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The Dakin oxidation. 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.
Benzaldehyde (C 6 H 5 CHO) is an organic compound consisting of a benzene ring with a formyl substituent. It is among the simplest aromatic aldehydes and one of the most industrially useful. It is a colorless liquid with a characteristic almond -like odor , and is commonly used in cherry -flavored sodas . [ 5 ]
4-Hydroxybenzaldehyde is prepared by reaction of phenol with chloroform, which gives isomeric hydroxybenzal chlorides. Hydrolysis of the C-Cl bonds gives the aldehyde. [5] 4-Hydroxybenzaldehyde is a precursor to 4-hydroxyphenylglycine, a precursor to penicillins.
It is often said the resonance stability of phenol makes it a stronger acid than that of aliphatic alcohols such as ethanol (pK a = 10 vs. 16–18). However, a significant contribution is the greater electronegativity of the sp 2 alpha carbon in phenol compared to the sp 3 alpha carbon in aliphatic alcohols.
Phenolic aldehydes are derivatives of phenol. [1] Phenolic aldehydes can be found in wines and cognacs. [2] Examples : Hydroxybenzaldehydes; Dihydroxybenzaldehydes; Vanillin and isovanillin; 2,3,4-trihydroxybenzaldehyde can be isolated from Antigonon leptopus. [3]
Salicylaldehyde is produced by condensation of phenol with formaldehyde to give hydroxybenzyl alcohol, which is oxidized to the aldehyde. [4] Salicylaldehydes in general are prepared by ortho-selective formylation reactions from the corresponding phenol, for instance by the Duff reaction, Reimer–Tiemann reaction, or by treatment with paraformaldehyde in the presence of magnesium chloride and ...
The Gattermann–Koch reaction can be used to synthesize benzaldehyde from benzene. [18] The Gatterman reaction describes arene reactions with hydrocyanic acid. [19] [20] The Houben–Hoesch reaction describes arene reactions with nitriles. [21] A reaction modification with an aromatic phenyl ester as a reactant is called the Fries rearrangement.
The hydroxide will also deprotonate the phenol (4) to give a negatively charged phenoxide (5). The negative charge is delocalised into the aromatic ring, making it far more nucleophilic. Nucleophilic attack on the dichlorocarbene gives an intermediate dichloromethyl substituted phenol (7). After basic hydrolysis, the desired product (9) is formed.