what is the difference between geometrical and optical isomerism?
Answers
Geometric isomers have the same structural formulas but differ in the arrangement of groups at a single atom, at double bonds, or in rings. Cis- and trans-platin (see Figure 37) are examples of geometric isomers based on the different arrangement of groups at a single atom. Cis- and trans-2-butene differ in the arrangement of the methyl groups about the double bonds.
geometric isomers
Although geometric isomers have completely different physical and chemical properties (for example, cis- and trans-2-butene have different boiling points and densities), optical isomers (also called enantiomers) differ in only one characteristic--their interaction with plane polarized light. When a beam of light is passed through a certain type of filter, all of the waves except those in one plane are removed. Figure 39 shows this plane-polarized light impinging upon and being rotated by two optical isomers. One of the optical isomers rotates the light in one direction, the other rotates the light in the opposite direction but by the same amount. In every other way, such as boiling point, density, refractive index, viscosity, etc., the two optical isomers are identical.
Answer:
The compounds having similar molecular formula but different arrangement of atoms or groups in space around the double bond are called geometrical isomers and the phenomenon is called as geometrical isomerism. Example: Cis and Trans isomerms
The compounds having similar molecular formula but rotate the polarized light in different directions are called as optical isomers and the phenomenon is called as optical isomerism. Example: dextro and laevo
A compound rotating the plane polarized light towards right is termed as dextrorotatory whereas a compound rotating the plane polarized light towards left is termed as laevorotatory.