The benzoic acid is a type of carboxylic acid whose formula has uses in the food and chemical industry due to its properties as a preservative and controlled toxicity when included in food, acne creams in cosmetics, and dermatology.
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Benzoic acid properties
It has the characteristic of being colorless and emitting a slight odor that makes it easily distinguishable. It also has the property of dissolving easily in hot water, so in many cases, the liquid in the mixture is heated, or it is incorporated into other chemicals in which it is soluble. Additionally, benzoic acid has the following chemical properties:
- Benzoic acid formula: C7H6O2.
- Decomposition: 390 °C.
- Molar mass: 122.12 g/mol.
- Density: 1.27 g/cm³.
- Melting point: 395 K or 122 °C.
- Water solubility: 3.4 g/L at 293 K or 20 °C – 70 g/L at 368 K or 95 °C.
- pKa: 4.202.
- Semi-developed formula: φCOOH.
- Properties for preserving food.
- Insoluble or poorly soluble in cold water.
- Prevents mold growth in food.
- Delays the fermentation of fresh products.
- Used as a tobacco additive.
- Used as an ingredient in toothpaste.
The production or synthesis of benzoic acid starts from a well-known element, benzene. The chemical transformation requires several steps as well as adding chemical compounds to change its chemical structure, ultimately achieving the benzoic acid formula.
Formula
To obtain the final compound, benzene must undergo a series of chemical reactions and industrial processes.
Thus, starting from benzene, it is possible to achieve the benzoic acid formula (C7H6O2) along with its properties and uses. This requires conducting the Friedel-Crafts alkylation with a methyl halide using aluminum chloride, meaning one of the atoms in the aromatic benzoic compound is replaced with an alkyl group. This reaction is named Friedel-Crafts alkylation due to its discovery.
The result of the alkylation is the element known as toluene, which must then be oxidized with potassium permanganate in an alkaline medium, converting it into manganese dioxide and potassium benzoate.
To complete the process and obtain benzoic acid, the aqueous phase must be acidified, ultimately yielding white benzoic acid.
Benzoyl chloride
To obtain it, phosphorus pentachloride or PCl5 must be added. It also works in combination with thionyl chloride or SOCl2. The formula of benzoyl chloride is used in the creation of esters.
Benzoic acid toxicity
Most humans tolerate it in low doses, although some people have hypersensitivity, making it possible for them to experience side effects from benzoic acid and toxicity.
The most common adverse reactions are typical allergic responses to consuming foods that contain it or to which it has been added during processing.
With acetylsalicylic acid
Although they are different substances in both composition and chemical structure, uses of acetylsalicylic acid show similarities when metabolized. If you have sensitivity to acetylsalicylic acid or salicylic acid, you should be extremely cautious when consuming a dose of benzoic acid, as it is very likely that you will also experience side effects from it.
Taking it with ascorbic acid
Additionally, when taking ascorbic acid or additive E300, which is another name for it, there is a possibility that a chemical reaction in the body may produce benzene. This substance is carcinogenic and highly harmful to human health.
Toxicity when mixed with sulfur
Similarly, the use of benzoic acid is discouraged in combination with sulfur dioxide or E220, as it increases risks, just like its derivatives and when mixed or ingested simultaneously with diazo dyes.
Pets, including dogs and cats, should avoid its consumption. Take appropriate precautions to prevent them from coming into contact with this substance, as it is highly toxic to cats.
Uses of benzoic acid
- Bakery.
- Dairy products.
- Cookies.
- Jam production.
- Margarine manufacturing.
- Processed products such as sauces and condiments for recipes.
- Preservation of frozen and fresh packaged products.
- Preparation of carbonated drinks and sugary soft drinks.
Uses as a preservative
It is widely used for this purpose today. The uses of benzoic acid as a preservative are extensive. Every year, a huge amount is used to extend the shelf life of fresh products, especially in processed foods that are packaged and therefore require a preservative additive.
The most common method is to add it in the form of sodium or potassium salts to acidic pH foods. It is also possible to use benzoic derivatives for the same purpose, preventing mold growth and slowing down the fermentation of food. Sulfur dioxide or sulfites are often added to enhance its preservative effects.
In dermatology and cosmetics
In many cases, there is a need to combine the action of two beneficial molecules for skin tissue. Benzoic acid is used in dermatology alongside salicylic acid because their combined effects and properties offer a broader range of benefits.
When used in a cream with benzoic acid, it works as a fungistatic and keratolytic treatment. It is commonly included as a paraben that promotes a longer duration of active ingredients in creams for the treatment of severe and juvenile acne.
Benzoic acid in acne cream
Some dermatologists recommend it for its chemical properties in treating skin eruptions and the appearance of pimples and blackheads. Benzoic acid in cream is used as an alternative to topical retinoids, meaning a substance similar to retinoic acid. Its benefits are somewhat lower, so it is less used in cosmetics, dermatology, and pharmaceutical products. However, depending on each case, it may be preferable to include it in the treatment instead of a retinoid derived from vitamin A.
p-aminobenzoic acid
Known as PABA, p-aminobenzoic acid is an organic compound containing a benzene ring attached to an amine group (a derivative of ammonia) and a carboxyl group.
It is marketed under various commercial names, such as:
- PABA
- Para-aminobenzoic acid.
- 4-aminobenzoic acid.
- Vitamin B10 for animals.
The uses of p-aminobenzoic acid include sun protection, as it absorbs solar radiation, protecting the skin from sun exposure.
