Handbook of Solvents - George Wypych - ChemTech - Ventech!

34 Estanislao Silla, Arturo Arnau and Iñaki Tuñón
Figure 2.1.18. Three different mechanism for the rate-limiting step of the reaction of Meyer-Schuster.
On comparing the solvolytic and intermolecular processes a smaller potential barrier
is observed for the latter, thus the solvent plays an active part in the Meyer-Schuster reaction,
being capable of changing radically the mechanism through which this takes place. It
seems clear that in the presence of aqueous solvents the nucleophilic attack on the C3 precedes
the loss of the water (solvolysis): a lesser activation energy corresponds to the
intermolecular process than to the solvolytic. Moreover, if we analyze the intermolecular
mechanism we can verify that the solvent stabilizes both the reactants as well as the products
by the formation of hydrogen bridges.
Epilogue
As a fish in the midst of the ocean, the reactants are usually found in the midst of a solution
in our laboratory tests. In the same way as in the ocean where there is both danger and a
heaven for the fish, in the internal scenery of a solution the chemical reactions can be
speeded up or slowed down, favored thermodynamically or prejudiced. In this way, on
passing from vacuum to a solution, the molecules of the reactants can experience alterations
in their geometry, the distribution of their charges, or their energy, which can have an effect
on the outcome of the reaction. In the preceding pages we have attempted to make clear
these solute-solvent influences, and to achieve this we have plunged, hand in hand with theoretical
chemistry, into the microscopic and recondite environment of the solutions.
REFERENCES
1 Ch. Reichardt, Solvents and Solvent Effects in Organic Chemistry, VCH, Weinheim, 1988, p. 1.
2 H. Metzger, Newton, Stahl, Boerhaave et la doctrine chimique, Alcan, Paris, 1930, pp. 280-289.
3 M.M. Pattison, A History of Chemical Theories and Laws, John Wiley & Sons, New York, 1907, p. 381.
4 H.M. Leicester, Panorama histórico de la química, Alhambra, Madrid, 1967, pp. 148, 149. (Transcription
from: The Historical Background of Chemistry, John Wiley & Sons, New York.)
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