L-Alanine (CH₃CH(NH₂)COOH) - R or S Configuration
Is L-Alanine R or S?
L-Alanine (CH₃CH(NH₂)COOH) has 1 chiral center. The simplest chiral amino acid. Demonstrates CIP priority with nitrogen and oxygen-containing groups.. The configuration is S based on CIP priority rules.
| Formula | CH₃CH(NH₂)COOH |
| Name | L-Alanine |
| Number of Chiral Centers | 1 |
| Configuration(s) | S |
| Difficulty | Intermediate |
Chiral Center Analysis
L-Alanine (CH₃CH(NH₂)COOH) contains 1 chiral center. The simplest chiral amino acid. Demonstrates CIP priority with nitrogen and oxygen-containing groups.. Each chiral center is analyzed below using CIP (Cahn-Ingold-Prelog) priority rules to determine R or S configuration.
CIP Priority Assignment
The four substituents on the chiral center are ranked by atomic number of the directly attached atom, with ties broken by exploring outward along each branch.
- Priority 1: -NH₂ - Nitrogen has atomic number 7 (highest first atom)
- Priority 2: -COOH - Carbon bonded to O,O (double bond counts twice)
- Priority 3: -CH₃ - Carbon bonded to H,H,H only
- Priority 4: H - Lowest atomic number (1)
R/S Configuration
With the lowest priority group (priority 4) oriented away from the viewer, the remaining three substituents trace a counterclockwise path from priority 1 to 2 to 3. This gives the S configuration.
Interactive stereochemistry explorer with guided walkthroughs and practice quizzes.
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