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    Good Evening TSR, I hope you're having a good day.

    I've got 2 optical isomers questions that I need help with please.
    Question 1. Can a carbon be chiral if it contain a double bond? i.e. would HC=OOH be an optical isomer, as it does not contain 4 different groups, but all group around the carbon are different?

    Question 2. In a racemic mixture, the + optical isomer rotates the plane of polarization of plane polarized light in the right direction and the - isomer in the left direction. Since they are in equal molar quantities, the effect of rotation to the left is countered against by the rotation to the right.
    But my text book says that a racemic mixture has no affect on plane polarized light. So which description is correct?

    Thanks you guys!
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    (Original post by Delta, Δ)
    Good Evening TSR, I hope you're having a good day.

    I've got 2 optical isomers questions that I need help with please.
    Question 1. Can a carbon be chiral if it contain a double bond? i.e. would HC=OOH be an optical isomer, as it does not contain 4 different groups, but all group around the carbon are different?

    Question 2. In a racemic mixture, the + optical isomer rotates the plane of polarization of plane polarized light in the right direction and the - isomer in the left direction. Since they are in equal molar quantities, the effect of rotation to the left is countered against by the rotation to the right.
    But my text book says that a racemic mixture has no affect on plane polarized light. So which description is correct?

    Thanks you guys!
    1) For a carbon to be chiral, it must be tetrahedral. That carbon is planar so isn't an optical isomer.

    2) A racemic mixture has no effect on light because the two effects cancel out.
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    (Original post by ThisIsOurDecision)
    1) For a carbon to be chiral, it must be tetrahedral. That carbon is planar so isn't an optical isomer.

    2) A racemic mixture has no effect on light because the two effects cancel out.
    Thanks!
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    Actually the thing about double bonds and chirality is a little bit more complicated. There are chiral allenes where chirality center lies on the carbon with two double bonds. Think (R1)(R2)C=C*=C(R3)(R4) and remember double bonds are perpendicular to each other.

    So your typical sp2 carbon won't be chiral, but carbon with double bonds can be.
 
 
 
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