F Dichloromethane

Dichloro-5,7,7,12,14,14-hexamethyl-l, 4,8,1 l-tetraaza-4,11-cyclotetradecadie-neiron(III) perchlorate, 3719 Dichloromaleic anhydride, 1355 f Dichloromethane, 0396... 

Additional dipping in a 0.001% solution of dansyl semipiperazide or bis-dansyl piperazide in dichloromethane — liquid paraffin (75 -F 25) stabilized the color of the chromatogram for a period of months. 

Fig. 3-18. Selectivity factors a determined for (3,5-dinitroben-zoyl)leucine diallylamide on CSP 15-24. Conditions analyte (3,5-dinitrobenzoyl)leucine diallylamide column 150 x 4.6 mm i.d. mobile phase 20 % hexane in dichloromethane flowrate 1 mL min f UV detection at 254 nm.

Dibenz[r,e,]azcpinium salts, e.g. 3 and 6, arc also obtained by O- and 5-alkylation of 6,7-dihydro-5//-dibenz[f,e]azepin-7-ones 2 and -7-thiones 5 with trimethyloxonium tetrafluo-roborate.181 iodomethane,181 or methyl trifluoromethanesulfonate.12 Treatment of the tri-fluoromethanesulfonates 3 and 6 (X = OTf), or the tetrafluoroborate 6 (X = BF4) with 2 M sodium hydroxide in dichloromethane liberates the free bases 4 and 7, respectively.7,181... 

A similar irradiation of imide 9 in acetonitrile gives a mixture of ethyl 4,5-bis(ethoxy-carbonylamino)-l//-l,2-diazepine-l-carboxylate (10) and the isomeric ethyl 5,6-bis(ethoxycar-bonylamino)-l/f-l,2-diazepine-l-carboxylate (11) in the ratio 6 1. In contrast, when the irradiation is carried out in dichloromethane, the ratio is reversed to 1 2.5.81... 

A solution of TMSOTf in dichloromethane (1% v/v, 1 ml) was added to a solution of the /3-lactam (2.01 mmol) and 1-phenyl-l-trimethylsilyl-oxyethene (2.2 mmol) in dichloromethane, cooled to -78°C. After being stirred at -78°C for 15 min, the reaction mixture was allowed to warm to ambient temperature over 20 min, and was stirred for a further 30 min. The lime-green solution was quenched with aqueous K.F (5% w/v, 20ml) and extracted with dichloromethane (2x25 ml). Drying, concentration and chromatography of the residue gave the -lactam (1.79 mmol, 89%) as a white solid, m.p. 141-143"C. 

Note Under the conditions employed emetine and cephaeline were not well separated but there was good resolution of the subsidiary alkaloids of the ipecacuanha tincture (Fig. 1). The separation and quantitative determination of the main alkaloids (Fig. 2) can be carried out under the following conditions Ascending, one-dimensional development in a trough chamber with chamber saturation layer HPTLC plates Silica gel 60 (Merck) mobile phase dichloromethane — methanol — ammonia solution (25%) (34+6+1) migration distance 6 cm running time 13 min h/ f cephaeline 65-70 emetine 75-80. 

Kohler-Staub D, S Hartmans, R Galli, F Suter, T Leisinger (1986) Evidence for identical dichloromethane dehalogenases in different methylotrophic bacteria. J Gen Microbiol 132 2837-2843. 

The choice of solvent may have a critical impact on efficiency too. In metathesis, dichloromethane, 1,2-dichloroethane and toluene are the solvents most commonly used. There are examples that show much higher yields in ring closing metathesis (RCM) when using fluorinated solvents [150]. An impressive effect of hexafluorobenzene as a solvent for CM is the modification of the steroid 93 the use of 1,2-dichloroethane leads to a very low yield and significant amounts of dimerisa-tion while the same reaction proceeds in 90% yield in C F (Scheme 3.14) [151]. 

The ionic potentials can be experimentally determined either with the use of galvanic cells containing interfaces of the type in Scheme 7 or electroanalytically, using for instance, polarography, voltammetry, or chronopotentiometry. The values of and Aj f, obtained with the use of electrochemical methods for the water-1,2-dichloroethane, water-dichloromethane, water-acetophenone, water-methyl-isobutyl ketone, o-nitrotol-uene, and chloroform systems, and recently for 2-heptanone and 2-octanone [43] systems, have been published. These data are listed in many papers [1-10,14,37]. The most probable values for a few ions in water-nitrobenzene and water-1,2-dichloroethane systems are presented in Table 1. 

Also known as DCM or dichloromethane. Often used as an adhesive solvent for acrylics. Pure DCM can be found in craft stores. DCM must be distilled first from all non-flammable paint strippers beforehand (they contain a paste that holds several unwanted substances.) The paint stripper may also contain methanol (most marine grade paint strippers are 80-90% DCM. Methanol is also an organic solvent. DCM distills at 47° C or 116° F. Pure DCM is best. May cause cancer and blindness. Take necessary precautions. Methylene chloride sinks to the bottom of the jar. 

Kennett, F. A. et al., J. Chem. Soc., Dalton Trans., 1982, 851-857 In attempted preparation of poly(selenium nitride), the black solid formed by interaction with selenium tetrabromide in acetonitrile exploded violently within 1 min at 0°C. The solid produced from diselenium tetrachloride in acetonitrile exploded at around 100°C, and in dichloromethane the product exploded in contact with a nickel spatula. 

Recently, Carreno, Urbano and coworkers were also able to synthesize almost enantiopure [7]helicene bisquinones 4-58 and 4-59 (96% ee) by reaction of the sulfoxide (S,S)-4-55 with the diene 4-56 in dichloromethane at -20 °C (Scheme 4.12) [19]. This six-step domino process includes a double Diels-Alder reaction, sulfoxide elimination, and aromatization of the rings B and F of the intermediate 4-57 to give 4-58, which could be oxidized to the fully aromatized 4-59. 

DDQ ( red = 0.52 V). It is noteworthy that the strong medium effects (i.e., solvent polarity and added -Bu4N+PFproduct distribution (in Scheme 5) are observed both in thermal reaction with DDQ and photochemical reaction with chloranil. Moreover, the photochemical efficiencies for dehydro-silylation and oxidative addition in Scheme 5 are completely independent of the reaction media - as confirmed by the similar quantum yields (d> = 0.85 for the disappearance of cyclohexanone enol silyl ether) in nonpolar dichloromethane (with and without added salt) and in highly polar acetonitrile. Such observations strongly suggest the similarity of the reactive intermediates in thermal and photochemical transformation of the [ESE, quinone] complex despite changes in the reaction media. 

In contrast, when boron trifluoride etherate is substituted for the free boron trifluoride, only a trace of the hydrocarbon is formed, even after weeks of reaction.143 The unique effectiveness of boron trifluoride gas in promoting these reductions is believed to be due to several factors, including the ability of the coordinatively unsaturated boron center to rapidly and tightly coordinate with oxygen centers and to the thermodynamically favorable creation of a Si-F bond.1 A slight pressure of boron trifluoride gas must be maintained over the surface of the solution throughout the reaction because boron trifluoride has only limited solubility in the weakly coordinating dichloromethane solvent. 

A specific assay of bromocriptine mesilate in the dosage form may be carried out by tic followed by uv-spectrophotometry (26)(The system can also serve for identification purposes). The drug substance is extracted with methanol in the absence of light, the chromatographic conditions are Merck plates F 254, mobile phase dichloromethane/dioxane/ ethanol abs./conc. ammonia 180 15 5 0.1 per volume. 

In some cases, the pyrrolo[l,2-f]oxazoles were epoxidized with hydrogen peroxide in dichloromethane affording the epoxide with control of stereoselectivity (Equation 52) <1997TA2421, 2000T2437, 2004TA1239>. 

A Chinese research team found <1997PS299> that derivative 21 of the new [l,3,4]thiadiazolo[3,2-f][l,3,5,2,]thia-diazaphosphorine ring system undergoes spontaneous oxidation on air, as shown in Scheme 5. Thus, storage of the dichloromethane solution of 21 for 48 h at room temperature results in formation of a mixture of 22 and 23. 

This compound was prepared as depicted in Scheme 1 using the following procedure To a 250-ml round-bottom flask was added lO.OOg (0.0170mol) of 2,2-bis[4-( 1-naphthoxy)phenyl]hexafluoropropane (1), 5.71 g (0.0360mol) of 4-fluorobenzoyl chloride, 2.3 g (0.0246 mol) of dimethyl sulfone, and 132 g of dichloromethane. The mixture was stirred under nitrogen until the solids dissolved, then cooled in an ice bath, and 14.5 g (0.109 mol) of aluminum chloride was added. The mixture was stirred for 1 h at ice-bath temperature, 24 h at room temperature, and 1 h at reflux. The mixture was allowed to cool to room temperature and poured into methanol. The resulting solid was filtered, washed with methanol and water, dried, and recrystallized from DMAc to yield 11.6 g (82% yield), m.p. = 261-263°C. Calculated for C HM04F, C, 70.67 H, 3.39 F, 18.25. Found C, 70.74 H, 3.36 F, 18.54. 

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