Chiral and specialty building blocks: Characteristics
Why the wrong-handed twin counts as an impurity
What this tab covers The physical and chemical properties that set its grade, price and uses, with the commercial grades and the standards that define them.The key commercial property is enantiomeric purity, along with chemical purity, residual solvents and metals, and consistency batch to batch. Buyers audit suppliers and lock in a qualified source for the life of a drug.
Properties that matter commercially
| Property | Value / specification | Why it matters | Source |
|---|---|---|---|
| Enantiomeric excess (ee) | typically at least 98-99.5% ee (indicative) | the wrong enantiomer is an impurity in the final drug | indicative |
| Chemical purity | typically at least 98-99% by HPLC (indicative) | carry-through of impurities into API | indicative |
| Residual metals | within ICH Q3D limits, e.g. ppm-level for rhodium or ruthenium in oral drugs (indicative) | safety | ICH Q3D |
| Residual solvents | within ICH Q3C class limits | safety | ICH Q3C |
Commercial grades
- Catalogue research grade (grams)
- Non-GMP intermediate grade
- GMP starting material or intermediate grade
- Registration-grade agrochemical intermediates