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The Hofmann–Martius rearrangement in organic chemistry is a rearrangement reaction converting an N-alkylated aniline to the corresponding ortho and / or para aryl-alkylated aniline. The reaction requires heat, and the catalyst is an acid like hydrochloric acid. [1] [2]
The Hofmann rearrangement (Hofmann degradation) is the organic reaction of a primary amide to a primary amine with one less carbon atom. [ 1 ] [ 2 ] [ 3 ] The reaction involves oxidation of the nitrogen followed by rearrangement of the carbonyl and nitrogen to give an isocyanate intermediate.
This organic reaction is closely related to the Hofmann elimination, but the base is a part of the leaving group. Sulfoxides can undergo an essentially identical reaction to produce sulfenic acids, which is important in the antioxidant chemistry of garlic and other alliums. Selenoxides likewise undergo selenoxide eliminations.
The rearrangement is widely used in organic synthesis. It is symmetry-allowed when it is suprafacial on all components. The transition state of the molecule passes through a boat or chair like transition state. An example of the Cope rearrangement is the expansion of a cyclobutane ring to a cycloocta-1,5-diene ring:
In organic chemistry, regioselectivity is the preference of chemical bonding or breaking in one direction over all other possible directions. [1] [2] It can often apply to which of many possible positions a reagent will affect, such as which proton a strong base will abstract from an organic molecule, or where on a substituted benzene ring a further substituent will be added.
While the Barton reaction has not enjoyed the popularity or widespread use of many other organic reactions, together with the mechanistically similar Hofmann–Löffler reaction it represents one of the first examples of C-H activation chemistry, a field which is now the topic of much frontline research in industrial and academic chemistry circles.
A stirred BZ reaction mixture showing changes in color over time. The discovery of the phenomenon is credited to Boris Belousov.In 1951, while trying to find the non-organic analog to the Krebs cycle, he noted that in a mix of potassium bromate, cerium(IV) sulfate, malonic acid, and citric acid in dilute sulfuric acid, the ratio of concentration of the cerium(IV) and cerium(III) ions ...
The Auwers synthesis is a series of organic reactions forming a flavonol from a coumarone.This reaction was first reported by Karl von Auwers in 1908. [1] [2] [3] [4 ...