Methylene chloride, as solvent

Methylene chloride as solvent for diazomethane etherifications, 41, 9 Methylene cyclohexane, 40, 66 Methylene iodide, reaction with zinc-copper couple and cyclohexene, 41, 73... 

DetkioketaKzation. Various thioacetals and thioketals are readily hydrolyzed by pyridinium bromide perbromide (1 equivalent) under phase-transfer conditions. Tetrabutylammonium bromide is used as catalyst and aqueous methylene chloride as solvent. The reaction is more efficient in the presence of pyridine as buffer. Yields are generally 75-90%.1... 

The promoter of choice for direct coupling of NPGs is NIS/EtjSiOTf [13]. The reaction is usually conducted in methylene chloride as solvent at room temperature [14]. Under these conditions, the coupling reaction is very fast, often being completed within the time it takes to sample the mixture by thin-layer chromatography (TLC). The process can be rationalized by an acid-induced heterolysis of NIS, whereby a very potent source of iodonium ion is generated (Scheme 5). Usually, only a catalytic amount of EtjSiOTf is... 

An antibiotic, cycloheximide, is to be extracted from the clarified fermentation beer by using methylene chloride as solvent. The distribution coefficient K is 23. The initial concentration of cycloheximide in the feed is 150 mg/L. The recovered solvent containing 5 mg/L of cycloheximide is being used with the flow rate 1 mi3 /hr. The required recovery of the antibiotic is 98 percent. 

The highly functionalised pyran 1 can be prepared in a one-pot operation and in yields up to 30% by reaction of the readily available sulfone 2 with methyl coumalate 3, using methylene chloride as solvent and DBU as base. 

At that time, our coatings were made in Towanda with methylene chloride as solvent, but our custom coating was done with butanone and isopropyl alcohol. The samples of TCTM-HABI had good solubility in this solvent pair. When Green precipitated the product from the oxidation of the 2,4-bis(2-chlorophenyl)-5-(3,4-dimethoxyphenyl)imidazole, he made a startling discovery. Some of it went into solution in the ketone solvent, but most did not. What did... 

Use of methylene chloride as solvent consistently leads to higher yields of demethylated product (V), accompanied mostly by a decrease in recovered starting material. Lower oxygen yields are also observed at all temperatures except at —78°C. 

Tri-O-benzyl-D-arabinofuranosyl chloride (15), presumably of the a configuration, has been used18 in the synthesis of 1-j8-d-arabinofuranosylcytosine (16) and l-/9-D-arabinofuranosyl-5-trifluoro-methyluracil (17). In this case, the Hilbert-Johnson reaction has been performed at room temperature in methylene chloride as solvent. The unusual benzyl protecting groups were removed smoothly by hydro-... 

Improved conditions for the oxidation of olefins with ozone to ketones (60-70%) have been described. The use of Dry Ice temperature and methylene chloride as solvent lessens the loss of volatile olefins in the... 

Acid chloride—olefin addition and Friedel-Crafts cyclization A previous procedure was improved by use of methylene chloride as solvent rather than carbon disulfide. To check the progress of the reaction, one can quench a 2 3-ml. aliquot with water in a test tube, separate and dry the organic phase, and evaporate. The infrared spectrum will show disappearance of the acid chloride carbonyl band at 5.6(1 /j and appearance of the... 

The results were checked by use of a common-ion procedure once again similar to that used by Sangster and Worsfold [46] in the polymerization of THF, and by workers in the field of anionic polymerizations [39]. In the case of methylene chloride as solvent, addition of a common salt depressed the overall value of fep indicating fep < fep, whereas in the case of nitrobenzene no effect was observed, so that — kp. Appropriate analysis of rate data obtained in the presence of common ion yielded values for fep and fep in both solvents, very similar to those already calculated (Table 11). 

Quinones - Quinone methides are produced on irradiation of /7-benzoqui-nones in the presence of the eneyne (267) in methylene chloride as solvent. 1,4-Naphthoquinones also afford quinone methides but unstable spirooxetenes were also detected. The photochemical addition of phenanthraquinone and ace-naphthenequinone to eneynes has also been studied. 1,4-Benzoquinones undergo addition to electron donating alkenes to yield spirooxetanes. The resultant cyclohexadienones are themselves photochemically reactive and irradiation converts these into dihydrobenzofurans via a dienone-phenol rearrangement. " ... 

Easier exhaust gas cleaning (no methylene chloride as solvent)... 

The amination reaction is not limited to aromatic hydrocarbons it is also applicable to r-alkanes. r-Butyl chloride reacts with trichloramine in the presence of aluminum chloride to give f-butylamine in 88% yield.5 Methylcyclohexane is converted into 1-amino-1-methylcyclohexane in yields as high as 67% (based on trichloramine). The most satisfactory conditions use C7H14-A1C13-NC13 in a 2 2 1 ratio with methylene chloride as solvent and a temperature of 0 5°.6 Under the same conditions adamantane gives 1 -aminoadamantane in nearly quantitative yield.7... 

Initially, the reduction of ester 45 proved to be problematic (Scheme 14). When THF was used as solvent, a large excess of DIBAL was required (10 equiv.) and the yield for the desired alcohol was still very low, 50%, with the remainder being unreacted 45. Use of methylene chloride as solvent led to complete reduction along with unwanted TES removal. Finally, it was found that the use of ether with 2.5 equivalents of DIBAL provided the desired alcohol in 91% yield. Oxidation gave the enal intermediate, which was converted to the diene ester 47 with allyl phosphonate 46. The selectivity was 19 1 E,Z Z,Z) and the yield was an excellent 93%. Previously, the more common methyl ester corresponding to 47 was employed. Hydrolysis to the desired acid with this substrate was... 

Molecular squares define cavities that are potential hosts for appropriate molecular guests. In methylene chloride as solvent, pyridine binds to the available Zn(II) sites of IZn with an association constant of 10 M Whether binding occurs on the square interior or exterior (or a combination of both) has not been established. Recall, however, that Zn porphyrins generally axially bind only one ligand. The free base form of the dipyridyl porphyrin used to assemble the squares binds to IZn with an equilibrium constant of 3 x 10 [7]. The stronger association is a consequence of... 

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