4-Hydroxybenzoic Acid

A summary of the most common chemical descriptors (InChI Key and SMILES codes) for 4-Hydroxybenzoic Acid are summarized together with 3D and 2D structures and relevant physico-chemical properties.

What is the 4-Hydroxybenzoic Acid?

The molecule 4-Hydroxybenzoic Acid presents a molecular formula of C7H6O3 and its IUPAC name is 4-hydroxybenzoic acid.

4-Hydroxybenzoic acid is a white, crystalline solid with a melting point of 122-124°C. It is insoluble in water and slightly soluble in ethanol. 4-Hydroxybenzoic acid is used as an intermediate in the synthesis of dyes, pharmaceuticals and other organic compounds..

3D structure

Cartesian coordinates

Geometry of 4-Hydroxybenzoic Acid in x, y and z coordinates (Å units) to copy/paste elsewhere. Generated with Open Babel software.

2D drawing


4-Hydroxybenzoic Acid FJKROLUGYXJWQN-UHFFFAOYSA-N chemical compound 2D structure molecule svg
4-Hydroxybenzoic Acid


Molecule descriptors

IUPAC name4-hydroxybenzoic acid
InChI codeInChI=1S/C8H11NO/c1-6-5-7(10-2)3-4-8(6)9/h3-5H,9H2,1-2H3

Other names (synonyms)

IUPAC nomenclature provides a standardized method for naming chemical compounds. Although this system is widely used in chemistry, many chemical compounds have also other names commonly used in different contexts. These synonyms can come from a variety of sources and are used for a variety of purposes.

One common source of synonyms for chemical compounds is the common or trivial names, assigned on the basis of appearance, properties, or origin of the molecule.

Another source of synonyms are historical or obsolete names employed in the past, however replaced nowadays by more modern or standardized names.

In addition to common and historical names, chemical compounds may also have synonyms that are specific to a particular field or industry.

Reference codes for other databases

There exist several different chemical codes commonly used in orded to identify molecules:

Physico-Chemical properties

IUPAC name4-hydroxybenzoic acid
Molecular formulaC7H6O3
Molecular weight138.121
Melting point (ºC)217
Boiling point (ºC)-
Density (g/cm3)-
Molar refractivity35.42
Topological polar surface area35.3

LogP and topological polar surface area (TPSA) values were estimated using Open Babel software.

The n-octanol/water partition coeficient (Kow) data is applied in toxicology and drug research. Kow values are used, to guess the environmental fate of persistent organic pollutants. High partition coefficients values, tend to accumulate in the fatty tissue of organisms. Molecules with a log(Kow) (or LogP) greater than 5 are considered to bioaccumulate.

TPSA values are the sum of the surface area over all polar atoms or molecules, mainly oxygen and nitrogen, also including hydrogen atoms.

In medicinal chemistry, TPSA is used to assess the ability of a drug to permeabilise cells.

For molecules to penetrate the blood-brain barrier (and act on receptors in the central nervous system), TPSA values below 90 Å2 are required. Thus, molecules with a polar surface area greater than 140 Å2 tend to be poorly permeable to cell membranes.