{"id":927,"date":"2018-07-02T19:18:10","date_gmt":"2018-07-02T19:18:10","guid":{"rendered":"https:\/\/www.studyorgo.com\/blog\/?p=927"},"modified":"2018-07-02T19:18:10","modified_gmt":"2018-07-02T19:18:10","slug":"how-to-assign-stereoisomer-configuration","status":"publish","type":"post","link":"https:\/\/www.studyorgo.com\/blog\/how-to-assign-stereoisomer-configuration\/","title":{"rendered":"How to Assign Stereoisomer Configuration"},"content":{"rendered":"

Chirality is an important aspect of life.\u00a0 This is so because many of metabolites used in living cells, in particular amino acids that form enzymes, are also chiral. Chirality contributes asymmetry to molecules, allowing them the ability to recognize \u201chandedness\u201d and further add to the complexity and specificity of reactions. Organic chemists must pay constant attention to the chirality of molecules both before and after reactions, less the compounds lose their biological or chemical activity.<\/p>\n

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Molecules, like your hands, that are not superimposable on their mirror images are called chiral\u00a0<\/strong>objects, from the Greek word cheir\u00a0 (meaning \u201chand\u201d). All 3D objects can be\u00a0<\/strong>categorized as either chiral or achiral.<\/strong>\u00a0Chemical molecules are 3D objects and can also be classified in this way. To help you remember, chiral molecules are like hands and are NOT superimposable on its mirror image while achiral molecules are like tennis rackets: they are superimposable on their mirror images.<\/p>\n

IUPAC recommended in 1996 that a tetrahedral carbon bearing four different groups be called a chirality center<\/strong>.\u00a0 Many other names are commonly used include chiral center, stereocenter, stereogenic cente<\/strong>r, and asymmetric center<\/strong>.\u00a0 They all mean the same thing, a carbon connected to 4 unique substituents that is not superimposable on its mirror image.<\/p>\n

When a compound is chiral, it will have one opposite molecule; a non-superimposable mirror image, called its enantiomer<\/strong> (from the Greek word meaning \u201copposite\u201d). The compound and its mirror image are said to be a pair of enantiomers. The word \u201cenantiomer\u201d is analogous to the word \u201ctwin\u201d. When two children are identical twins, each one is said to be the (“evil…”) twin of the other. Similarly, when two compounds are a pair of enantiomers, each compound is said to be the enantiomer of the other.\u00a0 A chiral compound will have exactly one enantiomer<\/strong>s, all other molecules with the same molecular formula and constitutional arrangement are diastereomers<\/strong>, but are only seen when there are more than two chiral centers in a molecule.<\/p>\n

In order to determine whether the stereocenter\u00a0is in the R or S configuration, there are a series of steps to follow.<\/p>\n

1. Identify the stereocenter<\/strong> as 4 unique substituents attached to the chiral center<\/p>\n