Benzyl acetate, preparation

It is prepared artificially, for use as a synthetic perfume, by several methods, for example, by heating benzyl chloride with oxide of lead to 100", or by heating benzyl chloride with potassium acetate and saponifying the benzyl acetate so formed, with caustic potash. 

Phenyl-propyl alcohol, CgH. CHj. CH.2. CHj. OH, is the next highest homologue of phenyl-ethyl alcohol, and is also known as hydro-cinnamyl alcohol. Like the last described bodies it has been known for many years, its first preparation being described in the Aivnalen (188, 202). It occurs as a cinnamic acid ester in storax, and as an acetic ester in cassia oil. It is prepared synthetically by the reduction of cinnamyl alcohol with sodium amalgam and water, or by the reduction of cinnamic or benzyl acetic esters with sodium and absolute alcohol. It has the following characters —... 

Benzyl acetate was prepared by addition of benzyl chloride (containing 0.6% pyridine as stabiliser) to preformed sodium acetate at 70°, followed by heating at 115°, then finally up to 135°C to complete the reaction. On one occasion, gas began to be evolved at the end of the dehydration phase, and the reaction accelerated to a violent explosion, rupturing the 25 mm thick cast iron vessel. This was attributed to presence of insufficient pyridine to maintain basicity, dissolution of iron by the... 

Nitrobenzyl acetate has been prepared by the action of alcoholic potassium acetate on />-nitrobenzy] chloride 1 or bromide 2 and by the nitration of benzyl acetate.3... 

Xu et al. have obtained similar results with n-butyl bromide using TBAB (10 mol%) and alumina (4 1 ivjxv) as the catalyst [13]. Benzyl acetate was also conveniently prepared from sodium acetate and benzyl halide by use of microwave irradiation and PTC in synergy [14]. 

Preparation of diethyl 3,5-di-t-butyl-4-hydroxybenzylphosphonate — Reaction of a benzylic acetate with a trialkyl phosphite... 

The procedure given here is essentially that described previously by the submitters2 and is based on the early work of Knoevenagel.8 2-Phenylindazole has been prepared by reduction of N-(o-nitrobenzyl)aniline with tin and hydrochloric acid,4 by reduction of N-(o-nitrobenzyl) -N-nitrosoaniline with tin and hydrochloric acid,5 by dehydration of 2-(phenylazo)benzyl alcohol,6 by elimination of acetic acid from 2-(phenylazo)benzyl acetate,7 by dehydrogenation of 3,3a,4,5,6,7-hexahydro-2-phenyl-indazole with sulfur,8 and by thermal decomposition of o-azido-benzalaniline.9... 

Cleavage conditions for alkyl benzyl ethers prepared from acid-labile benzyl alcohols are similar to those for the corresponding benzyl esters (Table 3.30). Aryl benzyl ethers, however, are generally cleaved more easily by acidolysis than esters or alkyl ethers. Phenols etherified with hydroxymethyl polystyrene, for instance, can even be released by treatment with TFA (Entry 1, Table 3.31). It has also been shown that Wang resin derived phenyl ethers are less stable than Wang resin derived esters towards refluxing acetic acid [29]. Alternatively, boron tribromide may be used to cleave aryl ethers from hydroxymethyl polystyrene [573],... 

The total synthesis of (+)-Macbecin I 78 [39] began with aldehyde 73, prepared via the addition of optically pure crotylsilane onto a benzylic acetal, which underwent an SMS reaction to give ester 75 in a 12 1 syn/anti ratio. Oxidative cleavage of the double bond, Wittig olefination of the resulting aldehyde and a reduction-oxidation sequence yielded a,/ -unsaturated aldehyde 76. A second SMS reaction was then performed leading to polyether 77 (dr > 20 1) that contains all the chiral centers of (+)-Macbecin I 78, Scheme 13.31. 

The benzyl acetate (18) is quantitatively determined by capillary column gas chromatography (GC). Benzyl butanoate (20), formed from butanoic acid (19) concurrently with the formation of benzyl acetate (18), serves as the internal standard (Mansson 1983). Since 1 mol of acetic acid (14) is converted to 1 mol of benzyl acetate (18), the total hydroxyl content of the lignin preparation can be determined by quantitative determination of the benzyl acetate (18). The Mansson procedure is a modification of the Bethge-Lindstrom method for determinating O-acetyl groups in acetylated carbohydrates (Bethge and Lindstrom 1973). 

The scope of this reaction is similar to that of 16-61. Anhydrides are somewhat less reactive than acyl halides, and they are often used to prepare carboxylic esters. Benzyl acetates have been prepared via microwave irradiation of benzylic alcohols... 

We will illustrate this strategy with an example found in the total synthesis of lysocellin by Yonemitsu [221,222]. As shown in Scheme 11.66, the Cl to C9 fragment was prepared by condensation of lactone 313 with the lithium salt of benzyl acetate. This part of the synthesis also serves as an illustration of sugar branching to reach a Prelog-Djerassi lactone type intermediate already mentioned in Section 11.3. A detailed discussion of this scheme follows. 

D) Preparation of Benzyl Acetate (Sm.). Place in an eight-inch tube 4 g of benzyl alcohol, 7.5 ml of glacial acetic acid, and 1 ml of concentrated sulfuric acid. Reflux by heating in a water bath for half an hour, and proceed as in section (C). Collect the fraction which boils at 210-217°. 

Esters are colorless, volatile liquids that often have pleasant odors. Many occur naturally in flowers and fruits. Isoamyl acetate (Fig. 7.27a) is generated in apples as they ripen and contributes to the flavor and odor of the fruit. Benzyl acetate, the ester formed from acetic acid and benzyl alcohol (see Fig. 7.27b), is a major component of oil of jasmine and is used in the preparation of perfumes. 

Acetoxylation of hydrocarbons. I n a paper of 1923Dimroth reported preliminary observations on the oxidation of aromatic hydrocarbons and olefins with lead tetraacetate. Toluene, he found, affords benzyl acetate in very low yield oxidation of diphenylmethane and triphenylmethane proceeded more readily but offered nothing of preparative promise. Dimroth observed also that anethole reacts to give in small yield a product of addition of two acetoxyl groups to the olefin linkage. 

R = CH3, C9H10O2, Mt 150.18, fepiookPa 215 °C, 4° 1.0550, reg1 1.5232, is the main component of jasmine absolute and gardenia oils. It occurs as a minor component in a large number of other essential oils and extracts. It is a colorless liquid with a strong, fruity, jasmine odor. Benzyl acetate is prepared by esterification of benzyl alcohol with acetic anhydride (e.g., with sodium acetate as a catalyst) or by reaction of benzyl chloride with sodium acetate. In terms of volume, benzyl acetate is one of the most important fragrance and flavor chemicals. 

Nitrobcnzyl alcohol has been secured by the oxidation of -nitrotolucne electrolytically1 or chemically,2 and by the hydrolysis of the acetate.3 4 -Iodobenzyl alcohol has been prepared by the hydrolysis of -iodobenzyl bromide and />-iodo-benzyl acetate.5 0... 

Preparation of benzyl acetate from toluene 216 Lead tetraacetate (120 g) and toluene (40 g) are boiled for 4 h in glacial acetic acid (200 ml previously distilled from potassium permanganate). Then most of the acetic acid is distilled off and the residue is treated with water and extracted with ether. The extract is washed with sodium hydrogen carbonate solution and dried then distillation in a vacuum affords the crude benzyl acetate (7.5 g). 

The acyl migration of benzylic acetates was also applied for the synthesis of indenes (equation 87). Isomeric indenes were also obtained as minor products. The transformation was actually shown to proceed via allenes, which could be independently prepared by Ag(I)-catalyzed 1,3-acetate migration from the same starting materials. Propargylic sulfides and dithioacetals undergo similar transformations as propargylic carboxylates to give indene derivatives with Au(I) or Au(III) catalysts. 

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