Adogen phase transfer catalyst

Sodium ra-chloroperbenzoate, 73 Trifluoroperacetic acid, 258 Triphenylsilane-Di-f-butyl peroxide, 334 Phase-transfer catalysts Adogen 464, 258, 281... 

In the second reaction, dibromomethane acts as the reagent. Since this requires working in a two-phase system, the phase-transfer catalyst Adogen 464 methyltrialkyl(Ca-C ammonium chloride] is added. 

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. 

PHASE-TRANSFER CATALYSTS Adogen 464. (-)-N-Benzyl-N-methylephedrinium bromide. Benzyltriethylamine. Benzyl triethylammonium chloride. 18-Crown-6. Dibenzo-18-crown-6. Diethyl phenylsulfinylmethylphosphonate. Hexadecyltributyl-phosphonium bromide. Methyltricaprylylammonium chloride. Tetra-n-butylammo-nium hydrogen sulfate. Tetra- -butylammonium iodide. 

PHASE-TRANSFER CATALYSTS Adogen. Benzyldimethyldodecylammonium bromide. Benzyltriethylammonium chloride. N-Dodeoylpentamethylphosphotamide. Hexadecyl-trlbutylphosphonium bromide. Methyltricapiylylaminonium chloride. Tetra- -butyl-ammonium chloride. 

CH2Br2, NaOH, H2O, Adogen, reflux, 3 h, 76-86% yield. Adogen = R3N CH3C1 , phase-transfer catalyst (R — Cg-C,o straight-chain alkyl groups). Earlier methods required anhydrous conditions and aprotic solvents. 

Adogen = MeR3N CI. phase transfer catalyst R = Cg-C Q straight chain alkyl groups... 

The 9,10-dihydrodiol of 3-MC (24a) was synthesized from 9-hy-droxy-3-MC by Method IV (86). Oxidation of this phenol with Fremy s salt in the presence of Adogen 464, a quaternary ammonium phase transfer catalyst, furnished 3-MC 9,10-dione. Reduction of the qui-none with NaBH -C gave pure 24a in good yield. Treatment of 24a with m-chloroperbenzoic acid was monitored by HPLC in order to optimize the yield of the anti diol epoxide (25 ) and minimize its decomposition. 

Adogen has been shown to be an excellent phase-transfer catalyst for the per-carbonate oxidation of alcohols to the corresponding carbonyl compounds [1]. Generally, unsaturated alcohols are oxidized more readily than the saturated alcohols. The reaction is more effective when a catalytic amount of potassium dichromate is also added to the reaction mixture [ 1 ] comparable results have been obtained by the addition of catalytic amounts of pyridinium dichromate [2], The course of the corresponding oxidation of a-substituted benzylic alcohols is controlled by the nature of the a-substituent and the organic solvent. In addition to the expected ketones, cleavage of the a-substituent can occur with the formation of benzaldehyde, benzoic acid and benzoate esters. The cleavage products predominate when acetonitrile is used as the solvent [3]. 

Selective oxidation of henzylic alcohols,l These alcohols are oxidized by Fremy s salt in benzene-water with Adogen 464 as the phase-transfer catalyst to aldehydes or ketones in generally high yields. Ally lie alcohols are completely stable under these conditions. See also sodium nitrosodisulfonate (this volume). 

Hydrogenolysis of vinyl sulfones.2 Vinyl sulfones are reduced by Na2S204 and NaHC03 in aqueous ethanol with retention of configuration. The reaction is facilitated by use of a phase-transfer catalyst such as Adogen. The reduction involves addition of HSOz to form a sulfone sulfinate salt which can be trapped by CH3I. The overall reaction thus involves a (3-syn-addition followed by an anti-elimination. This hydrolysis was used in a synthesis of several insect pheromones, such as (Z)-8-dodecenyl-l-acetate (1). 

Debrominatton of ic-dibromides. v/r-Dibromides are reduced to alkenes by treatment with Na,S or NaSH in benzene/HiO in the presence of catalytic amounts of meth-yltrioctylammonium chloride (Adogen 464). The debromination occurs by stereoselective / t/-climination. The phase-transfer catalyst is not required with water-soluble substrates. Example ... 

Reduction of ketones (8, 757). Reduction of methylcyclohexanones with sodium dithionite in a two-phase benzene-H20 mixture with Adogen 464 as a phase-transfer catalyst affords isomeric mixtures of methylcyclohexanols iq somewhat higher yield (70-82%) than that obtained when the reduction is conducted in aqueous solution only (15-68%). The stereoselectivity observed in the phase-transfer procedure is comparable to that reported with sodium borohydride. 

Methoxymethyl ethers of phenols. Phenols can be converted into methoxy-methyl ethers (Ar0CH20CH3> in 80-95% yield by reaction with chloromethyl methyl ether under phase-transfer conditions. Adogen 464 (6, 10) has been used as catalyst. 

In 1998, Peterson and Larock showed that Pd(OAc)2 in combination with NaHCOs as a base in DMSO as solvent catalyzed the aerobic oxidation of primary and secondary allylic and benzylic alcohols to the corresponding aldehydes and ketones, respectively, in fairly good yields [70]. In both cases, ethylene carbonate and DMSO acted both as the solvent and as the ligand necessary for a smooth reoxidation [71]. Similarly, PdCl2, in combination with sodium carbonate and a tetraalkylammonium salt, Adogen 464, as a phase transfer catalyst, catalyzed the aerobic oxidation of alcohols for example, 1,4- and 1,5-diols afforded the corresponding lactones (Eq. (5.11)) [72, 73]. 

While a number of different phase transfer catalysts such as tetrabutyl ammonium halides (Ref. 10, 11), tetrabutyl ammonium hydroxide (Ref. 16-18), tetrabutyl ammonium hydrogen sulfate (Ref. 21-22), Adogen-464 (Ref. 16, 18), tetrabutyl phosphonium bromide (Ref. 19, 20), 18-crown-6 (Ref. 12, 13, 19, 20), cryptand [222] (Ref. 21, 22), etc., have been used in the chemical modification of polymers, few systematic studies of the influence of the catalyst on the reactions have been done. It is presumed that the same considerations which govern the choice of a phase transfer catalyst for classical organic synthesis also apply in the case of reactions with polymers. 

SoHd-liguid phase-transfer catalysis. Crown ethers have commonly been used as catalysts for reactions between a solid-liquid interface, and quaternary ammonium and phosphonium salts have been used only as catalysts for reactions in two-phase liquid liquid reactions. However, several laboratories have reported that the latter catalysts are also satisfactory for two-phase solid liquid reactions. Thus dichlorocarbene can be generated from chloroform and solid sodium hydroxide under catalysis from benzyltriethylammonium chloride in yields comparable to those of the classical Makosza method. Another example of this type of catalysis is the oxidation of terminal and internal alkynes by solid potassium permanganate in CH2CI2 with Adogen 464 as catalyst. Aliquat 336 has been found to be as satisfactory as a crown ether for certain displacement reactions with NaOAc, KSCN, KNOa, and KF in CH3CN or CHaCla. ... 

A new procedure for the conversion of a catechol to a methylenedioxy function utilizes phase-transfer catalysis. The catalyst is Adogen 464, a methyl trialkylammonium chloride, and the alkylating agent is methylene bromide. Usual yields are around 80%. Another efficient method utilizes potassium fluoride and dibromomethane in... 

Lower molecular-weight quaternary ammonium halides, which partition across the two-phase system, transfer anions in measurable concentrations from the aqueous to the organic phase but, in contrast, many of the higher-molecular-weight quaternary ammonium halides with more than ca. 30 carbon atoms are virtually insoluble in aqueous media and their partition coefficients between aqueous and organic phases preclude the transfer of anions efficiently across the interface by the extraction process and yet catalysts, such as Aliquat 336 and Adogen 464, are extremely effective catalysts. 

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