Anthracene
Properties
| State | Solid (crystalline) |
| Color | Colorless to pale yellow (blue fluorescence under UV) |
| Solubility | Insoluble in water; slightly soluble in ethanol; soluble in benzene and CS2 |
| Melting Point | 218°C |
| Boiling Point | 342°C |
About Anthracene
Anthracene is the linear three-ring polycyclic aromatic hydrocarbon, and the simple geometric difference between linear (anthracene) and angular (phenanthrene) arrangement of three fused benzene rings produces a noticeable change in chemistry. Anthracene's central ring is markedly less aromatic than the two outer rings — the resonance energy distribution favors leaving the 9,10-positions chemically reactive, which is why anthracene is one of the few aromatic hydrocarbons to undergo Diels–Alder cycloaddition readily. Maleic anhydride adds across the 9 and 10 positions to give a triptycene-like adduct in nearly quantitative yield, and the reaction is reversible enough on heating that the retro-Diels–Alder is one of the cleanest demonstrations of pericyclic reaction reversibility available in undergraduate teaching labs. The molecule's other defining feature is its strong blue fluorescence under UV excitation, with quantum yield approaching 0.4 in dilute solution. That fluorescence has been the basis of organic scintillation detectors since the 1950s — anthracene crystals produce light pulses when ionizing radiation deposits energy in them, and the integrated pulse intensity scales linearly with deposited energy. Modern liquid-scintillation cocktails for radiometric assays usually use 2,5-diphenyloxazole (PPO) instead, but anthracene remains the historic reference standard against which other organic scintillators are calibrated. Industrially, the largest historical use was as the precursor to anthraquinone (and then to alizarin and a long list of other anthraquinone-derived dyes), one of the foundational chemistries of the 19th-century synthetic-dye industry.
Where you'll encounter it
If you've ever passed a black light over a coal-tar-based driveway sealer, the blue glow you saw was largely anthracene fluorescence — coal-tar fractions are rich in anthracene and other PAHs. In a teaching lab, anthracene is the substrate of choice for demonstrating Diels–Alder chemistry: the maleic-anhydride cycloaddition is robust enough to run reliably in an undergraduate setting, the product crystallizes cleanly, and the back-reaction can be demonstrated by heating the adduct. In contemporary research, anthracene-derivative thin films are the active emitters in many blue OLEDs, where the rigid planar π-system gives both high luminescence quantum yield and adequate mobility for charge transport, and the molecule's role as a scintillator continues in nuclear-physics and homeland-security detector arrays.
Common Uses
- Organic-crystal scintillator for ionizing-radiation detection
- Diels–Alder substrate at the 9,10-positions for teaching pericyclic chemistry
- Anthraquinone-precursor feedstock for traditional dye synthesis
- Blue-emitter material in organic light-emitting diode research
- Reference compound for fluorescence quantum-yield calibration
Safety Information
Skin sensitization risk on chronic dermal contact, especially when combined with sunlight exposure (PAHs can produce phototoxic reactions). Suspected carcinogen by chronic inhalation exposure to fine dust or aerosol — anthracene itself is generally considered less carcinogenic than several other PAHs in the same coal-tar mixture, but the IARC classification (2B) reflects uncertainty about the metabolic activation profile. GHS H315, H319, H335, H351. Use a dust mask when handling crystalline solid; wear gloves to avoid sensitization.
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.