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In organic chemistry, a rearrangement reaction is a broad class of organic reactions where the carbon skeleton of a molecule is rearranged to give a structural isomer of the original molecule. [1] Often a substituent moves from one atom to another atom in the same molecule, hence these reactions are usually intramolecular. In the example below ...
Dithiane chemistry opens the way to many new chemical transformations. One example is found in so-called anion relay chemistry in which a negative charge of an anionic functional group resulting from one organic reaction is transferred to a different location within the same carbon framework and available for secondary reaction. [7]
Phase transitions (phase changes) that help describe polymorphism include polymorphic transitions as well as melting and vaporization transitions. According to IUPAC, a polymorphic transition is "A reversible transition of a solid crystalline phase at a certain temperature and pressure (the inversion point) to another phase of the same chemical composition with a different crystal structure."
For example, in an S N 2 reaction, Walden inversion occurs at a tetrahedral carbon atom. It can be visualized by imagining an umbrella turned inside-out in a gale . In the Walden inversion, the backside attack by the nucleophile in an S N 2 reaction gives rise to a product whose configuration is opposite to the reactant.
Nuclear chemistry is a sub-discipline of chemistry that involves the chemical reactions of unstable and radioactive elements where both electronic and nuclear changes can occur. The substance (or substances) initially involved in a chemical reaction are called reactants or reagents .
Steric hindrance is the slowing of chemical reactions due to steric bulk. It is usually manifested in intermolecular reactions, whereas discussion of steric effects often focus on intramolecular interactions. Steric hindrance is often exploited to control selectivity, such as slowing unwanted side-reactions.
Femtochemistry is the area of physical chemistry that studies chemical reactions on extremely short timescales (approximately 10 −15 seconds or one femtosecond, hence the name) in order to study the very act of atoms within molecules (reactants) rearranging themselves to form new molecules (products).
The Fischer indole synthesis is a chemical reaction that produces the aromatic heterocycle indole from a (substituted) phenylhydrazine and an aldehyde or ketone under acidic conditions. [19] [20] The reaction was discovered in 1883 by Hermann Emil Fischer. The Fischer indole synthesis. The choice of acid catalyst is very important.