K. Chandrasenan, R. H. Thomson
1971
Citations
0
Influential Citations
24
Citations
Journal
Tetrahedron
Abstract
Abstract 2-Methyl-1,4-naphthaquinones, substituted at C-3 by alkyl, aralkyl, allyl, aryl or halogen groups, react in aqueous ethanolic NaOH to give dehydro-dimers, namely 1,2-bis(1,4-naphthaquinon-2-yl)ethanes. The reaction is analogous to the formation of bibenzyls from nitrotoluenes in basic media. In tBuOH containing tBuOK, 3-benzyl-2-methyl-1,4-naphthaquinone also undergoes oxidation at the benzyl carbon atom to give phthiocol and benzaldehyde, as well as dimer; allyl groups are cleaved similarly. A mechanism is proposed which also accounts for the final stage in the Dam-Karrer colour test for vitamin K. 2-Hydroxy-1,4-naphthaquinones are oxidised by persulphate to 2,2′-dihydroxy-3,3′-bi-1,4-naphtha-quinonyls.