Features of the Diels-Alder reaction between 9,10-diphenylanthracene and 4-phenyl-1,2,4-triazoline-3,5-dione

• Published in: Russian Journal of Physical Chemistry A 2014-12, Vol.88 (12), p.2073-2080
• Main Authors: Kiselev, V. D., Kornilov, D. A., Kashaeva, E. A., Potapova, L. N., Krivolapov, D. B., Litvinov, I. A., Konovalov, A. I.
• Format: Article
• Language: English
• Subjects: Chemical Kinetics and Catalysis; Chemistry; Chemistry and Materials Science; Physical Chemistry
• ISSN: 0036-0244; 1531-863X
• DOI: 10.1134/S0036024414120152

The Diels-Alder reaction between substituted anthracenes 1a−1j and 4-phenyl-1,2,4-triazoline-3,5 ( 2 ) is studied. In all cases except one, the reaction proceeds on the most active 9,10-atoms of substituted anthracenes. The orthogonality of the two phenyl groups at the 9,10-position of diene 1a is found to shield 9,10-reactive centers. No dienophiles with C=C bonds are shown to participate in the Diels-Alder reaction with 1a ; however, the reaction 1a + 2 proceeds with the very active dienophile 2,4-phenyl-1,2,4-triazoline-3,5-dione. It is shown that attachment occurs on the less active but sterically accessible 1,4-reactive center of diene 1a . The structure of adduct 3a is proved by 1 H and 13 C NMR spectroscopy and X-ray diffraction analysis. The following parameters are obtained for reaction 1a + 2 ⇆ 3a in toluene at 25°C: K eq = 2120 M −1 , Δ H f ≠ = 58.6 kJ/mol, Δ S f ≠ = −97 J/(mol K), Δ V f ≠ = −17.2 cm 3 /mol, Δ H b ≠ = 108.8 kJ/mol, Δ S b ≠ = 7.3 J/(mol K), Δ V b ≠ = −0.8 cm 3 /mol, Δ H r-n = −50.2 kJ/mol, Δ S r-n = −104.3 J/(mol K), Δ V r-n = −15.6 cm 3 /mol. It is concluded that the values of equilibrium constants of the reactions 1a−1j + 2 ⇆ 3a−3j vary within 4 × 10 1 −10 11 M −1 .