configurational entropy in chiral solutions—negative entropy of solvent envelopes在手性构型熵solutions-negative熵溶剂的信封.pdf

Entropy 2009, 11, 667-674; doi:10.3390/ OPEN ACCESS entropy ISSN 1099-4300 /journal/entropy Article Configurational Entropy in Chiral Solutions—Negative Entropy of Solvent Envelopes Meir Shinitzky Department of Biological Chemistry, the Weizmann Institute of Science, Rehovot, Israel; E-Mail: meir.shinitzky@weizmann.ac.il Received: 2 September 2009 / Accepted: 26 October 2009 / Published: 29 October 2009 Abstract: A homogeneous solution of a chiral substance is acquired with an overall asymmetry which is expressed by a specific rotation of a linearly polarized light. Such a solution, despite being at a complete equilibrium, stores configurational entropy in a form of negative entropy which can be nullified by mixing with a solution of the opposite enantiomer. This abundant, yet quite a specific case of inherent negative entropy, resides predominantly in the chiral configuration of the solvent envelopes surrounding the chiral centers. Heat release, amounting to several cal/mol, associated with the annulment of negative entropy in aqueous solutions of D- and L-amino acids, was recently documented by Shinitzky et al. [1]. This heat corresponds almost exclusively to TΔS stored in the solvent envelope upon adoption of a chiral configuratio