Sodium benzoate reacts with benzyl chloride

Structural formula
Surname Benzoic acid
other names
  • Phenylformic acid
  • Benzenecarboxylic acid
  • Benzene carboxylic acid
Molecular formula C.7H6O2
CAS number 65-85-0
Brief description colorless solid[1]
Molar mass 122.12 g mol−1
Physical state firmly
density 1.27 g cm−3 [1]
Melting point 122.1 ° C[1]
boiling point 250 ° C[1]
Vapor pressure

1.3 hPa (20 ° C)[1]

pKa value


  • easily soluble in chloroform, ethanol and acetone
  • poorly soluble in water: 2.7 g · l−1 (20 ° C)[1]
safety instructions

not fixed [1]


1700 mg kg−1 (Rat, perorally) [2]

As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions.

Benzoic acid is an aromatic carboxylic acid. It consists of a phenyl radical with a carboxyl group.


Benzoic acid forms colorless, shiny flakes or needle-shaped crystals, which are only slightly soluble in cold water and more readily soluble in warm water. Above 370 ° C, benzoic acid decomposes into benzene and carbon dioxide (CO2). Benzoic acid has an intense odor and is easily combustible. The absorption maxima are at the wavelengths 227 and 273 nm.


Benzoic acid is found in many frankincense mixtures as a major component of the benzoin resin. In addition to resins, benzoic acid is also found in fruits such as plums, blueberries and cranberries.

Benzoic acid can be obtained from the resin of a tree species (Siam Benzoin and Sumatran Benzoin) that is native to Indonesia.


Technically, the production takes place through an oxidation of toluene with manganese dioxide and sulfuric acid in the presence of manganese naphthenate, or through the reaction with potassium permanganate. Today, toluene is used industrially with oxygen in the gas phase in the presence of catalysts such. B. oxidized vanadium pentoxide.

Benzoic acid can also be produced from bromobenzene using a Grignard reaction. The bromobenzene reacts with magnesium to form phenylmagnesium bromide, which with carbon dioxide to form C.6H5COOMgBr and finally reacts to benzoic acid by adding a hydrochloric acid solution.


Benzoic acid is used in the manufacture of benzoic acid esters, which are used in the perfume industry. Benzoic acid is also used for plasticizers in the preparation of benzoyl compounds such as benzoyl chloride and dibenzoyl peroxide.

In the food industry, benzoic acid (E 210) is used as a preservative, especially for pickled foods. Because of their better solubility, it is more common to use the salts: sodium benzoate (E 211), potassium benzoate (E 212), calcium benzoate (E 213). Benzoic acid is often used in long-life foods such as B. used in ketchup, sausage, mustard and other sauces, margarine, fish salads and many other products as a preservative. The bacteriostatic and fungistatic effect is based on the inhibiting effect on enzymes that break down reactive oxygen species (catalase and peroxidase), which creates an accumulation of hydrogen peroxide in the cells of the microorganisms. This ultimately leads to their death. Benzoic acid is harmless in the human organism, since accumulation is prevented by converting and excreting the substance as hippuric acid.

Benzoic acid is highly toxic to many animals (e.g. dogs and cats).

Benzoic acid is a basic titer substance according to the pharmacopoeia.


  1. abcdefGH Entry on benzoic acid in the GESTIS substance database of the BGIA, accessed on 22 Aug 2007 (JavaScript required)
  2. Benzoic acid at ChemIDplus

Categories: Harmful Substance | Carboxylic acid | Aromat