Benzoic acid NEW

Benzoic acid is also known as benzoic acid, the molecular formula is C6H5COOH, carboxyl group directly connected with the benzene ring carbon atom the simplest aromatic acid, is a benzene ring hydrogen is replaced by a carboxyl group (-COOH) formed compound. It is colorless and odorless flake crystal. The melting point is 122.13℃, the boiling point is 249℃, and the relative density is 1.2659 (15/4 ℃). At 100℃ rapid sublimation, its vapor has a strong irritation, easy to cause cough after inhalation. Slightly soluble in water, soluble in ethanol, ether, chloroform, benzene, toluene, carbon disulfide, carbon tetrachloride and turpentine and other organic solvents. Widely occurring in nature in the form of free acids, esters or their derivatives, for example, in the form of free acids and benzyl esters in benzoin gum; It occurs free in the leaves and stem skins of some plants; Exists as methyl ester or benzyl ester in essential oils; It is present in horse urine in the form of its derivative hippuric acid. Benzoic acid is a weak acid, stronger than fatty acids. Their chemical properties are similar, can form salt, ester, acyl halide, amide, acid anhydride, etc., are not easy to be oxidized. Electrophilic substitution reactions can occur on the benzene ring of benzoic acid, mainly resulting in metamorphotic substitution.

Effect

Benzoic acid and its sodium salt sodium benzoate are commonly used as food preservatives. Under acidic conditions, the inhibitory effect on yeast and mold, when the pH value is 3, the antibacterial force is strong, and the pH value is 6, the effect on many molds is very poor, so the optimal antibacterial pH value is 2.5-4.0. In the food industry, the maximum use of concentrated fruit and vegetable juice in plastic drums shall not exceed 2.0g/kg; In jam (excluding canned), fruit juice (flavor) drinks, soy sauce, vinegar maximum use of 1.0g/kg; The maximum usage in soft candy, wine and fruit wine is 0.8g/kg; In low salt pickles, sauces, preserves, the maximum use of 0.5g/kg; The maximum amount used in carbonated beverages is 0.2g/kg. Because of the small solubility of benzoic acid, it must be fully stirred when used, or dissolved in a small amount of hot water or ethanol. When used in concentrated fruit juice for refreshing drinks, benzoic acid is easily volatilized with water vapor, so it is often used as sodium salt. Benzoic acid is a common preservative in the food industry, but it is not allowed to be added to dairy products. In general, benzoic acid is considered safe. However, for some special groups, including infants and young children, long-term intake of benzoic acid may also bring asthma, urticaria, metabolic acidosis and other adverse reactions. Benzoic acid is also used as a preservative in fruit drinks. Can be used as a paste fragrance into the aromatherapy fragrance essence. Can also be used in chocolate, lemon, orange, berries, nuts, preserves and other edible flavors. It is also commonly used in tobacco flavors. In addition, benzoic acid is also used as pesticide, dye, medicine, mordant and plasticizer production raw materials, polyamide resin and alkyd resin modifier and iron and steel equipment rust prevention agent.

Application:

1 Benzoic acid is an important acid type food preservative. Under acidic conditions, it has inhibitory effect on mold, yeast and bacteria, but weak effect on acid-producing bacteria. The optimal pH value for bacteriostasis is 2.5 ~ 4.0, and it is generally appropriate to be lower than pH 4.5 ~ 5.0. In the food industry, the maximum use of concentrated fruit and vegetable juice in plastic drums shall not exceed 2.0g/kg; In jam (excluding canned), fruit juice (flavor) drinks, soy sauce, vinegar maximum use of 1.0g/kg; The maximum usage in soft candy, wine and fruit wine is 0.8g/kg; In low salt pickles, sauces, preserves, the maximum use of 0.5g/kg; The maximum amount used in carbonated beverages is 0.2g/kg. Since benzoic acid is slightly soluble in water, a small amount of ethanol can be used to dissolve it.

2 benzoic acid is an important acid type feed preservative. Under acidic conditions, it has inhibitory effect on mold, yeast and bacteria, but weak effect on acid-producing bacteria. The optimal PH for bacteriostasis is 2.5-4.0, generally lower than 4.5-5.0.

3 Benzoic acid is mainly used for antifungal and antiseptic, but also used as an antimicrobial agent. Because of the small solubility of benzoic acid, it must be fully stirred when used, or dissolved in a small amount of hot water or ethanol. When used in concentrated fruit juice for refreshing drinks, benzoic acid is easily volatilized with water vapor, so it is often used as sodium salt. 1g sodium is equivalent to 0.847g of benzoic acid.

4 Usually used as a fixing agent or preservative. It is also used as a perfumer in fruit drinks. Can be used as a paste fragrance into the aromatherapy fragrance essence. Can also be used in chocolate, lemon, orange, berries, nuts, preserves and other edible flavors. It is also commonly used in tobacco flavors.

5 Benzoic acid and its sodium salts are important preservatives in food. Under acidic conditions, the inhibitory effect on yeast and mold, when the pH value is 3, the antibacterial force is strong, and the pH value is 6, the effect on many molds is very poor, so the optimal antibacterial pH value is 2.5-4.0. Benzoic acid is mainly used in the production of sodium benzoate food preservatives, dye intermediates, pesticides, plasticizers, mordant, medicine, spices, can also be used as alkyd resin and polyamide resin modifier, for the production of terephthalic acid raw material and used as steel equipment rust prevention agent.

6 Used in the production of medicine, dye carriers, plasticizers, fragrances and food preservatives, etc., and also used in the performance improvement of alkyd resin coatings; Used as an intermediate for pharmaceuticals and dyes, for plasticizers and fragrances, etc., and as an anti-rust agent for steel equipment

7 Quantitative standard for alkali. Iodine quantitative standard. Calorific value standard. Verification of aluminum, boron, cerium, copper, iron, lead, manganese, mercury, nickel, nitrate, nitrite, silver, titanium, tungsten and vanadium. Determination of aluminum, copper, iron, titanium and uranium. Standard for the determination of carbon, hydrogen, oxygen and relative molecular mass by organic microanalysis. Organic analysis is also used for benzoylation.