CID 6623

C₁₅H₁₆O₂

Bisphenol A

C 15
H 16
O 2

Ball-and-stick Stick Space-filling

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33 atoms, 34 bonds.

IUPAC name: 4-[2-(4-hydroxyphenyl)propan-2-yl]phenol
Molar mass: 228.291(35) g/mol
Atoms: 33
SMILES: CC(C)(C1=CC=C(C=C1)O)C2=CC=C(C=C2)O
InChIKey: IISBACLAFKSPIT-UHFFFAOYSA-N
PubChem CID: 6623

Made of

C H O

Structural formula of bisphenol A. Each unlabelled corner is a carbon atom, and the eight hydrogens on carbon are not drawn. It shows which atoms are joined to which, not the shape. The model above shows the shape.

Polycarbonate, a hard, clear plastic, and the epoxy resins lining the inside of some food and drink cans are both built from bisphenol A, known as BPA. Its manufacture from phenol and acetone was patented in the United States by Jansen in 1949, the Hazardous Substances Data Bank (HSDB) records.

In the description given by ChEBI (Chemical Entities of Biological Interest), two phenol units are joined through one carbon whose two hydrogens have been swapped for methyl groups. Fifteen carbon, sixteen hydrogen and two oxygen atoms make C₁₅H₁₆O₂, with a molar mass of 228.29 g/mol and the IUPAC name 4-[2-(4-hydroxyphenyl)propan-2-yl]phenol.

The solid comes as white crystals, flakes or powder. It melts at 150 to 157 °C according to the International Chemical Safety Cards, and at 160 °C according to HSDB. Water takes up very little of it, yet HSDB records it as very soluble in ethanol, ether and alkali.

Structure and bonding

The viewer holds 33 atoms and 34 bonds. One carbon sits at the centre, bonded to two methyl groups and to one carbon of each of two six-membered rings. With Labels on, the only two O symbols sit at opposite ends of the molecule, each bonded to the ring carbon straight across from that junction. In Ball-and-stick, the bonds around the central carbon open to between about 104° and 116° in this computed model. Turned, the model shows two flat rings whose planes stand about 88° apart.

Ball-and-stick and Stick draw each ring as three double bonds alternating with three single ones. In the molecule itself the ring electrons are delocalised, shared evenly around each ring as in benzene. The model’s ring bonds all measure 1.36 to 1.40 Å, however they are drawn. Space-filling merges the atoms into two broad slabs meeting at an angle, with the methyl groups bulging out at the hinge. HSDB gives bisphenol A a pK_a of 9.6, the number that rates how readily it gives up a hydrogen ion.

Where it turns up

The US National Institute of Environmental Health Sciences (NIEHS) lists shatterproof windows, eyewear and water bottles among the products that contain BPA. Epoxy resins made from it coat bottle tops, water supply pipes and some metal food cans. Thermal paper for cash-register receipts carries it too, the US Environmental Protection Agency (EPA) notes; in the EU that use has been banned since January 2020.

Diet is the main route into the body for most people, NIEHS says, and BPA can leach into canned food from the epoxy lining. Food packaging takes less than 5 per cent of the BPA used in the United States, yet people appear to be exposed mainly through it, the EPA says. BPA also reaches breast milk. In a 2003–2004 survey, the US Centers for Disease Control and Prevention detected it in 93 per cent of 2,517 urine samples from people aged six and over.

Why it matters

ChEBI classes bisphenol A as an endocrine disruptor, and the EPA calls it weakly oestrogenic. Such a compound, the EPA explains, may interfere with the body’s own hormones even at low exposures. In rodents BPA interacts with oestrogen receptors, HSDB records, while in human womb-lining cells its effects appeared to bypass oestrogen pathways.

The US Food and Drug Administration holds BPA safe at current levels in foods. The European Food Safety Authority judged BPA in food a health risk in April 2023. The European Commission adopted a ban on BPA in food contact materials in December 2024, citing possible harm to the immune system.

Standardised tests put levels in people and the environment below those of concern, the EPA says, and for now it plans no action over human health. Some low-dose studies, though, raise concern for aquatic life. The National Toxicology Program voiced “some concern” in 2008 for the brain, behaviour and prostate of babies and young children. Its 2018 CLARITY-BPA study in rats found few clear effects, except possibly on the female reproductive tract and male pituitary.

Properties

Properties of bisphenol A Molar mass summed from IUPAC/CIAAW 2024 standard atomic weights; formula, atom and bond counts and PubChem's molecular weight from PubChem CID 6623.
Property	Value	Unit	Source
Molecular formula (Hill order)	C₁₅H₁₆O₂
Molar mass	228.291(35) g/mol	g/mol	IUPAC/CIAAW 2024
Carbon atoms	15
Hydrogen atoms	16
Oxygen atoms	2
Bonds	34
Single bonds	28
Double bonds	6
PubChem molecular weight	228.29 g/mol	g/mol	PubChem

Safety

Bisphenol A carries the signal word Danger under the European Union’s harmonised classification. It may damage fertility, causes serious eye damage, may cause an allergic skin reaction or respiratory irritation, and is very toxic to aquatic organisms, with lasting effects. The European Chemicals Agency (ECHA) has listed it since 2017 as a Substance of Very High Concern: toxic to reproduction, and endocrine-disrupting for human health and for the environment. The PubChem Laboratory Chemical Safety Summary for bisphenol A gathers these hazards and the workplace limits.

Questions

How are the two rings of bisphenol A arranged?

Two benzene rings, each with an OH group at its far end, hang from one carbon that also holds two methyl groups. The US National Cancer Institute's thesaurus calls it a derivative of diphenylmethane bearing two hydroxyphenyl groups. No single shape word fits, since the central carbon, the ring carbons, the methyl carbons and the oxygens each set their own geometry. In PubChem's computed conformer the two rings stand about 88° apart.

What is BPA used for?

The Hazardous Substances Data Bank (HSDB) names polycarbonate plastic as its largest use, with epoxy resins next. Haz-Map, an occupational health database, adds that the epoxies are made by reacting it with epichlorohydrin. Of the BPA used in the United States in 1984, polycarbonate took 52 per cent and epoxy resins 41 per cent, on HSDB's figures. Smaller outlets are flame retardants and unsaturated polyester, polyacrylate, polyetherimide and polysulfone resins.

Is BPA banned?

The EU banned it from polycarbonate baby feeding bottles in January 2011 and from plastic bottles and packaging holding food for under-threes in September 2018. The European Commission then adopted a wider ban, on 19 December 2024, covering food contact materials. The US FDA stopped allowing it in baby bottles and sippy cups in July 2012 and in infant-formula can coatings in July 2013. It did so because those uses had been abandoned, not for safety reasons.

What happens to BPA in the body?

Swallowed BPA is quickly converted to an inactive form, the US FDA says, which keeps internal exposure to the active form much lower than after an injection. Primates of all ages, humans included, clear it far faster and more efficiently than rodents. HSDB names the main product as BPA-monoglucuronide. In a study of human placentas recorded by HSDB, the fat-soluble compound appeared to cross by passive diffusion, from mother to unborn baby and back again.

Made of the same elements

C₁₃H₁₈O₂ Ibuprofen 33 atoms, 33 bonds.
C₁₄H₁₄O₃ Naproxen 31 atoms, 32 bonds.
C₂₀H₁₄O₄ Phenolphthalein 38 atoms, 41 bonds.
C₁₀H₂₀O Menthol 31 atoms, 31 single bonds.
C₁₈H₂₄O₂ Estradiol 44 atoms, 47 bonds.
C₉H₈O₄ Aspirin 21 atoms, 21 bonds.
C₈H₈O₃ Methyl salicylate 19 atoms, 19 bonds.
C₁₉H₂₈O₂ Testosterone 49 atoms, 52 bonds.

All 51 compounds made of carbon, hydrogen and oxygen

C₈H₈O₃ Vanillin 19 atoms, 19 bonds.
C₆H₁₂O₆ Fructose 24 atoms, 24 single bonds.
C₆H₁₂O₆ Glucose 24 atoms, 24 single bonds.
C₁₆H₃₂O₂ Palmitic acid 50 atoms, 49 bonds.
C₄H₉OH 1-Butanol 15 atoms, 14 single bonds.
C₆H₅COOH Benzoic acid 15 atoms, 15 bonds.
C₂H₅OC₂H₅ Diethyl ether 15 atoms, 14 single bonds.
C₁₂H₂₂O₁₁ Lactose 45 atoms, 46 single bonds.
C₁₂H₂₂O₁₁ Sucrose 45 atoms, 46 single bonds.
C₆H₅CHO Benzaldehyde 14 atoms, 14 bonds.
C₃H₇COOH Butyric acid 14 atoms, 13 bonds.
CH₃COOC₂H₅ Ethyl acetate 14 atoms, 13 bonds.
C₇H₆O₃ Salicylic acid 16 atoms, 16 bonds.
C₄H₈O Butanone 13 atoms, 12 bonds.
C₆H₅OH Phenol 13 atoms, 13 bonds.
C₂₁H₃₀O₂ Progesterone 53 atoms, 56 bonds.
C₃H₈O₂ Propylene glycol 13 atoms, 12 single bonds.
C₃H₇OH 1-Propanol 12 atoms, 11 single bonds.
C₆H₈O₆ Ascorbic acid 20 atoms, 20 bonds.
C₃H₈O₃ Glycerol 14 atoms, 13 single bonds.
C₃H₈O Isopropyl alcohol 12 atoms, 11 single bonds.
C₁₈H₃₄O₂ Oleic acid 54 atoms, 53 bonds.
C₆H₈O₇ Citric acid 21 atoms, 20 bonds.
C₂H₅COOH Propionic acid 11 atoms, 10 bonds.
C₃H₆O Acetone 10 atoms, 9 bonds.
C₂₁H₃₀O₅ Cortisol 56 atoms, 59 bonds.
C₂H₆O₂ Ethylene glycol 10 atoms, 9 single bonds.
C₃H₆O₃ Lactic acid 12 atoms, 11 bonds.
CH₃OCH₃ Dimethyl ether 9 atoms, 8 single bonds.
C₂H₅OH Ethanol 9 atoms, 8 single bonds.
C₄H₆O₅ Malic acid 15 atoms, 14 bonds.
CH₃COOH Acetic acid 8 atoms, 7 bonds.
C₄H₆O₆ Tartaric acid 16 atoms, 15 bonds.
CH₃CHO Acetaldehyde 7 atoms, 6 bonds.
C₂H₄O Ethylene oxide 7 atoms, 7 single bonds.
C₂H₄O₃ Glycolic acid 9 atoms, 8 bonds.
CH₃OH Methanol 6 atoms, 5 single bonds.
HCOOH Formic acid 5 atoms, 4 bonds.
H₂CO₃ Carbonic acid 6 atoms, 5 bonds.
CH₂O Formaldehyde 4 atoms, 3 bonds.
H₂C₂O₄ Oxalic acid 8 atoms, 7 bonds.
C₂₇H₄₄O Cholecalciferol 72 atoms, 74 bonds.
C₂₇H₄₆O Cholesterol 74 atoms, 77 bonds.