The key difference between epimerization and racemization is that epimerization involves the conversion of an epimer into its chiral counterpart whereas racemization is a conversion of an optically active species into an optically inactive species.
Epimerization and racemization are chemical conversions. They are different from each other in different ways including the process, end product, reaction conditions, etc. The final product of the epimerization process is a chiral counterpart of the epimer while the final product of racemization is an optically inactive chemical species. We call this optically inactive species a “racemate” or “racemic mixture”.
CONTENTS
1. Overview and Key Difference
2. What is Epimerization
3. What is Racemization
4. Side by Side Comparison – Epimerization vs Racemization in Tabular Form
5. Summary
What is Epimerization?
Epimerization is a chemical conversion reaction which includes the transform of an epimer into its chiral counterparts. Mainly, this type of reactions takes place during condensed tannins depolymerization reactions. Generally, the epimerization reaction is a spontaneous reaction and a slow process. Therefore, it can be catalyzed by enzymes. For example, conversion of N-acetylglucosamine into N-acetylmannosamine is an epimerization reaction which takes place in the presence of renin-binding protein. Here, this renin-binding protein acts as the catalyst for the reaction.
What is Racemization?
Racemization is a chemical conversion reaction which involves the conversion of an optically active species into an optically inactive species. This means this reaction can convert half of the molecules of a mixture containing optically active species into their mirror image enantiomers. This is because, after this conversion, this mixture contains equal numbers of molecules with opposite optical rotations and becomes optically inactive. We call this process racemization because a mixture containing equal amounts of opposite optical rotations is called a racemic mixture or racemate.
Figure 01: A Racemic Mixture Contains a Mixture of Enantiomers with Opposite Optical Rotations
Besides, this conversion causes differences in chemical and physical properties between the initial chemical species and the racemic mixture. Racemization changes the density, melting point, heat of fusion, solubility, refractive index, etc. When considering the racemization process, we can obtain a racemic mixture easily by mixing equal quantities of pure enantiomers. Moreover, it occurs in chemical interconversion processes. Besides, racemization may take place during unimolecular substitution reactions, unimolecular elimination reactions, unimolecular aliphatic electrophilic substitution reactions, free radical substitution reactions, etc.
What is the Difference Between Epimerization and Racemization?
Epimerization and racemization are chemical conversions. They are different from each other in different ways including the process, end product, reaction conditions, etc. The key difference between epimerization and racemization is that epimerization involves the conversion of an epimer into its chiral counterpart whereas racemization is a conversion of an optically active species into an optically inactive species. Moreover, in epimerization, the final product is a chiral counterpart of the epimer whereas, in racemization, the final product is an optically inactive chemical species, i.e. a racemic mixture or racemate.
Besides, a further difference between epimerization and racemization is that generally, epimerization is a spontaneous process and a slow process that can be accelerated using catalysts. However, racemization is a non-spontaneous process, so we have to make it happen by chemical means. We can easily do it by mixing equal quantities of pure enantiomers.
Summary – Epimerization vs Racemization
Epimerization and racemization are chemical conversions. They are different from each other in different ways including the process, end product, reaction conditions, etc. The key difference between epimerization and racemization is that epimerization involves the conversion of an epimer into its chiral counterpart whereas racemization is a conversion of an optically active species into an optically inactive species.
Reference:
1. “19.11: Racemization.” Chemistry LibreTexts, Libretexts, 5 June 2019, Available here.
2. “Racemization.” Wikipedia, Wikimedia Foundation, 30 Oct. 2019, Available here.
3. “Epimer.” Wikipedia, Wikimedia Foundation, 1 Mar. 2019, Available here.
Image Courtesy:
1. “Chirality with hands” By Original:UnknownVector:– πϵρήλιο – Chirality with hands.jpg (Public Domain) via Commons Wikimedia