Work

Entropic Contributions to Rate Accelerations in Enzymic and Intramolecular Reactions and the Chelate Effect

Year: 1971

Type: article

Abstract: It is pointed out that translational and (overall) rotational motions provide the important entropic driving force for enzymic and intramolecular rate accelerations and the chelate effect; internal rotations and unusually severe orientational requirements are generally of secondary importance. The loss of translational and (overall) rotational entropy for 2 --> 1 reactions in solution is ordinarily on the order of 45 entropy units (e.u.) (standard state 1 M, 25 degrees C); the translational entropy is much larger than 8 e.u. (corresponding to 55 M). Low-frequency motions in products and transition states, about 17 e.u. for cyclopentadiene dimerization, partially compensate for this loss, but "effective concentrations" on the order of 10(8) M may be accounted for without the introduction of new chemical concepts or terms.

Source: Proceedings of the National Academy of Sciences

DOI: 10.1073/pnas.68.8.1678

Authors: Michael I. Page, William P. Jencks

Institution: Brandeis University

Language: English

Topic: Physical Organic Chemistry and Reaction Kinetics

Subfield: Organic Chemistry

Field: Chemistry

Domain: Physical Sciences

Open Access status: green

Funders: National Science Foundation, National Institutes of Health, National Institute of Child Health and Human Development

OpenAlex ID: W2072660673

FWCI: 16.98

Cites: 17

Cited by: 1,023

Related to: 10