Phenols benzylic

Benzyl chloride reacts with benzene in the presence of a Lewis acid catalyst to give dipbenylmetbane [101 -81-5]. It undergoes self-condensation to form polymeric oils and soHds (21). With phenol, benzyl chloride produces a mixture of o- andp-her zylpbeno1. 

Mel, K2CO3, acetone, reflux, 6 h. This is a veiy common and often veiy efficient method for the preparation of phenolic methyl ethers it is also applicable to the. formation of phenolic benzyl ethers. 

Sodium A-methylanilide, xylene, HMPA, 60-120°, 70-95% yield. Methyl ethers of polyhydric phenols are cleaved to give the mono-phenol. Benzyl ethers are also cleaved. Halogenated phenols are not effectively cleaved, because of competing aromatic substitution. 

Catalytic hydrogenation in acetic anhydride-benzene removes the aromatic benzyl ether and forms a monoacetate hydrogenation in ethyl acetate removes the aliphatic benzyl ether to give, after acetylation, the diacetate. Trisubstituted aDcenes can be retained during the hydrogenolysis of a phenolic benzyl ether. ... 

Sanchez, A. J. Konopelski, J. P. Phenol benzylic epoxide to quinone methide electron reorganization synthesis of ( )-taxodone. J. Org. Chem. 1994, 59, 5445-5452. 

Toluene is used more commonly than the other BTXs as a commercial solvent. There are scores of solvent applications, though environmental constraints and health concerns diminish the enthusiasm for these uses. Toluene also is used to make toluene diisocyanate, the precursor to polyurethane foams. Other derivatives include phenol, benzyl alcohol, and benzoic acid. Research continues on ways to use toluene in applications that now require benzene. The hope is that the dealkylation-to-benzene or disproportionation steps can be eliminated. Processes for manufacturing styrene and terephthalic acid—the precursor to polyester fiber—are good, commercial prospects. 

Hydroxy compounds in the aromatic series behave dilferently depending on whether the hydroxy group is phenolic, benzylic or more remote from the ring. 

Problem 19,14 Assign numbers from 1 for least to 4 for most to indicate the relative acid strengths in the following groups (a) phenol, m-chlorophenol, m-nitrophenol, m-cresol (b) phenol, benzoic acid, p-nitro-phenol, carbonic acid (c) phenol, p-chlorophenol, p-nitrophenol, p-cresol (d) phenol, o-nitrophenol, m-nitrophenol, p-nitrophenol (e) phenol, p-chlorophenol, 2,4,6-trichlorophenol, 2,4-dichlorophenol (/) phenol, benzyl alcohol, benzenesulfonic acid, benzoic acid. ... 

Preservative agents are added to injectable preparations when multiple dosing is expected out of the same unit. Examples of preservatives used in injectable preparations include phenol, benzyl alcohol, methyl and ethyl parabens, and benzalkonium... 

For bipolar organic liquids, especially for hydrogen-bonding liquids such as alcohols and amines, the tendency to orient in the liquid phase, due to these highly directional intermolecular attractions, is greatly increased by this intermolecular interaction. We can see the effect of this in the significantly larger entropies of vaporization of bipolar chemicals, like aniline, phenol, benzyl alcohol, or ethanol (Table 4.2). 

Regioselective reductive openings of mixed phenolic-benzylic cyclic acetals, using BH3-NMe3-AlCl3, under mild conditions to yield a benzylic ether and free the phenol group have been attributed to association of boron with the more basic oxygen (benzylic) followed by reaction with aluminium chloride.309... 

Buu-Hoi, N. P. Demerseman, P. Zinc chloride-catalyzed benzylations of phenols and naphthols./. Org. Chem. 1955, 20, 1129—1134. Curtin, D. Y. Crawford, R. J. Wilhelm, M. Factors controlling position of alkylation of alkali metal salts of phenols, benzyl and allyl halides./. Am. Chem. Soc. 1958, 80, 1391— 1397. 

Castellan, A., Vanucci, C., Bous-Laurent, H., "Photochemical Degradation of Lignin Through a C-0 Bond Cleavage of Non-phenolic Benzyl Aryl Ether Units. A Study of the Photochemistry of a(2 ,4 -Trimethyl-Phenoxy)-3,4 Dimethoxy Toluene.", Hohforschmg, 1987, 41(4), 231. 

No strong differences were observed when multicomponent mixtures of phenols (phenol, benzyl alcohol, 1-phenyl-ethanol and m-cresol) were treated (Morao et al. 2004) the experimental results were interpreted well by assuming that all the components in the mixture were degraded in the same time and that the combustion of the compounds to C02 occurred at the anode surface by means of hydroxyl radicals electrogenerated. The instantaneous current efficiency was unity, until the reaction became diffusion controlled. 

Show how you would use extractions with a separatory funnel to separate a mixture of the following compounds benzoic acid, phenol, benzyl alcohol, aniline. 

These benzaldehydes could then be directly used as a feedstock for various polymeric products or reduced to form phenolic benzylic alcohol derivatives (i.e., p-methylol groups). The p-methylol groups would thus be active sites, whereas in unmodified lignins, the C-l site is blocked and unreactive. In addition, the oxidative-cleavage step will hydrolyze a portion of the lignin interunit ether bonds, and thus increase the total fraction of free phenolic units to further enhance the reactivity. Other possible benefits are that the lignin would be extensively depolymerized and would form a more uniform feedstock material both conditions would give a product that is easier to handle. 

In the penultimate step of a synthesis of the unstable antibiotic Streptazolin, an iron tricarbonyl group co-ordinated to a 1.3-diene unit and two benzyl ethers were severed simultaneously using tribromoborane at -90 °C [Scheme 4.148].274 Tribromoborane has also been used to deprotect a phenolic benzyl ether in the presence of two phenolic methyl ethers in a synthesis of the alkaloid Lythrancepine [Scheme 4.149].275... 

Catalytic hydrogenolysis of BOM ethers is typically accomplished with Pd/C in ethanol, ethyl acetate or THF. At the close of a synthesis of FR-900482, a phenolic benzyl ether and a benzyloxy BOM ether were hydrogenolysed without... 

A variety of benzene-derivatives are found in many grape varieties, including vinyl phenols, benzyl alcohol, 2-phenyl ethanol and raspberry ketone. Vinyl phenols are characterised by spice and dove-like, 2-phenyl ethanol by rose and lilac, and raspberry ketone by a raspberry attribute (Francis and Newton 2005). It should be noted that, although a portion of 2-phenyl ethanol can derive from glycoside hydrolysis, a greater proportion of this compound is formed in the metabolism of the amino acid phenylalanine (Ugliano et al. 2006). 

Aldehydes have been formed from alcohols by the use of other oxidizing agents. Dihydroxyacetone has been oxidized with excess cupric acetate to hydroxypyruvic aldehyde in 87% yield. p-Cyanobenzyl alcohol treated at 0° with a chloroform solution of nitrogen tetroxide gives practically pure p-cyanobenzaldehyde (90%). Aromatic alcohols containing nitro groups have been oxidized to the corresponding nitro aldehydes with concentrated nitric acid, e.g., o- and p-nitrobenzaldehydes (80-85%). m-Nitrobenzenesulfonic acid in basic media has been used for the oxidation of substituted benzyl alcohols, most satisfactorily for the water-soluble phenolic benzyl alcohols. Selenium dioxide, or less effectively tellurium dioxide, oxidizes benzyl alcohol slowly to benzaldehyde. ... 

The phenolic benzyl ether is much more acid labile than the benzyl ethers of serine and threonine. Therefore, O-benzyltyrosine is not adequately stable for multistep SPPS with the Boc/Bzl strategy. To prevent loss of the O-benzyl protection, halogenated benzyl deriva-tivesP have been developed (Scheme 7) the most often used derivative, H-Tyr[Bzl(2,6-Cl2)]-OH, is -5000 times more stable to 50% TFA/CH2CI2 treatment than the unsubstituted benzyl compound. 

IR phenol, benzyl alcohol, di- and triphenyl carbinols in various solvents, 3m-... 

In the final step, palladium on charcoal is used for the hydrogenation of the double bonds with concomitant removal of the phenolic benzyl protection group to provide 27 ,4i ,8i -a-tocopherol (1) in a 1 1 mixture with the 27 ,4 S, 87 -epimer. 

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