The key difference between dextrorotatory and levorotatory is that dextrorotatory refers to the rotation of plane-polarized light to the right side, whereas levorotatory refers to the rotation of plane-polarized light to the left side.
Optical rotation refers to the rotation of the orientation of the plane (of light) when the light passes through a chemical compound. In this, the terms dextrorotation and levorotation explains the direction of this optical rotation. Thus, dextrorotation and levorotation are two types of optical rotations.
CONTENTS
1. Overview and Key Difference
2. What is Dextrorotatory
3. What is Levorotatory
4. Side by Side Comparison – Dextrorotatory vs Levorotatory in Tabular Form
5. Summary
What is Dextrorotatory?
Dextrorotatory is a term that refers to chemical compounds that can rotate plane-polarized light to the right side. Dextrorotatory is the opposite term of levorotatory, which refers to the rotation to the left side. Besides, we can describe a dextrorotatory rotation as a clockwise rotation as well because a clockwise rotation is a right-handed rotation. If a compound is able to do this rotation when plane-polarized light passes through it, we say that material is optically active.
Figure 01: Rotation of Plane-Polarized Light
When naming dextrorotatory compounds, we need to use a prefix; the prefix can be either “(+)” or “d”. Moreover, there is another important term, “specific rotation” regarding these chemical compounds. Specific rotation describes the degree to which a compound is dextrorotatory or levorotatory. Here, dextrorotatory is known to have a positive specific rotation.
What is Levorotatory?
Levorotatory is a term that refers to chemical compounds that can rotate plane-polarized light to the left side. It is the opposite of the term dextrorotatory, which refers to the rotation to the left side. We can describe this rotation as an anti-clockwise rotation as well because an anti-clockwise rotation is a left-handed rotation. If a compound is able to do this rotation when plane-polarized light passes through it, we say that material is optically active.
Figure 02: Levorotatory and Dextrorotatory Compounds
When naming levorotatory compounds, we need to use a prefix; the prefix can be either “(-)” or “l”. When considering the specific rotation for levorotatory compounds, they are known to have a negative specific rotation.
What is the Difference Between Dextrorotatory and Levorotatory?
The terms dextrorotatory and levorotatory are useful when describing the rotation of plane-polarized light by different chemical compounds. The key difference between dextrorotatory and levorotatory is that dextrorotatory refers to the rotation of plane-polarized light to the right side, whereas levorotatory refers to the rotation of plane-polarized light to the left side. Thus, the process of this rotation of light is named as dextrorotation and levorotation. Further, we can refer to the rotation of plane-polarized light in the clockwise direction as dextrorotary and anti-clockwise rotation is levorotatory.
When naming these compounds, we need to use prefixes. For dextrorotary compounds, there are two prefixes that we can use: either “(+)” or “d”. Similarly, for levorotatory compounds, the prefixes we can use are “(-)” or “l”. Furthermore, there is another important term, “specific rotation” regarding these chemical compounds. The specific rotation for dextrorotary compounds is said to be positive while for levorotatory compounds, it is negative.
Below infographic tabulates the difference between dextrorotatory and levorotatory.
Summary – Dextrorotatory vs Levorotatory
The terms dextrorotatory and levorotatory are useful when describing the rotation of plane-polarized light by different chemical compounds. The key difference between dextrorotatory and levorotatory is that dextrorotatory refers to the rotation of plane-polarized light to the right side, whereas levorotatory refers to the rotation of plane-polarized light to the left side. The process of this rotation of light is named as dextrorotation and levorotation.
Reference:
1. “Dextrorotation and Levorotation.” Wikipedia, Wikimedia Foundation, 29 Aug. 2019, Available here.
2. “Levorotatory Compounds.” Van Nostrands Encyclopedia of Chemistry, 2005, doi:10.1002/0471740039.vec1518.
3. “Levorotatory Quartz.” Dictionary Geotechnical Engineering/Wörterbuch GeoTechnik, 2014, pp. 796–796., doi:10.1007/978-3-642-41714-6_121185.
Image Courtesy:
1. “Levo dextro” By File:Levo dextro.png: Deneapol (talk)Original uploader was Deneapol.derivative work: KES47 – File:Levo dextro.png (CC BY-SA 3.0) via Commons Wikimedia
2. “Racemorphan” By Harbin (talk · contribs), edited by Fvasconcellos (talk · contribs) – File:Dextrorphan.svg by Harbin (talk · contribs) (Public Domain) via Commons Wikimedia