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Intramolecular
 
 
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Intramolecular in chemistry
Chemistry

Chemistry is the science concerned with the composition, structure, and properties of matter, as well as the changes it undergoes during chemical reactions....
 describes a process or characteristic limited within the structure of a single molecule
Molecule

In chemistry, a molecule is defined as a sufficiently stable, electric charge neutral group of at least two atoms in a definite arrangement held together by very strong chemical bonds....
; a property or phenomenon limited to the extent of a single molecule.


In intramolecular organic reaction
Organic reaction

Organic reactions are chemical reactions involving organic compounds. The basic organic chemistry reaction types are addition reactions, elimination reactions, substitution reactions, pericyclic reactions, rearrangement reactions and organic redox reaction....
s, two reaction sites are contained within a single molecule. This creates a very high effective concentration
Concentration

In chemistry, concentration is the measure of how much of a given chemical substance there is mixed with another substance. This can apply to any sort of chemical mixture, but most frequently the concept is limited to homogeneous solutions, where it refers to the amount of solute in the solvent....
 (resulting in high reaction rate
Reaction rate

The reaction rate or rate of reaction for a reactant or product in a particular chemical reaction is intuitively defined as how fast a reaction takes place....
s) and therefore many intramolecular reactions take place that would not occur as an intermolecular reaction between two compounds.

Examples of intramolecular reactions are the Smiles rearrangement
Smiles rearrangement

The Smiles rearrangement is an organic reaction and a rearrangement reaction. It is an intramolecular nucleophilic aromatic substitution of the type:...
, the Dieckmann condensation
Dieckmann condensation

The Dieckmann condensation is the intramolecular chemical reaction of diesters with base to give ?-ketoesters. It is named after the German chemist Walter Dieckmann ....
 and the Madelung synthesis
Madelung synthesis

The Madelung synthesis is a chemical reaction that produces indoles by the intramolecular cyclization of N-phenylamides using strong base at high temperature....
.

niche concept called molecular tethers otherwise intermolecular reactions can be made temporarily intramolecular by anchoring both reactions by a tether
Tether

A tether is a cord that anchors something movable to a stationary point. There are a number of applications for tethers, but the primary use is limiting the movement of animals....
 with all the advantages associated to it.






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Intramolecular in chemistry
Chemistry

Chemistry is the science concerned with the composition, structure, and properties of matter, as well as the changes it undergoes during chemical reactions....
 describes a process or characteristic limited within the structure of a single molecule
Molecule

In chemistry, a molecule is defined as a sufficiently stable, electric charge neutral group of at least two atoms in a definite arrangement held together by very strong chemical bonds....
; a property or phenomenon limited to the extent of a single molecule.

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 reaction
Organic reaction

Organic reactions are chemical reactions involving organic compounds. The basic organic chemistry reaction types are addition reactions, elimination reactions, substitution reactions, pericyclic reactions, rearrangement reactions and organic redox reaction....
s, two reaction sites are contained within a single molecule. This creates a very high effective concentration
Concentration

In chemistry, concentration is the measure of how much of a given chemical substance there is mixed with another substance. This can apply to any sort of chemical mixture, but most frequently the concept is limited to homogeneous solutions, where it refers to the amount of solute in the solvent....
 (resulting in high reaction rate
Reaction rate

The reaction rate or rate of reaction for a reactant or product in a particular chemical reaction is intuitively defined as how fast a reaction takes place....
s) and therefore many intramolecular reactions take place that would not occur as an intermolecular reaction between two compounds.

Examples of intramolecular reactions are the Smiles rearrangement
Smiles rearrangement

The Smiles rearrangement is an organic reaction and a rearrangement reaction. It is an intramolecular nucleophilic aromatic substitution of the type:...
, the Dieckmann condensation
Dieckmann condensation

The Dieckmann condensation is the intramolecular chemical reaction of diesters with base to give ?-ketoesters. It is named after the German chemist Walter Dieckmann ....
 and the Madelung synthesis
Madelung synthesis

The Madelung synthesis is a chemical reaction that produces indoles by the intramolecular cyclization of N-phenylamides using strong base at high temperature....
.

Molecular tethers

In a niche concept called molecular tethers otherwise intermolecular reactions can be made temporarily intramolecular by anchoring both reactions by a tether
Tether

A tether is a cord that anchors something movable to a stationary point. There are a number of applications for tethers, but the primary use is limiting the movement of animals....
 with all the advantages associated to it. Popular choices of tether contain a carbonate ester
Carbonate ester

A carbonate ester is a functional group in organic chemistry consisting of a carbonyl group flanked by two alkoxy groups. The general structure of these carbonates is R1OOR2 and they are related to esters R1OR and ethers R1OR2 and also to the inorganic chemistry carbonates....
, boronic ester, silyl ether
Silyl ether

Silyl ethers are a group of chemical compounds which contain a silicon atom covalent bond to an alkoxy group. The general structure is R1R2R3Si-O-R4 where R4 is an alkyl group or an aryl group....
 or a silyl acetal link (silicon tethers) which are fairly inert in many organic reactions yet can be cleaved by specific reagents. The 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

In this particular reaction the tether angle bringing the reactive groups together is effectively reduced by placing isopropyl
Isopropyl

In organic chemistry, isopropyl is a substituent form of propane, the three-carbon alkyl functional group. As an isomer of propyl, bonding to an R group occurs at the secondary carbon....
 groups on the silicon atom via the Thorpe-Ingold effect
Thorpe-Ingold effect

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 on a tetrahedral center leads to enhanced reactions between parts of the other two substituents....
. No reaction takes place when these bulky groups are replaced by smaller methyl groups.

Another example is a photochemical [2+2]cycloaddition
Cycloaddition

A cycloaddition is a pericyclic chemical reaction, in which two pi bond are lost and two sigma bond are gained. The resulting reaction is a cyclization reaction....
 with two alkene groups tethered through a silicon acetal group (racemic, the other enantiomer
Enantiomer

In chemistry, an enantiomer is one of two stereoisomers that are Superpose complete mirror images of each other, much as one's left and right Chirality are "the same" but opposite....
 not depicted) which is subsequently cleaved by TBAF yielding the endo-diol.

Without the tether the exo isomer forms .

See also

  • Intermolecular