Encyclopedia of Astrobiology

2015 Edition
| Editors: Muriel Gargaud, William M. Irvine, Ricardo Amils, Henderson James (Jim) CleavesII, Daniele L. Pinti, José Cernicharo Quintanilla, Daniel Rouan, Tilman Spohn, Stéphane Tirard, Michel Viso


  • Jeffrey BadaEmail author
Reference work entry
DOI: https://doi.org/10.1007/978-3-662-44185-5_1330


Racemization is a process wherein optically active compounds (which consist of only one  enantiomer) are converted into an equal mixture of enantiomers with zero optical activity (a  racemic mixture). Racemization rates are dependent on the molecule and conditions such as pH and temperature. For example, aqueous racemization of free protein amino acids takes place on timescales of 103–104 years at neutral pH and 25 °C. For comparison, hydrocarbons that contain a hydrogen atom attached to a chiral carbon atom have racemization  half-lives under similar conditions that are much longer.

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© Springer-Verlag Berlin Heidelberg 2015

Authors and Affiliations

  1. 1.Scripps Institution of OceanographyLa JollaUSA