The Experts below are selected from a list of 321 Experts worldwide ranked by ideXlab platform
Tomihiro Nishiyama - One of the best experts on this subject based on the ideXlab platform.
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COMPARISON OF THE EFFICIENCIES OF THE FUSED HETEROCYCLIC COMPOUNDS, 9H-XANTHENE-2,7-DIOLS, AND RELATED CHAIN-BREAKING PHENOLIC ANTIOXIDANTS
Bulletin of the Chemical Society of Japan, 1996Co-Authors: Tatsuo Yamamura, Takafumi Ishida, Hiroyuki Ueyama, Hirokazu Hayashida, Takuya Ishimaru, Tomihiro NishiyamaAbstract:The antioxidant activities of 9H-xanthene-2,7-diols that are structurally related to tocopherols and 2,2′-alkylidenedi(hydroquinones) were measured by the inhibition of the thermally initiated autoxidation of tetralin at 60 °C using an oxygen-absorption method. The stoichiometric factors were calculated as n = 3.3—5.5 for 9H-xanthene-2,7-diols and 0.5—0.9 for 2,2′-alkylidenedi(hydroquinones) that lack the fused six-membered heterocyclic ring. Comparison of the alkyl substituent on the bridged methylene carbon showed that 9-methyl-9H-xanthene-2,7-diols increased in n value compared with 9-ethyl-9H-xanthene-2,7-diols. For the 9-methyl-9H-xanthene-2,7-diols, alkyl groups ortho to the phenolic hydroxyl group decreased the Rinh value: two methyl groups by 10-fold, one methyl group by 1.9-fold, and one t-butyl group by 1.4-fold, compared to that for the 9-methyl-9H-xanthene-2,7-diol. On the other hand, 2,2′-alkylidenedi(hydroquinones) were poorer antioxidants than the structurally comparable 9H-xanthene-2,7-dio...
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9H-Xanthene-2,7-diols as Antioxidant for Autoxidation of Tetralin
Bulletin of the Chemical Society of Japan, 1993Co-Authors: Tomihiro Nishiyama, Takafumi Ishida, Satoshi Miyazaki, Ryuhei Tsuji, Fukiko YamadaAbstract:The antioxidant activities of 9H-xanthene-2,7-diols were evaluated by means of an oxygen-absorption method at 60 °C for tetralin. Very good activities were observed for 1,3,4,5,6,8-hexamethyl-9H-xanthene-2,7-diol and 1,3,4,5,6,8,9-heptamethyl-9H-xanthene-2,7-diol.
Fukiko Yamada - One of the best experts on this subject based on the ideXlab platform.
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9H-Xanthene-2,7-diols as Antioxidant for Autoxidation of Tetralin
Bulletin of the Chemical Society of Japan, 1993Co-Authors: Tomihiro Nishiyama, Takafumi Ishida, Satoshi Miyazaki, Ryuhei Tsuji, Fukiko YamadaAbstract:The antioxidant activities of 9H-xanthene-2,7-diols were evaluated by means of an oxygen-absorption method at 60 °C for tetralin. Very good activities were observed for 1,3,4,5,6,8-hexamethyl-9H-xanthene-2,7-diol and 1,3,4,5,6,8,9-heptamethyl-9H-xanthene-2,7-diol.
Takafumi Ishida - One of the best experts on this subject based on the ideXlab platform.
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COMPARISON OF THE EFFICIENCIES OF THE FUSED HETEROCYCLIC COMPOUNDS, 9H-XANTHENE-2,7-DIOLS, AND RELATED CHAIN-BREAKING PHENOLIC ANTIOXIDANTS
Bulletin of the Chemical Society of Japan, 1996Co-Authors: Tatsuo Yamamura, Takafumi Ishida, Hiroyuki Ueyama, Hirokazu Hayashida, Takuya Ishimaru, Tomihiro NishiyamaAbstract:The antioxidant activities of 9H-xanthene-2,7-diols that are structurally related to tocopherols and 2,2′-alkylidenedi(hydroquinones) were measured by the inhibition of the thermally initiated autoxidation of tetralin at 60 °C using an oxygen-absorption method. The stoichiometric factors were calculated as n = 3.3—5.5 for 9H-xanthene-2,7-diols and 0.5—0.9 for 2,2′-alkylidenedi(hydroquinones) that lack the fused six-membered heterocyclic ring. Comparison of the alkyl substituent on the bridged methylene carbon showed that 9-methyl-9H-xanthene-2,7-diols increased in n value compared with 9-ethyl-9H-xanthene-2,7-diols. For the 9-methyl-9H-xanthene-2,7-diols, alkyl groups ortho to the phenolic hydroxyl group decreased the Rinh value: two methyl groups by 10-fold, one methyl group by 1.9-fold, and one t-butyl group by 1.4-fold, compared to that for the 9-methyl-9H-xanthene-2,7-diol. On the other hand, 2,2′-alkylidenedi(hydroquinones) were poorer antioxidants than the structurally comparable 9H-xanthene-2,7-dio...
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9H-Xanthene-2,7-diols as Antioxidant for Autoxidation of Tetralin
Bulletin of the Chemical Society of Japan, 1993Co-Authors: Tomihiro Nishiyama, Takafumi Ishida, Satoshi Miyazaki, Ryuhei Tsuji, Fukiko YamadaAbstract:The antioxidant activities of 9H-xanthene-2,7-diols were evaluated by means of an oxygen-absorption method at 60 °C for tetralin. Very good activities were observed for 1,3,4,5,6,8-hexamethyl-9H-xanthene-2,7-diol and 1,3,4,5,6,8,9-heptamethyl-9H-xanthene-2,7-diol.
Ayoob Bazgir - One of the best experts on this subject based on the ideXlab platform.
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Solvent-free synthesis of aryl-14H-dibenzo[a,j]Xanthenes and 1,8-dioxo-octahydro-Xanthenes using silica sulfuric acid as catalyst
Dyes and Pigments, 2008Co-Authors: Mozhdeh Seyyedhamzeh, Peiman Mirzaei, Ayoob BazgirAbstract:Abstract A simple and efficient method for the synthesis of aryl-14 H -dibenzo[ a , j ]Xanthenes and 1,8-dioxo-octahydro-Xanthenes using silica sulfuric acid as a reusable eco-friendly catalyst under solvent-free conditions is described.
Tatsuo Yamamura - One of the best experts on this subject based on the ideXlab platform.
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COMPARISON OF THE EFFICIENCIES OF THE FUSED HETEROCYCLIC COMPOUNDS, 9H-XANTHENE-2,7-DIOLS, AND RELATED CHAIN-BREAKING PHENOLIC ANTIOXIDANTS
Bulletin of the Chemical Society of Japan, 1996Co-Authors: Tatsuo Yamamura, Takafumi Ishida, Hiroyuki Ueyama, Hirokazu Hayashida, Takuya Ishimaru, Tomihiro NishiyamaAbstract:The antioxidant activities of 9H-xanthene-2,7-diols that are structurally related to tocopherols and 2,2′-alkylidenedi(hydroquinones) were measured by the inhibition of the thermally initiated autoxidation of tetralin at 60 °C using an oxygen-absorption method. The stoichiometric factors were calculated as n = 3.3—5.5 for 9H-xanthene-2,7-diols and 0.5—0.9 for 2,2′-alkylidenedi(hydroquinones) that lack the fused six-membered heterocyclic ring. Comparison of the alkyl substituent on the bridged methylene carbon showed that 9-methyl-9H-xanthene-2,7-diols increased in n value compared with 9-ethyl-9H-xanthene-2,7-diols. For the 9-methyl-9H-xanthene-2,7-diols, alkyl groups ortho to the phenolic hydroxyl group decreased the Rinh value: two methyl groups by 10-fold, one methyl group by 1.9-fold, and one t-butyl group by 1.4-fold, compared to that for the 9-methyl-9H-xanthene-2,7-diol. On the other hand, 2,2′-alkylidenedi(hydroquinones) were poorer antioxidants than the structurally comparable 9H-xanthene-2,7-dio...