Structure Determination of Anthracene
Structure of anthracene was established by the following facts, evidences and synthesis of it-
1. Elemental analysis and molecular weight determination shows that the molecular formula of anthracene is C14H10.
2. Anthracene is an aromatic compound but it also forms some addition products with hydrogen, chlorine etc.
3. Degradation
i. 1,2,3,4,5,6,7,8-octahydroanthracene on oxidation gives benzene 1,2,4,5-tetracarboxylic acid.
ii. Anthracene on oxidation gives anthraquinone which on fusion with potash at 240° C yields two moles of benzoic acid.
iii. Monobromoanthracene on potash fusion gives hydroxylanthracene which on oxidation gives phthalic acid and a little o-benzoil acid.
Degradation reactions especially last one indicate that anthracene contains at least two benzene nuclei with the following type of skeleton.
The above skeleton has all the fourteen carbon atoms and thus to fit the ten hydrogen atoms while maintaining the tetravalency of all the carbon atoms, the central ring must be closed. So, Graebe and Libermann proposed that anthracene is composed of three fused benzed rings in a linear manner.
The above structure of anthracene is confirmed by the synthesis(especially by Diels Alder Reaction).
1. Elemental analysis and molecular weight determination shows that the molecular formula of anthracene is C14H10.
2. Anthracene is an aromatic compound but it also forms some addition products with hydrogen, chlorine etc.
3. Degradation
i. 1,2,3,4,5,6,7,8-octahydroanthracene on oxidation gives benzene 1,2,4,5-tetracarboxylic acid.
ii. Anthracene on oxidation gives anthraquinone which on fusion with potash at 240° C yields two moles of benzoic acid.
iii. Monobromoanthracene on potash fusion gives hydroxylanthracene which on oxidation gives phthalic acid and a little o-benzoil acid.
Degradation reactions especially last one indicate that anthracene contains at least two benzene nuclei with the following type of skeleton.
The above skeleton has all the fourteen carbon atoms and thus to fit the ten hydrogen atoms while maintaining the tetravalency of all the carbon atoms, the central ring must be closed. So, Graebe and Libermann proposed that anthracene is composed of three fused benzed rings in a linear manner.
The above structure of anthracene is confirmed by the synthesis(especially by Diels Alder Reaction).
