Benzoic acid

Main Applications Food and Pharmaceutical Preservation: Benzoic acid and its sodium salt (sodium benzoate) are internationally recognized food preservatives. They function by inhibiting the respiratory enzyme systems of microbial cells and are particularly effective against fungi, yeasts, and bacteria. They are suitable for acidic foods (optimal effect at pH 2.5-4.0), such as soy sauce, vinegar, jams, and beverages. Chinese standards stipulate a maximum usage level of 0.1-0.2 g/kg. In the pharmaceutical field, they are used in topical preparations (such as ointments and lotions) to inhibit skin fungi (e.g., for the treatment of athlete's foot). Chemical Intermediates: Synthesis of benzoate esters (e.g., benzyl benzoate, used as a fragrance and insect repellent), benzoyl chloride (an acylating agent in organic synthesis), and terephthalic acid (a raw material for polyesters). Preparation of plasticizers (e.g., phthalate substitutes) and dye intermediates (e.g., acid dyes). Other Fields: Textile mildew inhibitors, tobacco flavor fixatives, and metal rust inhibitors (by complexing with metal ions). Used in laboratories as a primary standard for titrating alkaline solutions (due to high purity and good stability).