CHIRAL CENTER Meaning and
Definition
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A chiral center refers to an atom within a molecule that is bonded to four distinct substituents, resulting in non-superposable mirror images – enantiomers. It is an essential concept in organic chemistry, as it is responsible for the existence of stereoisomers.
In order to qualify as a chiral center, the atom in question must possess tetrahedral geometry, usually carbon, but it can also be nitrogen, phosphorus, or sulfur. These substituents surrounding the chiral center must have unique functional groups or atoms attached to them, often represented by different colors or shapes. For example, if a carbon atom has a hydrogen atom (H) as one substituent, a hydroxyl group (-OH) as another, a methyl group (-CH3) as a third, and a carboxyl group (-COOH) as the fourth, it would constitute a chiral center.
An important characteristic of chiral centers is their ability to produce enantiomers. These are molecules that possess the same chemical formula and connectivity but differ in their spatial arrangement. They are mirror images that cannot be exactly superimposed upon one another. The presence of a chiral center is crucial for biological activity, as enantiomers can have differing physiological effects. For instance, the human body may react differently to the left- and right-handed (S and R) enantiomers of a drug, perceivably leading to therapeutic benefits or potential side effects.
Overall, chiral centers are fundamental in the study of stereoisomers and their importance cannot be understated in understanding the three-dimensional nature of molecules and their impact on various chemical and biological processes.
Etymology of CHIRAL CENTER
The term "chiral center" has a primarily English etymology, and it is derived from the combination of two words: "chiral" and "center".
The word "chiral" originates from the Greek word "cheir" (χειρ), which means "hand". It was first introduced in 1894 by the French chemist and Nobel laureate, Lord Kelvin (William Thomson), who used it to describe an object that cannot be superimposed onto its mirror image. In chemistry, chirality refers to a property of molecules that exist in two non-superimposable mirror-image forms, called enantiomers.
The term "center" is an English word used to describe a point or place that represents a central position. In the context of chemistry, a chiral center refers to a specific atom within a molecule where the change in configuration gives rise to enantiomers.
