Glucose
Properties
| State | Solid (white crystalline powder) |
| Color | White |
| Solubility | Highly soluble in water (909 g/L at 25°C) |
| Melting Point | 146°C (decomposes) |
| Boiling Point | Decomposes before boiling |
About Glucose
Glucose is the six-carbon aldose at the center of carbohydrate metabolism — molar mass 180.156 g/mol, an aldehyde at C1 plus hydroxyls at C2 through C6, with the D-configuration at C5 that defines its biological identity. In aqueous solution at room temperature, less than 0.01% exists as the open-chain aldehyde; the rest cyclizes into a six-membered pyranose ring with the C1 hydroxyl in either alpha (38%) or beta (62%) configuration. That equilibrium is the reason glucose tastes about 70% as sweet as sucrose and why a fresh glucose solution slowly changes its specific rotation over an hour or two as the anomers equilibrate (mutarotation, +112° → +52.7°). Inside a cell, glucose enters glycolysis via hexokinase phosphorylation to glucose-6-phosphate, generating 30-32 ATP per molecule when oxidized completely through the TCA cycle and oxidative phosphorylation. Industrially, glucose is produced by enzymatic hydrolysis of corn starch using alpha-amylase followed by glucoamylase — about 30 million tonnes per year worldwide, mostly going on to high-fructose corn syrup via glucose isomerase. In the lab it's the standard reducing sugar for Benedict's, Fehling's, and Tollens' tests because the small fraction of open-chain aldehyde at equilibrium is enough to reduce Cu(II) to Cu2O brick-red precipitate or Ag(I) to a silver mirror.
Where you'll encounter it
If you've ever pricked a finger for a blood-sugar reading, fermented bread or beer, or watched the brown caramel form when you heated table sugar, you've worked with glucose chemistry — the glucose oxidase strip in a glucometer literally counts H2O2 molecules generated as glucose oxidizes, and bread fermentation runs on yeast pulling glucose from amylase-digested starch. In a cell-culture room, DMEM media is formulated with 4.5 g/L glucose (25 mM) — high enough that overnight HEK293 cultures consume only a fraction before passage. In a hospital pharmacy, D5W (5% dextrose in water) is the standard maintenance IV fluid for hypoglycemia, while D50W (50%) goes through a central line in cardiac-arrest protocols. In a teaching lab running Benedict's test, the brick-red Cu2O precipitate that drops out of an alkaline tartrate-Cu(II) solution is the visual confirmation that glucose's open-chain aldehyde tautomer reduced the copper.
Common Uses
- Substrate for yeast fermentation in brewing, baking, and bioethanol production
- Intravenous nutrition (D5W and D50W solutions in clinical medicine)
- Reference reducing sugar for Benedict's and Fehling's diagnostic tests
- Feedstock for glucose isomerase conversion to high-fructose corn syrup
- Energy substrate for cell culture media (DMEM uses 4.5 g/L)
- Cryoprotectant in sperm and oocyte preservation
- Reagent in glucose-oxidase biosensor electrodes for blood glucose meters
Safety Information
GRAS for food and pharmaceutical use; oral LD50 in rats exceeds 25 g/kg. No GHS hazard classification. The realistic safety concerns are downstream: chronic high glucose intake drives insulin resistance and type 2 diabetes, and IV bolus of hypertonic glucose (D50W) into a peripheral line causes vein irritation and phlebitis — clinical guidelines require central line access for sustained D50W infusion. Glucose powder dust at concentrations above 50 g/m3 is a Class St1 dust explosion hazard (Kst around 75 bar·m/s), so industrial handling needs grounded equipment and dust-collection systems just like flour mills do.
This safety summary is for educational reference only and may not be complete. It is not a substitute for Safety Data Sheets (SDS), medical advice, or professional chemical safety guidance. Always consult appropriate SDS and qualified professionals before handling chemicals. We deliberately do not publish occupational exposure limits or other regulatory thresholds: those values are revised over time and differ between jurisdictions, so the only correct source is the current SDS and the regulations that apply where you work.