Benzoic acid phenol from

Retention volumes of monosubstituted benzenes, benzoic acid, phenols, and anilines have been measured in RPLC [76]. Buffered acetonitrile/water and tetrahydrofuran/water eluents were used with an octadecylsilica adsorbent. From the net retention volumes, a substituent interaction effect was calculated and described with the linear free energy relationship developed by Taft. The data was interpreted in terms of hydrogen bonding between the solutes and the eluent. 

A potentiometric method for determination of ionization constants for weak acids and bases in mixed solvents and for determination of solubility product constants in mixed solvents is described. The method utilizes glass electrodes, is rapid and convenient, and gives results in agreement with corresponding values from the literature. After describing the experimental details of the method, we present results of its application to three types of ionization equilibria. These results include a study of the thermodynamics of ionization of acetic acid, benzoic acid, phenol, water, and silver chloride in aqueous mixtures of acetone, tetrahydrofuran, and ethanol. The solvent compositions in these studies were varied from 0 to ca. 70 mass % nonaqueous component, and measurements were made at several temperatures between 10° and 40°C. 

TEMPERATURE TRANSFER STANDARD. A device for the transfer of a temperature scale from one standardizing laboratory to another. One form consists of a sample of a purified material, the freezing point of which (when realized by a prescribed technique) is reproducible within narrow limits. Materials commonly employed are metals, such as zinc and tin, and organic compounds, such as benzoic acid, phenol, naphthalene, and phthalic anhydride. Another form is a tungsten ribbon-filament lamp, characterized by a stable lamp current-brightness temperature relation. This device is particularly useful for temperatures above 1.050WC. 

Studies of benzene and toluene oxidation in the turbulent flow reactor at Princeton University have provided valuable information on the mechanisms of oxidation at temperatures in excess of 1000 K [213]. The first extensive study of benzene and toluene at temperatures of about 750 K was made by Burgoyne [35]. Apart from CO and CO2, the major products of benzene oxidation that were detected were phenols and acids. An autocatalytic reaction was observed by Burgoyne [35] presumably driven by H2O2 formation and decomposition. Amongst the main products of toluene slow oxidation were benzyl alcohol, benzaldehyde and benzoic acid. Phenolic compounds were also reported. This reaction also showed an autocatalytic development. An equilibrium constant for the equilibrium between benzyl and benzylperoxy radicals has been measured by Fenter et al. [214], but this cannot be followed by an isomerization in the way that is possible in alkanes. 

SkeUand [83] was the first to utilize non-Newtonian liquids in the design ofELM. In this and related studies, the non-Newtonian LMs were prepared from Soltrol 220 (an isoparaffinic oil. Chevron Philips Chemical, Spring, TX, USA) as the diluent, polystyrene [81], polyisobutylene [74], and polybutadiene [80] as polymers, SPAN 80 as the surfactant and different aqueous solutions were used as stripping phases depending on the nature of the solute removed from the treated wastewaters [74]. SkeUand and Meng [80] studied the removal of benzoic acid, phenol and ammonia from simulated wastewater. 

Little work has been reported on salicylate solutions Downes (22) found G(C02) = 1.53 in aerated alkaline solutions, and reported the formation of 2,3- and 2,5-dihydroxybenzoic acids. In a reference (30) to unpublished work by Capellos and Swallow, all three isomeric hydroxy-benzoic acids were reported to undergo further hydroxylation salicylic acid gave the 2,3-, 2,4- and 2,5-dihydroxybenzoic acids. More detailed studies (37) have indicated that in deaerated solutions of salicylate at pH 6.3 there is no detectable hydroxylation, the products being almost exclusively C02 and dihydroxydiphenyl with the simple stoichiometry G(-salicylate) = G(C02) = 1.6 = 2G(dihydroxydiphenyl). In both acid and alkaline solutions a wider range of products was found, including dihydroxybenzoic acids, benzoic acid, phenol and catechol. The formation of catechol from salicylic acid has also been reported by Matthews and Sangster (31). 

The reactions of aromatic compounds (Chapter 19 and 20) now come after carbonyl chemistry. If something needs to be deleted from the course to find room to teach the organic chemistry that occurs in cells, some of the material in these chapters might be omitted. Electronic effects (now introduced in Chapter 8) are important, but these could be revisited by showing how they affect pA" values substituted benzoic acids, phenols and anilinium ions rather than how they affect the reactivity of a benzene ring (Section 19.16). The electrophilic aromatic substitution reactions of benzene and the nucleophilic substitution reactions of pyridine are important, but the rest of the material in these chapters could be omitted as it will not be important to material that appears in subsequent chapters. 

Xylenes can also be degraded microbiologically to methylbenzoic acids and to xylenols [111, 112]. Since benzoic acids, phenols, xylenols etc. are hydrophilic decomposition products of volatile aromatics, it may be mentioned that these derivatives are easily biodegraded further by microbes [113-120]. Appart from these aerobic biodegredation reactions, also anaerobic biodegradation reactions are possible under special circumstances [113]. 

Separations based upon differences in the chemical properties of the components. Thus a mixture of toluene and anihne may be separated by extraction with dilute hydrochloric acid the aniline passes into the aqueous layer in the form of the salt, anihne hydrochloride, and may be recovered by neutralisation. Similarly, a mixture of phenol and toluene may be separated by treatment with dilute sodium hydroxide. The above examples are, of comse, simple apphcations of the fact that the various components fah into different solubihty groups (compare Section XI,5). Another example is the separation of a mixture of di-n-butyl ether and chlorobenzene concentrated sulphuric acid dissolves only the w-butyl other and it may be recovered from solution by dilution with water. With some classes of compounds, e.g., unsaturated compounds, concentrated sulphuric acid leads to polymerisation, sulphona-tion, etc., so that the original component cannot be recovered unchanged this solvent, therefore, possesses hmited apphcation. Phenols may be separated from acids (for example, o-cresol from benzoic acid) by a dilute solution of sodium bicarbonate the weakly acidic phenols (and also enols) are not converted into salts by this reagent and may be removed by ether extraction or by other means the acids pass into solution as the sodium salts and may be recovered after acidification. Aldehydes, e.g., benzaldehyde, may be separated from liquid hydrocarbons and other neutral, water-insoluble hquid compounds by shaking with a solution of sodium bisulphite the aldehyde forms a sohd bisulphite compound, which may be filtered off and decomposed with dilute acid or with sodium bicarbonate solution in order to recover the aldehyde. 

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). 

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. 

Benzoic Acid. Ben2oic acid is manufactured from toluene by oxidation in the liquid phase using air and a cobalt catalyst. Typical conditions are 308—790 kPa (30—100 psi) and 130—160°C. The cmde product is purified by distillation, crystallization, or both. Yields are generally >90 mol%, and product purity is generally >99%. Kalama Chemical Company, the largest producer, converts about half of its production to phenol, but most producers consider the most economic process for phenol to be peroxidation of cumene. Other uses of benzoic acid are for the manufacture of benzoyl chloride, of plasticizers such as butyl benzoate, and of sodium benzoate for use in preservatives. In Italy, Snia Viscosa uses benzoic acid as raw material for the production of caprolactam, and subsequendy nylon-6, by the sequence shown below. 

In the Hquid-phase process, both benzaldehyde and benzoic acid are recovered. This process was iatroduced and developed ia the late 1950s by the Dow Chemical Company, as a part of their toluene-to-phenol process, and by Snia Viscosa for their toluene-to-caprolactam process. The benzaldehyde recovered from the Hquid-phase air oxidation of toluene may be purified by either batch or continuous distillation. Liquid-phase air oxidation of toluene is covered more fully (see Benzoic acid). 

Benzaldehyde is produced ia the United States by Kalama Chemical Incorporated, Kalama, Washington and ia Canada by Chatterton Petrochemical Corporation, Delta, British Columbia. Both plants were constmcted by The Dow Chemical Company ia the early 1960s to produce phenol from benzoic acid and both produce benzaldehyde as a by-product of that process (6). Production and sales figures for benzaldehyde are not available. 

The hydroxyl group of the resulting phenol is situated immediately adjacent to where the carboxyl group was previously located. This same Hquid-phase copper oxidation process chemistry has been suggested for the production of cresols by the oxidation of toluic acids. y -Cresol would be formed by the oxidation of either ortho or para toluic acids a mixture of 0- and -cresols would be produced from y -toluic acid (6). A process involving the vapor-phase catalytic oxidation of benzoic acid to phenol has been proposed, but no plants have ever been built utilizing this technology (27). 

Caprolactam. At the same time that Dow was constmcting toluene to phenol plants, Snia Viscosa (28—30) introduced two processes for the manufacture of caprolactam (qv) from benzoic acid. The earlier process produced ammonium sulfate as a by-product, but the latter process did not. In either process benzoic acid is hydrogenated to cyclohexanecarboxyHc acid [98-89-5] which then reacts with nitrosylsulfuric acid to form caprolactam [105-60-2]. 

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. 

A mixture of 10 g of 4-(2, 4 -difluorophenyl)-phenol and 27.2 g of potassium carbonate is exposed to carbon dioxide at 1,300 psi and 175°C. The dark mass obtained from this car-donation is then dissolved in 300 ml of water and 200 ml of methylene chloride and the two layers separated. The water layer is then extracted with 100 ml of methylene chloride and then acidified with 2.5 N hydrochloric acid. This mixture is then filtered and the cake dried in vacuo to yield 5.32 g of the crude product. The crude product is then recrystallized from benzene-methanol. An additional crystallization of this semipure material from benzene-methanol yields analytically pure 2-hydroxy-5-(2, 4 -difluorophenyl)-benzoic acid (MP 210°-211°C). 

Phenol is also produced from chlorobenzene and from toluene via a benzoic acid intermediate (see Reactions and Chemicals from Toluene ). 

Phenol was the first commercial antiseptic its introduction into hospitals in the 1870s led to a dramatic decrease in deaths from postoperative infections. Its use for this purpose has long since been abandoned because phenol burns exposed tissue, but many modern antiseptics are phenol derivatives. Toluene has largely replaced benzene as a solvent because it is much less toxic. Oxidation of toluene in the body gives benzoic acid, which is readily eliminated and has none of the toxic properties of the oxidation products of benzene. Indeed, benzoic acid or its sodium salt (Na+, C6H5COO ions) is widely used as a preservative in foods and beverages, including fruit juices and soft drinks. 

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