Benzoic acid purification

Performance data have been reported by Kennedy et al. (The Purification of Inorganic and Organic Mateiials, Marcel Dekker, New York, 1969, p. 261) for continuous-zone refining of benzoic acid. 

Crude TNT produced by either batch or continuous methods requires purification. The ultimate objective of TNT purification is to remove all those products which are more reactive than TNT itself (isomers, nitrocresols, nitro-benzoic acids, etc), or which can easily give oily exudation products, such as isomers or lower nitrated substances... 

Wang CL, You SL, Wang SL (2006) Purification and characterization of a novel catechol 1, 2-dioxygenase from Pseudomonas aeruginosa with benzoic acid as a carbon source. Process Biochem 41 1594—1601... 

Purification. See also Impurities Refining Wastewater treatment Water purification adsorbents for, 7 612 adsorption processes for, 7 612-613 aminophenols, 2 660-661 benzoic acid, 3 627-628 of carbide-generated acetylene, 7 207-208... 

Benzoic acid is ordinarily obtained as a highly crystalline material, which aids in its purification and contributes to its use as a reference material. The x-ray powder diffraction pattern of benzoic acid was obtained on a Jeol JDX-3530 diffractometer system. The x-ray radiation was provided by copper target, operated at 40.0 kV and 30 mA. The powder pattern was obtained using a step angle of0.040 degrees 2-0, and each step was... 

Manufacture. ///-Hydroxybenzoic acid was first obtained by the action of nitrous acid on / -aminobenzoic acid (48). It is more conveniendy prepared by the sulfonation of benzoic acid with fuming sulfuric acid. The resulting ///-sulfobenzoic acid is mixed with salt and fused with caustic soda at 210—220°C. The fusion melt is dissolved in water and acidified with hydrochloric acid to precipitate the cmde product. Final purification is generally achieved by recrystallization from water. 

The basic process usually consists of a large reaction vessel in which air is bubbled through pressurized hot liquid toluene containing a soluble cobalt catalyst as well as the reaction products, a system to recover hydrocarbons from the reactor vent gases, and a purification system for the benzoic acid product. 

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. 

A mixture of 4-(chloromethyl)benzoic acid (50 g, 0.29 mol) and (COCl)2 (100 g, 0.79 mol) in anhyd benzene (100 mL) (CAUTION carcinogen ) was stirred at 25 °C and then refluxed for 2h. Unreacted (COQ)2 and benzene were removed by distillation. Traces of the remaining reagents were removed under reduced pressure to give 92 as a colorless liquid. The acid chloride was used in the next step without further purification. 

It is noteworthy that benzaldehyde can be obtained as a main product with up to 85 % yield with concomitant of 10 % acetophenone and a small amount of benzoic acid if the co-catalyst CuCl is absent by using a biphasic scC02/PEG system, as shown in Scheme 3.5. The presence of C02 could suppress the generation of acetophenone. In addition, the oxidized products could be extracted with scC02, or with diethyl ether, and the PEG phase which immobilized the catalyst is readily reused without further purification or activation. PdCl2 can be recycled for at least five times and the yield of benzaldehyde still reaches over 80 %. Pd leaching is found to be at the level of 0.5 ppm measured by Atomic Absorption Spectroscopy. 

MURFITT, L. M., KOLOSOVA, N., MANN, C. J., DUDAREVA, N Purification and characterization of S-adenosyl-L-methionine Benzoic acid carboxyl methyltransferase, the enzyme responsible for biosynthesis of the volatile ester methyl benzoate in flowers of Antirrhinum majus., Arch Biochem. Biophys., 2000, 382,145-151. 

Some examples for the isolation of the desired poly(trifluoromethyl) compounds from product mixtures by chemical purification have been reported.128 129 In the reaction of benzene-1,2,3-tricarboxylic acid with sulfur tetrafluoride/hydrogen fluoride a mixture of l,2,3-tris(tri-fluoromethyl)benzene (9), l,l,3,3-tetrafluoro-4-(trifluoromethyl)-l,3-dihydroisobenzofuran (10), and 2.6-bis(trifluoromcthyl)benzoyl fluoride (11) is obtained in a 1 3.5 13 ratio.129 Treatment of the mixture with aqueous potassium hydroxide, followed by acidification, yields pure 2,6-bis(trifluoromethyl)benzoic acid (12). 

Terephthalic acid is a useful source material of PET, as well as benzoic acid and benzoates. However, in order to recycle the terephthalic acid, produced further purification is required, because other organic compounds are also produced as impurities in the degradation process of waste plastic mixtures, e.g. PE and PET mixtures described in Section 2.3. 

In search of less expensive, less toxic, and lower viscosity eluants, a few authors have proposed diluting the active ingredient with a common SEC eluant such as toluene, dichloromethane, or chloroform. To lower the operating temperature and minimize polymer degradation, mixtures of m-cresol with chlorobenzene (50 50, v/v, 43°C), dichloromethane (50 50, room temperature), and chloroform have been used, with 0.25 wt% benzoic acid added to prevent adsorption. In the same vein, o-chlorophenol has been diluted with chloroform (25 75) and used at 20°C. The main disadvantage in this latter solvent was a small dnidc for the polymer, which rendered refractive index measurements difficult. In addition, careful purification of the phenol is required to obtain a detection signal. Dichloroacetic acid diluted to 20 vol% with dichloromethane has been proposed as the mobile phase. However, even at this concentration, PA tends to degrade at room temperature. 

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