Permanganate methylene chloride

Alkah manganate(VI) salts are used as oxidants in synthetic organic reactions (100) and their reactions have been observed to be similar to permanganate, except that manganate(VI) exhibits lower reactivity. Additionally, sohd BaVInO in methylene chloride has been reported to achieve high yields for the oxidation of diols to dialdehydes (101). 

Benzyltriethylammonium permanganate has also been used for the mild oxidation of sulphoxides to sulphones at — 10 °C in methylene chloride in the presence of keto, amino and ester groups in > 65% yields142. 

We developed and applied two oxidation methods to lycopene and p-carotene. The first chemical oxidation method was performed in biphasic medium using the potassium permanganate hydrophilic oxidant. Cetyltrimethylammoniumbromide was the phase transfer agent used to achieve contact of the hydrophilic oxidant with the lycopene lipophilic carotenoid dissolved in methylene chloride/toluene (50/50, v/v). 

Several typical extraction constants, Kgr for the transfer of permanganate from an aqueous solution into methylene chloride are listed in Table 1. 

Table I. Extraction Constants for the Transfer of Permanganate from Water into Methylene Chloride (32)...

It can be seen from these data that permanganate can easily be transfered from an aqueous phase into methylene chloride solutions. Quaternary phosphonium ions and polyethers (both cyclic and linear) also exhibit large Ke values (30,32). 

Quaternary ammonium and phosphonium permanganates exist as intimate ion pairs in nonpolar solvents such as methylene chloride and toluene (1). However, in more polar solvents, such as acetone, nmr studies indicate that they are better described as being solvent separated ion pairs (37). In water, these salts separate completely and exist as individual ions. 

However, the effects on the rates in nonpolar solvent systems is dramatically larger and often of apparent contradiction. For example, the Hammett rho value for the oxidation of substituted methyl cinnamates and cinnamic acids by tetrabutylammonium permanganate in methylene chloride solutions is positive (33,49). See Figure lb. However, a rho value of converse sign (-0.6) is obtained from a Taft plot (Figure Ic) for the oxidation of vinyl ethers in aqueous tetrahydrofuran (33,50). For many other compounds the Hammett relationships are no longer linear, but concave upward ... 

Figure 1. Hammett and Taft plots for the oxidation of unsaturated compounds by permanganate. (a) aqueous solutions (b) methylene chloride and (c) aqueous THF,...

Solvent Effects. Information on the effect of solvent polarity of the phase transfer assisted permanganate oxidation of alkenes has been obtained by studying the oxidation of methyl cinnamate by tetrabutylammonium permanganate in tv/o different solvents, acetone and methylene chloride (37). 

Formaldehyde, Methylnitramine, Methylene chloride, Magenesium sulfate. Sulfuric acid. Chloroform, Hexane Nitric acid. Diethanolamine, Ethanol, Ether, Acetone Potassium permanganate, 3-Amino-l,2,4-triazole, Sodium hydroxide. Sodium bisulfite. Hydrochloric acid. Nitric acid, Acetic anhydride. Acetone... 

Aluminum foil, Iodine powder. Carbon disulfide, 1,4,6,9-Tetrabromodiamantane, Sodium bisulfite. Hydrochloric acid. Methanol, Acetonitrile, Acetone, Sodium hydroxide. Magnesium sulfate. Potassium permanganate. Toluene Methylene chloride, 2-Bromomethanol, Trioxane, Aluminum chloride. Magnesium sulfate, Nitroform, Acetone, Sodium bicarbonate. Hexane, Silver nitrate. Acetonitrile 1,2-Dichloroethane, HexamethyldisUane, Iodine, Cyclohexane, 1,3-Dioxolane, Nitroform, Methylene chloride, Dimethylformamide, Sodium sulfate. Hydrochloric acid. Magnesium sulfate. Nitric acid. Sulfuric acid Sulfuryl chloride. Acetic anhydride. Nitric acid. Sodium bicarbonate. Sodium sulfate Nitric acid. Sulfuric acid, Malonamide Nitric acid. Sulfuric acid, Cyanoacetic acid Sulfuric acid, Acetasalicyclic acid. Potassium nitrate Nitroform, Diethyl ether, 1-Bromo-l-nitroethane, Sodium sulfuate... 

Another important feature is the solvent. For example, in dry organic solvents like acetone, methanol, acetonitrile or methylene chloride la was not oxidized by potassium permanganate within 24 h. If a small amount of water (pH 4.1) was added to the reaction mixture, the oxidation took place. Figure 1 shows the variation of the yield of 2a and 4a as... 

Reserpine Bulk HPLC treated) Silica ide—methanol (1.5. 100) Methylene chloride permanganate 254 nm 1LC [1.8] HPLC [8.611. [ 1... 

Sodium permanganate, commercially available although more expensive than potassium permanganate (14), was found to be an even more potent oxidant. The monohydrate form (NaMnO. H.O) can be used as purchased to oxidize a variety of functionalities by stirring the solid with substrates dissolved in hexane or methylene chloride (Table II). The solid phase oxidation would seem particularly useful for small-scale reactions (< 1 gram substrate). 

Oxidations of aikynes (1, 947). A reinvestigation of this reaction indicates that oxidation to diketones is best effected in dry methylene chloride with excess powdered potassium permanganate and a phase-transfer catalyst (Adogen 464). Typical yields are 40-80%. If some water is also present, further oxidative cleavage of the enol of the diketone results in two carboxylic acids. An example is shown in equation (I). Oxidation of terminal aikynes to a carboxylic acid with one less carbon atom may also proceed through a dicarbonyl intermediate. 

The oxidation of c -cyclooctene with basic permanganate illustrates the new method. The octene (0.1 mole) in methylene chloride is treated with a 40% aqueous solution of sodium hydroxide and I g. of benzyltricthylammonium chloride. The mixture is cooled to 0° and KMnO (0.1 mole) is added in small portions over 2 hr. with vigorous stirring after standing overnight at 0°, the precipitated MnOj is dissolved by S02- The rii -l,2-cyclooctanediol is isolated by ether extraction and crystallization in 50% yield. The yield of diol obtained without a phase-transfer catalyst is 7%. ... 

Purification. The commercial solvent, made by addition of SOj to butadiene and hydrogenation, contains various contaminants. One method of purification is by passage through a column of Linde molecular sieves and fractionation. Another is by repeated vacuum distillation from sodium hydroxide pellets until a mixture of 1 ml. with 1 ml. of 100% sulfuric acid developes no color in 5 min. the solvent is then distilled again from calcium hydride. Another involves treatment with permanganate and sulfuric acid to remove oxidizable impurities, addition of enough sodium pyrosulfite to give a clear solution, extraction with methylene chloride, treatment with P Os, decantation, and distillation. 

Volumetric determination may be made by reducing the titanium to the trivalent condition with zinc and then titrating with potassium permanganate, ferric chloride, or methylene blue.5... 

Similarly, the uranyl ion is extracted from aqueous nitrate solution into isobutanol by associating with two nitrate ions (U02 , 2N03 ), with the uranium probably being solvated by the solvent to make it solventlike. Permanganate forms an ion pair with tetraphenylarsonium ion [(C6H5)4As , Mn04"], which makes it organiclike, and it is extracted into methylene chloride. There are numerous other examples of ion-association extractions. 

Pachter and Sued have prepared (80) in 68% yield by POCI3-promoted condensation of 2,3,4,9-tetrahydro-lH-pyrido[3,4-b]indol-l-one with methyl N-methylanthranilate. Catalytic reduction of (80) yields (67). Danieli and Palmisano 54) have found that (67) can be converted into (68) by a variety of oxidants. In particular, Tl(OAc)3 and DDQ give (68) in 85 and 67% yield, respectively. The yield of (68) from alkaline permanganate oxidation of (67) (in acetone at 0° 65% yield) was improved markedly to 91%, by use of dicyclohexyl-18-crown-6 (methylene chloride at room temperature). 

Bromine-methylene chloride Potassium permanganate Ignition test... 

Now add 10-15 mg of oxalic acid, enough to decolorize the excess purple permanganate, followed by 0.5 mL of methylene chloride solvent. Stopper, shake, and vent the test tube and allow the layers to separate. Observe the color of the CH2Q2 (lower) layer. 

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