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Conversely, a mirror image of an achiral object, such as a sphere, cannot be distinguished from the object. A chiral object and its mirror image are called enantiomorphs (Greek, "opposite forms") or, when referring to molecules, enantiomers. A non-chiral object is called achiral (sometimes also amphichiral) and can be superposed on its mirror ...
An object that is not chiral is said to be achiral. A chiral object and its mirror image are said to be enantiomorphs. The word chirality is derived from the Greek χείρ (cheir), the hand, the most familiar chiral object; the word enantiomorph stems from the Greek ἐναντίος (enantios) 'opposite' + μορφή (morphe) 'form'.
Chiral molecules are always dissymmetric (lacking S n) but not always asymmetric (lacking all symmetry elements except the trivial identity). Asymmetric molecules are always chiral. [6] The following table shows some examples of chiral and achiral molecules, with the Schoenflies notation of the point group of the molecule.
Enantiotopic groups are identical and indistinguishable except in chiral environments. For instance, the CH 2 hydrogens in ethanol (CH 3 CH 2 OH) are normally enantiotopic, but can be made different (diastereotopic) if combined with a chiral center, for instance by conversion to an ester of a chiral carboxylic acid such as lactic acid, or if coordinated to a chiral metal center, or if ...
Any planar pattern that does not have a line of mirror symmetry is 2d-chiral, and examples include flat spirals and letters such as S, G, P. In contrast to 3d-chiral objects, the perceived sense of twist of 2d-chiral patterns is reversed for opposite directions of observation.
The simplest chiral knot is the trefoil knot, which was shown to be chiral by Max Dehn. All nontrivial torus knots are chiral. The Alexander polynomial cannot distinguish a knot from its mirror image, but the Jones polynomial can in some cases; if V k ( q ) ≠ V k ( q −1 ), then the knot is chiral, however the converse is not true.
A theory that is asymmetric with respect to chiralities is called a chiral theory, while a non-chiral (i.e., parity-symmetric) theory is sometimes called a vector theory. Many pieces of the Standard Model of physics are non-chiral, which is traceable to anomaly cancellation in chiral theories.
A planar chiral derivative of ferrocene, used for kinetic resolution of some racemic secondary alcohols [1]. This term is used in chemistry contexts, [2] e.g., for a chiral molecule lacking an asymmetric carbon atom, but possessing two non-coplanar rings that are each dissymmetric and which cannot easily rotate about the chemical bond connecting them: 2,2'-dimethylbiphenyl is perhaps the ...