SME
Organic Chemistry I
Stereochemistry
Use this for “Are (2R,3S)- and (2S,3R)-2,3-dichlorobutane enantiomers, diastereomers or the same compound?”
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How is each pair related?
Tap a card, then tap its group.
Enantiomers flip every stereocenter; diastereomers flip some but not all; a meso compound is its own mirror image.
Assumptions
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Constitutional isomers have the same formula with the atoms joined in a different order.
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Stereoisomers have the atoms joined in the same order and differ only in how they sit in space: R or S, cis or trans.
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A compound with two alike stereocenters, one R and one S, is meso: it has a mirror plane, so it is not chiral.
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Turning a drawing over or spinning it never changes R or S.
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Each card draws the two structures side by side, a wedge toward you and a dash away.
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Specific rotation and enantiomeric excess
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More problem types
Specific rotation and enantiomeric excess
Use this for “A solution of butan-2-ol (0.100 g/mL) rotates light +0.945° in a 1.00 dm tube. Pure (S)-butan-2-ol has [α] = +13.5°. Find the ee.”
Percent equatorial from the A-value
Use this for “A methyl group’s A-value is 7.3 kJ/mol. What percent of methylcyclohexane molecules hold the methyl equatorial at 298.15 K?”
CIP priority: rank the groups
Use this for “Rank –CH₃, –OH, –H and –CH₂OH by Cahn–Ingold–Prelog priority, highest first.”