Benzyl bromide, reaction with metals

PMMA cross-linked by ethylene dimethacrylate with immobilized side oligooxy-ethylene chains were used as interfacial transfer catalysts [80]. Also studied was the formation of benzyl acetate, benzyl bromide and alkali metal acetates in boiling chloroform and of n-octylphenyl ester from n-octyl iodide and K or Na phenoxide in toluene at 100 °C in the presence of a catalytic polymer amount. The product yield increased with an increase in the reaction time and the catalyst/acetate or catalyst/ phenoxide molar ratio. The conversion of benzyl bromide increased according to the following sequence of acetates Napolymeric catalyst could be regenerated and used many times. 

Reactions with Metals and Organometallics. Difficulties encountered in the preparation of benzylic metal compounds with active metals are due primarily to the tendency of these compounds to undergo Wurtz coupling (self condensation). Benzylmagne-sium bromide may nevertheless be prepared from benzyl bromide and used under standard or Barbier conditions. Benzyllithium cannot be obtained practically from benzyl bromide. Benzylzinc bromide and the cyanocuprate BnCu(CN)ZnBr have both been... 

The sulfur atom of the thiocarbonyl group is a good nucleophile, and reaction between benzyl bromide and l-(2-thiazolyl)thiourea yields the isothiouronium salt (496). The sulfur atom may also be engaged in a chelate, as exemplified by the Cu chelate of 2-thioureido-4-methylthiazole (491). These chelates with metal ions were thoroughly studied in acidic, neutral, and alkaline media for 66 metal ions in order to define their analytical use. They are formed in the molar ratio of 1 2 for metal II compounds (498). 

The reaction of benzyl bromide with vinyltrimethylsilane was used for studying a general kinetics of addition under conditions of metal complex initiation (ref. 26). One of the crucial questions in this case is how the chain transfer step proceeds by "purely" homolytic mechanism (via benzyl bromide) ... 

Similarly, reactions which are substantially enhanced by the use of PTC can be carried out even with reduced use of PTC with substantial enhanced rates of reaction as has been demonstrated by Sivakumar and Pandit (2000) in the case of conversion of benzamide to benzonitrile. In the case of A-alkylation of diphenylamine with benzyl bromide, in the presence of KOH as the anion source and PEG methyl ether as the PTC, some improvement in the rate has been observed. (Cains et al., 1998). Metal catalysed hydrogenations, such as those based on Ni, Pd/C, and Ru/C also benefit from ultra-sound. 

The formation of arylzinc reagents can also be accomplished by using electrochemical methods. With a sacrificial zinc anode and in the presence of nickel 2,2-bipyridyl, polyfunctional zinc reagents of type 36 can be prepared in excellent yields (Scheme 14) . An electrochemical conversion of aryl halides to arylzinc compounds can also be achieved by a cobalt catalysis in DMF/pyridine mixture . The mechanism of this reaction has been carefully studied . This method can also be applied to heterocyclic compounds such as 2- or 3-chloropyridine and 2- or 3-bromothiophenes . Zinc can also be elec-trochemically activated and a mixture of zinc metal and small amounts of zinc formed by electroreduction of zinc halides are very reactive toward a-bromoesters and allylic or benzylic bromides . ... 

Alkylation of Alkali Metal Cyanides by Alkyl Halides Activated in the a-Posi-tion by a Double Bond. When a mixture consisting of 4 to 8 moles of an alkyl halide activated in the apposition by a double bond is heated with 1 mole of alkali metal ferrocyanide, several alkylation products of the ferrocyanide anion can be isolated from the reaction mixture (12). The relative proportions of the tetra-, penta-, and hexaalkylated complexes can be varied by varying the alkyl halide to ferrocyanide ratio and the time of reaction. When potassium ferrocyanide is alkylated with benzyl bromide at a ratio of 4 alkyl halides to ferrocyanide anion, short reaction times favor the tetraalkylated complex an 8 to 1 ratio and long reaction times favor the hexaalkylated complex of the alkylating agents tested benzyl bromide provided the fastest alkylation ... 

Lithium phenylethynolate (520) has been prepared in a rather intriguing fashion through the elimination of benzonitrile from 5-lithio-3,4-diphenylisoxazole (519) (75AG(E)765). Reaction of the ynolate with an aldehyde or ketone was shown to afford a metallated /3-lactone (521). Treatment of this intermediate in turn with an electrophilic reagent such as benzyl bromide produced a tri- or tetra-substituted /3-lactone (522 Scheme 114). 

The metallation of 3-methyl-4//-5,6-dihydro-l,2-oxazine has been shown to take place at the methyl group with hindered bases and at the methylene group with unhindered bases (81JA5916). Deprotonation of (753) with lithium dimethylamide at -65 °C followed by reaction with benzyl bromide gave (754) in 85% yield. This product was converted to enone (755) by reaction first with triethyloxonium tetrafluoroborate to produce an oxoiminium salt. The salt was stirred with trimethylamine and the resulting a,/3-unsaturated imine hydrolyzed with wet silica gel to the enone (Scheme 174). The lithiated derivative of (753) serves as a synthon for the unknown a-anion of methyl vinyl ketone. 

Reaction of [FeCp(C6Me6)][PF6] [33-35] with excess KOH (or tBuOK) in THF or DME and excess alkyl iodide, allyl bromide, or benzyl bromide leads to one-pot hexasubstitution (Scheme 5a) [36-38]. With allyl bromide (or iodide) in DME, the hexaallylated complex has been isolated and its X-ray crystal structure determined, but the extremely bulky dodeca-allylation [52] product can also be reached when the reaction time is extended to two weeks at 40 °C. The chains are fixed in a directionality such that conversion to the enantiomer is not possible, thus making the metal complex chiral (Scheme 5b). 

Tributylstannyl ethers are covalent derivatives with the nucleophilic properties of soft metal alkoxides they react with benzyl bromide on heating in non-polar solvents in the presence of tetraalkylammonium bromides or iodides to give the O-benzyl ether [Scheme 4.166]. 309 310 The moisture sensitive tributylstannyl ethers are formed by reaction of an alcohol with bis(tributyltin) oxide (bp... 

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