1992 Fiscal Year Final Research Report Summary
Chemical Structures and Chemical Modification of Condensed Tannin.
| Project/Area Number |
03660170
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
林産学
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| Research Institution | Mie University |
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Principal Investigator |
ABE Isao Mie University, Faculty of Bioresources, Professor, 生物資源学部, 教授 (20024581)
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| Co-Investigator(Kenkyū-buntansha) |
MITSUNAGA Tohoru Mie University, Faculty of Bioresources, Assistant, 生物資源学部, 助手 (20219679)
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| Project Period (FY) |
1991 – 1992
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| Keywords | Condensed tannin / Phenolic pattern of condensed tannin / Characteristics of bark extractive / Ring-open of (+)-catechin / Phenol modification of tannin |
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| Research Abstract |
1. Chemical Analysis and Characteristics of Condensed Tannins. Appropriate compositions of the phenyl Nucleus-Exchange (NE) reagent, reaction temperature and the time were selected to evaluate the characteristics or the phenolic patterns of condensed tannins. Furthermore, the necessary care to be taken on determining the purity and the phenolic characteristics by the NE method were discussed by the use of a flavonol dimer isolated from Quebracho tannin. After then, Karamatsu barks extractives by the successive extraction were characterized, compared with Wattle and Quebracho tannins. The results obtained by the NE-method and the other analytical method indicated that the outer bark contained about twice of the extractives by weight, but involved the more amount of the destructive A-rings than the inner bark.
2. Mechanisms of the Phenolation and the NE-reaction for a Monomeric Model. The behavior of the phenolation and the NE-reaction in the phenol -BF_3 system for (+)-catechin was followed and further, three compounds formed during the reaction were isolated and identified. From the results, we discussed the mechanisms of the phenolation and the NE- reaction, and recognized the formation of the ring opening and phenolated flexible compound under the mild reaction conditions, indicating the convertible possibility of rigid structure of tannins to the flexible polyvalent phenol-polymers by the phenolation.
3. Chemical Modification of Condensed Tannin. In order to convert the rigid tannin molecules into the flexible and more uniform nucleophilic phenol-polymer by the phenolation, the effects of a kind of phenolic medium and the added amount of acid catalyst on the behavior of the phenolation were examined. The selective condition was 100g of resorcinol and 0.05mols of H_2SO_4, and 120C-2hrs. The rate of ionization and the reaction with a nucleophilic reagent of phenolized tannin obtained by such the conditions was much faster than that of original tannin preparation.
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