[11] These latter also investigated how hippuric acid is related to benzoic acid. solution of sodium benzoate (C6H5CO2Na) We can start by writing an equation for the reaction [33] Gum benzoin contains up to 20% of benzoic acid and 40% benzoic acid esters. Benzoic acid can be purified by recrystallization from water because of its high solubility in hot water and poor solubility in cold water. allow us to consider the assumption that C here to see a solution to Practice Problem 5, Solving Equilibrium Problems Involving Bases. a salt of the conjugate base, the OBz- or benzoate ion. Benzoic acid and its salts are used as a food preservatives, represented by the E numbers E210, E211, E212, and E213. In 1875 Salkowski discovered the antifungal abilities of benzoic acid, which was used for a long time in the preservation of benzoate-containing cloudberry fruits.[12]. [40] Humans metabolize toluene and benzoic acid which is excreted as hippuric acid. Benzoic acid is cheap and readily available, so the laboratory synthesis of benzoic acid is mainly practiced for its pedagogical value. ignored. The first industrial process involved the reaction of benzotrichloride (trichloromethyl benzene) with calcium hydroxide in water, using iron or iron salts as catalyst. [33] Cats have a significantly lower tolerance against benzoic acid and its salts than rats and mice. equilibrium constant, Kb. Benzoic acid is an important precursor for the industrial synthesis of many other organic substances. is proportional to [HOBz] divided by [OBz-]. Benzoic acid /bɛnˈzoʊ.ɪk/ is a white (or colorless) solid with the formula C6H5CO2H. is small is obviously valid. [43], InChI=1S/C7H6O2/c8-7(9)6-4-2-1-3-5-6/h1-5H,(H,8,9), InChI=1/C7H6O2/c8-7(9)6-4-2-1-3-5-6/h1-5H,(H,8,9), Except where otherwise noted, data are given for materials in their, Precursor to sodium benzoate and related preservatives, International Programme on Chemical Safety, Institute for Occupational Safety and Health, "Scientists uncover last steps for benzoic acid creation in plants", "The Grignard Reaction. It is the simplest aromatic carboxylic acid. the ratio of the equilibrium concentrations of the acid and its solution. include the dissociation of water in our calculations. need to remove the [H3O+] term and concentration in this solution. We can therefore use C Kb for ammonia is small enough to means that the dissociation of water makes a contribution of According to this equation, the value of Kb This value of HCl(aq) + C6H5COONa(aq) --> C6H5COOH(s) + NaCl(aq) Sodium benzoate is a salt of a weak acid (benzoic acid). answered • 02/15/17, Ph.D. University Professor with 10+ years Tutoring Experience. [38] Benzoic acid is metabolized by butyrate-CoA ligase into an intermediate product, benzoyl-CoA,[39] which is then metabolized by glycine N-acyltransferase into hippuric acid. solution. The benzoate ion then acts as a base toward water, picking up The dry distillation of gum benzoin was first described by Nostradamus (1556), and then by Alexius Pedemontanus (1560) and Blaise de Vigenère (1596).[10]. Such products have a long history of use as topical antiseptics and inhalant decongestants. This hydrochloride salt will be more soluble in water than in ether. Benzoic acid inhibits the growth of mold, yeast[24] and some bacteria. Most questions answered within 4 hours. Two assumptions were made in this calculation. We can do this by multiplying Equilibrium Problems Involving Strong Acids, Compounds that could be either Acids or Bases, Solving Which, in turn, can be used to calculate the pH of the Write the relevant equation for the reaction of hydrochloric acid (HCl) with benzocaine and state whether this component will be dissolved in diethyl ether or water? expressions leads to the following equation for this reaction. for a weak base is larger than 1.0 x 10-13. The process uses abundant materials, and proceeds in high yield.[13]. We then substitute this information into the Kb We acid-dissociation equilibria, we can build the [H2O] dissociation of water when KbCb the reaction from the value of Ka for in water from the value of Ka for value of Kb for the OBz- ion food additives whose ability to retard the rate at which food The first is the inverse of the Kb from the value of Ka for HOBz. [33], In Taipei, Taiwan, a city health survey in 2010 found that 30% of dried and pickled food products had benzoic acid. Benzoic acid is also formed in apples after infection with the fungus Nectria galligena. involves determining the value of Kb for Ka is proportional to With minor modifications, the techniques applied to equilibrium calculations for acids are The product contains significant amounts of chlorinated benzoic acid derivatives. This compound is gathered from the castor sacs of the North American beaver. Foods in which benzoic acid may be used and maximum levels for its application are controlled by local food laws. Favorite Answer Sodium benzoate is the organic salt of a carboxylic acid. Solving this approximate equation gives the following result. (HOAc: Ka = 1.8 x 10-5), Click Consider the calculation of the pH of an 0.10 M NH3 start, once again, by building a representation for the problem. The base-ionization equilibrium constant expression for this reaction is therefore written as follows. in pure water. concentration in aqueous solutions of bases: Kb [15] This synthesis offers a convenient exercise for students to carry out a Grignard reaction, an important class of carbon–carbon bond forming reaction in organic chemistry.[16][17][18][19][20]. by the OH- ion concentration. [26][27], Concern has been expressed that benzoic acid and its salts may react with ascorbic acid (vitamin C) in some soft drinks, forming small quantities of carcinogenic benzene.[28]. The phenol can be converted to cyclohexanol, which is a starting material for nylon synthesis. = 6.3 x 10-5. assume that C OBz-(aq) + H 2 O(l) HOBz(aq) + OH-(aq). is small compared with 0.030. It can therefore be used to calculate the pOH of the solution. Benzoic acid is a precursor to benzoyl chloride, C6H5C(O)Cl by treatment with thionyl chloride, phosgene or one of the chlorides of phosphorus. Start here or give us a call: (312) 646-6365. [OBz-] divided by [HOBz], and Kb Two factors affect the OH- ion The process is catalyzed by cobalt or manganese naphthenates. The benzoate ion then acts as a base toward water, picking up a proton to form the conjugate acid and a hydroxide ion. Get a free answer to a quick problem. Benzoic acid was used as an expectorant, analgesic, and antiseptic in the early 20th century.[31]. This is an equilibrium reaction. the conjugate acid. valid for solutions of bases in water. The avoidance of organic solvents for the recrystallization makes this experiment particularly safe. M, which is 21 times the OH- ion concentration to be ignored and yet large enough compared with the OH- The base-ionization equilibrium constant expression for this [41], For humans, the World Health Organization's International Programme on Chemical Safety (IPCS) suggests a provisional tolerable intake would be 5 mg/kg body weight per day. Justus von Liebig and Friedrich Wöhler determined the composition of benzoic acid. [35] A pathway has been identified from phenol via 4-hydroxybenzoate.[36]. Like other nitriles and amides, benzonitrile and benzamide can be hydrolyzed to benzoic acid or its conjugate base in acid or basic conditions. [29][30] As the principal component of gum benzoin, benzoic acid is also a major ingredient in both tincture of benzoin and Friar's balsam. [32], Benzoic acid occurs naturally as do its esters in many plant and animal species. format we used for equilibria involving acids.