Question

Explain three examples of chiral and Achiral compounds?

Answer 1

Optical isomers:

• The optical isomers are the compounds that have the ability to rotate plane-polarized light either in the right direction or left direction.
• The compounds that rotate the plane of polarized light to the right or clockwise, then it is said to be dextro-rotatory.
• The compound that rotates the plane of polarized light to the left or anticlockwise, then it is said to be laevo-rotatory.
• A compound to be optically active must possess one or more chiral centers (an atom that has four unique atoms or groups attached to it).
• The Optically active compounds which are mirror images of each other are known as Enantiomers.
• The Compounds should be chiral to show the property of enantiomers.

Chiral compound

• A chiral compound is a compound that possesses a plane of symmetry and is non-superimposable mirror images of each other.
• The groups surrounding the compound are non-superimposable images so they are chiral.
• Example of the chiral compound is Glucose, Mannose, and L-Ribose
• Glucose is composed of six carbon atoms out of which four atoms are chiral.

• The molecules of Mannose form chiral compounds with a total of four chiral centers.

• The molecule of Ribose also shows chirality as it has a total number of three chiral centers.

Achiral compound

• Achiral molecules have superimposable mirror images.
• They lack chiral centers and the center of a compound that is attached to similar types of the substituent is known as the achiral Centre
• The presence of a minimum of two similar substituents to the Carbon atom can make it an achiral Centre.
• Examples of the achiral compounds are 1,1 Dibromo 2,2 dichloromethane, 1,2 Dibromo cinnamic acid, and 1,2 Dichloro 1,2 ethanediol.
• The compound 1,1 Dibromo 2,2 dichloroethane shows achirality since two similar groups are added to a single Carbon atom

• In 1,2 Dibromo cinnamic acid molecule, the Carbon atom is attached to the different atoms but the entire compound is divided into two equal halves therefore it is an achiral compound.

• In 1,2 Dichloro 1,2 ethanediol molecule also, the Carbon is attached to different atoms and thus they have two chiral atoms but the entire compound is divided into two equal halves, therefore it is an achiral compound