Phenols phenyl benzoate

Dissolve 5 g. of phenol in 75 ml. of 10 per cent, sodium hydroxide solution contained in a wide-mouthed reagent bottle or conical flask of about 200 ml. capacity. Add 11 g. (9 ml.) of redistilled benzoyl chloride, cork the vessel securely, and shake the mixture vigorously for 15-20 minutes. At the end of this period the reaction is usually practically complete and a sohd product is obtained. Filter oflf the soUd ester with suction, break up any lumps on the filter, wash thoroughly with water and drain well. RecrystaUise the crude ester from rectified (or methylated) spirit use a quantity of hot solvent approximately twice the minimum volume required for complete solution in order to ensure that the ester does not separate until the temperature of the solution has fallen below the melting point of phenyl benzoate. Filter the hot solution, if necessary, through a hot water funnel or through a Buchner funnel preheated by the filtration of some boiling solvent. Colourless crystals of phenyl benzoate, m.p. 69°, are thus obtained. The yield is 8 g. 

The three chemical reactions in the toluene—benzoic acid process are oxidation of toluene to form benzoic acid, oxidation of benzoic acid to form phenyl benzoate, and hydrolysis of phenyl benzoate to form phenol. A typical process consists of two continuous steps (13,14). In the first step, the oxidation of toluene to benzoic acid is achieved with air and cobalt salt catalyst at a temperature between 121 and 177°C. The reactor is operated at 206 kPa gauge (2.1 kg/cm g uge) and the catalyst concentration is between 0.1 and 0.3%. The reactor effluent is distilled and the purified benzoic acid is collected. The overall yield of this process is beheved to be about 68 mol % of toluene. 

The second processing step, in which benzoic acid is oxidized and hydrolyzed to phenol, is carried out in two reactors in series. In the first reactor, the benzoic acid is oxidized to phenyl benzoate in the presence of air and a catalyst mixture of copper and magnesium salts. The reactor is operated at 234°C and 147 kPa gauge (1.5 kg/cm g uge). The phenyl benzoate is then hydrolyzed with steam in the second reactor to yield phenol and carbon dioxide. This occurs at 200°C and atmospheric pressure. The overall yield of phenol from benzoic acid is around 88 mol %. Figure 2 shows a simplified diagram for the toluene—benzoic acid process. 

Phenylben oate [93-99-2] CgH COOCgH, mp, 70—71°C bp, 314°C at 101.3 kPa. This has been suggested as an antioxidant (qv) for certaiu high temperature lubricants (41). Phenyl benzoate exists as a nonisolated iatermediate iu the production of phenol from benzoic acid. 

Uses Antiseptic and disinfectant pharmaceuticals dyes indicators slimicide phenolic resins epoxy resins (bisphenol-A) nylon-6 (caprolactum) 2,4-D solvent for refining lubricating oils preparation of adipic acid, salicylic acid, phenolphthalein, pentachlorophenol, acetophenetidin, picric acid, anisole, phenoxyacetic acid, phenyl benzoate, 2-phenolsulfonic acid, 4-phenolsulfonic acid, 2-nitrophenol, 4-nitrophenol, 2,4,6-tribromophenol, 4-bromophenol, 4-/ert-butylphenol, salicylaldehyde, and many other organic compounds germicidal paints laboratory reagent. 

Solvent polarity has a strong influence on the yield of rearranged products as indicated in Table 1 for the PFR of phenyl benzoate (14) in several solvents [31]. Polar solvents favor the rearrangement, whereas nonpolar solvents favor phenol formation. An experiment carried out with methanol-ether mixtures... 

The crude solid was suspended in benzene/hexanes (1 1, 100 mL), heated, and decanted after cooling. The supernatant was applied to a column of silica gel G (70 g, benzene/hexanes 1 1) to separate the benzophenone derivative from the phenyl benzoate contaminant. The column was eluted with the same solvent (250 mL), followed by benzene/hexanes (3 1, 350 mL), and finally with benzene. Fractions (50 mL) were collected. Fractions containing the component with Rf 0.14 (silica gel, benzene) were pooled and concentrated on a rotary evaporator. Recrystallization (abs EtOH) of the residue [2.4 g (15% based on starting phenol)] gave colorless needles of 94 yield 2.2 g (14%) mp 137-138°C. 

The toluene-benzoic acid process involves three chemical reactions (1) oxidation of toluene to form benzoic acid, (2) oxidation of benzoic acid to form phenyl benzoate, and (3) hydrolysis of phenyl benzoate to form phenol. 

Zeolites H-BEA and H-Y were found to be the most active catalysts, however all catalysts readily form the phenyl benzoate (Table 4.1). In the conditions of the reaction, the formation of phenyl benzoate (PB) occurs rapidly via O-acylation of phenol. Direct C-alkylation of phenol with benzoic anhydride (B) and Fries rearrangement of phenyl benzoate results in the formation of 2- and 4-hydroxy-benzophenones (2-HPB and 4-HPB) (Scheme 4.3). 

Like alcohols, phenols form ethers such as anisole (PhOMe) and esters such as phenyl acetate and phenyl benzoate (PhCOjPh). 

Ester iealUm of phenols. The direct esterification of phenols is catalyzed by a combination of boric acid and sulfuric acid. Thus phenyl benzoate (I) can be prepared... 

In a reaction similar to that shown above for aliphatic esters [Eq. (13)], it has been reported that aromatic esters may also be reduced to the corresponding diketone provided the reduction is carried out using a cadmium cathode and magnesium anode [60]. Earlier work demonstrated that phenyl benzoate anion radical cleaves to form phenolate in good yield and presumably benzoyl radical, which leads to dibenzoyl [16]. Nitro-substituted phenyl benzoates are similarly cleaved on reduction to give phenolate [62,63]. 

The crucial step of the new phenol synthesis is oxidizing the obtained benzoic acid to phenol. Early literature data indicated that heating copper benzoate or benzoic acid in the presence of copper salts gave various phenol precursors—e.g., phenyl benzoate and salicylic acid, as well as phenol itself (3, 10, 13, 24, 26, 36). In one of the initial approaches, by Dow Chemical Co., mixtures of benzoic acid vapors, air, and steam were passed over a CuO catalyst promoted with metal salts, giving phenol and phenyl benzoate (5). However, much tar was produced, probably because of the high reaction temperature, which led to excessive decomposition. Because of this, the vapor-phase method was abandoned in favor of the liquid-phase process. Next, benzoic acid was oxidized in aqueous solution with inorganic copper salts, as shown below (18) ... 

Heating a phenol ester in the presence of Nafion-H gave good yields of the hydroxy phenyl ketone.This Fries rearrangement gave a mixture of the ortho and para hydroxy compounds in a 1 2-2.5 ratio (Eqn. 22.19). A study of the rearrangement of phenyl benzoate over a number of solid acid catalysts indicated that Nafion-H was more effective than montmorilIonite or amorphous aluminum silicate for this reaction. " ... 

F) Preparation of Phenyl Benzoate (Sm.). The use of acyl chlorides in the formation of esters is illustrated in the following preparation. Place in an eight-inch tube 1 g of phenol, 15 ml of 10 per cent sodium hydroxide solution, and 1.5 ml of benzoyl chloride. Place a solid rubber stopper firmly in the mouth of the tube and shake vigorously at intervals for 10 minutes. Remove the stopper, warm the mixture slightly, and shake again for one minute. The ester which separates is filtered, washed with cold water, and dried. The yield is about 2 g. 

Dewar, M. J. S., Hart, L. S. Aromatic rearrangements in the benzene series. I. Fries rearrangement of phenyl benzoate the benzoylation of phenol. Tetrahedron 1970, 26, 973-1000. 

Cupric benzoate decarboxylates thermally with the production of cuprous benzoate and phenyl benzoate. It is regenerated by the action of oxygen and benzoic acid. Phenol. is obtained by the steam hydrolysis of phenyl benzoate. 

Unmodified BEA zeolite, on the other hand, shows the highest activity in the acylation of phenol wifh benzoic anhydride. Phenyl benzoate (PB) is the main product (61% yield), accompanied by C-acylated products (35%), with an interesting para-selectivity (ortho/para = 0.48). When the reaction time is increased from 4 to 20 h, an increase in para-hydroxy-benzophenone yield (from 11% to 23%) fogefher wifh a decrease in PB yield (from 79% to 64%) is observed however, a small increase in the orf/zo-hydroxybenzophenone yield (from 9% to 10%) cannof be avoided. The acfivify of the catalyst, together with its selectivity, does not distinctly decrease when the catalyst is used from fresh to firsf recycle. 

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