Benzyl alcohol esterification

Ben /ben ate [120-51-4] CgH COOCH2CgH, mp, 21°C, cff , 1.118 bp, 323—324°C at 101.3 kPa , 1.5681. This is a colorless, oily liquid with a faiat, pleasant aromatic odor and a sharp, burning taste. It occurs naturally iu Pern and Tolu balsams, is spariugly volatile with steam, and is iusoluble iu water. Benzyl benzoate is prepared commercially by the direct esterification of benzoic acid and benzyl alcohol or by reaction of benzyl chloride and sodium benzoate. The pleasant odor of benzyl benzoate, like other benzoic esters, has long been utilized iu the perfume iadustry, where it is employed as a solvent for synthetic musks and as a fixative. It has also been used iu confectionery and chewing gum flavors. 

Ethylenediamine (70,71), benzyl alcohol and acetone (72), ethylene glycol (73) and C2—C g carboxyUc acids (74) are claimed to increase the reactivity of cellulose toward acetylation. Sodium hydroxide and Hquid ammonia (71) are excellent swelling agents and have been used to activate cellulose before esterification. Ultrasonic treatment of cellulose slurries (75) reportedly swells the fibers and improves reactivity. 

Izumi and Urabe [105] found first that POM compounds could be entrapped strongly on active carbons. The supported POMs catalyzed etherization of ferf-butanol and n-butanol, esterification of acetic acid with ethanol, alkylation of benzene, and dehydration of 2-propanol [105], In 1991, Neumann and Levin [108] reported the oxidation of benzylic alcohols and amines catalyzed by the neutral salt of Na5[PV2Mo10O40] impregnated on active carbon. Benzyl alcohols were oxidized efficiently to the corresponding benzaldehydes without overoxidation ... 

A variant that eliminates the production of water and that has proved effective for esterification of hydroxy and aromatic amino acids involves the use of thionyl chloride instead of acid. At a low temperature, the alcohol reacts with the chloride, generating methyl sulfinyl chloride, which produces the ester, probably through the mixed carboxylic acid-sulfinic acid anhydride (Figure 3.18, B). p-Toluenesulfonyl chloride added to the acid and benzyl alcohol serves the same purpose in the preparation of benzyl esters. 

Figure 1 Structural formula of HA and the ethyl (Hyaff7), docecyl (Hyaff73) and benzyl (Hyaffl 1) esters. The esterification reaction was carried out starting from a quaternary ammonium salt of HA and the ethyl, dodecyl and benzyl alcohols, respectively, in a suitable aprotic solvent.

Furthermore, the apphcabihty in a Mitsunobu esterification reaction and a Diels-Alder reaction was proven (Scheme 10.13). The polymer-bound benzyl alcohol (70) was reacted with 4-acetamidophenol in the presence of the Mitsunobu reagent to give phenyl ether (71) in quantitative yield. It was released from the polymeric support in high yield. 

With the methylated PAHs, another bioactivation pathway leading to benzylic carbocations becomes available through side chain oxidation to form a benzylic alcohol, followed by esterification and solvolysis. Thus, benzylic sulfate ester formation (via initial formation of benzyl alcohol) constitutes an additional route that could contribute to metabolic activation (Fig. 2). ... 

Benzyl alcohol readily undergoes the reactions characteristic of a primary alcohol, such as esterification and etherification, as well as halide formation. In addition, it undergoes ring substitution. In the presence of acid, polymerization is observed, and the alcohol can be thermally dehydrated to toluene [108-88-3], Catalytic oxidation over copper oxide yields benzaldehyde benzoic acid is obtained by oxidation with chromic acid or potassium permanganate. Catalytic hydrogenation of the ring gives cyclohexylmethanol [100-49-2]. 

Attachment of carboxylic acids to supports as trityl esters is achieved by treatment of the corresponding trityl chloride resin with the acid in the presence of an excess of a tertiary amine (Figure 3.5 see also Section 13.4.2). This esterification usually proceeds more quickly than the acylation of benzyl alcohol linkers. Less racemization is generally observed during the esterification of A-protected a-amino acids with trityl linkers than with benzyl alcohol linkers [47], If valuable acids are to be linked to insoluble supports, quantitative esterification can be accomplished by using excess 2-chlorotrityl chloride resin, followed by displacement of the remaining chloride with methanol [64]. 

Most acid-labile benzyl alcohol linkers suitable for the attachment of carboxylic acids to insoluble supports can also be used to attach aliphatic or aromatic alcohols as ethers. The attachment of alcohols as ethers is less easily accomplished than esterification, and might require the use of strong bases (Williamson ether synthesis [395,552,553]) or acids. These harsh reaction conditions limit the range of additional functional groups that may be present in the alcohol. Some suitable etherification strategies are outlined in Figure 3.31. Etherifications are treated in detail in Section 7.2. 

Carbonyl)chlorohydridotris(triphenylphosphine)ruthenium(II) was used as a catalyst in the transfer hydrogenation of benzaldehyde with formic acid as a hydrogen source. Under these conditions, the reduction ofbenzaldehyde to benzyl alcohol is accompanied by esterification of the alcohol with the excess of formic acid to provide benzyl formate (Scheme 4.16). In this microwave-assisted reaction, the catalyst displayed improved turnover rates compared to the thermal reaction (280 vs. 6700 turnovers/h), thus leading to shorter reaction times36. 

Pyrethroids from Chrysanthemic Acid, The unsaturated side chains of the allethrolone alcohol moieties of the natural pyrethrins are readily epoxidized by microsomal oxidases and converted to diols, thus detoxifying the insecticides. Esterification of chrysanthemic acid (9), R = CH3, with substituted benzyl alcohols produces useful insecticides barthrin [70-43-9], 2-chloro-3,4-methylenedioxybenzyl ( )-of,/ra/w-chrysanthemate, and dimethrin [70-38-2], 2,4-dimethylbenzyl ( )-og/rinsecticidal activity but are of very low mammalian toxicity, ie, rat oralLDBOs >20,000 mg/kg. 

Aromatic esters may be prepared by direct esterification methods similar to those already described for aliphatic esters (Section 5.12.3, p. 695). A large range of examples of simple alkyl esters of aromatic carboxylic acids is included in Expt 6.163. Corresponding esterification of a simple aliphatic acid (e.g. acetic acid) with benzyl alcohol is illustrated in Expt 5.142. 

It is prepared by esterification of benzyl alcohol, by heating with either an excess of acetic anhydride or acetic acid with mineral acids. 

Acyl chloride-functionalized SWCNTs are also susceptible to reactions with other nucleophiles, e.g. alcohols. Haddorfs group reported the preparation of soluble ester-functionalized carbon nanotubes SWCNT-COO(CH2)17CH3 (Fig. 1.6a) obtained by esterification with octadecanol [134]. The syntheses of soluble polymer-bound and dendritic ester-functionalized SWCNTs have been reported by Riggs et al. by attaching poly(vinyl acetate-co-vinyl alcohol) (Fig. 1.6b) [135] and hydrophilic and lipophilic dendron-type benzyl alcohols [119], respectively, to SWCNT-COC1 (Fig. 1.6c). These functional groups could be removed under basic and acidic hydrolysis conditions and thus additional evidence for the nature of the attachment was provided [119, 136]. 

Possible competitive reactions (e.g., cycloadditions on the double bond) proceed only very slowly with diazotoluene dibenzyl ether is produced by the reaction with water so that strictly anhydrous conditions are not necessary. Similarly, the presence of traces of water does not interfere with the esterification with the aid of N,N -dicyclohexyl-0-benzylisourea, which reacts with water with the production of benzyl alcohol. The reagent is synthesized from dicyclohexylcarbodiimide and benzyl alcohol with copper(I) chloride as the catalyst. The esterification proceeds according to Scheme 5.16. 

Benzyl and p-nitrobenzyl esters are usually made by classical methods such as reaction of benzyl alcohol with an acid chloride in the presence of pyridine or with a carboxylic acid in the presence of a carbodiimide (see general esterification methods). We have already shown the conversion of the cesium salt of a carboxylic acid to its benzyl ester by reaction with benzyl bromide [Scheme 6.40] ... 

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