Q38E What is the relationship between... [FREE SOLUTION]

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Chapter 5: Q38E (page 148)

What is the relationship between the specific rotations of (2R,3R)-dichloropentane and (2S,3S)-dichloropentane? Between (2R,3S)-dichloropentane and (2R,3R)-dichloropentane?

Short Answer

Expert verified

(2R,3R)-dichloropetane and (2S,3S)-dichloropetane have equal specific rotation in magnitude but opposite in direction.

(2R,3S)-dichloropentane and (2R,3R)-dichloropentane don't have any relationship with optical activity.

Step by step solution

Step-by-Step Solution Step 1:Specific Rotation

When the plane-polarized light plane is passed through a tube whosepath length is 1dm or 10 cm, compound concentration is 1g/mL at a specific temperature, and wavelength degree of rotation is specific rotation.

It is mathematically expressed as:

${[伪]}_{D}^{t} = \frac{伪_{Observed}}{length 脳 Concentration}$

Specific Rotation relationship between (2R,3S)-dichloropentane and (2R,3R)-dichloropentane

Enantiomers have the specific property known as optical activity, is it rotates the plane-polarized light (PPL) in the left (levorotatory) and right direction (dextrorotatory). (2R,3R)-dichloropetane and (2S,3S)-dichloropetane are enantiomers due to a lack of symmetry;their specific rotation is equal in magnitude and opposite in sign.

Diastereomers don't have any property of optical activity, so they cannot rotate the plane-polarized light (PPL). (2R,3S)-dichloropetane and (2R,3R)-dichloropentane are diastereomers due to the presence of symmetry, so they are optically inactive; thus, there is no predictable relationship between them with Specific rotation.