CID 5793

C₆H₁₂O₆

Glucose

C 6
H 12
O 6

Ball-and-stick Stick Space-filling

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24 atoms, 24 single bonds.

IUPAC name: (3R,4S,5S,6R)-6-(hydroxymethyl)oxane-2,3,4,5-tetrol
Molar mass: 180.156(20) g/mol
Atoms: 24
SMILES: C(C1C(C(C(C(O1)O)O)O)O)O
InChIKey: WQZGKKKJIJFFOK-GASJEMHNSA-N
PubChem CID: 5793

Made of

C H O

Structural formula of glucose. Each unlabelled corner is a carbon atom, and the seven hydrogens on carbon are not drawn. Wedges come toward you, hashes go back. It shows which atoms are joined to which, not the shape. The model above shows the shape.

Nature holds far more D-glucose than any other sugar, according to the Hazardous Substances Data Bank (HSDB) quoted on PubChem. It is also the unit that starch, cellulose and glycogen are built from. Its formula, C₆H₁₂O₆, keeps carbon, hydrogen and oxygen in the 1:2:1 ratio of a carbohydrate, and its molar mass is 180.16 g/mol.

Glucose is a hexose, a sugar with six carbons, and an aldose: its open-chain form ends in an aldehyde group, R-CHO. Galactose and fructose share its formula with the atoms arranged differently, so the three are structural isomers. OpenStax traces their different chemistry to how their functional groups are arranged around their asymmetric carbons, carbons bonded to four different groups. The IUPAC name, (3R,4S,5S,6R)-6-(hydroxymethyl)oxane-2,3,4,5-tetrol, describes the ring form: an oxane ring with four OH groups and a CH₂OH arm.

Structure and bonding

The viewer holds 24 atoms and 24 single bonds. With Labels on, the ring reads as five C and one O, the oxane of the name. Four ring carbons carry OH groups; the fifth carries the CH₂OH arm. In Ball-and-stick the angles around each carbon of this computed conformer, a 3D shape PubChem calculated, span 106.4° to 112.0°. The angle at the ring oxygen is 112.6°. With no single central atom, OpenStax gives a molecule like this only a local geometry at each interior atom.

That ring is one picture of a sugar that changes form. In water, OpenStax says, glucose sits in equilibrium between linear and ring forms, usually as rings. The open chain carries a carbon–oxygen double bond, the aldehyde group, which this model never draws. When the ring closes, the OH on carbon 1 locks into one of two positions, α below the ring or β above it. PubChem’s record leaves that carbon unassigned, so its name covers both; the model still has to place the OH on one side.

In water, α-glucose twists polarised light by +112.2°, a figure called its specific optical rotation, and β-glucose by +18.7°. Either solution ends at +52.7°, HSDB records.

Where it turns up

Free glucose sits in honey, fruits and berries, and it is also bound into larger molecules. Sucrose, table sugar, joins glucose to fructose; lactose in milk joins it to galactose; maltose is two glucose units. Each link is a glycosidic bond, made when one sugar’s hydroxyl group combines with another’s hydrogen and a water molecule leaves. Plants store surplus glucose as starch in roots and seeds, and build cellulose, the main material of wood and paper, from it. Vertebrates, humans included, keep theirs as glycogen in liver and muscle cells.

Glucose turns up in medicine too. Helen Free and Alfred Free produced the first test strip for measuring it. Fludeoxyglucose (FDG), a glucose analogue carrying fluorine-18, reveals cancers in positron emission tomography (PET) scans, because cancers use glucose differently from normal tissue.

Why it matters

Plants make glucose from carbon dioxide and water with light absorbed by chlorophyll, releasing six O₂ molecules for every glucose. Heterotrophs are the organisms that rely on the sugars photosynthetic organisms produce for their energy. OpenStax Biology puts nearly all the energy living cells use in the bonds of glucose.

A cell takes the sugar in through GLUT proteins, glucose transporters that assist its facilitated diffusion. Hexokinase then attaches a phosphate group, and the negatively charged phosphate cannot cross the membrane’s hydrophobic interior, so the sugar stays inside. Glycolysis, in the cytoplasm, turns the six-carbon ring into two molecules of pyruvate, a three-carbon keto acid, without using oxygen directly. It makes four adenosine triphosphate (ATP) molecules and spends two, a net gain of two ATP.

A cell that cannot break the pyruvate down further keeps only those two, and yeast ferment it to the ethanol in alcoholic drinks. In the blood, insulin moves glucose into cells, and glycogen breaks down to release more when levels fall. Diabetes is defined by high blood glucose.

Properties

Properties of glucose Molar mass summed from IUPAC/CIAAW 2024 standard atomic weights; formula, atom and bond counts and PubChem's molecular weight from PubChem CID 5793.
Property	Value	Unit	Source
Molecular formula (Hill order)	C₆H₁₂O₆
Molar mass	180.156(20) g/mol	g/mol	IUPAC/CIAAW 2024
Carbon atoms	6
Hydrogen atoms	12
Oxygen atoms	6
Bonds	24
PubChem molecular weight	180.16 g/mol	g/mol	PubChem

Safety

Glucose in food or as a white powder is essentially harmless. In 97.6% of reports to the European Chemicals Agency it meets no criteria of the Globally Harmonized System (GHS) of hazard classification. The cautions its safety cards list concern industrial handling: finely dispersed dust can form explosive mixtures in air, and glucose reacts violently with strong oxidants. The PubChem Laboratory Chemical Safety Summary for glucose is the authoritative sheet.

Questions

Does glucose dissolve in water?

Readily. HSDB data on PubChem give about 479 grams per litre at 20 °C and 546 grams per litre at 30 °C, and one gram of the anhydrous alpha form dissolves in 1.1 millilitres of water at 25 °C. Glucose is only slightly soluble in ethanol and does not dissolve in acetone or ethyl acetate.

What is the difference between alpha and beta glucose?

They differ only at carbon 1, the carbon that becomes asymmetric when the ring closes. With its OH below the ring the sugar is alpha; above the plane, it is beta. The difference carries into polymers: starch links glucose through alpha 1-4 and alpha 1-6 bonds, cellulose through beta 1-4 bonds, and human digestive enzymes cannot break the beta 1-4 linkage, so people digest starch but not cellulose.

Is glucose the same as dextrose?

Yes. Dextrose is another name for D-glucose, the form that predominates in nature, though glucose is the preferred term according to the dictionary PubChem cites. Industry still sells it as dextrose: crystals in an anhydrous form or as a monohydrate carrying one water molecule, and syrups that are 95 to over 99 per cent dextrose. Pharmaceuticals use it as a nutrient and a fluid replenisher.

How is glucose made from corn?

Starch is broken down to its glucose units. In the United States the feedstock is almost always corn starch; other countries also use sorghum, wheat, rice, potato and tapioca. A bacterial alpha-amylase first cuts the starch, then glucoamylase, a fungal enzyme, finishes the job. Before the 1960s acid processes gave about 86 per cent dextrose. Enzymes removed the acid breakdown products and raised the yield to about 95 to 97 per cent.

Made of the same elements

C₆H₁₂O₆ Fructose 24 atoms, 24 single bonds.
C₆H₈O₆ Ascorbic acid 20 atoms, 20 bonds.
C₆H₈O₇ Citric acid 21 atoms, 20 bonds.
C₄H₆O₆ Tartaric acid 16 atoms, 15 bonds.
C₄H₉OH 1-Butanol 15 atoms, 14 single bonds.
C₉H₈O₄ Aspirin 21 atoms, 21 bonds.
C₂H₅OC₂H₅ Diethyl ether 15 atoms, 14 single bonds.
C₄H₆O₅ Malic acid 15 atoms, 14 bonds.

All 51 compounds made of carbon, hydrogen and oxygen

C₈H₈O₃ Methyl salicylate 19 atoms, 19 bonds.
C₈H₈O₃ Vanillin 19 atoms, 19 bonds.
C₃H₇COOH Butyric acid 14 atoms, 13 bonds.
CH₃COOC₂H₅ Ethyl acetate 14 atoms, 13 bonds.
C₃H₈O₃ Glycerol 14 atoms, 13 single bonds.
C₇H₆O₃ Salicylic acid 16 atoms, 16 bonds.
C₆H₅COOH Benzoic acid 15 atoms, 15 bonds.
C₄H₈O Butanone 13 atoms, 12 bonds.
C₆H₅OH Phenol 13 atoms, 13 bonds.
C₃H₈O₂ Propylene glycol 13 atoms, 12 single bonds.
C₃H₇OH 1-Propanol 12 atoms, 11 single bonds.
C₆H₅CHO Benzaldehyde 14 atoms, 14 bonds.
C₃H₈O Isopropyl alcohol 12 atoms, 11 single bonds.
C₃H₆O₃ Lactic acid 12 atoms, 11 bonds.
C₁₄H₁₄O₃ Naproxen 31 atoms, 32 bonds.
C₂H₅COOH Propionic acid 11 atoms, 10 bonds.
C₃H₆O Acetone 10 atoms, 9 bonds.
C₂H₆O₂ Ethylene glycol 10 atoms, 9 single bonds.
CH₃OCH₃ Dimethyl ether 9 atoms, 8 single bonds.
C₂H₅OH Ethanol 9 atoms, 8 single bonds.
C₂H₄O₃ Glycolic acid 9 atoms, 8 bonds.
CH₃COOH Acetic acid 8 atoms, 7 bonds.
H₂C₂O₄ Oxalic acid 8 atoms, 7 bonds.
CH₃CHO Acetaldehyde 7 atoms, 6 bonds.
C₁₅H₁₆O₂ Bisphenol A 33 atoms, 34 bonds.
C₂H₄O Ethylene oxide 7 atoms, 7 single bonds.
C₁₃H₁₈O₂ Ibuprofen 33 atoms, 33 bonds.
C₁₀H₂₀O Menthol 31 atoms, 31 single bonds.
H₂CO₃ Carbonic acid 6 atoms, 5 bonds.
CH₃OH Methanol 6 atoms, 5 single bonds.
C₂₀H₁₄O₄ Phenolphthalein 38 atoms, 41 bonds.
HCOOH Formic acid 5 atoms, 4 bonds.
CH₂O Formaldehyde 4 atoms, 3 bonds.
C₁₂H₂₂O₁₁ Lactose 45 atoms, 46 single bonds.
C₁₂H₂₂O₁₁ Sucrose 45 atoms, 46 single bonds.
C₁₈H₂₄O₂ Estradiol 44 atoms, 47 bonds.
C₁₉H₂₈O₂ Testosterone 49 atoms, 52 bonds.
C₂₁H₃₀O₅ Cortisol 56 atoms, 59 bonds.
C₁₆H₃₂O₂ Palmitic acid 50 atoms, 49 bonds.
C₂₁H₃₀O₂ Progesterone 53 atoms, 56 bonds.
C₁₈H₃₄O₂ Oleic acid 54 atoms, 53 bonds.
C₂₇H₄₄O Cholecalciferol 72 atoms, 74 bonds.
C₂₇H₄₆O Cholesterol 74 atoms, 77 bonds.