Studies on Pitch Problems Caused by Pulping and Bleaching of Tropical Woods. XIV. Chemistry of the Aurone Derivatives at the Conventional Bleaching Stages
Rengasin (1), which is responsible for the colored specks on a sheet of bleached sulfate pulp from the woods of rengas (Anacardiaceae), was converted into R1 7 having a novel carbon skeleton.A closely related analogue, S1 8, prepared from sulfuretin (2) was used as a model to investigate further conversions under bleaching conditions.Chlorination of S1 8 produced an equilibrium mixture involving compound 9 as a dominant compound.The latter was transformed by the treatment with chlorine dioxide into an orthoquinone (16) via two pathway containing 10 in one and 15 in another.The monomeric quinone (16) immediately dimerized in acidic media to give 20 under the same conditions as above, and the further oligomerization by the process similar to that in dimerization of 16 finally afforded a mixture of colored oligomers 26.
Ohtani, Yoshito,Sumimoto, Masashi
p. 613 - 622
(2007/10/02)
Carbon-13 Nmr Spectroscopy of Methoxy- and Acetoxyaurones
The 13C nmr chemical shifts of methoxy and acetoxyaurones are reported.The signals are assigned on the basis of substituent effects and comaprison with structurally related compounds.Assignments are also verified by Sford.
Sharma, Anil,Chibber, S. S.
p. 275 - 277
(2007/10/02)
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