18916-57-9

Upstream product

• 74097-20-4 2-hydroxy-1,4-dimethoxynaphthalene 
• 84-85-5 4-methoxynaphth-1-ol 
• 24390-69-0 1-phenylazo-4-methoxynaphthalene 

Downstream Products

• 67979-43-5 2-(4-methylanilino)-4-[(4-methylphenyl)imino]naphthalen-1(4H)-one 
• 83-72-7 2-hydroxynaphtho-1,4-quinone 
• 69085-39-8 4-((4-methylphenyl)amino)naphthalene-1,2-dione 

Relevant academic research and scientific papers

Oxidation of 4-methoxy-1-naphthol on promoted platinum catalysts

Oxidative coupling of naphthols is a useful method for the formation of new carbon-carbon bonds in organic synthesis. In the presence of hydrogen peroxide, platinum supported on activated carbon catalyses this reaction. The outcome is influenced by the solvent, the reaction temperature and the physical structure of the catalyst. The catalyst structure is determined by the synthesis method and the modifier used (Bi or Sb). Within 40 min 4-methoxy-1-naphthol can be converted to 4,4'-dimethoxy-2,2'-binaphthalenyl-1,1'-diol with a yield of up to 94%, or to 4,4'-dimethoxy-2,2'-binaphthalenylidene-1,1'-dione with a yield of 92%. High amounts of quinoid byproducts (≤22%) are observed in nitromethane as the solvent.

IBS-catalyzed regioselective oxidation of phenols to 1,2-quinones with oxone

We have developed the first example of hypervalent iodine(V)-catalyzed regioselective oxidation of phenols to o-quinones. Various phenols could be oxidized to the corresponding o-quinones in good to excellent yields using catalytic amounts of sodium salts of 2-iodobenzenesulfonic acids (pre-IBSes) and stoichiometric amounts of Oxone as a co-oxidant under mild conditions. The reaction rate of IBS-catalyzed oxidation under nonaqueous conditions was further accelerated in the presence of an inorganic base such as potassium carbonate (K2CO3), a phase transfer catalyst such as tetrabutylammonium hydrogen sulfate (nBu4NHSO4), and a dehydrating agent such as anhydrous sodium sulfate (Na2SO4).

Physical Quenching and Chemical Reaction of Singlet Molecular Oxygen with Azo Dyes

The quenching rate constants of singlet oxygen liefetime by dialkylamino azo dyes 1 and tautomeric azo dyes 2 and 5 (as well as azo- and hydrazone-model methylated derivatives 3 and 4) were determined by measuring the 1.27-μm 1O2 emission lifetime, and the values obtained are in the range 106 - 108 M-1 s-1.The quenching involves a charge-transfer interaction, and different correlations with the oxidation potentials of the two classes of azo dyes are observed.Chemical reactions take place with a rate in the range 103 - 104 M-1 s-1 and are rationalized as a secondary pathway for the charge-transfer complex between 1O2 and the azo dye.Products include dealkylated amino azo dyes 6 from 1; compounds arising from the fragmentation of the aryl-azo bond, viz., benzenes 7 and phenoles 8 from 1 and 2; and 1,4-naphthoquinone 10 as well as the dimer 9 and the oxidized cyclic derivative 11 from 2.The methoxy derivative 3 yields an endoperoxide, which rearranges to a 1,2-naphthoquinone derivative 14.The results are discussed in comparison with the currently accepted mechanism for the reaction of 1O2 with azo dyes.

Dimeric Naphthoquinones, XVIII. - Ammonium Cerium(IV) Nitrate as Oxidising Agent: peri-Hydroxylation of Juglones giving Naphthazarins

5,8-Dialkoxy-1-naphthols (type 6a) which are easily accessible starting from juglones (5a) are oxidised under mild conditions using ammonium cerium(IV) nitrate, yielding with high p-selectivity the corresponding 1,4-naphthoquinones (7a).By dealkylation of the latter, substituted 1,8-dihydroxy-1,4-naphthoquinones (1a) are obtained in good yields.