Synthesis of Benzoquinones by Oxidation*Present address: Department of Chemistry, University of California, Berkeley, Cal.

Abstract

p‐Benzoquinone or quinone was discovered in 1838 as a product of the action of manganese dioxide in sulfuric acid on the natural product, quinic acid, However, benzoquinones generally prepared by the oxidation of disubstituted aromatic hydrocarbons derivatives having hydroxyl or amino groups in the ortho and para positions. The quinone results from the oxidation of hydroquinone, p‐aminophenol, or p‐phenylendiamine. Certain quinones are obtainable in moderate or fair yield by oxidation of starting materials containing only one hydroxyl or amino group as exemplified by the industrial production of quinine from aniline. Oxidation of phenols and amines constitutes the chief topic of discussion in this chapter.

Physiological and Molecular Response of Prorocentrum minimum to Tannic Acid: An Experimental Study to Evaluate the Feasibility of Using Tannic Acid in Controling the Red Tide in a Eutrophic Coastal Water

“…The presence of microbial entities could promote the sensitivity of phytoplankton species to tannic acid [ 67 ]. pH also significantly promotes tannic acid toxicity specifically in an alkaline environment [ 68 ]. Since saline water is basically alkaline in nature, application of tannic acid to P. minimum would be more effective.…”

Quinones

“…The initial compounds are useful for conversion to heterocyclic products, eg, 58. The yields for various R groups are as follows: 3 89…”

“…Synthesis by oxidation remains the first choice for commercial and laboratory preparation of quinones (3). Compounds related to 3 must be prepared using mild conditions because of their great sensitivity to both electrophiles and nucleophiles (4).…”

Plant Polyphenols

“…It is well understood that most phenolics are susceptible to autoxidation at pH values > 7 in the presence of oxygen (Cason, 1967). Furthermore, the toxicity of polyphenols is significantly enhanced when oxidized (Lyr, 1965).…”

“…Furthermore, the toxicity of polyphenols is significantly enhanced when oxidized (Lyr, 1965). In the phytoplankton system, this mechanism might apply to the very proximity of phototrophs, since under alkaline pH conditions, autoxidation would not maintain polyphenols as oxidized monomers, but continue to polymerization (Lyr, 1965;Cason, 1967). In the phytoplankton system, this mechanism might apply to the very proximity of phototrophs, since under alkaline pH conditions, autoxidation would not maintain polyphenols as oxidized monomers, but continue to polymerization (Lyr, 1965;Cason, 1967).…”