Benzoic acid chromatography

Trace impurities present in commercial benzoic acid include methyl diphenyls and phthaHc acids. The concentration and presence of these impurities vary by product grade and by manufacturer. Gas chromatography and high pressure Hquid chromatography are useful for determining the concentrations of those impurities. 

THIN-LAYER CHROMATOGRAPHY OF BENZOIC ACIDS WITH EXTERNAL CONTROL PROPERTIES OF THE MOBILE PHASE... 

The synthesis of 1 -benzothiepin 1 -oxide (23) can be achieved via complex formation with tricarbonyl iron, and quantitative oxidation of the coordination compound 22 with 3-chloroperoxy-benzoic acid. Subsequent irradiation at — 50 C provides 23, which crystallized as yellow needles after low-temperature (-40 C) chromatography, and was characterized by 1H NMR spectroscopy at — 30 C23 before loosing sulfur within one hour at 13°C to give naphthalene. 

Tezuka s group (Tezuka and Ando, 1985 Tezuka et al., 1986) was able to isolate and characterize the benzenediazo ether of 1-naphthol (6.10). They stirred a solid mixture of the molecular complex 6.9 formed between an a-azohydroperoxide acid and benzene with an excess of 1-naphthol at room temperature in the dark for several hours. The separation of this solid by thin layer chromatography (silica gel, with a benzene-ethyl acetate mixture [9 1] as eluent) afforded the diazo ether 6.10 as a yellow oil in 17 % yield, together with 4- and 2-phenylazo-l-naphthol (6.11 and 6.12, 4% and 42%, respectively), 4-phenylbenzaldehyde (32%), benzoic acid (23%), and traces of other compounds (Scheme 6-6). Higher yields of the diazo ether (up... 

Figure 1 Ultraviolet spectra for benzaldehyde and benzoic acid solvent, methanol reference, methanol cell, 1.0 cm. (From Pfeiffer, C. D., Larson, J. R., and Ryder, J. F., Linearity testing of ultraviolet detectors in liquid chromatography, Anal. Chem., 54, 1622, 1983. Copyright American Chemical Society Publishers. With permission.)...

The procedure described has advantages over previously published methods. The starting material is easily obtained on a large scale at low cost. The ozonolysis can be conducted even on a large scale (150 g) and the workup is simple since the benzoic acid that is also formed can be removed by distillation, chromatography, or crystallization. The method is general and can be applied to different esters including chiral derivatives such as dimenthyl mesoxalate (see Table). 

Xiao-Hua Yang et al. [ 1 ] determined nanomolar concentrations of individual low molecular weight carboxylic acids (and amines) in seawater. Diffusion of the acids across a hydrophobic membrane was used to concentrate and separate carboxylic acids from inorganic salts and most other organic compounds prior to the application of ion chromatography. Acetic propionic acid, butyric-1 acid, butyric-2 acid, valeric and pyruvic acid, acrylic acid and benzoic acid were all found in reasonable concentrations in seawater. 

PANFILI G, MANZI P, COMPAGNONE D, SCARCIGLIA L and PALLESCHI G (2000), Rapid assay of chohne in foods using microwave hydrolysis and a choline biosensor , J Agric Food Chem, 48, 3403-7. pant I and trennery v c (1995), The determination of sorbic acid and benzoic acid in a variety of beverages and foods by micellar electrokinetic capillary chromatography , Food Chem, 53(2), 219-26. pare j r j and Belanger j m r (1997), Instrumental Methods in Food Analysis. Series Techniques and instrumentation in analytical chemistry - Vol. 18, Amsterdam, Elsevier. 

THF, -78 °C) gave a 10 1 mixture of (+)-230 to (+)-229. Column chromatography (silica gel) afforded pure (+)-230 in 82 % yield. Treatment of (+)-230 with diethyl azodicarboxylate/triphenylphosphine/benzoic acid, followed by saponification (MeOH, MeONa), yielded (+)-229 in 85 % yield . The enantiomeric forms (-)-229 and (-)-230 can be derived in a similar way from Our approach is, in... 

The ultraviolet reflectance absorbance spectrum of a benzoic acid spot on a thin-layer chromatography place was recorded on a Shimadzu CS-930 TLC scanner, and is shown in Figure 5. The spectrum was obtained on a silica-gel F254 pre-coated TLC-plate (E. Merck) after elution with 7 2 2 acetone/ammonia 25 %/isopropanol. The absorbance maximum for this system was determined to be 225 nm. 

Kirkland, J. J. Analysis of Polychlorinated Benzoic Acid by Gas Chromatography Anal. Chem., 1961, J33, 1521. 

A reactor was charged with a benzoic acid-acrylic ether derivative (81 mmol), 2,5-dihydroxybenzaldehyde (37 mmol), 4-dimethylaminopyridine (22 mmol), and 200 ml of CH2CI2 and then treated with the dropwise addition of 1,3-dichlorohexylcarbodi-mide (81 mmol) dissolved in 100 ml of CH2CI2. After the addition the mixture was stirred at ambient temperature for 10 hours and a precipitate formed that was removed and the organic layer was washed with water, dried with MgSOzt, and concentrated. The residue was purified by column chromatography, recrystallized from ethanol, and 27 mmol of product isolated. 

MS Ali. Rapid quantitative method for simultaneous determination of benzoic acid, sorbic acid, and four parabens in meat and nonmeat products by liquid chromatography. J Assoc Off Anal Chem 68 488-492, 1985. 

J Carnevale. Determination of ascorbic, sorbic and benzoic acids in citrus juices by high-performance liquid chromatography. Food Tech Aust 32 302, 304-305, 1980. 

I Pant, VC Trenerry. The determination of sorbic acid and benzoic acid in a variety of beverages and foods by micellar electrokinetic capillary chromatography. Food Chem 53 219-226, 1995. 

One of the older methods used to detect the presence of preservatives in soft drinks and juices is thin-layer chromatography (Woidich el al., 1967). This provides a useful method to detect benzoic and sorbic acids as well as the substituted benzoic acids. The first stage involves the extraction of the preservatives with diethyl ether prior to their chromatographic separation on polyamide plates. Although it is difficult to use this procedure to quantify the level of these preservatives in a sample, it is not impossible. This approach can still be used today by a laboratory that does not have access to HPLC. 

Aldehyde 1 (0.2 mmol), alkene 2 (1.0 mmol), 2-amino-3-picoline (0.08 mmol), benzoic acid (0.02 mmol) and RhCl(PPh3)3 (0.01 mmol) were mixed in the absence of any organic solvent and then submitted for 10 min to microwave irradiation inside a domestic microwave oven (Samsung, RE-431H, 700 W) or in a monomode Syntliewave 402 Prolabo where power is enslaved to temperature at 140 °C. After the reaction, the product 3 was purified by column chromatography 38-85%. 

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