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1 Biologically-active Chiral Molecules HO HO OH HO O O O OH - - PDF document
1 Biologically-active Chiral Molecules HO HO OH HO O O O OH - - PDF document
Chapter 7 - Stereochemistry Enantiomers of bromochlorofluoromethane Non-superimposable mirror images Enantiomers YSU YSU Biologically-active Chiral Molecules YSU YSU 1 Biologically-active Chiral Molecules HO HO OH HO O O O OH
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The Chirality Centre - Stereoisomerism
Carbon atom here is asymmetric C is a stereogenic center
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7.3 Symmetry in Achiral Structures
Mirror images of chlorodifluoromethane are superimposable Figure 7.2
Achiral i.e. not chiral
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Typical polarimeter setup : []D = 100 x (rotation)/(cell length) x (concentration)
7.4 Measurement of Optical Activity
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7.8 Enantiomers
- same physical properties except rotation of plane polarized light
- one enantiomer positive rotation (+) other negative rotation (‐)
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Which molecules contain chiral (stereogenic) centers?
The stereogenic C must have 4 different groups attached
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7.5 Absolute and Relative Configuration
Absolute Configuration – Actual arrangement of substituents in space (+)‐2‐butanol and (‐)‐2‐butanol, but which is which? Relative Configuration ‐ Configuration relative to another compound. Pre‐1951, compounds could be related to each other but the absolute configuration was not able to be determined.
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7.6 Nomenclature - Use of the Cahn-Ingold-Prelog System
S enantiomer R enantiomer R ‐ Rectus ‐ the clockwise arrangement of groups S ‐ Sinestre ‐ the counterclockwise arrangement of groups
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7.6 Nomenclature - Use of the Cahn-Ingold-Prelog System
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7.7 Fischer Projection Formulas
Figure 7.5
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7.9 Reactions that create a Chirality Center
Figure 7.6
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7.10 Chiral molecules with two Chirality Centers
Figure 7.7
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7.10 Representations of (2R, 3R)-dihydroxybutanoic acid
All the same molecule: (a) and (b) differ only by bond rotation (b) leads to correct Fischer projection
Conversion of “zig‐zag” picture to Fischer projection
Figure 7.8
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7.10 Chiral molecules with two Chirality Centers
Important stereochemical labels later, particularly in carbohydrate (sugar) chemistry and biochemistry
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7.10 Chiral molecules with two Chirality Centers
Applies to other cycles, including cyclohexane; increases the molecular diversity possible using simple structures
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7.11 Achiral molecules with two Chirality Centers
Figure 7.9
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Meso-2,3-butanediol
Figure 7.10
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7.11 Stereogenic Centers in Cholic Acid
Figure 7.11
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7.13 Reactions that produce diastereomers
Figure 7.12
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7.13 Reactions that produce diastereomers
Figure 7.12
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7.14 Resolution of a chiral substance into its enantiomers
Figure 7.13
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