stoichiometry and stability of resulted complexes were determined. The same method was used to examine the complexation of Cd(II) cation with 12-crown-4 ether, azacrown ether 1,4,8,11-tetra-azacyclotetradecane, and thiaazacrown... 

A portion (10.2 cm x 17.8 cm) of each RSP sample was sequentially extracted in a Soxhlet apparatus with cyclohexane, di-chloromethane and acetone, (8 hr. for each solvent) in the order given. A more complete extraction of the organic compounds present in particulate matter is achieved and a partial separation of the organic compounds into non-polar, moderately polar and polar fractions is obtained by this method. The volume of each extract was reduced to 10.0 ml using a rotary evaporator. The samples were then stored in a freezer at -15 C until further analysis. Weights of extracts were determined by weighing duplicate 100 yl aliquots of each, taken to dryness on a slide warmer (40 C), on a Cahn Electrobalance. 

The average ambient concentrations of the cyclohexane-, di-chloromethane- and acetone-soluble organic fractions from January, 1978 to August, 1979 were 2.9 yg/m, 1.0 yg/m and 4.4 yg/m. Respirable suspended particulate matter averaged 30.3 yg/m. ... 

Media Acetone, benzene, benzyl alcohol, butanol, 2-butanol, carbon tetrachloride, cetane, chlorocyclohexane, chloroform, cyclohexane, cyclohexanone, diehloroeihane, di-chloromethane, dioxane, ethanol, ether, ethyl acetate, hexane, methanol, 2-propa-nol, pyridine, letrachloromethane, toluene, water, xylene... 

Table 4. Occupational exposure limits and guidelines for di-chloromethane ...

Stannylenes are oxidized to keto-alcohols by dropwise addition of bromine in di-chloromethane. The reaction proceeds at room temperature at the speed of a titration. The attention of chemists who want to check their reaction by infrared (IR) examination in situ is drawn to the fact that the ketone may be chelated to tin in these conditions (vqj 1685 cm-1). The reaction is regiospecific, giving only one of the two possible keto-alcohols. It has been used in total synthesis for instance, in the synthesis of (+)-spectinomycin (described under Sec. QI.G) [12,13]. The replacement of bromine by IV-bromosuccinimide as oxidant has been reported [14]. 

Sedatives. To 3.0 cm of suspect serum or normal serum containing a known amount of standard, 2.5 cm3 of pH 3.5 phosphate buffer is added. This solution is extracted with 18 cm3 of di-chloromethane and the organic layer is filtered into a screw cap tube and evaporated under nitrogen until about 0.5 cm remains. This is quantitatively transferred into a 1.5-cm3 Reacti-vial (Pierce Chemical Co.) and evaporated to dryness under nitrogen. The residue is dissolved in 50 pi of internal standard solution and after capping, the vial is heated at 50°C for 15 min. A 0.5-to 0.7-pl aliquot is injected into the column. 

Low-temperature p-nitrobenzoylation of 2-deoxy-D-n bo-hexose (68) in pyridine gave an anomerically pure tetrakis-p-nitrobenzoate (69), presumably having the /3-d configuration at C-l. The reaction of (69) in di-chloromethane with hydrogen chloride or with hydrogen bromide gave crystalline 2-deoxy-3,4,6-tri-O-p-nitrobenzoyl-a-D-nbo-hexosyl chloride (70) and the corresponding, crystalline bromide (70a), respectively.87... 

Compared with monohaloalkanes, polyhalogen compounds have quite different reactivities and behavior toward nucleophiles and bases. Thus di-chloromethane reacts with hydroxide ion by an SN2 mechanism much less readily than methyl chloride. The chloromethanol formed then undergoes a rapid E2 elimination to give methanal (formaldehyde), a substance that exists in water largely as dihydroxymethane ... 

The most widely used mercury salts for this transformation are Hg(OAc)2 in the presence of catalytic amounts of HCIO4375 or Hg(02CCFj)2.376 While hydrogen peroxide itself can be used, mono- and di-mercuration products have been observed.377 Alkyl hydroperoxides generally give cleaner reactions. Di-chloromethane is commonly employed as the solvent. 

Using a competition method, Lillya et a/.15,16 obtained relative reactivities for a series of substituted diene-tricarbonyliron compounds toward the methyloxocarbonium tetrachloroaluminate ion pair in di-chloromethane. The results are qualitatively summarized in Scheme 4. 

A mixture of epoxide 1 (1 mmol), amine 2 (1 mmol) and montmorillonite K-10 clay (0.2 g) was placed in a Teflon container with a screw cap. Then the mixture was irradiated with high power (900 W) in a conventional microwave oven for 1 min. After the mixture was cooled to room temperature, it was washed with di-chloromethane (2xl0mL). The solvent was evaporated and the products were identified. 

The reagent was prepared by adding silica gel (20 g, 230-400 mesh, SRL) to a stirred solution of NaBiC>3 (6.5 g, 23.35 mmol) in 30 mL of water. After removal of water, the resulting powder was dried in an oven at 120 °C for 12 h. The reagent (2.3 g) was moistened with water (0.5 mL) and was mixed with the neat ketoxime (1 mmol) in a 25-mL Erlenmeyer flask. The flask was then placed in an alumina bath (heat sink) inside a BPL-SANYO domestic microwave oven (2450 MHz) operating at full power (1200 W) for the specified time. After completion of the reaction (monitored by TLC) the product was extracted with di-chloromethane (3x10 mL). All the compounds obtained were characterized by 1H NMR spectroscopy and by comparison with infrared spectra of authentic samples. 

Ceramides prepared in this way have been used for the partial synthesis of the a-L-fucopyranosyl ceramide (84) (a compound previously isolated from metastatic human carcinoma). Condensation [88] of 2,3,4-tri-Obenzyl-a-L-fucopyranosyl bromide (80) with an unprotected ceramide in the presence of tetraethylammonium bromide in di-chloromethane and subsequent chromatographic purification gave (81) which on catalytic hydrogenation gave the saturated fucosyl ceramide (84). The dichloroacetamido derivative (82) was prepared similarly and converted into the free sphingosine derivative (83) by the action of barium hydroxide. 

More recently, sulfide oxidations with [hydroxy(tosyloxy)iodo]benzene (4, HTIB) have been reported [15]. Such reactions proceed readily in di-chloromethane at room temperature and stop at the sulfoxide stage (Scheme 2). HTIB can also be generated in situ from iodosylbenzene (5) and 10 mol% p-toluenesulfonic acid for catalytic oxidations of sulfides to sulfoxides [16]. Oxidations of unsymmetrical sulfides with the chiral (+)-10-camphorsulfonyloxy analog of HTIB afford the corresponding sulfoxides (82-92%) with low enan-tioselectivities (2.7-13.7% ee) [15]. 

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