Benzyl methyl carbonate

The reaction of benzyl methyl carbonate with sodium benzenesulflnate and different palladium catalysts has shown that the best yields were obtained when a Pd( 3-C3H5)Cl2 - (DPEphos) catalyst was used in DMSO at 80 °C.121 Most of the reactions gave >90% yields of the benzyl aryl sulfone. In the suggested mechanism, the methyl carbonate leaving group is displaced by the catalyst, forming an (j 3-benzyl)palladium intermediate that reacts with the sodium salt of the arenesulfinate. 

Elimination. oQuinodimethane is generated from (o-trimethylsilylmethyl)benzyl methyl carbonate on heating with the Pd complex and DPPE in DMSO at 120°. 

Substitution reactions. Benzylation of phenols by benzyl methyl carbonates with Pd catalysis proceeds via transesterification and decarbonylation. Triarylmethanes are obtained from a reaction of benzhydryl carbonates with arylboronic acids. ... 

Water with aniline, benzene, benzyl alcohol, carbon disulfide, carbon tetrachloride, chloroform, cyclohexane, cyclohexanol, cyclohexanone, diethyl ether, ethyl acetate, isoamyl alcohol, methyl ethyl ketone, nitromethane, tributyl phosphate or toluene. 

NOTE - Petrochemical plants also generate significant amounts of solid wastes and sludges, some of which may be considered hazardous because of the presence of toxic organics and heavy metals. Spent caustic and other hazardous wastes may be generated in significant quantities examples are distillation residues associated with units handling acetaldehyde, acetonitrile, benzyl chloride, carbon tetrachloride, cumene, phthallic anhydride, nitrobenzene, methyl ethyl pyridine, toluene diisocyanate, trichloroethane, trichloroethylene, perchloro-ethylene, aniline, chlorobenzenes, dimethyl hydrazine, ethylene dibromide, toluenediamine, epichlorohydrin, ethyl chloride, ethylene dichloride, and vinyl chloride. 

Breslow and co-workers have found that cosolvents such as ethanol increase the solubility of hydrophobic molecules in water and provide interesting results for nucleophilic substitutions of phenoxide ions by benzylic chlorides carbon alkylation occurs in water but not in nonpolar organic solvents, and it is observed only when the phenoxide has at least one methyl substituent (ortho, meta, or para). This has been discussed in Chapter 6 (Section 6.4.2). 

An N-benzyl-N-methyl carbonate in EtOH was hydrogenated on 10% Pd/C under 60 psi hydrogen for 20 hours. NMR analysis indicated that no deuterium scrambling had occurred during debenzylation (Scheme 4.81).328... 

There is a 4kcalmol 1 smaller intrinsic barrier As for nucleophilic addition of water to the benzylic carbocations X-[6+] than for deprotonation of X-[6+] by solvent. This difference reflects the greater ease of direct addition of solvent to the charged benzylic carbon of X-[6+] than of proton transfer at the adjacent a-methyl carbon. This may result in some way from the greater number of bonds formed and cleaved in the proton transfer than in the nucleophile addition reaction. However, it is our impression that there is little or no theoretical justification for generalizations of this type. 

Durst and co-workers (309) investigated in detail the stereochemistry of deuteration and methylation of carbanions derived from optically active (+)-(5)-benzyl methyl sulfoxide 34 and (+)-(i )-benzyl t-butyl sulfoxide 290. The reactions, which allowed the extent of asymmetric induction on the a-carbon atom as well as the stereochemistry of deuteration and methylation to be determined, are summarized in Schemes 30 and 31. 

The intermediate organolithium compounds equilibrate configurationally at the lithiated center since, independent of the initial configuration of the benzylic carbon atom of the benzyl methylated product, a deprotonation/reprotonation sequence gave the same mixture of diastereo-meric products. 

Benzyl methyl ketone. Fill the Pyrex combustion tube with catalyst and proceed as in Expt 5.92 but use a temperature of 400-450 °C for the conversion of thorium carbonate into the corresponding oxide 6-12 hours are usually... 

Benzyl acetates react with trimethylsilane and CO in the presence of Co2(CO)8 as catalyst to give P-phenethyl alcohols by a one-carbon homologation. The active catalyst is assumed to be (CH3)3SiCo(CO)4. The reaction proceeds under CO at atmospheric pressure at 25°. It fails with benzyl alcohol itself, but is successful with benzyl formate and benzyl methyl ether.5... 

S)-l is obtained from the bis(methyl carbonate) of (Z)-2-butene-l,4-diol and l,2-bis(tosyl-amino)ethane through a tandem pa]ladium(0)-catalyzed allylic substitution in the presence of (R)-BINAP (I) as chiral ligand79. Equilibration of the 7t-allylpalladium intermediates formed before the intramolecular nucleophilic attack is necessary for high enantioselectivity. Thus, only a racemic piperazine is produced in the reaction of the more nucleophilic l,2-bis(benzyl-amino)ethane with the diacetate of (Z)- or ( )-2-butene-l,4-diol. 

The hydroxylation of cyclohexane, of potential interest for the production of cyclohexanone, is exceedingly slow at near room temperature and has low selectivity at 100 °C [27, 28]. Tertiary C—H bonds yield tertiary alcohols, with little or no oxidation observed at the secondary carbons that may be present in the alkyl chain t-C—H sec-C—H (Table 18.3). The steric constraints introduced by alkyl substitution strongly favor the competition of side reactions, at the expense of hydroxylation. On arylalkanes, oxidation occurs on both the aromatic ring and the alkyl chain, with a general preference for the latter. Consistently, the competitive hydroxylation of benzene and n-hexane or cyclohexane mainly occurs on the alkane. However, benzylic methyls, despite the relative weakness of their C—H... 

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