IN THE NAME OF ALLAH THE MOST BENIFICIENT

THE MOST MERCIFUL

Benzoic acid

C7H6O2 or ( C6H5COOH)

CONTENTS What is benzoic acid? History Production Uses Biology and health effects Reactions

What is benzoic acid?

Benzoic acid C7H6O2 (or C6H5COOH), is a colorless crystalline solid and a simple aromatic carboxylic acid.

The name is derived from gum benzoin, which was for a long time it’s only known source. Benzoic acid occurs naturally in many plants and it serves as an intermediate in the biosynthesis of many secondary metabolites.

O OH

HistoryBenzoic acid was discovered in the sixteenth century.

The dry distillation of gum benzoin was first described by

Nostradamus (1556), and then by Alexius Pedemontanus (1560) and

Blaise de Vigenère (1596).

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.

It is also one of the chemical compounds found in castoreum. This

compound is gathered from the beaver plant food.

ProductionBenzoic Acid is Produced by following method :1. Industrial preparations:And Benzoic Acid also Produced by : 2 . Laboratory synthesis by following method:i. By hydrolysisii. From Benz aldehydeiii. From bromobenzeneiv. From benzyl alcoholv. From benzyl chloridevi. Historical preparation

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ProductionIndustrial preparations:Benzoic acid is produced commercially by 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.

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

CH3O2

OH2

O OH

ProductionLaboratory synthesis:Benzoic acid is cheap and readily available, so the laboratory synthesis of benzoic acid is mainly practiced for its pedagogical value. It is a common undergraduate preparation. Benzoic acid can be purified by recrystallization from water because of its high solubility in hot water and poor solubility in cold water

1. By hydrolysis2. From Benz aldehyde3. From bromobenzene4. From benzyl chloride

ProductionLaboratory synthesis:1. By hydrolysis:Like other nitriles and amides, benzonitrile and benzamide can be hydrolyzed to benzoic acid or its conjugate base in acid or basic conditions.

2 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

Production Laboratory synthesis:From Benz aldehyde:The base-induced disproportionation of benzaldehyde, the Cannizzaro reaction, affords equal amounts of benzoate and benzyl alcohol; the latter can be removed by distillation.

Uses

Benzoic acid is mainly consumed in the production of phenol by oxidative decarboxylation at 300−400 °C:C6H5CO2H + 1/2 O2 → C6H5OH + CO2

Precursor to plasticizers:Benzoate plasticizers, such as the glycol-, diethylenegylcol-, and triethyleneglycol esters, are obtained by transesterification of methyl benzoate with the corresponding diol.

Niche and laboratory uses:In teaching laboratories, benzoic acid is a common standard for calibrating a bomb calorimeter.

Uses Medicinal:Benzoic acid is a constituent of Whitfield's ointment which is used for the treatment of fungal skin diseases such as tinea, ringworm, and athlete's foot. Whitfield's ointment

Biology and health effects

Benzoic acid is relatively nontoxic. It is excreted as hippuric acid. Benzoic acid is metabolized by butyrate-CoA ligase into an intermediate product, benzoyl-CoA, which is then metabolized by glycine N-acyltransferase into hippuric acid.

Gum benzoin contains up to 20% of benzoic acid and 40% benzoic acid esters.

Cryptanaerobacter phenolicus is a bacterium species that produces benzoate from phenol via 4-hydroxybenzoate.

Benzoic acid is present as part of hippuric acid (N-benzoylglycine) in urine of mammals, especially herbivores (Gr. hippos = horse; ouron = urine).

Humans produce about 0.44 g/L hippuric acid per day in their urine, and if the person is exposed to toluene or benzoic acid, it can rise above that level.

Reactions

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

Electrophilic aromatic substitution reaction will take place mainly in 3-position due to the electron-withdrawing carboxylic group; i.e. benzoic acid is meta directing.

O OH

HO3S

O OH O OH

NO2O2N

H2SO4H2O-

HNO3

H2O-

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