Why carbon has a chiral optical activity?

Because chiral molecules are able to rotate the plane of polarization differently by interacting with the electric field differently, they are said to be optically active.

Why there is free rotation around a single bond?

Carbon atoms in single bonds rotate freely. Rotation can occur because the heaviest electron density in the σ bond exists along an imaginary line between two carbon nuclei. Rotation does not change this electron distribution; the bond strength remains constant throughout rotation.

Is chiral carbon necessary for optical isomerism?

Chiral and achiral molecules The essential difference between the two examples we’ve looked at lies in the symmetry of the molecules. If there are two groups the same attached to the central carbon atom, the molecule has a plane of symmetry. Only chiral molecules have optical isomers.

Are chiral molecules optical isomers?

Each non-superimposable mirror image structure is called an enantiomer. Molecules or ions that exist as optical isomers are called chiral. Not all coordination compounds have optical isomers.

Why do chiral compounds rotate?

Any polarized light has two and only two parts (clockwise and counter-clockwise). The two parts are combined and the light shows a direction of polarization. When these two parts of light pass through chiral matter, one goes faster and the other slower. The result is that the polarization of light is rotated.

Why only some materials exhibit the property of optical rotation?

Optical activity occurs only in chiral materials, those lacking microscopic mirror symmetry. This can include gases or solutions of chiral molecules such as sugars, molecules with helical secondary structure such as some proteins, and also chiral liquid crystals.

Is there free rotation around the carbon-carbon bond?

Carbon-carbon single bonds enable essentially free rotation about their axes. There is actually a small torsional barrier of about 12 kJ/mol (compared to the C-C bond energy of 350 kJ/mol), which slightly favors the staggered over the eclipsed conformation of the two methyl groups in ethane.

Why there is free rotation around a single bond and no free rotation around double bond?

Rotation around a single bond occurs readily, while rotation around a double bond is restricted. The pi bond prevents rotation because of the electron overlap both above and below the plane of the atoms. In alkenes, the carbon-carbon double bond is rigidly fixed.

Why does optical isomerism occur?

Optical isomers can occur when there is an asymmetric carbon atom. An asymmetric carbon atom is one which is bonded to four different groups. It forms a chiral centre of the molecule. The four groups can be something hideously complex, or something comfortably simple like a hydrogen atom or a chlorine atom.

Why do optical isomers exist?

You only get optical isomers if all four groups attached to the central carbon are different. The essential difference between the two examples we’ve looked at lies in the symmetry of the molecules. If there are two groups the same attached to the central carbon atom, the molecule has a plane of symmetry.