stereochemistry Stereochemistry, a subdiscipline of chemistry, studies the spatial arrangement of atoms that form the structure of molecules and their manipulation. The study of stereochemistry focuses on the relationships between stereoisomers, which are defined ...

, cryptochirality is a special case of

chirality Chirality () is a property of asymmetry important in several branches of science. The word ''chirality'' is derived from the Greek (''kheir''), "hand", a familiar chiral object. An object or a system is ''chiral'' if it is distinguishable fro ...

in which a molecule is chiral but its

specific rotation In chemistry, specific rotation ( �'') is a property of a chiral chemical compound. It is defined as the change in orientation of monochromatic plane-polarized light, per unit distance–concentration product, as the light passes through a sampl ...

is non-measurable. The underlying reason for the lack of rotation is the specific electronic properties of the molecule. The term was introduced by

Kurt Mislow Kurt Martin Mislow (June 5, 1923 – October 5, 2017) was a German-born American organic chemist who specialized in stereochemistry. Early life and education Born in Berlin on June 5, 1923, Mislow had moved to London by 1938, after some time in ...

in 1977. For example, the

alkane In organic chemistry, an alkane, or paraffin (a historical trivial name that also has other meanings), is an acyclic saturated hydrocarbon. In other words, an alkane consists of hydrogen and carbon atoms arranged in a tree structure in whi ...

5-ethyl-5-propylundecane found in certain species of ''

Phaseolus vulgaris ''Phaseolus vulgaris'', the common bean,, is a herbaceous annual plant grown worldwide for its edible dry seeds or green, unripe pods. Its leaf is also occasionally used as a vegetable and the straw as fodder. Its botanical classification, alo ...

'' is chiral at its central

quaternary carbon A quaternary carbon is a carbon atom bound to four other carbon atoms. For this reason, quaternary carbon atoms are found only in hydrocarbons having at least five carbon atoms. Quaternary carbon atoms can occur in branched alkanes, but not in ...

, but neither enantiomeric form has any observable optical rotation: It is still possible to distinguish between the two enantiomers by using them in

asymmetric synthesis Enantioselective synthesis, also called asymmetric synthesis, is a form of chemical synthesis. It is defined by IUPAC as "a chemical reaction (or reaction sequence) in which one or more new elements of chirality are formed in a substrate molecul ...

of another chemical whose stereochemical nature can be measured. For example, the Soai reaction of 2-(3,3-dimethylbut-1-ynyl)pyrimidine-5-carbaldehyde with diisopropylzinc performed in the presence of 5-ethyl-5-propylundecane forms a secondary alcohol with a high

enantiomeric excess In stereochemistry, enantiomeric excess (ee) is a measurement of purity used for chiral substances. It reflects the degree to which a sample contains one enantiomer in greater amounts than the other. A racemic mixture has an ee of 0%, while a sing ...

based on the major enantiomer of the alkane that was used. Even a slight enantiomeric excess of the alkane is rapidly amplified due to the

autocatalytic In chemistry, a chemical reaction is said to be autocatalytic if one of the reaction products is also a catalyst for the same reaction. Many forms of autocatalysis are recognized.Steinfeld J.I., Francisco J.S. and Hase W.L. ''Chemical Kinetics and ...

nature of this reaction. Cryptochirality also occurs in

polymer A polymer () is a chemical substance, substance or material that consists of very large molecules, or macromolecules, that are constituted by many repeat unit, repeating subunits derived from one or more species of monomers. Due to their br ...

ic systems growing from chiral initiators, for example in

dendrimer Dendrimers are highly ordered, Branching (polymer chemistry), branched molecules, polymeric molecules. Synonymous terms for dendrimer include arborols and cascade molecules. Typically, dendrimers are symmetric about the core, and often adopt a sph ...

s having lobes of different sizes attached to a central core. The term is also used to describe a situation where an enantiomeric excess lies far below the observational horizon, but is still relevant, e.g. in highly enantiosensitive, self-amplifying reactions.''Absolute Asymmetric Synthesis: A Commentary'', Kurt Mislow, Collect. Czech. Chem. Commun. 2003, 68, 849-864, https://doi.org/10.1135/cccc20030849

References

Stereochemistry {{Stereochemistry-stub