- The nature of lithium perchlorate and gallium chloride salt effect in cycloaddition reactions
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Comparing the acceleration effects of (4 + 2)-, (3 + 2)- and (2 + 2)-cycloaddition reactions in the presence of the salts of two types: gallium chloride in inert solvents and lithium perchlorate (LP) in diethyl ether (DE) it was observed that in the presence of GaCl3 the acceleration effect is approximately the same (104 times) for the studied reactions, while in LPDE medium for the same reactions strong increase (up to 104 times), weak increase or even decrease of the rate and equilibrium constants take place even with the common dienophile depending on the nature of the second reagent. it was suggested that the acceleration effect of cycloaddition reactions in the presence of such Lewis acids as aluminum, gallium or boron halides is due to the sharp increase of Π-acceptor properties of dienophiles and therefore increasing energy of orbital interaction, whereas LPDE medium demonstrates strong stabilization of static and/or dynamic polar forms and favors reactions with charge control.
- Shtyrlin, Yury G.,Murzin, Dmitry G.,Luzanova, Natalia A.,Iskhakova, Gulnara G.,Kiselev, Vladimir D.,Konovalov, Alexandr I.
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- BISREAGENTS IN THE DIELS-ALDER REACTION VI. KINETICS AND THERMOCHEMISTRY OF REACTIONS OF POLYMETHYLCYCLOPENTADIENES AND SOME BISDIENES WITH SOME DIENOPHILES
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From kinetic and thermochemical data on Diels-Alder reactions with the participation of 1,2,3,4-tetra-, penta-, and hexa-methylcyclopentadienes, 1,2-bis(pentamethylcyclopentadienyl)ethane and 1,4-bis(pentamethylcyclopentadienyl)butane it follows that these dienes are highly reactive and with dienophiles form addition products that are fairly stable to decomposition.By the reactions of α,ω-bis(pentamethylcyclopentadienyl)-ethane and -butane with N,N'-m-phenylenebismaleimide products with a molecular weight of up to 80,000 were obtained.
- Kiselev, V. D.,Sakhabutdinov, A. G.,Shakirov, I. M.,Konovalov, A. I.
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p. 1437 - 1443
(2007/10/02)
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