Q5E - Organic Chemistry (Mcmurry)

Question

Polymers such as polypropylene contain a large number of chirality centers. Would you therefore expect samples of isotactic, syndiotactic, or atactic polypropylene to rotate plane-polarized light? Explain.

Step-by-Step Solution

Answer

None of the polypropylene show planes polarise light because the polypropylene is the optical inactive and absence of a chiral center.

Step 1: Rotation of plane polarise light

The molecule which is optically active in nature has a chiral center that can rotate the plane polarised light. When the rotation of the light is towards a clockwise direction, dexo-rotatory and anti-clockwise are laevorotatory.

Step 2: Polymer form of polypropylene

As polypropylene contain the symmetric carbon and has the chiral center so shows the rotation of the plane of polarised light but the polymeric forms like isotactic, syndiotactic and atactic forms are the asymmetric formic having no chiral center hence, optical inactive in nature so they don’t show the rotation of plane polarised light.