4-Hydroxyphenylacetic acid

CAS NO.：156-38-7
Empirical Formula: C8H8O3
Molecular Weight: 152.15
MDL number: MFCD00004347
EINECS: 205-851-3
SAFETY DATA SHEET (SDS)
Update Date: 2026-03-13 23:13:44

What is 4-Hydroxyphenylacetic acid?

Chemical properties

4-Hydroxyphenylacetic acid is a white to cream or light tan crystalline powder. sublimation. Insoluble in cold water, soluble in hot water, ether, ethanol, ethyl acetate. In the case of ferric chloride, it is a purple-green precipitate. It is used as a pharmaceutical raw material for the synthesis of cephalosporin antibiotics, antipyretic analgesics.

The Uses of 4-Hydroxyphenylacetic acid

4-Hydroxyphenylacetic acid (4-HPAA) is a natural phenolic metabolite and is used as a reagent for the acylation of phenols and amines, as an intermediate in fine chemicals, and as a fluorometric assay for oxidative enzymes. Clinically, 4-HPAA is also used as an ecological disorder marker, and urinary phenylacetic acid has been shown to be negatively correlated with depressive symptoms.

Definition

ChEBI: 4-hydroxyphenylacetic acid is a monocarboxylic acid that is acetic acid in which one of the methyl hydrogens is substituted by a 4-hydroxyphenyl group. It has a role as a plant metabolite, a fungal metabolite, a human metabolite and a mouse metabolite. It is a monocarboxylic acid and a member of phenols. It derives from an acetic acid. It is a conjugate acid of a 4-hydroxyphenylacetate.

Preparation

4-Hydroxyphenylacetic acid is synthesized by diazotization and hydrolysis of 4-aminophenylacetic acid.
4-aminophenylacetic acid and alkali solution are prepared into sodium salt, and then sulfuric acid is added. Cool to 0°C, control the temperature at 0-5°C, and add sodium nitrate solution dropwise, and the reaction is completed for 0.5h. The obtained diazonium was added dropwise to dilute sulfuric acid at 90-95°C for about 1 hour, and the reaction was continued for 1 hour. The reaction solution was decolorized and filtered, cooled and extracted with ethyl acetate, and the extract was recovered with ethyl acetate to obtain 4-Hydroxyphenylacetic acid. The yield is about 85%.

Purification Methods

Crystallise the acid from water or Et2O/pet ether. The p-bromophenacyl ester has m 117o (from EtOH). [Beilstein 10 II 112, 10 III 430, 10 IV 543.]

Properties of 4-Hydroxyphenylacetic acid

Melting point:	148-151 °C(lit.)
Boiling point:	234.6°C (rough estimate)
Density	1.2143 (rough estimate)
vapor pressure	0.007Pa at 25℃
refractive index	1.4945 (estimate)
storage temp.	Inert atmosphere,Room Temperature
solubility	50g/l
pka	4.50±0.10(Predicted)
form	Crystalline Powder
color	White to cream or light tan
PH	2.0-2.4 (30g/l, H2O, 20℃)
Water Solubility	Soluble in dimethyl sulfoxide and methanol. Slightly soluble in water.
BRN	1448766
CAS DataBase Reference	156-38-7(CAS DataBase Reference)
NIST Chemistry Reference	Benzeneacetic acid, 4-hydroxy-(156-38-7)
EPA Substance Registry System	Benzeneacetic acid, 4-hydroxy- (156-38-7)

Safety information for 4-Hydroxyphenylacetic acid

Signal word	Warning
Pictogram(s)	Exclamation Mark Irritant GHS07
GHS Hazard Statements	H315:Skin corrosion/irritation H319:Serious eye damage/eye irritation H335:Specific target organ toxicity, single exposure;Respiratory tract irritation
Precautionary Statement Codes	P261:Avoid breathing dust/fume/gas/mist/vapours/spray. P305+P351+P338:IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continuerinsing.