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Chromic acid in aqueous sulfuric acid and acetone is known as the Jones reagent, which will oxidize primary and secondary alcohols to carboxylic acids and ketones respectively, while rarely affecting unsaturated bonds. [12] Pyridinium chlorochromate is generated from chromium trioxide and pyridinium chloride.
The reaction stoichiometry implicates the Cr(IV) species "CrO 2 OH −", which comproportionates with the chromic acid to give a Cr(V) oxide, which also functions as an oxidant for the alcohol. [ 6 ] The oxidation of the aldehydes is proposed to proceed via the formation of hemiacetal -like intermediates, which arise from the addition of the O ...
The reaction process begins with deprotonation at the halogenated position. In a related reaction, α-halo carboxylic esters can be reduced by lithium aluminium hydride to the α-halo alcohols, which can be converted to the α-epoxides. [5] α-Halo-esters can be converted to vinyl halides. upon reaction with ketones and chromous chloride. [6]
Substrates are broadly limited to methyl ketones and secondary alcohols oxidizable to methyl ketones, such as isopropanol.The only primary alcohol and aldehyde to undergo this reaction are ethanol and acetaldehyde, respectively. 1,3-Diketones such as acetylacetone also undergo this reaction. β-ketoacids such as acetoacetic acid will also give the test upon heating.
Further condensation reactions can occur in strongly acidic solution with the formation of trichromates, Cr 3 O 2− 10, and tetrachromates, Cr 4 O 2− 13. [2] All polyoxyanions of chromium(VI) have structures made up of tetrahedral CrO 4 units sharing corners. [3] The hydrogen chromate ion, HCrO 4 −, is a weak acid: HCrO − 4 ⇌ CrO 2−
The Dakin oxidation (or Dakin reaction) is an organic redox reaction in which an ortho- or para-hydroxylated phenyl aldehyde (2-hydroxybenzaldehyde or 4-hydroxybenzaldehyde) or ketone reacts with hydrogen peroxide (H 2 O 2) in base to form a benzenediol and a carboxylate. Overall, the carbonyl group is oxidised, whereas the H 2 O 2 is reduced.
Reaction mechanism for the bromination of acetone while in the presence of acetic acid. Basic (in aqueous NaOH): Reaction mechanism for the bromination of acetone while in the presence of aqueous NaOH. In acidic solution, usually only one alpha hydrogen is replaced by a halogen, as each successive halogenation is slower than the first.
The Wolff–Kishner reduction is a reaction used in organic chemistry to convert carbonyl functionalities into methylene groups. [1] [2] In the context of complex molecule synthesis, it is most frequently employed to remove a carbonyl group after it has served its synthetic purpose of activating an intermediate in a preceding step.