Intramolecular in chemistry describes a process or characteristic limited within the structure of a single molecule; a property or phenomenon limited to the extent of a single molecule. Chemistry (from Egyptian kēme (chem meaning "earth") is the Science concerned with the composition structure and properties In Chemistry, a molecule is defined as a sufficiently stable electrically neutral group of at least two Atoms in a definite arrangement held together by

Contents 1 Examples 2 Molecular tethers 3 See also 4 References

Examples

• intramolecular hydride transfer (transfer of a hydride ion from one part to another within the same molecule)
• intramolecular hydrogen bond (a hydrogen bond formed between two functional groups of the same molecule)

In intramolecular organic reactions, two reaction sites are contained within a single molecule. Organic reactions are Chemical reactions involving Organic compounds The basic Organic chemistry reaction types are Addition reactions Elimination This creates a very high effective concentration (resulting in high reaction rates) and therefore many intramolecular reactions take place that would not occur as an intermolecular reaction between two compounds. In Chemistry, concentration is the measure of how much of a given substance there is mixed with another substance The reaction rate or rate of reaction for a Reactant or product in a particular reaction is intuitively defined as how fast a reaction takes In Physics, Chemistry, and Biology, intermolecular forces are forces that act between stable Molecules or between functional groups of

Examples of intramolecular reactions are the Smiles rearrangement, the Dieckmann condensation and the Madelung synthesis. The Smiles rearrangement is an Organic reaction and a Rearrangement reaction. The Dieckmann condensation is the Intramolecular Chemical reaction of di Esters with base to give β-ketoesters The Madelung synthesis is a Chemical reaction that produces (substituted or unsubstituted Indoles by the Intramolecular cyclization of N-phenylamides using

Molecular tethers

In a niche concept called molecular tethers otherwise intermolecular reactions can be made temporarily intramolecular by anchoring both reactions by a tether with all the advantages associated to it. A tether is a cord that anchors something movable to a stationary point Popular choices of tether contain a carbonate ester, boronic ester, silyl ether or a silyl acetal link (silicon tethers) which are fairly inert in many organic reactions yet can be cleaved by specific reagents. A carbonate ester is a Functional group in Organic chemistry consisting of a Carbonyl group flanked by two Alkoxy groups A boronic acid is an Alkyl or Aryl substituted Boric acid containing a Carbon to Boron Chemical bond belonging to Silyl ethers are a group of Chemical compounds which contain a Silicon atom covalently bonded to an Alkoxy group Organosilicon compounds are organic compounds containing Carbon Silicon bonds. Main hurdle for this strategy to work is selecting the proper length for the tether and making sure reactive groups have an optimal orientation with respect to each other. An examples is a Pauson-Khand reaction of an alkene and an alkyne tethered together via a silyl ether ^[1]

In this particular reaction the tether angle bringing the reactive groups together is effectively reduced by placing isopropyl groups on the silicon atom via the Thorpe-Ingold effect. The Pauson–Khand reaction (or PKR or PK-type reaction) is a Chemical reaction described as a Cycloaddition between an In Organic chemistry, isopropyl is a substituent form of Propane, the three- Carbon Alkyl Functional group. The Thorpe-Ingold effect or gem-dimethyl effect, or angle compression is an effect observed in Organic chemistry where increasing the size of two substituents No reaction takes place when these bulky groups are replaced by smaller methyl groups.

Another example is a photochemical [2+2]cycloaddition with two alkene groups tethered through a silicon acetal group (racemic, the other enantiomer not depicted) which is subsequently cleaved by TBAF yielding the endo-diol. Photochemistry, a sub-discipline of Chemistry, is the study of the interactions between Atoms, small Molecules, and light (or Electromagnetic radiation A cycloaddition is a Pericyclic Chemical reaction, in which two π bonds are lost and two σ bonds are gained the resulting reaction is a In Chemistry, an enantiomer ( from the Greek ἐνάντιος opposite and μέρος part or portion is one of two Stereoisomers that are nonsuperimposable Tetra- n -butylammonium fluoride or TBAF is a Quaternary ammonium salt with the chemical formula (CH3CH2CH2CH24N+F-

Without the tether the exo isomer forms ^[2]. Endo-exo isomerism is a special type of Isomerism found in Organic compounds with a Substituent on a bridged ring system

See also

• Intermolecular

References

Chemical Communications, known as ChemComm, is a peer-reviewed Scientific journal. A digital object identifier ( DOI) is a permanent identifier given to an Electronic document.

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