What is Anthracene Definition Structure Reactions and Uses in Organic Chemistry
Anthracene is a colourless crystalline aromatic hydrocarbon utilised in the chemical industry that is created by distilling natural crude oils. Anthracene is a three-fused benzene ring solid polycyclic aromatic hydrocarbon (PAH) with the formula C14H10. It's a substance found in coal tar. Anthracene is used to make the red dye alizarin as well as other dyes. It is colourless but fluoresces blue (400–500 nm peak) when exposed to ultraviolet light. This article will study the use of anthracene in detail.
Anthracene Sigma Aldrich
Three benzene rings are fused together to form anthracene, a polycyclic aromatic hydrocarbon. A polycyclic refers to a molecule with more than one ring, aromatic refers to a molecule with alternating double-single bonds all over the ring structure, and hydrocarbon refers to a molecule composed entirely of carbon and hydrogen atoms.
Anthracene Sigma
It is the three rings that were bound together, as well as the network of alternating double and single bonds that ran all the way around them.
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Reactions of Anthracene
Anthracene to Anthraquinone
Anthracene is converted to anthraquinone when it is reacted with an oxidising agent like hydrogen peroxide. Anthracene with two carbon-oxygen double bonds at the two middle carbons of the molecule is easily recognised as anthraquinone. Anthraquinone may be formed from direct combustion processes in motor-operated vehicles and engines. They are the extensive category of naturally occurring quinones, together with some of the most crucial native colourants like alizarin, purpurin, munjistin, emodin, chrysophanol, aloe-emodin, physcion, rhein, etc. With over 700 chemicals identified, anthraquinone is the biggest group of natural pigments.
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Methyl Anthracene
The Elbs reaction is an organic reaction in which an ortho methyl-substituted benzophenone is pyrolyzed to produce a condensed polyaromatic. The reaction is named after Karl Elbs, a German chemist, who also invented the Elbs oxidation. In 1884, the reaction was written. Elbs, on the other hand, misinterpreted the reaction product due to a lack of understanding of naphthalene structure.
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Dibenzo Anthracene
The action of UV light causes anthracene to photo dimerize. The 4+4 cycloaddition results in a pair of new carbon-carbon bonds connecting the dimer, which is known as Dianthracene (or sometimes paranthracene). Thermally or with UV irradiation below 300 nm, it reverts to anthracene. The behaviour of substituted anthracene derivatives is similar. The presence of oxygen has an effect on the reaction.
Magnesium Anthracene
Magnesium anthracene is an organomagnesium compound that is almost always isolated as tetrahydrofuran (THF) adduct with three ligands. The air and water sensitive orange solid Mg(C14H10)(thf)3 is made by heating a suspension of magnesium in a thf solution of anthracene.
Use of Anthracene
Anthracene is primarily converted to anthraquinone, a dye precursor.
Anthracene, an organic semiconductor with a large bandgap, is used as a scintillator for high-energy photon, electron, and alpha particle detectors. Plastics, such as polyvinyl toluene, can be doped with anthracene to create a water-equivalent plastic scintillator for use in radiation therapy dosimetry. The emission spectrum of anthracene peaks between 400 and 440 nm.
It is present in wood preservatives, insecticides, and coating materials.
Anthracene is widely used as a UV tracer in printed wiring board conformal coatings. The anthracene tracer allows for UV inspection of the conformal coating. Anthracene is also used in anthraquinone use.
Anthracene derivatives are used in a number of applications. 1-hydroxyanthracene and 2-hydroxyanthracene are hydroxylated derivatives of phenol and naphthols, and hydroxyanthracene (also known as anthrol and anthracenol) is pharmacologically active. 9,10-dihydroxy anthracene is an example of anthracene with several hydroxyl groups.
During combustion processes, anthracene, like many other polycyclic aromatic hydrocarbons, is produced. Tobacco smoke and consumption of food tainted with combustion materials are the primary sources of human exposure.
Anthracene is non-carcinogenic, as according to several studies it "consistently gives negative results in numerous in vitro and in vivo genotoxicity experiments." Since crude samples were tainted with other polycyclic aromatic compounds, early studies suggested otherwise. It is also easily biodegradable in soil. In the presence of light, it is particularly vulnerable to deterioration.
It is also used as a smokescreen, scintillation counter crystals, and inorganic semiconductor research.
Did You Know?
A polycyclic aromatic hydrocarbon (PAH) is a hydrocarbon with many aromatic rings and is a chemical compound containing only carbon and hydrogen. The aromatic hydrocarbons are a significant subset of this category. Naphthalene, which has two aromatic rings, and the three-ring compounds anthracene and phenanthrene are the most basic of these chemicals. This principle is also known as polyaromatic hydrocarbon or polynuclear aromatic hydrocarbon. PAHs are non-polar, uncharged molecules with unique properties owing to delocalized electrons in their aromatic rings. Many are contained in coal and oil fields, as well as the thermal decomposition of organic matter in engines and incinerators, or when biomass burns in forest fires.
Polycyclic aromatic hydrocarbons are addressed as potential starting materials for the abiotic synthesis of materials needed by life's earliest forms. When inhaled, Anthracene can irritate the throat, nose and lungs leading to wheezing and coughing. Contact to the skin may cause irritation, burns, itching which is provoked by sunlight. Regular contact may cause thickening of the skin and changes in pigment. Studies show, Anthracene may turn into an allergy and once the allergy is developed completely in an individual even very low future exposure can cause a skin rash.
How to Identify Anthracene?
Anthracene is between colourless to pale yellow, which feels like sand when touched with a bluish glow. Exposure to such harmful substances should be regularly checked thoroughly. It may include collecting personal samples and surrounding samples. Remember you have a legal right to this information under OSHA 1910.1020. You can obtain copies of samples from your respective employer. If you feel you are experiencing any health problems due to the nature of your work, see a doctor who has expertise in recognizing occupational diseases.
How to Reduce Exposure to Anthracene?
Use local exhaust ventilation where the chemical is released. If local exhaust ventilation is not suitable for the job make sure to use respirators which can be worn easily. Protective work clothing will help to reduce exposure. After exposure to anthracene, immediately wash at the end of the shift. Wear a face shield along with safety glasses when working with toxic substances to protect your eyes. Never use contact lenses while working with such substances.
Dimerization of Anthracene
When we expose anthracene to ultraviolet light, it undergoes a dimerization reaction. This occurs when two anthracene molecules join together to produce a bigger hydrocarbon structure. Also, the prefix “di” in dimerization signifies 'two' (e.g. two molecules of anthracene)
Compounds like anthracene dimers and other polycyclic aromatic hydrocarbons play a key part in organic semiconductors in terms of utility. They've also gotten a lot of interest from scientists for their potential use as organic materials in solar panels to harness the sun's energy.
Oxidation of Anthracene
When anthracene is exposed to an oxidising agent such as hydrogen peroxide, it is converted to anthraquinone. Anthracene with two carbon-oxygen double bonds at the two middle carbons of the molecule is easily identified as anthraquinone.
Interesting facts
The melting point of Anthracene is 218 degrees Celsius and the boiling point is 354 degrees Celsius. When Anthracene is at its purest form it is colourless. When anthracene is exposed to daylight it darkens. It is quite soluble in carbon disulfide but insoluble in water. However, Anthracene is relatively soluble in methanol, ethanol, chloroform, benzene, etc.
Conclusion
Anthracene, with its intriguing structure, versatile reactivity, and diverse applications, is a true champion of the chemical world. As research progresses, we can expect even more exciting discoveries and innovations built upon this three-ringed wonder. So, the next time you see a vibrant dye, a flexible electronic device, or a glowing detector, remember the power of anthracene, dancing its way into the future of chemistry.
FAQs on Anthracene Structure Properties and Chemical Behavior
1. What is anthracene?
Anthracene is a polycyclic aromatic hydrocarbon (PAH) with the molecular formula C14H10 consisting of three fused benzene rings arranged linearly. It is a solid aromatic compound derived mainly from coal tar and is used in dye and organic synthesis. Its structure contains 14 carbon atoms forming a conjugated π-electron system, which gives it characteristic fluorescence and chemical reactivity typical of aromatic hydrocarbons.
2. What is the structure of anthracene?
The structure of anthracene consists of three linearly fused benzene rings sharing carbon–carbon bonds. Key structural features include:
- Molecular formula: C14H10
- Planar arrangement of carbon atoms
- Delocalized π-electron system over all three rings
- Each carbon atom is sp2-hybridized
This extended conjugation makes anthracene aromatic and responsible for its stability and photochemical properties.
3. Is anthracene aromatic?
Yes, anthracene is aromatic because it satisfies Hückel’s rule (4n + 2 π electrons) with 14 π electrons. Since 14 = 4(3) + 2, it fulfills the aromaticity condition. Additional reasons include:
- It is cyclic and planar.
- It has continuous conjugation of π electrons.
- All carbon atoms are sp2-hybridized.
These factors confirm anthracene as an aromatic hydrocarbon.
4. What is the molecular formula and molar mass of anthracene?
The molecular formula of anthracene is C14H10 and its molar mass is approximately 178.23 g·mol-1. The molar mass is calculated as:
- Carbon: 14 × 12.01 = 168.14 g·mol-1
- Hydrogen: 10 × 1.008 = 10.08 g·mol-1
- Total ≈ 178.23 g·mol-1
This value is commonly used in stoichiometric and thermochemical calculations involving anthracene.
5. What are the physical properties of anthracene?
Anthracene is a colorless to pale yellow crystalline solid with characteristic fluorescence under UV light. Important physical properties include:
- Melting point: about 216 °C
- Insoluble in water but soluble in organic solvents like benzene and ether
- High thermal stability due to aromaticity
- Exhibits blue fluorescence under ultraviolet radiation
These properties make anthracene useful in photochemistry and materials science.
6. How is anthracene prepared or obtained?
Anthracene is primarily obtained from coal tar during the fractional distillation of coal. The preparation process involves:
- Distillation of coal tar to obtain anthracene oil
- Cooling and crystallization of anthracene
- Purification by recrystallization
In laboratories, anthracene can also be synthesized via organic reactions such as cyclodehydration of suitable aromatic precursors.
7. What reactions does anthracene undergo?
Anthracene mainly undergoes electrophilic substitution and addition reactions, especially at the 9,10-positions. Common reactions include:
- Nitration and sulfonation (electrophilic substitution)
- Diels–Alder reactions at the central ring
- Oxidation to anthraquinone
For example, oxidation with oxygen forms anthraquinone:
C14H10 + O2 → C14H8O2 + H2O (simplified representation).
8. What is the difference between anthracene and phenanthrene?
The main difference between anthracene and phenanthrene is the arrangement of the three fused benzene rings. Key differences include:
- Anthracene: Linear arrangement of rings.
- Phenanthrene: Angular (bent) arrangement of rings.
- Phenanthrene is thermodynamically more stable.
- Anthracene is more reactive at the 9,10-positions.
Both compounds have the same molecular formula, C14H10, but differ structurally (they are structural isomers).
9. What are the uses of anthracene in chemistry and industry?
Anthracene is mainly used in the production of anthraquinone dyes and other organic chemicals. Important uses include:
- Manufacture of dyes such as alizarin
- Production of anthraquinone for hydrogen peroxide synthesis
- Scintillation counters for radiation detection
- Organic semiconductor materials
Its aromatic structure and photophysical properties make it valuable in materials chemistry and industrial applications.
10. Why does anthracene show fluorescence?
Anthracene shows fluorescence because it has an extended conjugated π-electron system that absorbs UV light and re-emits it as visible blue light. The process involves:
- Absorption of ultraviolet radiation
- Excitation of π electrons to higher energy levels
- Emission of visible light as electrons return to the ground state
This fluorescence property is commonly used in photochemistry experiments and radiation detection devices.
