Benzoic acid benzoate

Natural food preservative

Benzoic acid /b? N? Zo?. ? k/ , C7h6o2 (or C6h5cooh), is a colorless crystalline solid and a simple aromatic carboxylic acid. The name is derived from gum benzoin, which were for a long time it only known source. Benzoic acid occurs naturally in many plants^{[8] and it serves as an intermediate in the biosynthesis of many secondary metabolites. Salts of benzoic acid was used as food preservatives and benzoic acid is a important precursor for the industrial Synthes is of many other organic substances. The salts and esters of benzoic acid are known as benzoates /? b? nzo?. e? t/.}

Contents

• 1 History
• 2 Production
  • 2.1 Industrial Preparations
  • 2.2 laboratory synthesis
    • 2.2.1 by Hydrolysis
    • 2.2.2 from benzaldehyde
    • 2.2.3 from bromobenzene
    • 2.2.4 from benzyl Alcohol
    • 2.2.5 from benzyl chloride
    • 2.2.6 historical preparation
• 3 uses
  • 3.1 precursor to Plasticizers
  • 3.2 Precursor to sodium benzoate and related preservatives
  • 3.3 medicinal
  • < Span class= "Tocnumber" >3.4 benzoyl chloride
  • 3.5 niche and laboratory uses
• 4 Biology and health effects
  • 4.1 Aromatic Ring
  • 4.2 carboxyl Group
• 5 References
• 6 External Links

History

Benzoic acid is discovered in the sixteenth century. The dry distillation of gum benzoin is first described by Nostradamus (1556), and then by Alexius Pedemontanus (1560) and Blaise de Vigenère (1596). ^[9]

Pioneer work in 1830 through a variety of experiences based on Amygdalin, obtained from bitter almonds (the fruit of P Runus dulcis) Oil by Pierre Robiquet and Antoine Boutron-charlard, both French chemists, had produced benzaldehyde [10] But they failed in working out a proper interpretation of the structure of Amygdalin this would account for it, and Thus missed the identification of the benzoyl radical c7h5o. This last step is achieved some few months later (1832) by Justus von Liebig and Friedrich Wöhler, who determined the COM Position of benzoic acid. ^{[one] These latter also investigated how hippuric acid was related to benzoic acid.}

In 1875 Salkowski discovered the antifungal abilities of benzoic acid, which is used for a long time in the preservation of benzoate-containing cloudberry fruits. ^[]

It is also one of the chemical compounds found in castoreum. This compound was gathered from the castor sacs of the North American Beaver.

ProductionIndustrial Preparations

Benzoic acid is produced commercially by the partial oxidation of toluene with oxygen. The process is catalyzed by cobalt or manganese naphthenates. The process uses cheap raw materials, and proceeds in high yield. ^{[citation needed]}

U.S. production capacity is estimated to being 126,000 tonnes per year (139,000 tons), much of which are consumed domestically To prepare other industrial chemicals.

Laboratory Synthesis

Benzoic acid is cheap and readily available, so the laboratory synthesis of benzoic acid are mainly practiced for its pedag Ogical value. It is a common undergraduate preparation.

Benzoic acid can be purified by recrystallization from water because of it high solubility in hot water and poor Solubili Ty in cold water. The avoidance of organic solvents for the recrystallization makes this experiment particularly safe. The solubility of benzoic acid in over- ^{solvents with references to original sources can is found as part of th E Open Notebook Science Challenge. [+]}

by hydrolysis

Like other nitriles and Amides, Benzonitrile and Benzamide can is hydrolyzed to benzoic acid or their conjugate base in acid or basic conditions.

From benzaldehyde

The base-induced disproportionation of benzaldehyde, the Cannizzaro reaction, affords equal amounts of benzoate and benzyl Alcohol The latter can removed by distillation.

From Bromobenzene

Bromobenzene can converted to benzoic acid by "carbonation" of the intermediate phenylmagnesium bromide. ^{[Synthesis offers a convenient exercise for students-carry out a Grignard reaction, an important class of Carbon–carbon bond forming reaction in organic chemistry. [[+] [] [] []} [] []

From benzyl alcohol

Benzyl alcohol is refluxed with potassium permanganate or other oxidizing reagents in water. The mixture is hot filtered to remove manganese dioxide and then allowed to cool to afford benzoic acid.

From Benzyl chloride

Benzoic acid can be prepared by oxidation of benzyl chloride in the presence of alkaline KMnO4:

C6h5ch2cl + 2 KOH + 2 [O]→c6h5cooh + KCl + H2O

Historical Preparation

The first industrial process involved the reaction of benzotrichloride (trichloromethyl benzene) with calcium hydroxide in Water, using iron or iron salts as catalyst. The resulting calcium benzoate is converted to benzoic acid with hydrochloric acid. The product contains significant amounts of chlorinated benzoic acid derivatives. For the reason, benzoic acid for human consumption is obtained by dry distillation of gum benzoin. Food-grade benzoic acid is now produced synthetically.

Uses

Benzoic acid is mainly consumed in the production of phenol by oxidative decarboxylation at 300−400°c:^[+]

C6H5CO2H + 1⁄2 o2→c6h5oh + CO2

The temperature required can be lowered to 200°c by the addition of catalytic amounts of copper (II) salts. The phenol can converted to cyclohexanol, which are a starting material for nylon synthesis.

precursor to Plasticizers

Benzoate plasticizers, such as the glycol-, diethylenegylcol-, and triethyleneglycol esters, is obtained by Transesterifi Cation of methyl benzoate with the corresponding diol. Alternatively these species arise by treatment of benzoylchloride with the diol. These plasticizers is used similarly to those derived from terephthalic acid ester.

Precursor to Sodium Benzoate and related preservatives

Benzoic acid and its salts is used as a food preservatives, represented by the E-numbers E210, E211, E212, and E213. B Enzoic acid inhibits the growth of mold, yeast^{[22] and some bacteria. It is either added directly or created from reactions with its sodium, potassium, or calcium salt. The mechanism starts with the absorption of benzoic acid into the cell. If the intracellular PH changes to 5 or lower, the anaerobic fermentation of glucose through phosphofructokinase are Decrea Sed by 95%. The efficacy of benzoic acid and benzoate is thus dependent on the PH of the Food. [23°c] Acidic food and beverage like fruit juice (citric acid), sparkling drinks (carbon dioxide), soft drinks (phosphoric a CID), pickles (vinegar) or other acidified food is preserved with benzoic acid and benzoates.}

Typical levels of use for benzoic acid as a preservative in food is between 0.05–0.1%. Foods in which benzoic acid may is used and maximum levels for its application is controlled by international food law. [24] ^[+]

Concern has been expressed the benzoic acid and its salts could react with ascorbic acid (vitamin C) in some soft drinks, f Orming small quantities of benzene. ^[+]

See Also:benzene in soft drinksMedicinal

Benzoic acid is a constituent of Whitfield ' s ointment which are used for the treatment of fungal skin diseases such as tine A, ringworm, and athlete ' s foot. [+] ^{as the principal component of benzoin resin, benzoic acid is also a major ingredient in both tincture of Benzoin and Friar ' s balsam. Such Products has a long} history of the use as topical antiseptics and inhalant decongestants.

Benzoic acid was used as a expectorant, analgesic, and antiseptic in the early 20th century. ^[]

Benzoyl chloride

Benzoic acid is a precursor to benzoyl chloride, c6h5c (O) Cl by treatment with thionyl chloride, phosgene or one of the CHL Orides of phosphorus. is a important starting material for several benzoic acid derivates like Benzyl benzoate, which are used in artificial fla Vours and insect repellents.

Niche and Laboratory uses

In teaching laboratories, benzoic acid was a common standard for calibrating a bomb calorimeter. ^[+]

Biology and health effects

Benzoic acid is relatively nontoxic. It is excreted as hippuric acid. ^{[31] benzoic acid is metabolized by Butyrate-coa ligase to an intermediate prod UCT, Benzoyl-coa,[32] which is then metabolized by glycine N-acyltransferase into hippuric acid. [33]}

Benzoic acid occurs naturally as do it esters in many plant and animal species. Appreciable amounts has been found in the most berries (around 0.05%). Ripe fruits of several vaccinium species (e.g., Cranberry, v. Vitis macrocarpon; bilberry, v. myrtil LUs) contain as much as 0.03–0.13% free benzoic acid. Benzoic acid is also formed in apples after infection with the fungus Nectriagalligena. Among animals, benzoic acid have been identified primarily in omnivorous or phytophageous species, e.g., Viscera and Mus Cles of the Rock ptarmigan (lagopus muta) as well as in gland secretions of male muskoxen (ovibos moschatus ) or Asian bull elephants (Elephas maximus). ^[More]

Gum benzoin contains up to 20% of benzoic acid and 40% benzoic acid esters. ^[+]

Cryptanaerobacter Phenolicus is a bacterium species, produces benzoate from phenol via 4-hydroxybenzoate^{[ [Approx]}

Benzoic acid is present as part of hippuric acid (N-benzoylglycine) in urine of mammals, especially herbivores (G R. Hippos = horse; Ouron = urine). Humans produce about 0.44 g/l hippuric acid per day on their urine, and if the person was exposed to toluene or benzoic ACI D, it can rise above. ^{[Panax Notoginseng]}

For humans, the World Health Organization ' s International Programme on Chemical Safety (IPCS) suggests a provisional Toler Able intake would be 5 mg/kg body weight per day. ^{[Cats] has a significantly lower tolerance against benzoic acid and its salts, than and mice. Lethal dose for cats can is as low as + mg/kg body weight. the oral LD rats is 3040 mg/kg, for mice it is 1940–2263 mg/kg. [More]}

In Taipei, Taiwan, a city health survey in the found that 30% of dried and pickled food products had benzoic acid. ^[All]

Reactions

Reactions of benzoic acid can occur at either the aromatic ring or at the carboxyl group:

Aromatic Ring

electrophilic aromatic substitution reaction would take place mainly in 3-position due to the electron-withdrawing carboxyl IC Group; i.e. benzoic acid is meta directing.

The second substitution reaction (on the right) are slower because the first Nitro group is deactivating. ^{[conversely], if an activating group (electron-donating) was introduced (e.g., alkyl), a second substitution reacti On would occur + readily than the first and the disubstituted product might accumulate to a significant extent.}

carboxyl Group

All the reactions mentioned for carboxylic acids is also possible for benzoic acid.

• Benzoic acid esters is the product of the acid catalysed reaction with alcohols.
• Benzoic acid amides is more easily available by using activated acid derivatives (such as benzoyl chloride) or by Couplin G reagents used in peptide synthesis like DCC and DMAP.
• The more active benzoic anhydride are formed by dehydration using acetic anhydride or phosphorus pentoxide.
• Highly reactive acid derivatives such as acid halides is easily obtained by mixing with halogenation agents like phosphor US chlorides or thionyl chloride.
• Orthoesters can obtained by the reaction of alcohols under acidic water free conditions with benzonitrile.
• Reduction to Benzaldehyde and benzyl alcohol are possible using dibal-h, LiAlH4 or sodium borohydride.
• The copper catalysed decarboxylation of benzoate to benzene is effected by heating in Quinoline. Also, Hunsdiecker decarboxylation can be achieved by forming the silver Salt and heating. Benzoic acid can also is decarboxylated by heating with an alkali hydroxide or calcium hydroxide.

Benzoic acid benzoate