Benzoic acid, from oxidation

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. 

The following example illustrates in detail the preparation of amino benzoic acids from the hot reaction product obtained by the oxidation of a xylene and containing a mixture of salt, amide salt and diamide of a phthalic acid. 

We have also found that BTMA Br3 can be used as a reagent for the oxidation of benzyl alcohols to benzoic acids. That is, the reaction of benzyl alcohols with 2-equiv. of BTMA Br3 in an aq. alkaline solution at room temperature or at 70°C afforded benzoic acids in good yields. Thus, we could selectively obtain the oxidation products, benzaldehydes and benzoic acids, from benzyl alcohols by using a stoichiometric amount of BTMA Br3 (Fig. 24) (ref. 32). 

A minor route, which now accounts for 2% of phenol, takes advantage of the usual surplus of toluene from petroleum refining. Oxidation with a number of reagents gives benzoic acid. Further oxidation to p-hydroxybenzoic acid and decarboxylation yields phenol. Here phenol competes with benzene manufacture, also made from toluene when the surplus is large. The last 2% of phenol comes from distillation of petroleum and coal gasification. 

Kennedy and Stock reported the first use of Oxone for many common oxidation reactions such as formation of benzoic acid from toluene and of benzaldehyde, of ben-zophenone from diphenyhnethane, of frawi-cyclohexanediol Ifom cyclohexene, of acetone from 2-propanol, of hydroquinone from phenol, of e-caprolactone from cyclohexanone, of pyrocatechol from salicylaldehyde, of p-dinitrosobenzene from p-phenylenediamine, of phenylacetic acid from 2-phenethylamine, of dodecylsulfonic acid from dodecyl mercaptan, of diphenyl sulfone from diphenyl sulfide, of triphenylphosphine oxide from triphenylphosphine, of iodoxy benzene from iodobenzene, of benzyl chloride from toluene using NaCl and Oxone and bromination of 2-octene using KBr and Oxone . Thus, they... 

The recovery and purification of benzoic acid from a liquid-phase toluene oxidizer may involve distillation alone or it may involve a combination of distillation followed by extraction and crystallization. 

The activity and selectivity of 19 oxides at 400—450°C were investigated by Germain and Laugier [133], The activities are compared with those for the oxidation of toluene in Fig. 8, and show a linear relationship for the major part of the oxides, the toluene oxidation being approximately twice as fast as the benzene oxidation. The only selective catalysts, i.e. those that produce substantial amounts of benzoquinone and maleic anhydride from benzene, and benzaldehyde and benzoic acid from toluene are the oxides of V, Mo and W. Remarkably, these oxides clearly deviate from the average correlation in Fig. 8 and show a much higher tol-uene/benzene activity ratio (about 10/1). The order of activity, maximum yield of maleic aldehyde and initial selectivity with respect to benzoquinone is the same for these oxides V > Mo > W. 

A halo acid, p-(/S-bromoethyl)-benzoic acid (87%), a hydroxy acid, yS-hydroxyisovaleric acid (9%), and an acetylated amino acid, p-(/3-acetyl-aminoethyl)4>enzoic acid (78%), have been made by this method. Attempts to prepare 3-nitro- and 4-hydroxy-benzoic acids from the corresponding acetophenones have failed. Oxidation of the methylene group of 2-acetylfluorene occurs during the reaction to give fluorenone-2-car-boxylic acid (60%). ... 

Derivation (1) Decarboxylation of phthalic anhydride in the presence of catalysts (2) chlorination of toluene to yield benzotrichloride, which is hydrolyzed to benzoic acid (3) oxidation of toluene (4) from benzoin resin. 

From the pioneering experiments of Spath and Kahovec (128a) which were reviewed in Volume II, the partial formula XXI was proposed for tazettine to accommodate the degradation of the alkaloid to hydrastic acid by permanganate oxidation and to phenanthridine by zinc dust distillation. Tazettine methine, the product of the Hofmann degradation, was formulated as XXII to explain the formation of benzoic acid on oxidation with permanganate. Hofmann degradation of tazettine methine methohydroxide afforded 6-phenylpiperonyl alcohol. 

Preparation of the corresponding cA-16a,17a-diol relies on the known propensity of many inorganic oxidizing agents to produce cA-diols. The sequence for synthesizing that isomer starts with heat-induced elimination of the elements of benzoic acid from estradiol 17-benzoate. The resulting 16-dehydro compound, 31-2, is then treated with osmium tetraoxide (Scheme 3.31). The stereochemistry of that transformation can be rationalized by positing the intermediacy of a complex such as that depicted in 31-3. The overall result is the formation of the c -diol 16a-hydroxy-a-estradiol (31-4). 

The production of benzoic acid from naphthalene, practised up to the end of World War II, is possible in one stage, without the isolation of the intermediate phthalic acid. Oxidation of naphthalene is carried out at 340 °C with zinc oxide. This decarboxylates the phthalic acid in the gas-phase however, conversion in this reaction is not complete, and the benzoic add must be separated from the phthalic acid. Separation is possible by dissolving the phthalic acid in water. 

Compound A (C Hjj) shows prominent peaks in its mass spectrum at miz 120 and 105. Compound B (also C Hjj) shows prominent peaks at mIz 120 and 91. On vigorous oxidation with chromic acid, both compounds give benzoic acid. From this information, deduce the structural formulas of compounds A and B. 

Peroxy benzoic acid N-Oxide radicals from amines... 

Oxidation Products.—Ai-omatic alcohols possessing the group -CHoOH may readih be oxidized to the corresponding acid. Example Benzoic acid from benzyl alcohol. The method is similar to that to be outlined later in this chapter for the oxidation of side-chains of aromatic hydrocarbons except that the reaction is more rapid and the yields are higher. 

In Table 3 are listed the structures and transcriptional activation activities of retinoids reported as receptor-selective based on their preferential ability to induce one retinoid receptor complex to activate gene transcription from a particular RE compared to the activities of the standards. These retinoid agonists are commonly used to identify the retinoid receptor having the most influence on a particular retinoid-signalling pathway. Four retinoids—TTNPB [23], TTNN [51], TTAB [53, 54], SRI 1256 [104], and SRI 1365 [105]—are listed as RAR class selective because they only activate the RARs. Of these, TTNPB, TTAB, and the A-oxide SRI 1365 are the most transcriptionally selective across all RAR subtypes, whereas TTNN preferentially activates RAR(3 and RARy. At higher concentrations SRI 1256,4-[3-(5,6,7,8-tetrahy-dro-5,5,8,8-tetramethyl-2-naphthalenyl)phenyl]benzoic acid, can also activate the RXRs. The parent 4-(6,7,8,9-tetrahydro-6,6,9,9-tetramethylnaphtho[2,3-Z ]pyridin-2-yl)benzoic acid from which SRI 1365 is derived was first reported by the Shudo group [106]. 

It was first described in 1608 when it was sublimed out of gum benzoin. It also occurs in many other natural resins. Benzoic acid is manufactured by the air oxidation of toluene in the liquid phase at 150°C and 4-6 atm. in the presence of a cobalt catalyst by the partial decarboxylation of phthalic anhydride in either the liquid or vapour phase in the presence of water by the hydrolysis of benzotrichloride (from the chlorination of toluene) in the presence of zinc chloride at 100°C. 

Prepare a mixture of 30 ml, of aniline, 8 g. of o-chloro-benzoic acid, 8 g. of anhydrous potassium carbonate and 0 4 g. of copper oxide in a 500 ml. round-bottomed flask fitted with an air-condenser, and then boil the mixture under reflux for 1 5 hours the mixture tends to foam during the earlier part of the heating owing to the evolution of carbon dioxide, and hence the large flask is used. When the heating has been completed, fit the flask with a steam-distillation head, and stcam-distil the crude product until all the excess of aniline has been removed. The residual solution now contains the potassium. V-phenylanthrani-late add ca. 2 g. of animal charcoal to this solution, boil for about 5 minutes, and filter hot. Add dilute hydrochloric acid (1 1 by volume) to the filtrate until no further precipitation occurs, and then cool in ice-water with stirring. Filter otT the. V-phcnylanthranilic acid at the pump, wash with water, drain and dry. Yield, 9-9 5 g. I he acid may be recrystallised from aqueous ethanol, or methylated spirit, with addition of charcoal if necessary, and is obtained as colourless crystals, m.p. 185-186°. 

I. Oxidation to benzoic acid. Boil a mixture of i ml. of benzyl chloride, 50 ml. of saturated aqueous KMn04 solution and 2 g. of anhydrous Na.jCOj under reflux for 30 minutes. Acidify with cone. HCl and then add 25% Na SOj solution until the brown precipitate of MnOj has dissolved. On cooling, benzoic acid crystallises out. Filter through a small Buchner funnel, wash with water and identify (P 347) When recrystallised from water, benzoic acid has m.p. 121 . 

Decarbonylation of aromatic aldehydes proceeds smoothly[71], Terephthalic acid (86), commercially produced by the oxidation of p-.xylene (85), contains p-formylbenzoic acid (87) as an impurity, which is removed as benzoic acid (88) by Pd-catalyzed decarbonylation at a high temperature. The benzoic acid produced by the decarbonylation can be separated from terephthalic acid (86) based on the solubility difference in water[72]. 

Synthetic phenol capacity in the United States was reported to be ca 1.6 x 10 t/yr in 1989 (206), almost completely based on the cumene process (see Cumene Phenol). Some synthetic phenol [108-95-2] is made from toluene by a process developed by The Dow Chemical Company (2,299—301). Toluene [108-88-3] is oxidized to benzoic acid in a conventional LPO process. Liquid-phase oxidative decarboxylation with a copper-containing catalyst gives phenol in high yield (2,299—304). The phenoHc hydroxyl group is located ortho to the position previously occupied by the carboxyl group of benzoic acid (2,299,301,305). This provides a means to produce meta-substituted phenols otherwise difficult to make (2,306). VPOs for the oxidative decarboxylation of benzoic acid have also been reported (2,307—309). Although the mechanism appears to be similar to the LPO scheme (309), the VPO reaction is reported not to work for toluic acids (310). 

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