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Many chiral molecules have point chirality, namely a single chiral stereogenic center that coincides with an atom. This stereogenic center usually has four or more bonds to different groups, and may be carbon (as in many biological molecules), phosphorus (as in many organophosphates), silicon, or a metal (as in many chiral coordination compounds).
Chirality (/ k aɪ ˈ r æ l ɪ t i /) is a property of asymmetry important in several branches of science. The word chirality is derived from the Greek χείρ (kheir), "hand", a familiar chiral object. An object or a system is chiral if it is distinguishable from its mirror image; that is, it cannot be superposed (not to be confused with ...
A chirality center (chiral center) is a type of stereocenter. A chirality center is defined as an atom holding a set of four different ligands (atoms or groups of atoms) in a spatial arrangement which is non-superposable on its mirror image. Chirality centers must be sp 3 hybridized, meaning that a chirality center can only have single bonds. [5]
Drugs that exhibit handedness are referred to as chiral drugs. Chiral drugs that are equimolar (1:1) mixture of enantiomers are called racemic drugs and these are obviously devoid of optical rotation. The most commonly encountered stereogenic unit, [2] that confers chirality to drug molecules are stereogenic center. Stereogenic center can be ...
The presence of two chiral centers in this molecule means that the compound can exist as any of four isomers. The biologic activity has been found to be associated with the α-isomer. Resolution of that isomer into its optical antipodes showed the d isomer to be the active analgesic; this is now denoted as propoxyphene.
While most stereoisomers can be arranged in pairs of mirror-image forms, there are some non-chiral stereoisomers that are identical to their mirror images, in spite of having chiral centers. This happens whenever the molecular graph is symmetrical, as in the 3-ketopentoses H(CHOH) 2 (CO)(CHOH) 2 H, and the two halves are mirror images of each ...
If two identical substituents are attached to an sp 3-hybridized atom, the descriptors pro-R and pro-S are used to distinguish between the two. Promoting the pro-R substituent to higher priority than the other identical substituent results in an R chirality center at the original sp 3-hybridized atom, and analogously for the pro-S substituent.
Besides the 2-ketoses, there are only the 3-Ketoses, and they do not exist in nature, although at least one 3-ketohexose has been synthesized, with great difficulty. In the linear form, the 2-ketohexoses have three chiral centers and therefore eight possible stereoisomers (2 3), comprising four pairs of