Benzoic acid – Its Uses And Harms

Benzoic acid, C₆H₅COOH, is a colourless organic compound. It is classified as the simplest aromatic carboxylic acid. The name derived from gum benzoin. It is weakly acidic, with a pH of 2.8. In normal conditions it has a white, flaky appearance that actually consists of small, needle-like crystals.This weak acid and its salts are used as a food preservative. Benzoic acid is an important precursor for the synthesis of many other organic substances.

History

Benzoic acid was discovered in the 16th century. The dry distillation of gum benzoin was first described by Nostradamus (1556), and subsequently by Alexius Pedemontanus (1560) and Blaise de Vigenère (1596).
Justus von Liebig and Friendrich Wohler determined the structure of benzoic acid in 1832. They also investigated how hippuric acid is related to benzoic acid. 
In 1875 Salkowski discovered the antifungal abilities of benzoic acid, which were used for a long time in the preservation of benzoate containing fruits.

Industrial 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, proceeds in high yield, and is considered environmentally attractive.


Uses of Benzoic Acid

Food preservative

Benzoic acid and its salts are used as a food preservative, Benzoic acid inhibits the growth of mold, yeast and some bacteria, a major causes of food spoilage. It  is either added directly or it is created from reactions with its sodium, potassium or calcium salt. The mechanism starts with the absorption of benzoic acid in to the cell. If the intracellular pH changes to 5 or lower the anaerobic fermentation of glucose through phosphofructokinase is decreased by 95 percent. The effectivity of benzoic acid and benzoate is thus dependent on the pH of the food. Acidic food and beverage like fruit juice (citric acid) , sparkling drinks (carbon dioxide) , soft drinks (phophorus acid), pickles vinegar or other acidified food are preserved with benzoic acid and benzoates.

Medicinal Uses

Benzoic acid is a constituent of Whitfield Ointment which is used for the treatment of fungal skin diseases such as tinea, ringworm and athlete's foot. It is also considered an effective treatment for acne. Benzoic acid was used as an expectorant, analgesic and antiseptic in the early 20th century.


Cosmetic Products and Pharmaceutical Products

Many toothpastes and mouthwashes also contain benzoic acid, as well as a diaper cream. Some of the perfumes is added with benzoic acid too.

Synthesis Of Other Chemicals
Benzoic acid is used to make a large number of chemicals, important examples:

• Benzoyl chloride, C₆H₅C(O)Cl, is obtained by treatment of benzoic with thionyl chloride, phosgene or one of the chlorides of phosphorus. C₆H₅C(O)Cl is an important starting material for several benzoic acid derivates like benzyl benzoate, which is used as artificial flavours and insect repellents.
• Benzoyl peroxide, [C₆H₅C(O)O]₂, is obtained by treatment with peroxide. The peroxide is a radical starter in polymerization reactions and also a component in cosmetic products.
• Benzoate plasticizers, such as the glycol-, diethylengylcol-, and triethyleneglycol esters are obtained by transesterification of methyl benzoate with the corresponding diol. Alternatively these species arise by treatment of benzoylchloride with the diol. These plasticizers are used similarly to those derived from terephthalic acid ester.
• Phenol, C₆H₅OH, is obtained by oxidative decarboxylation at 300-400°C. The temperature required can be lowered to 200°C by the addition of catalytic amounts of copper(II) salt. The phenol can be converted to cyclohexanol, which is than starting material for nylon synthesis.

Harms Of Benzoic Acid

If Benzoic Acid is inhaled, it can cause damage to the nervous system. Eaten in food, it’s mildly toxic. Benzoic Acid has been linked to asthma problems and increased levels of hyperactivity in children. That is why children nowadays are very hyperactive, causing a lot of troubles in school.

There is some concern that benzoates added to some types of soft drinks might produce benzene, a dangerous carcinogen and environmental pollutant. Scientists believed that benzene is one of the substances that cause cancer in human. Benzene exposure typically comes from breathing exhaust fumes, but it can also be produced from the interaction of benzoic acid and ascorbic acid, a precursor of vitamin C. The pH of the beverage, the temperature at which it is stored and the extent of exposure to UV light could all affect the extent to which benzene is produced.


Considerations
Because benzoic acid is toxic, the amount of benzoates that can be added to foods is carefully controlled. Codex Alimentarius, an international treaty dictating food safety standards, limits the amount of benzoic acid or sodium benzoate to 0.05 to 0.1 percent by volume. Most foods are allowed no more than 1,000 mg per kilogram. Liquid egg products, diet foods, chewing gum and processed vegetables are among the foods with the highest amount of benzoate legally allowed.

Benzoic acid has been deemed safe to use in small quantities, but is very harmful and should be avoided in large quantities. If you must work with benzoic acid, wear appropriate safety gear and follow recommended cleanup and containment procedures. Avoid prolonged exposure. It would be wise to limit use of products or foods containing benzoic acid to limit the chances of toxic build-up within the body.



Conclusion

Benzoic acid is a carboxylic acid organic compound which provide many usage to the human. Benzoic acid can acts as a food preservative, cosmetic products, pharmaceutical products and also important in medical uses. Despite of having a lot of advantages, benzoic acid also causes harms to human. First of all, benzoic acid is believe to cause hyperactive in children. Benzoic acid can reacts with other products, producing benzene, which is a cancer causing substances. In fact, benzoic acid is not suitable for human who have asthma. Since benzoic acid brings a lot of usages and also harms to us, we must be careful in using benzoic acid. For example, we should prevent the overdose of benzoic acid, avoid prolonged exposure to benzoic acid and also try to prevent the using of benzoic acid whenever is necessary. Thank you.