4-Hydroxybenzoic acid

4-Hydroxybenzoic acid Chemical Properties
Melting point 213-217 °C (lit.)
Boiling point 213.5°C (rough estimate)
density 1,46 g/cm3
vapor pressure 0Pa at 20℃
refractive index 1.4600 (estimate)
FEMA 3986 | 4-HYDROXYBENZOIC ACID
Fp 199 °C
storage temp. Store below +30°C.
solubility methanol: soluble5%, clear to slightly hazy, colorless to faintly yellow
pka4.48(at 19℃)
form Crystalline Powder
color White to ivory
PH3.3 (1g/l, H2O, 20℃)
Odorat 100.00 %. phenolic nutty
Odor Typephenolic
Water Solubility 5 g/L (20 ºC)
Merck 14,4812
JECFA Number957
BRN 970950
InChIKeyFJKROLUGYXJWQN-UHFFFAOYSA-N
LogP0.878 at 22℃
CAS DataBase Reference99-96-7(CAS DataBase Reference)
NIST Chemistry ReferenceBenzoic acid, 4-hydroxy-(99-96-7)
EPA Substance Registry Systemp-Hydroxybenzoic acid (99-96-7)
Safety Information
Hazard Codes Xi
Risk Statements 36-36/37/38
Safety Statements 26-37/39-36
WGK Germany 1
RTECS DH1925000
Autoignition Temperature>250 °C
TSCA Yes
HS Code 29182930
Hazardous Substances Data99-96-7(Hazardous Substances Data)
ToxicityLD50 orally in Rabbit: > 5000 mg/kg
MSDS Information
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4-Hydroxybenzoic acid Usage And Synthesis
Description4-Hydroxybenzoic acid, also known as p-hydroxybenzoic acid or PHBA, is a monohydroxybenzoic acid, a phenolic derivative of benzoic acid. It is a white crystalline solid that is slightly soluble in water and chloroform but more soluble in polar organic solvents such as alcohol and acetone. It is isomeric with salicylic acid (2-hydroxybenzoic acid), a forerunner to aspirin, and 3-hydroxybenzoic acid. The esters of 4-hydroxybenzoic acid, also called parabens, are widely used as preservatives in cosmetics and some ophthalmic solutions.
Chemical Properties4-Hydroxybenzoic acid is an odorless white crystalline astringent powder. In pure form, it imparts a sweetish taste at first, which quickly becomes acrid and disagreeable
Occurrence4-Hydroxybenzoic acid is a phenolic acid that has been found in a variety of fruit peels and leaves. It can be found naturally in coconut. It is one of the main catechins metabolites found in humans after consumption of green tea infusions. It is also found in wine, in vanilla, in Macrotyloma uniflorum (horse gram), carob and in Phyllanthus acidus (Otaheite gooseberry).
Uses4-Hydroxybenzoic acid is used as an intermediate for dyes, antiseptics and active pharmaceutical ingredients. It is also used as a food preservative, corrosion inhibitor, anti-oxidant and an emulsifier. It reacts with 6-hydroxynaphthalene-2-carboxylic acid to prepare aromatic polyester called Vectran fiber. It acts as a precursor to prepare p-hydroxyphenylbenzoate, p-acetoxybenzoyl chloride and 4,4'-dihydroxybenzophenone. Further, it is used in paint additives, coating additives, processing aids, electrical and electronic products. In addition to this, it acts as a preservative in cosmetics and some ophthalmic solutions.
UsesIn organic. syntheses; intermediate for dyes, fungicides.
Usesp-Hydroxybenzoic acid is of significant commercial importance. The most familiar application is the use of several of its esters as preservatives, known as parabens. Also of interest is the use in liquid crystal polymer applications.
Definition ChEBI: 4-hydroxybenzoic acid is a monohydroxybenzoic acid that is benzoic acid carrying a hydroxy substituent at C-4 of the benzene ring. It has a role as a plant metabolite and an algal metabolite. It is a conjugate acid of a 4-hydroxybenzoate.
PreparationPrepared from p-bromophenol or p-hydroxybenzaldehyde, or from saponification of methyl salicylate, a major component of oil of wintergreen.
In 1947, H. Gilman and C. E. Arntzen at Iowa State College (Ames) reported the synthesis of 4-HBA from 4-hydroxybenzaldehyde. Several other preparation methods were developed since then. Today it is produced commercially via the Kolbe–Schmitt reaction, which originated in the mid-1800s. Potassium phenoxide and CO2 are heated under pressure; the reaction mixture is then acidified to obtain the product 4-Hydroxybenzoic acid. (Oddly, if the sodium salt is used, the product is 2-hydroxybenzoic acid, or salicylic acid.)
Org. Synth. 1934, 14, 48
DOI: 10.15227/orgsyn.014.0048
Application4-Hydroxybenzoic acid can be used as a starting material to synthesize organic intermediates such as 4-acetoxybenzoic acid and 4-hydroxy-3,5-diiodobenzoic acid.
4-Hydroxybenzoic acid is used as an intermediate for dyes, antiseptics and active pharmaceutical ingredients. It is also used as a food preservative, corrosion inhibitor, anti-oxidant and an emulsifier. It reacts with 6-hydroxynaphthalene-2-carboxylic acid to prepare aromatic polyester called Vectran fiber. It acts as a precursor to prepare p-hydroxyphenylbenzoate, p-acetoxybenzoyl chloride and 4,4′-dihydroxybenzophenone. Further, it is used in paint additives, coating additives, processing aids, electrical and electronic products. In addition to this, it acts as a preservative in cosmetics and some ophthalmic solutions.
Aroma threshold valuesDetection at 5 ppm (water)
Synthesis Reference(s)Journal of the American Chemical Society, 106, p. 174, 1984 DOI: 10.1021/ja00313a035
The Journal of Organic Chemistry, 29, p. 3459, 1964 DOI: 10.1021/jo01035a003
General DescriptionPharmaceutical secondary standards for application in quality control provide pharma laboratories and manufacturers with a convenient and cost-effective alternative to the preparation of in-house working standards. 4-Hydroxybenzoic acid belongs to the class of aromatic acids, which may be used as a preservative in cosmetics, pharmaceuticals and as a synthetic flavoring agent in food products.
Flammability and ExplosibilityNonflammable
Purification MethodsCrystallise the hydroxyacid from water. [Beilstein 10 IV 345.]
3-Hydroxybenzoic acid 4-HYDROXYBENZOIC ACID METYL ESTER,4-HYDROXYBENZOIC ACID METHYL ESTER 4-Hydroxybenzoic acid Salicylic Acid (Pharm) 2'-Hydroxy-3-phenylpropiophenone 2,4,5-Trimethoxybenzoic acid 2,4-Dimethoxybenzoic acid 5-BROMO-2,4-DIHYDROXYBENZOIC ACID 4-HYDROXYBENZOIC ACID ETHYL ESTER 3-CHLORO-4-HYDROXYBENZOIC ACID 4-HYDROXYBENZOIC ACID N-BUTYL ESTER,4-HYDROXYBENZOIC ACID BUTYL ESTER 2,3,4-Trimethoxybenzoic acid 2,3,4-Trihydroxybenzoic acid 3,5-Dihydroxybenzoic acid 2-Fluoro-4-hydroxybenzoic acid Octyl gallate 2-Chloro-4-hydroxybenzoic acid 4-Methoxysalicylic acid

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