(R)-α-Methylphenylalanine (C₁₀H₁₃NO₂) - R or S Configuration

Chiral Center Analysis

(R)-α-Methylphenylalanine (C₁₀H₁₃NO₂) contains 1 chiral center. A quaternary stereocenter with a benzyl side chain. The chiral carbon has NO hydrogen - four non-H groups including an aromatic ring. CH₃ is the lowest priority substituent.. 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 directly bonded (atomic number 7) - highest first-atom priority
• Priority 2: -COOH - Carboxyl: C bonded to O, O, O at second level - oxygen beats carbon at second level
• Priority 3: -CH₂C₆H₅ - Benzyl: C bonded to C, H, H at second level - phenyl ring carbons at third level, but COOH's oxygens win at second
• Priority 4: -CH₃ - Methyl: C bonded to H, H, H - lowest priority (no hydrogen on this chiral center!)

R/S Configuration

With the lowest priority group (priority 4) oriented away from the viewer, the remaining three substituents trace a clockwise path from priority 1 to 2 to 3. This gives the R configuration.

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