1. What is Optical Purity?

Definition: Optical purity is a comparison of the optical rotation of a pure sample of unknown stereochemistry versus the optical rotation of a sample of pure enantiomer.

Purpose: It helps determine the enantiomeric excess of a chiral compound, which is important in pharmaceuticals and asymmetric synthesis.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( OP \) — Optical purity (percentage)
• \( [α]_{obs} \) — Observed specific rotation (rad·m³·kg⁻¹·m⁻¹)
• \( [α]_{max} \) — Maximum specific rotation of pure enantiomer (rad·m³·kg⁻¹·m⁻¹)

Explanation: The observed rotation is divided by the maximum possible rotation and multiplied by 100 to get the percentage purity.

3. Importance of Optical Purity

Details: Optical purity is crucial in pharmaceuticals as different enantiomers can have different biological activities. High optical purity ensures the desired therapeutic effect.

4. Using the Calculator

Tips: Enter the observed specific rotation and the maximum specific rotation of the pure enantiomer. Both values must be in the same units.

5. Frequently Asked Questions (FAQ)

Q1: What is specific rotation?
A: Specific rotation is a property of chiral compounds that describes how they rotate plane-polarized light.

Q2: How is optical purity related to enantiomeric excess?
A: For most purposes, optical purity is numerically equal to enantiomeric excess (ee).

Q3: What does 100% optical purity mean?
A: It indicates a sample consisting of only one enantiomer with no contamination from its mirror image.

Q4: Can optical purity be negative?
A: No, optical purity is always expressed as a positive percentage, but the sign of rotation indicates which enantiomer is in excess.

Q5: Where can I find maximum specific rotation values?
A: These values are typically found in chemical literature or databases for specific compounds.