Biomacromolecules 2002, 3, 187-193
187
Peroxidase-Catalyzed Oxidative Polymerization of Bisphenols Hiroshi Uyama, Naoyuki Maruichi, Hiroyuki Tonami, and Shiro Kobayashi* Department of Materials Chemistry, Graduate School of Engineering, Kyoto University, Kyoto, 606-8501, Japan Received September 3, 2001; Revised Manuscript Received November 12, 2001
Oxidative polymerization of bisphenolic monomers has been performed using peroxidase as catalyst in an aqueous organic solvent. Peroxidase induced the polymerization of an industrial product, bisphenol F, consisting of 2,2′-, 2,4′-, and 4,4′-dihydroxydiphenylmethanes. Under the selected conditions, the quantitative formation of the polymer was observed. Among the isomers, 2,4′- and 4,4′-dihydroxydiphenylmethanes were polymerized to give the polymer in high yields, whereas no polymerization of the 2,2′-isomer occurred. These data suggest that the radical transfer reaction between a phenoxy radical of the enzymatically polymerizable monomer and the enzymatically nonpolymerizable monomer frequently took place during the polymerization. Various 4,4′-dihydroxyphenyl compounds were also polymerized by peroxidase catalyst. The polymerization behaviors, and solubility and thermal properties of the resulting polymers strongly depended on the bridge structure as well as the enzyme origin. Polymers from dihydroxydiphenylmethanes showed relatively high thermal stability. Introduction Phenol-formaldehyde resins using prepolymers such as novolaks and resols are widely used in industrial fields.1 These resins show excellent toughness and temperatureresistant properties. However, toxic nature of formaldehyde involves problems in their manufacture and use. Therefore, an alternative process for preparation of phenol polymers without using formaldehyde is strongly desired. In the past decade, enzymatic syntheses of polyaromatics have been extensively investigated.2,3 Oxidative polymerization of various phenol derivatives catalyzed by peroxidase produced a new class of polyphenols showing high thermal stability. From nonsubstituted phenol, the soluble polymer consisting of a mixture of phenylene and oxyphenylene units was obtained by using horseradish peroxidase (HRP) as catalyst in an aqueous methanol.4 The coupling selectivity (regioselectivity) could be controlled by the mixing ratio of the organic solvent and buffer. In the oxidative polymerization of phenols having an unsaturated group, peroxidase catalysis induced the chemoselective polymerization, yielding the polyphenols bearing the unsaturated group in the side chain.5 Some bisphenol derivatives were reported to polymerize through peroxidase catalysis to give soluble polymers despite bifunctional monomers.6 A thermally curable polyphenol was synthesized by peroxidase-catalyzed polymerization of bisphenol A.6a The polymer was cross-linked at 150-200 °C and the curing improved the thermal stability of the polymer. The reaction with epoxy resin produced the insoluble network polymer. Formation of R-hydroxy-ω-hydroxyoligo(oxy-1,4phenylene)s was observed in the HRP-catalyzed oxidative polymerization of 4,4′-oxybisphenol in aqueous methanol.6b During the reaction, the redistribution and/or rearrangement of the quinone-ketal intermediate take place, involving the
Chart 1
elimination of hydroquinone to give oligo(oxy-1,4-phenylene)s. In this study, effects of linkage position and structure of bisphenol monomers have been examined in the peroxidase-catalyzed oxidative polymerization. Results and Discussion Oxidative Polymerization of Dihydroxydiphenylmethanes. Bisphenol F, a mixture of 2,2′-dihydroxydiphenylmethane (1a), 2,4′-dihydroxydiphenylmethane (1b), and 4,4′dihydroxydiphenylmethane (1c) (1a:1b:1c ) 16:49:35), are widely employed for various purposes in industrial fields (Chart 1). In this study, bisphenol F and dihydroxydiphenylmethanes (1a-1c) were polymerized by peroxidase catalyst in a mixture of polar organic solvent and buffer at room temperature for 3 h. Catalysts used were HRP and soybean peroxidase (SBP). SBP was reported to show a high catalytic activity toward the oxidative polymerization of bisphenol A and meta-substituted phenols having a bulky
10.1021/bm0101419 CCC: $22.00 © 2002 American Chemical Society Published on Web 12/21/2001
188
Biomacromolecules, Vol. 3, No. 1, 2002
Uyama et al.
Table 1. Peroxidase-Catalyzed Oxidative Polymerization of Dihydroxydiphenylmethane Derivativesa entry
monomer
enzymeb
organic solvent
yield (%)
TSPc (%)
Mnd
Mw/Mnd
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
bisphenol F bisphenol F bisphenol F bisphenol F bisphenol F bisphenol F 1a 1a 1a 1b 1b 1b 1c 1c 1c
HRP (1) HRP (1) HRP (1) SBP (4) SBP (4) SBP (4) SBP (4) HRP (1) HRP (1) SBP (4) HRP (1) HRP (1) SBP (4) HRP (1) HRP (1)
acetone 2-propanol methanol acetone 2-propanol methanol acetone 2-propanol methanol acetone 2-propanol methanol acetone 2-propanol methanol
95 100 92 97 99 71 0 0 0 99 100 88 98 99 92
65 84 100 22 41 72
1600 2700 1400 1300 1600 1400
1.4 2.0 2.0 1.9 1.9 2.3
21 69 90 24 99 87
580 1200 1300 610 470 950
3.3 14.4 6.6 7.8 6.6 2.9
a Polymerization of dihydroxydiphenylmethane (5.0 mmol) using peroxidase catalyst in an equivolume mixture of an organic solvent and phosphate buffer (pH 7) (total 25 mL) at room temperature for 3 h under air. b In parentheses, enzyme amount (mg). c THF-soluble part. d Data of THF-soluble part, determined by SEC.
substituent.6a,7 The catalytic activity of SBP (52 units/mg) is ca. one-fourth as large as that of HRP (220 units/mg); thus, a four times greater amount of SBP was employed.7 Molecular weight was estimated by size exclusion chromatography (SEC). Polymerization results are summarized in Table 1. Bisphenol F was polymerized by both peroxidases. Except for the SBP-catalyzed polymerization in the aqueous methanol (entry 6), the polymer yield was high (>90%). The HRPcatalyzed polymerization in the aqueous methanol produced the polymer soluble in tetrahydrofuran (THF), N,N-dimethylformamide (DMF), and dimethyl sulfoxide (DMSO). As for the other samples, on the other hand, the polymer solubility decreased; the polymer was partly soluble in THF. In using acetone as cosolvent, the polymer solubility was the lowest. The THF-soluble part of the polymer obtained by using HRP as catalyst was larger than that by the SBP catalyst. In the polymerization without the enzyme (control experiment), the monomer was recovered unchanged, indicating that the present polymerization proceeded via the enzyme catalysis. Next, three dihydroxydiphenylmethane isomers (1a-1c) were polymerized by the peroxidase catalyst. No reaction of 1a took place under the reaction conditions examined (entries 7-9), whereas the polymerization results of 1b and 1c were similar to those of bisphenol F (entries 10-15). The solubility of the homopolymers of 1b and 1c was slightly lower than that of bisphenol F; these homopolymers obtained using HRP catalyst in an aqueous methanol contained a small amount of the THF-insoluble part (entries 12 and 15), although they were soluble in DMF and DMSO. The molecular weight of poly(1c) was smaller than that of poly(bisphenol F). In most cases, the molecular weight distribution of poly(1b) or poly(1c) was larger than that of poly(bisphenol F) (see Supporting Information). These data might be related to the lower solubility of the homopolymer from 1b or 1c than that of poly(bisphenol F). The above data suggest that the monomer showing no homopolymerizability toward the enzymatic oxidative coupling can be copolymerized with other polymerizable
Figure 1. Addition of hydrogen peroxide vs monomer conversion: (2) 1a; (9) 1b; (b) 1c. The polymerization of bisphenol F (5.0 mmol) was carried out by using HRP (1.0 mg) catalyst in an equivolume mixture of methanol and pH 7 phosphate buffer at room temperature under air. Hydrogen peroxide (5.0 mmol) was added dropwise to the reaction mixture for 2 h.
monomers, since the polymerization of bisphenol F produced the polymer quantitatively under the selected reaction conditions (entry 2) despite no homopolymerizability of 1a, a component of bisphenol F. Thus, the polymerization of bisphenol F in an equivolume mixture of methanol and phosphate buffer (pH 7) was monitored by using HPLC. The monomer conversion gradually increased as a function of the added volume of hydrogen peroxide and the conversions of 1a-1c were relatively close to each other, indicating the similar oxidative reactivities of 1a-1c (Figure 1). In the peroxidase-catalyzed oxidative coupling of phenol derivatives, a phenoxy free radical is first formed, and then two molecules of the radical species dimerize via coupling.8 Since peroxidase often does not recognize larger molecules,7 a radical transfer reaction between monomeric phenoxy radical and polyphenol takes place to give the polymeric radical species. In the propagation step, such propagating radicals are subjected to the oxidative coupling to give the polymer of higher molecular weight. Data of Figure 1 suggest that a phenoxy radical of 1a is formed by the radical transfer of the radical species of 1b or 1c with 1a, and subsequently the radical coupling takes place (Scheme 1), leading to the
Oxidative Polymerization of Bisphenols
Biomacromolecules, Vol. 3, No. 1, 2002 189
Scheme 1
formation of the polymer-containing 1a unit. These results clearly show that even phenolic compounds which are not recognized by peroxidase catalyst can be copolymerized by the enzymatic oxidative coupling. Iron-N,N′-ethylenebis(salicylideneamine) (Fe-salen) was reported to show high catalytic activity for oxidative polymerization of various phenols.9 For reference, Fe-salen was used as catalyst for the polymerization of bisphenol F and 1a in THF at room temperature using hydrogen peroxide as an oxidizing agent.10 Both monomers were efficiently polymerized to give the soluble polymer in high yields (bisphenol F, conversion ) 86%, Mn ) 3100; 1a, conversion ) 87%, Mn ) 2800). These data suggest that no generation of radical species from 1a did not induce the enzymatic
homopolymerization of 1a. Namely, HRP-1a complex formation strongly demands the steric factor of monomers to induce the reaction, which is characteristics of HRPcatalyzed reactions, in general. The enzymatically synthesized polyphenols often have a structure consisting of a mixture of phenylene and oxyphenylene units.2-7 Here, the structure of poly(dihydroxydiphenylmethane)s was analyzed by FT-IR spectroscopy as well as titration of the phenolic hydroxy group in the polymer. Figure 2 shows FT-IR spectra of the polymers from bisphenol F, 1b, and 1c. For reference, an IR spectrum of an equimolar mixture of 1a-1c was also shown (Figure 2D). In the IR spectrum of poly(bisphenol F) (entry 3), a broad peak centered at 3430 cm-1 due to the vibration of O-H linkage
190
Biomacromolecules, Vol. 3, No. 1, 2002
Uyama et al.
Figure 2. FT-IR spectra of (A) poly(bisphenol F) (entry 3), (B) poly(1b) (entry 12), (C) poly(1c) (entry 15), and (D) an equimolar mixture of 1a, 1b, and 1c.
of phenolic group, peaks at 1219 and 1170 cm-1 ascribed to the asymmetric vibrations of the C-O-C linkage and to the C-OH vibration, and a peak at 1101 cm-1 due to the symmetric vibration of the ether bond were observed, suggesting the formation of a polymer consisting of phenylene and oxyphenylene units. The IR spectra of poly(1b) and poly(1c) (entries 12 and 15, respectively) were very similar to that of poly(bisphenol F). On the other hand, the peak pattern of the polymer was much different from that
of the monomer. The unit content of residual phenolic group in the polymer was determined by conventional titration methods.4,7 The phenylene unit content of poly(bisphenol F) (entry 3) was 65%. These data show that the resulting polymer is composed of a mixture of phenylene and oxyphenylene units. Oxidative Polymerization of Bisphenol Derivatives. Enzymatic polymerization of various 4,4′-dihydroxyphenyl compounds bridged via various X groups (2-10, Chart 1) has been examined. The polymerization was carried out in an equivolume mixture of methanol and pH 7 phosphate buffer except the monomers insoluble in this mixed solvent. Polymerization results are summarized in Table 2. In most cases, the solubility of the polymer obtained by using HRP catalyst was better than that by SBP. 4,4′Biphenol (2) quantitatively produced the polymer insoluble in any solvents (entries 1 and 2). Bisphenol A (4) afforded the soluble polymer in high yields (entries 5 and 6),6a whereas monomers having an electron-drawing linkage group (6 and 7) showed no or very low enzymatic polymerizability (entries 9-12). This is due to their higher oxidation-reduction potential. A similar tendency was observed in the peroxidasecatalyzed polymerization of halogenated phenols.7,11 Polymerization behaviors of 5 were distinct; only SBP catalyzed the polymerization, and the monomer was recovered unchanged by HRP catalyst (entries 7 and 8). Our previous study on the peroxidase-catalyzed polymerization of meta-substituted phenols showed that HRP could readily polymerize the monomer having a small substituent, whereas in the case of large substituent monomers, the high yield was achieved by using SBP catalyst.5c,7 A similar tendency was observed in the present study. More bulky monomer (10) was not polymerized even using SBP catalyst (entry 18). Monomers with ether and thioether bridges (8 and 9) also produced the polyphenols effectively (entries 13-16). These data indicate that the polymerization behaviors strongly depended on the bridge structure.
Table 2. Peroxidase-Catalyzed Oxidative Polymerization of Bisphenol Derivativesa entry
monomer
organicb solvent
enzymec
yield (%)
TSPd (%)
Mne
Mw/Mne
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 10 10
acetone (50) acetone (50) methanol (50) methanol (50) methanol (50) methanol (50) 2-propanol (50) 2-propanol (50) methanol (50) methanol (50) methanol (50) methanol (50) methanol (50) methanol (50) methanol (50) methanol (50) 1,4-dioxane (80) 1,4-dioxane (80)
HRP (1) SBP (4) HRP (1) SBP (4) HRP (1) SBP (4) HRP (1) SBP (4) HRP (1) SBP (4) HRP (1) SBP (4) HRP (1) SBP (4) HRP (1) SBP (4) HRP (1) SBP (4)
100 100 94 90 93 80 0 94 15 1 0 0 83 59 74 91 0 0
0 0 100 83 100 100
1600 2400 1400 1700
1.4 4.4 1.3 1.5
100 100
2300 1000
1.4 1.2
100 67 75 29
1100 590 1900 1600
1.1 2.0 2.6 4.1
a Polymerization of dihydroxydiphenylmethane (5.0 mmol) using peroxidase catalyst in a mixture of organic solvent and phosphate buffer (pH 7) (total 25 mL) at room temperature for 3 h under air. b In parentheses, ratio of organic solvent (vol %). c In parentheses, enzyme amount (mg). d THF-soluble part. e Data of THF-soluble part, determined by SEC.
Biomacromolecules, Vol. 3, No. 1, 2002 191
Oxidative Polymerization of Bisphenols
Figure 3. DSC traces of (A) poly(bisphenol F), (B) poly(5), and (C) poly(6). The measurements were performed at a heating rate of 10 °C/min under nitrogen. Table 3. Thermal Properties of Enzymatically Synthesized Polyphenols from Bisphenol Derivativesa polymer polymerization entry
monomer
enzyme
solvent
1 2 3 4 5 6 7 8 9 10
bisphenol F 1b 1c 2 3 4 5 6 8 9
HRP HRP HRP HRP HRP HRP SBP HRP HRP HRP
methanol methanol methanol acetone methanol methanol 2-propanol methanol methanol methanol
Tgb Td5c,d residuec,e (°C) (°C) (%) 165 151 171 f 136 114 146 151 f 108
296 284 290 244 270 253 259 272 280 307
50 47 44 56 35 23 20 38 33 26
a Polymer preparation; see footnote of Tables 1 and 2. b Glass transition temperature, determined by DSC under nitrogen at a heating rate of 10 °C/min. c Determined by TG under nitrogen at a heating rate of 10 °C/ min. d Temperature at 5 wt % loss. e Weight % of residue at 1000 °C. f Not detected.
Thermal Properties of Poly(bisphenol)s. Thermal properties of the present polyphenols were evaluated by differential scanning calorimetry (DSC) and thermogravimetry
(TG). DSC measurement was carried out under nitrogen and the glass transition temperature (Tg) was determined in the second or third scan. Figure 3 shows DSC charts of the polymers from bisphenol F, 5 and 6. In most cases, a clear Tg was observed (Table 3). Tg values depended on the monomer structure. Poly(bisphenol F) possessed Tg close to poly(1c), and larger than poly(1b) (entries 1-3). In case of poly(bisphenol F), the transition was broader than that of poly(1b) or poly(1c), which may be because poly(bisphenol F) was composed from three isomers (1a-1c), whereas poly(1b) or poly(1c) is homopolymer. Thermal stability was evaluated by TG measurement under nitrogen. The decomposition behavior of poly(bisphenol)s was similar to that obtained from monomeric phenols (Figure 4).2-5,7, In the first step, a slight gradual weight loss of the polymer (less than 10% of the weight loss) was observed below 200 °C. This may be due to the evaporation and/or evolution of low molecular compounds. Among the polymers examined, poly(9) had the highest temperature at 5 wt % loss (Td5) (entry 10) and Td5 value of poly(dihydroxydiphenylmethane)s was relatively large (entries 1-3).
Figure 4. TG traces of (A) poly(bisphenol F), (B) poly(3), (C) poly(5), and (D) poly(6). The measurements were performed at a heating rate of 10 °C/min under nitrogen.
192
Biomacromolecules, Vol. 3, No. 1, 2002
Poly(2) showed the largest residual weight at 1000 °C (entry 4). In the case of poly(dihydroxydiphenylmethane)s, the yield of the carbonized polymer at 1000 °C was relatively large (entries 1-3), suggesting that these polymers possess many possibilities for new precursors of functional carbonized materials. As for polymers from bis(4-hydroxyphenyl)alkanes (1c, 3, and 4), Tg and Td5 values as well as the residual weight at 1000 °C decreased with increasing bulkiness of the linkage group (entries 3, 5, and 6).
Uyama et al.
SSC/5200 differential scanning calorimeter calibrated with an indium reference standard. TG analysis was performed using a Seiko SSC/5200 apparatus for thermogravimetry/ differential thermal analysis at a heating rate of 10 °C/min under nitrogen in a gas flow rate of 300 mL/min. Acknowledgment. This work was partly supported by Program for Promotion of Basic Research Activities for Innovative Bioscience. We acknowledge the gift of bisphenol F from Mitsui Chemical Inc.
Conclusion An industrial product, bisphenol F consisting of three dihydroxydiphenylmethane isomers, was successfully polymerized by peroxidase catalyst to give the polymer showing relatively high thermal stability. Under the appropriate reaction conditions, the polymer was quantitatively formed via copolymerization of the three isomers, although among the isomers of bisphenol F, 2,2′-dihydroxydiphenylmethane (1a) was not homopolymerized. These data indicate the frequent occurrence of the radical transfer reaction between a phenoxy radical of the enzymatically polymerizable monomer and the enzymatically nonpolymerizable one during the polymerization. The resulting polymer from bisphenol-F has a large potential as a highly reactive prepolymer for curing thermally or with epoxy resins.6a Peroxidase catalysis induced the oxidative polymerization of various 4,4′-dihydroxyphenyl compounds in an aqueous organic solvent. The bridge structure due to X groups greatly affected the polymerization behaviors and thermal properties of the resulting polyphenols. Experimental Section Materials. Bisphenol F of industrial grade was kindly donated by Mitsui Chemical Inc. Other monomers, peroxidases, and reagents were commercially available and used as received. Enzymatic Polymerization. A typical run was as follows. Under air, bisphenol monomer (5.0 mmol) and HRP (1.0 mg) in a mixture of organic solvent and 0.1 M phosphate buffer (pH 7) (total 25 mL) were placed in a 50 mL flask. Hydrogen peroxide (5% aq. solution, 3.4 mL, 5.0 mmol) was added dropwise to the mixture for 2 h at room temperature. After 3 h, polymer precipitates were collected by centrifugation. The polymer was washed with an aqueous methanol (50:50 vol %), followed by drying in vacuo to give the polymer. Measurements. SEC analysis was carried out using a TOSOH SC8010 apparatus with a refractive index (RI) detector at 40 °C under the following conditions: TSKgel G3000HHR column and THF eluent at a flow rate of 1.0 mL/ min. The calibration curves for SEC analysis were obtained using polystyrene standards. HPLC analysis was performed using a TOSOH LC80200 system equipped with UV detector at 40 °C under the following conditions: TSKgel ODS-80Ts column and methanol/water (98/2 vol %) eluent at a flow rate of 0.5 mL/min. IR measurement was carried out with a Horiba FT-720 spectrometer. DSC measurement was made at a 10 °C/min heating rate under nitrogen using a Seiko
Supporting Information Available. Figures showing SEC traces of poly(bisphenol F), poly(1b), and poly(1c). This material is available free of charge via the Internet at http:// pubs.acs.org. References and Notes (1) Kopf, P. W. In Encyclopedia of Polymer Science and Engineering, 2nd ed.; John Wiley & Sons: New York, 1986; Vol. 11, pp 45-95. (2) For recent reviews on enzymatic polymerizations, see: (a) Kobayashi, S.; Shoda, S.; Uyama, H. AdV. Polym. Sci. 1995, 121, 1. (b) Kobayashi, S.; Shoda, S.; Uyama, H. In The Polymeric Materials Encyclopedia; Salamone, J. C., Ed.; CRC Press: Boca Raton, FL, 1996; pp2102-2107. (c) Kobayashi, S.; Shoda, S.; Uyama, H. In Catalysis in Precision Polymerization; Kobayashi, S., Ed.; John Wiley & Sons: Chichester, England, 1997; Chapter 8. (d) Ritter, H. In Desk Reference of Functional Polymers, Syntheses and Applications; Arshady, R., Ed.; American Chemical Society: Washington, DC, 1997; pp 103-113. (e) Gross, R. A.; Kaplan, D. L.; Swift, G., Ed.; ACS Symp. Ser. 1998, 684. (f) Kobayashi S.; Uyama H. In Materials Science and TechnologysSynthesis of Polymers; Schlu¨ter A.-D., Ed.; Wiley-VCH: Weinheim, Germany, 1998; Chapter 16. (g) Joo, H.; Yoo, Y. J.; Dordick, J. S. Kor. J. Chem. Eng. 1998, 15, 362. (h) Kobayashi, S.; Uyama, H.; Ohmae, M. Bull. Chem. Soc. Jpn. 2001, 74, 613. (i) Gross, R. A.; Kumar, A.; Kalra, B. Chem. ReV. 2001, 101, 2097. (j) Kobayashi, S.; Uyama, H. In Encyclopedia of Polymer Science and Technology, 3rd ed; Kroschwitz, J. I., Ed.; John Wiley & Sons: New York, in press. (k) Kobayashi, S.; Uyama, H.; Kimura, S. Chem. ReV. 2001, 101, 3792. (l) Kobayashi, S.; Kimura, S.; Sakamoto, J. Prog. Polym. Sci. 2001, 26, 1515. (3) For recent papers on enzymatic synthesis of polyaromatics, see: (a) Akkara, J. A.; Ayyagari, M. S. R.; Bruno, F. F. Trends Biotechnol. 1999, 17, 67. (b) Uyama, H.; Kobayashi, S. CHEMTECH 1999, 29 (10), 22. (c) Reihmann, M. H.; Ritter, H. Macromol. Chem. Phys. 2000, 201, 798. (d) Reihmann, M. H.; Ritter, H. Macromol. Chem. Phys. 2000, 201, 1593. (e) Liu, W.; Bian, S.; Li, L.; Samuelson, L.; Kumar, J.; Tripathy, S. Chem. Mater. 2000, 12, 1577. (f) Mandal, B. K.; Walsh, C. J.; Sooksimuang, T.; Behroozi, S. J. Chem. Mater. 2000, 12, 6. (g) Wu, X.; Kim, J.; Dordick, J. S. Biotechnol. Prog. 2000, 16, 513. (h) Iwahara, K.; Honda, Y.; Watanabe, T.; Kuwahara, M. Appl. Microbiol. Biotechnol. 2000, 54, 104. (i) Nagarajan, R.; Tripathy, S.; Kumar, J.; Bruno, F. F.; Samuelson, L. Macromolecules 2000, 33, 9542. (j) Kobayashi, S.; Ikeda, R.; Oyabu, H.; Tanaka, H.; Kobayashi, S. Chem. Lett. 2000, 1214. (4) (a) Oguchi, T.; Tawaki, S.; Uyama, H.; Kobayashi, S. Macromol. Rapid Commun. 1999, 20, 401. (b) Oguchi, T.; Tawaki, S.; Uyama, H.; Kobayashi, S. Bull. Chem. Soc. Jpn. 2000, 73, 1389. (c) Mita, N.; Tawaki, S.; Uyama, H.; Kobayashi, S. Polym. J. 2001, 33, 374. (d) Kobayashi, S.; Uyama, H.; Tonami, H.; Oguchi, T.; Higashimura, H.; Ikeda, R.; Kubota, M. Macromol. Symp. 2001, 175, 1. (5) (a) Uyama, H.; Lohavisavapanich, C.; Ikeda, R.; Kobayashi, S. Macromolecules 1998, 31, 554. (b) Tonami, H.; Uyama, H.; Kobayashi, S.; Fujita, T.; Taguchi, Y.; Osada, K. Biomacromolecules 2000, 1, 149. (c) Ikeda, R.; Tanaka, H.; Uyama, H.; Kobayashi, S. Polym. J. 2000, 32, 589. (6) (a) Kobayashi, S.; Uyama, H.; Ushiwata, T.; Uchiyama, T.; Sugihara, J.; Kurioka, H. Macromol. Chem. Phys. 1998, 199, 777. (b) Fukuoka, T.; Tonami, H.; Maruichi, N.; Uyama, H.; Kobayashi, S.; Higashimura, H. Macromolecules 2000, 33, 9152. (7) Tonami, H.; Uyama, H.; Kobayashi, S.; Kubota, M. Macromol. Chem. Phys. 1999, 200, 2365. (8) Ryu K.; McEldoon, J. P.; Pokora, A. R.; Cyrus, W.; Dordick, J. S. Biotechnol. Bioeng. 1993, 42, 807.
Oxidative Polymerization of Bisphenols (9) (a) Tonami, H.; Uyama, H.; Kobayashi, S.; Higashimura, H.; Oguchi, T. J. Macromol. Sci.sPure Appl. Chem. 1999, A36, 719. (b) Tonami, H.; Uyama, H.; Higashimura, H.; Oguchi, T.; Kobayashi, S. Polym. Bull. 1999, 42, 125. (c) Ikeda, R.; Tanaka, H.; Uyama, H.; Kobayashi, S. Macromol. Rapid Commun. 2000, 21, 496. (d) Tsujimoto, T.; Ikeda, R.; Uyama, H.; Kobayashi, S. Chem. Lett. 2000, 1122. (e) Ikeda, R.; Tanaka, H.; Uyama, H.; Kobayashi, S. Macromolecules 2000, 33, 6648.
Biomacromolecules, Vol. 3, No. 1, 2002 193 (10) It should be noted that Fe-salen catalyst cannot be used in an aqueous organic solvent and that the catalyst does not need to involve an intermediate of Fe-salen/1a complex like HRP catalyst. (11) Ikeda, R.; Maruichi, N.; Tonami, H.; Tanaka, H.; Uyama, H.; Kobayashi, S. J. Macromol. Sci.sPure Appl. Chem. 2000, A37, 983.
BM0101419
