L-Isoleucine (CH₃CH₂CH(CH₃)CH(NH₂)COOH) - R or S Configuration
Is L-Isoleucine R or S?
L-Isoleucine (CH₃CH₂CH(CH₃)CH(NH₂)COOH) has 1 chiral center. Has two chiral centers (α and β carbons). The sec-butyl side chain branches at the β-carbon with both ethyl and methyl groups. Focus on the α-carbon for R/S assignment.. The configuration is S based on CIP priority rules.
| Formula | CH₃CH₂CH(CH₃)CH(NH₂)COOH |
| Name | L-Isoleucine |
| Number of Chiral Centers | 1 |
| Configuration(s) | S |
| Difficulty | Advanced |
Chiral Center Analysis
L-Isoleucine (CH₃CH₂CH(CH₃)CH(NH₂)COOH) contains 1 chiral center. Has two chiral centers (α and β carbons). The sec-butyl side chain branches at the β-carbon with both ethyl and methyl groups. Focus on the α-carbon for R/S assignment.. 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 (8) beats carbon
- Priority 3: -CH(CH₃)CH₂CH₃ - sec-Butyl: C bonded to C, C, H at second level - COOH's O, O, O still wins
- Priority 4: H - Hydrogen always 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.
Assign R/S Configuration for L-Isoleucine Step by StepRelated Topics
L-Tryptophan - R or S?
Determine the R/S configuration of L-Tryptophan
L-Threonine - R or S?
Determine the R/S configuration of L-Threonine
L-Arginine - R or S?
Determine the R/S configuration of L-Arginine
Isomer Explorer
Compare enantiomers, diastereomers, and constitutional isomers in 3D
Drug Chirality
See how chirality affects drug activity with real pharmaceutical examples
Bromochlorofluoromethane - R or S?
Determine the R/S configuration of Bromochlorofluoromethane