Question

ap 5. Conformational Enantiomers and Cyclic Compounds a. Construct a model of methanol (CH3OH). Is methanol chiral? Why or why not? b. Orient your model so that the plane of symmetry (indicated by the dotted rectangle) contains the H-C-O-H bonds that are in the plane of the paper, as shown below: Now rotate the C-O bond, so that the plane no longer contains the O-H bond. All of the bonds in methanol freely rotate at room temperature, so you are just showing a different conformation of methanol. Does this conformation of methanol have a plane of symmetry? Yes_ No- Even though one conformation of methanol has a plane of symmetry, and one doesn't, methanol is still considered to be achiral. It is only necessary to find one conformation with a plane of symmetry for a molecule to be achiral. Now consider cyclohexanol, shown below. Looking at the flat, hexagonal representation of cyclohexanol, does cyclohexanol contain a plane of symmetry? Yes No HOH

Answer 1

1. imagine below example as a model of methanol. No, methanol is not chiral as stereocenter or assymetric carbon(carbon with four different groups attached) is absent. Also, presence of plane of symetry makes it achiral.

Model A. Methanol: red ball - yellow ball

2. No, this molecule doesnot have a plane of symmetry. as on rotating the C-O bond, OH bond goes out of the plane so no plane can now divide the molecule in two same halves, so plane of symmetry is absent.

3. Yes, even if one of the conformation of molecule has a plane of symmetry then is a said to be achiral.

4. No, plane of symmetry is not present in the given cyclohexanol structure. As no plane can divide the molecule in equal half(which are mirror images).