Benzoic acid potassium salt

Benzoate of potash benzoic acid potassium salt E212 kalium benzoat potassium salt trihydrate ProBenz PG. 

Benzoic acid, potassium salt EINECS 209-481-3 Potassium benzoate. Anti-corrosive, preservative, fermentation-inhibitor, antifungal agent for tobacco production, pyrotechnical additive. White solid soluble in H2O, EtOH. Am. Biorganics Lancaster Synthesis Co. Uallinckrodt Inc. Pentagon Chems. Lid VerdugtBV. 

Benzoic acid potassium salt. See Potassium benzoate... 

CAS 16782-08-4 EINECS/ELINCS 240-830-2 Synonyms Benzoic acid, 4-hydroxy-, potassium salt 4-Hydroxybenzoic acid, potassium salt p-Hydroxybenzoic acid, potassium salt Potassium 4-hydroxybenzoate Classification Organic salt Empirical C7H6O3 K Uses Preservative in cosmetics Potassium PCA... 

Uses Sweetener in foods Manuf./Distrib. AB R Lundberg Potassium salicylate CAS 578-36-9 EINECS/ELINCS 209-421-6 Synonyms Benzoic acid, 2-hydroxy-, potassium salt 2-Hydroxy benzoic acid monopotassium salt Potassium 2-hydroxybenzoate Saiicyiic acid, potassium salt Definition Potassium salt of salicylic acid Empirical C7H6O3 K... 

Henkel Rearrangement of Benzoic Acid and Phthalic Anhydride. Henkel technology is based on the conversion of benzenecarboxyhc acids to their potassium salts. The salts are rearranged in the presence of carbon dioxide and a catalyst such as cadmium or zinc oxide to form dipotassium terephthalate, which is converted to terephthahc acid (59—61). Henkel technology is obsolete and is no longer practiced, but it was once commercialized by Teijin Hercules Chemical Co. and Kawasaki Kasei Chemicals Ltd. Both processes foUowed a route starting with oxidation of napthalene to phthahc anhydride. In the Teijin process, the phthaHc anhydride was converted sequentially to monopotassium and then dipotassium o-phthalate by aqueous recycle of monopotassium and dipotassium terephthalate (62). The dipotassium o-phthalate was recovered and isomerized in carbon dioxide at a pressure of 1000—5000 kPa ( 10 50 atm) and at 350—450°C. The product dipotassium terephthalate was dissolved in water and recycled as noted above. Production of monopotassium o-phthalate released terephthahc acid, which was filtered, dried, and stored (63,64). 

Sodium and Potassium Benzoate. These salts are available in grades meeting the specifications of the 25ationalVormulary (18) and the Vood Chemicals Codex (19) (Table 7). Sodium benzoate [532-32-1] is produced by the neutralization of benzoic acid with caustic soda and/or soda ash. The resulting solution is then treated to remove trace impurities as weU as color bodies and then dried in steam heated double dmm dryers. The product removed from the dryers is light and fluffy and in order to reduce shipping and storage space the sodium benzoate is normally compacted. It is then milled and classified into various product forms, the names of which often bear Httle relationship to the actual form of the product. 

Benzoic acid is suppHed to this market in the form of salts because the benzoate salts have a high solubiUty in water and aqueous stock solutions of up to 35% can easily be prepared. In addition, it is easier, and therefore cheaper, to purify sodium and potassium benzoate than to produce the USP/FCC grade of benzoic acid. 

Sodium and potassium benzoate are substances that may be added direcdy to human food and are affirmed as GRAS (33—35). Benzoic acid and sodium and potassium benzoate are now used as preservatives in such foods as sauces, pickles, cider, fmit juices, wine coolers, symps and concentrates, mincemeat and other acidic pie fillings, margarine, egg powder, fish (as a brine dip component), bottled carbonated beverages, and fmit preserves, jams, and jellies. The popularity of diet soft drinks has led to increased demand for both benzoate salts. 

The use of the potassium salt of benzoic acid is relatively new. Concerns regarding sodium intake and its possible relationship to high blood pressure have caused some soft drink manufacturers to switch to potassium benzoate. 

The present method for preparing aromatic dicarboxylic acids has been used to convert phthalic or isophthalic acid to tereph-thalic acid (90-95%) 2,2 -biphenyldicarboxylic acid to 4,4 -biphenyldicarboxylic acid 3,4-pyrroledicarboxylic acid to 2,5-pyr-roledicarboxylic acid and 2,3-pyridinedicarboxylic acid to 2,5-pyridinedicarboxylic acid. A closely related method for preparing aromatic dicarboxylic acids is the thermal disproportionation of the potassium salt of an aromatic monocarboxylic acid to an equimolar mixture of the corresponding aromatic hydrocarbon and the dipotassium salt of an aromatic dicarboxylic acid. The disproportionation method has been used to convert benzoic acid to terephthalic acid (90-95%) pyridine-carboxylic acids to 2,5-pyridinedicarboxylic acid (30-50%) 2-furoic acid to 2,5-furandicarboxylic acid 2-thiophenecar-boxylic acid to 2,5-thiophenedicarboxylic acid and 2-quinoline-carboxylic acid to 2,4-quinolinedicarboxylic acid. One or the other of these two methods is often the best way to make otherwise inaccessible aromatic dicarboxylic acids. The two methods were recently reviewed. ... 

N-(m-methylmercapto-phenyl)-aniline (MP 59° to 61°C) is prepared by condensing m-methyl-mercapto-aniline (BP 163° to 165°C/16 mm Hg) with the potassium salt of o-chloro-benzoic acid and decarboxylating the resultant N-(m-methylmercapto-phenyl)-anthranilic acid (MP 139° to 141°C) by heating, and then distilling. 

This compound is a widely used preservative as the acid or its potassium salt. The pKa is 4.8 and, as with benzoic acid, activity decreases with increasing pH and ionization. It is most effective at pH 4 or below. Pharmaceutical products such as gums, mucilages and syrups are usefully preserved with this agent. 

It is possible to alkylate benzoic acids directly, without the need to prepare reactive potassium salts in a separate step, because they can be generated in situ by reacting the acid with a base (potassium carbonate or hydroxide) in the presence of a phase-transfer catalyst. 

Phenylacetamide has been obtained by a wide variety of reactions from benzyl cyanide with water at 250-260° 6 from benzyl cyanide with water and cadmium oxide at 240° 6 from benzyl cyanide with sulfuric acid 7 8 by saturation of an acetone solution of benzyl cyanide with potassium hydrosulfide 9 from benzyl cyanide with sodium peroxide 10 by electrolytic reduction of benzyl cyanide in sodium hydroxide 11 from ethyl phenyl-acetate with alcoholic 12 or aqueous 13 ammonia from phenyl-acetic acid with ammonium acetate 14 or urea 15 from diazoacetophenone with ammoniacal silver solution 16 from phenyl-acetic acid imino ether hydrochloride and water 17 from acetophenone with ammonium poly sulfide at 215° 18 from benzoic acid 19 and by heating the ammonium salt of phenyl-acetic acid.20... 

If the potassium salt s not isolated but the reaction mixture is immediately acidified, there is mixed with the benzilic add a certain amount of benzoic add which is difficult to remove. This may be done either by fractional solution in sodium carbonate 1 (benzilic acid is a stronger acid than benzoic), by shaking with ligroin,2 which extracts the benzoic acid from the benzilic, or by boiling with water 3 for some time until the odor of benzoic acid has disappeared. It is better to isolate the potassium salt, since upon acidification very pure benzilic acid is obtained in spite of the fact that it is slightly colored. 

Pure benzoic acid is a white powdery crystalline solid (m.p. 122°C) only sparingly soluble in water at normal temperatures. Because of this, it is added to the drink in the soluble form of its sodium or potassium salts. It is normal practice to disperse the benzoate completely during batch makeup before addition of the acid component, with its resulting pH reduction, to avoid localised precipitation of the free benzoic acid due to its solubility having been exceeded (the solubility of benzoic acid = 0.35% m/v at 20°C). It is the free or undissociated form of benzoic acid that exhibits preservative action and hence its use is only effective when low pH values are encountered, ideally below pH 3, at which point the degree of dissociation reduces to below 10%. 

It is normal to use additionally a mixture of both benzoic and sorbic acids, added as their sodium and potassium salts respectively. Current UK preservative regulations permit a maximum level of 300 mg/1 of sorbic acid and 150 mg/1 of benzoic acid, both at drinking strength. For this reason it is normal to suggest on the product label a dilution ratio, which can then be used as a factor in calculating the amount of these preservatives to be used. An example is set out in Table 6.7. 

The benzoic acid was quantitatively coupled within 5 min via its cesium salt by using a dedicated multi-mode batch reactor, carried out in standard glassware under atmospheric reflux conditions. In a more extended study, various substituted carboxylic acids (Fig. 7.7) were coupled to chlorinated Wang resin, employing an identical reaction protocol. In a majority of cases, the microwave-mediated conversion reached at least 85% after 3-15 min. These microwave conditions represented a significant rate enhancement, in contrast to the conventional protocol, which took 24-48 h. The microwave protocol has additional benefits in comparison to the conventional method, as the amounts of acid and base equivalents can be reduced and potassium iodide as an additive can be eliminated from the reaction mixture27. 

Either phthalic anhydride or toluene, both in ample supply as raw materials, can be used in the Henkel processes. Use of phthalic anhydride depends only upon dry isomerization of the potassium salt of the ortho derivative to the para form at about 430°C and 20 atmospheric pressure or toluene is oxidized to benzoic acid, whose potassium salt can be converted to benzene and the potassium salt of terephthalic acid by disporportionation. 

Although this is the classical method of anhydride formation it has been replaced to a large extent by the acylation of free carboxylic acids (method 341). The conditions employed and the solvents used in this reaction vary widely. Excellent directions are given for the preparations of nicotinic anhydride (89%) and acetic propionic anhydride (60%) from the respective potassium and sodium salts of the carboxylic acids. Silver salts of acids have also been used. The reaction has been extended to the preparation of mixed anhydrides of short- and long-chain fatty acidsbut has failed in the preparation of mixed anhydrides of substituted benzoic acids. ... 

---