Chemistry Essay Example: Benzoic Acid and Its Use

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Middlebury College
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Benzoic Acid is also known as Dracylic Acid, Carboxybenzene, Benzeneformic Acid and Benzenecarboxylic acid. The acids molecular formula is C6H5COOH or C7H6O2. Benzoic Acid is a simple aromatic carboxylic acid which is colorless and crystalline. Various plant and animal species produce benzoic acid which occurs naturally as benzoic acid esters. Considerable quantities occur in most berries such as cranberries which have approximately 300 to 1500 milligrams of free benzoic acid in every kilogram of the fruit. It is used to preserve foods because the acid is a fungistatic compound. In animals, benzoic acid is broken down in the liver to form glycine to facilitate its excretion as hippuric acid. Phenylalanine metabolism unique to bacteria also produces benzoic acid. Similarly, when gut bacteria act on polyphenols, the product of this action is Benzoic Acid.

Most laboratories produce benzoic acid from the reaction of chemicals instead of the old method of extracting it from gum benzoin. Gum benzoin is a fragrant resin that almost smells like vanilla and originates from trees that belong to the Styrax genus. Benzoates, on the other hand, are bi-products of benzoic acid and are widely used as preservatives. When a benzoate reacts with vitamin C, ascorbic acid common in drinks, benzene is produced which can cause allergic reactions as well as cancer in humans because it is a carcinogen. This essay seeks to elaborate on benzoic acid and its chemical structure, the mode of action, its uses, its limitations, as well as the permitted limits of the preservative. The essay goes further to note the sources of benzoic acid in Australia and to calculate the amount of preservative required in an individual batch.

Chemical Structure and Formula of Benzoic Acid

Benzoic acid, solid in nature, resembles white needles due to its crystalline appearance. The chemical formula is C7H6O2 or C6H5COOH because its structure comprises of seven carbon (C) atoms, six hydrogen (H) atoms in addition to two oxygen (O) atoms

The chemical structure of Benzoic acid

Figure 1: The image on the left shows all the carbon and hydrogen atoms on the benzene ring while the one on the right depicts a simple way of drawing the benzene ring.

The presence of carbon in its structure confirms the acid is an organic compound. It is also referred to as an aromatic carboxylic acid since it contains a benzene ring. The aromatic nature of benzene is brought about by the alternating double bonds between each carbon atom. Finally, Benzoic acid is a type of carboxylic acid due to the presence of the carboxyl group, COOH ("Benzoic Acid," 2005, p. 9).

Uses of Benzoic Acid and Mode of Action

Benzoic acid has numerous uses. First, this essay looks at its use as a preservative. Benzoic acid prevents the multiplication and growth of yeast, mould and some bacteria. It is either created or added directly from Calcium, Sodium or potassium salt. The process commences with the absorption of the acid into the cell. In instances when the intracellular PH reduces to 5 or below, the action of enzyme phosphofructokinase that facilitates anaerobic fermentation of glucose decreases by 95%. The effectiveness of benzoic acid, as well as the benzoates, therefore depends on the PH of the food it is preserving. Beverages and juices containing citric acid, sparkling drinks and soft drinks containing carbon dioxide and phosphoric acid respectively, pickles and other acidic foods accommodate the use of benzoic acid and benzoates as the main food preservative. The suitable amount of benzoic acid as a preservative ranges between 0.05 to 0.1%. There are some other foods where the application of preservative has to increase. The international food law indicates the amount of additive used in such cases. The downside of the use of benzoic acid and its salts comes amidst recent claims that the reaction with vitamin C (ascorbic acid) contained in fizzy drinks results in a carcinogenic compound called benzene ("CHEM-GUIDE: Uses of benzoic acid," n.d.).

Benzoic acid is essential in the manufacture of a variety of chemicals. One example is in the production of Benzoyl chloride with chemical formula C6H5C(O)Cl. Benzoyl chloride is a byproduct of the treatment of benzoic with chlorides of phosphorus, thionyl chloride or phosgene. C6H5C(O)Cl is an essential material for various benzoic acid derivatives like benzyl benzoate vital in the making of insect repellents and artificial flavors. Benzoic Acid is a key ingredient in the production of Benzoate plasticizers which include glycol-, di-ethylengylcol-, and tri-ethylene glycol esters. Transesterification of methyl benzoate with its relevant diol results in the manufacture of the plasticizers. These species also arise from the treatment of benzoyl chloride with the corresponding diol. These plasticizers operate similarly with products derived from the terephthalic acid ester. Oxidative decarboxylation results in the production of Phenol, a chemical by-product of benzoic acid, with chemical formula C6H5OH at temperatures ranging between 300 and 400 oC. Catalysts such as copper (II) salts reduce the required temperature of production to approximately 200oC. Cyclohexanol, a converted form of Phenol which is a necessary material for nylon production.

In medicine, benzoic acid is beneficial because of its anti-fungal properties. Due to this factor, it is available in many products such as ointments, creams, and lotions which purpose is to treat anti-fungal infections that may include ringworms, athletes foot amongst others. These topical solutions also help calm skin inflammation and irritation ("CHEM-GUIDE: Uses of benzoic acid," n.d.). Benzoic acid is the principal constituent in benzoin resin, and the main component of Whitfields ointment, a famous product widely used for the treatment of fungal skin ailments.

Limitations in the use of Benzoic Acid

Similar to most toxic chemicals, the concentration of benzoic acid determines how effective it can be. Moderate amounts mostly found in foods and plants do not pose a threat to human beings. Once an individual ingests benzoic acid, absorption through the lining of the gut followed by conversion into hippuric acid occurs. Hippuric acid is a component in urine. In accordance to the Material Safety Data Sheet for chemicals, benzoic acid is capable of eye, lung, skin, and gut irritation ("Benzoic Acid," 2005, p. 35). Usually, people do not come across high concentrations that might irritate, but when it happens, individuals working in chemical plants handling concentrated mixtures must be careful since the acid can penetrate the skin, the respiratory and digestive tracts as well.

Maximum Permitted Limits of Benzoic Acid

The permitted limit of benzoic acid in cosmetic product preservation is at a maximum concentration of 0.5%. For non-preservative purposes in cosmetics, especially in rinse-off products, the limit rises to a maximum of 2.5% with oral cosmetic care at a maximum of 1.7%. Leave-on products have a maximum concentration of 0.5%.

The regulated use of benzoic acid as food preservatives is most suitable in foods, soft drinks, and fruit juices. For optimum food preservation, the product must be kept in an acidic PH range. The maximum permitted concentration of benzoic acid in non-alcoholic drinks is 150 mg/l, in alcoholic drinks it is 200 mg/l, in Aspic it is at 500 mg/kg, in jams and jellies the concentration is also at 500mg/kg.

In medicine, the concentration of benzoic acid also varies. 0.15% in oral medicine, 0.17% in parental drugs, and 0.2% in topical drugs. Benzoic acid is the active ingredient in anti-fungal medication usually concentrated at a maximum of 6%. The above figures are as per the Food and Drug Administration (FDA) and the EU Cosmetics directives 76/768/EEC.

Sources of Benzoic Acid in Australia

Suppliers of Benzoic acid in Australia are mainly two companies by the name Bronson and Jacobs PTY limited and Quantum chemicals PTY limited. As far as pricing goes, 100 grams of the acid costs AU$ 9.90. The product specification sheet for Quantum chemicals is as follows;


Product Name: Benzoic acid

Product number: 213

Supplier: Quantum chemicals

Dandenong, South, Victoria

Telephone : +61 3 8795 8000


Dangerous in cases of skin contact (irritant), eye contact (irritant), ingestion, and inhalation.

The chemical is toxic to mucus membranes, lungs, and the nervous system. Repeated or continued exposure to the substance results in organs damage.


Name CAS# % by weight

Benzoic acid 65-85-0 100


General advice, consult a physician and produce this sheet to the doctor.

If inhaled, move person into fresh air. If not breathing, give artificial respiration.

In case of skin contact, wash off with soap and plenty of water.

In case of eye contact, rinse thoroughly with plenty of water for at least 15 minutes and consult a physician.

If swallowed, rinse mouth with water.


Not flammable or combustible.

Use water spray, alcohol-resistant foam, dry chemical or carbon dioxide to extinguish.

Wear self-contained breathing apparatus for firefighting if necessary.

Hazardous combustion products form under combustion- Carbon oxides


Use personal protective equipment, avoid dust formation, and avoid breathing vapors, mist or gas.

Ensure adequate ventilation while evacuating personnel to safe areas.

Do not let product enter drains.

Pick up and arrange disposal without creating dust. Keep in suitable, closed containers for disposal.


Avoid contact with skin and eyes.

Avoid formation of dust and aerosols.

Provide appropriate exhaust ventilation at places where dust is formed.

Keep container tightly closed in a dry and well-ventilated place.


Use process enclosures, local exhaust ventilation, or other engineering controls to keep airborne levels below recommended exposure limits.

If user operations generate dust, fume or mist, use ventilation to keep exposure to airborne contaminants below the exposure limit.


PH : 2.5 - 3.5 at 20 0C (68 0F)

Melting point/freezing point Melting point/ range: 121 - 125 0C (250 - 257 0F)

Boiling point : 249 0C (480 0F)

Flash point : 121 0C (250 0F)

Ignition temperature : 572 0C (1,062 0F)

Vapor pressure : 13 hPa (10 mmHg) at 132 0C (270 0F)

Density : 1.320 g/cm3 at 20 0C (68 0F)

Water solubility : 2.9 g/l at 25 0C (77 0F)

Partition coefficient: n-octanol/water log Pow: 1.88


The product is stable.

Polymerization will not occur.

Materials to avoid include, strong bases, strong oxidizing agents, and strong reducing agents.


Offer surplus and non-recyclable solutions to a licensed disposal company. Contact a licensed professional waste disposal service to dispose of this material.


UN number: 3077 Class: 9 packing group: III

Proper shipping name: Environmentally hazardous substan...

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