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Publication numberUSRE35247 E
Publication typeGrant
Application numberUS 08/270,867
Publication dateMay 21, 1996
Filing dateJul 5, 1994
Priority dateJun 9, 1992
Fee statusPaid
Also published asUS5278055
Publication number08270867, 270867, US RE35247 E, US RE35247E, US-E-RE35247, USRE35247 E, USRE35247E
InventorsWilliam L. Cyrus, Jr., Alexander R. Pokora
Original AssigneeThe Mead Corporation
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Biocatalytic production of phenolic resins with ramped peroxide addition
US RE35247 E
Abstract
A process for preparing a phenolic resin which comprises preparing a reaction medium containing a phenol and a peroxidase enzyme and adding a solution of a peroxide to said medium, said peroxide being added to said medium at a rate which decreases from an initial rate of about 2 to 3 millimolar/min as the amount of phenol in said medium decreases such that the concentration of peroxide does not exceed about 12 millimolar.
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Claims(6)
What is claimed is:
1. A process for preparing a phenolic resin which comprises preparing a reaction medium containing a phenol and a peroxidase enzyme and adding a solution of a peroxide to said medium, said peroxide being added to said medium at a rate which decreases from an initial rate .[.of about 2 to 3 millimolar/min.]. as the amount of phenol in said medium decreases such that the concentration of peroxide .Iadd.in said medium .Iaddend.does not exceed about 12 millimolar.
2. The process of claim 1 wherein said medium is a mixture of water and an organic solvent.
3. The process of claim 2 wherein said organic solvent is a water-miscible solvent.
4. The process of claim 2 wherein said peroxidase is horseradish peroxidase or soybean peroxidase.
5. The process of claim 4 wherein said phenol is present in said medium in a concentration of 1 to 100 g/100 ml
6. The process of claim 5 wherein said rate decreases such that the concentration of peroxide in said reaction medium does not exceed about 3 to 12 millimolar.
Description

The present invention is an improvement in the biocatalytic processes for producing phenolic resins described in U.S. Pat. No. 4,900,671 and U.S. application Ser. No. 07/599,584 filed Oct. 18, 1990 now U.S. Pat. No. 5,147,793.

U.S. Pat. No. 4,900,671 commonly assigned to The Mead Corporation discloses a method for preparing a phenolic resin which comprises preparing a solution of a phenol in a water miscible or a water-immiscible solvent and an aqueous solution of a peroxidase or oxidase enzyme, mixing the two solutions and adding a peroxide or oxygen. The preferred method described in this patent makes use of horseradish peroxidase. Hydrogen peroxide is added to the system and reaction occurs on the enzyme. U.S. application Ser. No. 07/599,584 now U.S. Pat. No. 5,147,793 discloses that soybean peroxidase and other plant peroxidases can be used in this method.

SUMMARY OF THE INVENTION

In the biocatalytic processes described above, the peroxide is consumed and converted into free radicals by the enzyme catalyst. As the reaction proceeds, monomeric phenol is converted to resin product. In the later stages of the reaction, the concentration of monomeric phenol falls and the consumption of the peroxide slows to a point at which an excess of peroxide is present. The excess peroxide is believed to interfere with the reaction of the remaining phenol by inhibiting the catlayst or terminating chain transfer. This results in poor reaction and production efficiencies as reflected in higher concentrations of residual monomer than are desirable in the resin and lower molecular weight resins.

In accordance with the present invention, the peroxide addition is ramped, i.e., high concentrations of peroxide are used at the beginning of the reaction when high concentrations of monomeric phenol are present and lower concentrations of peroxide are used in later stages of the reaction when higher peroxide concentrations would lead to premature termination of the reaction.

Accordingly, one manifestation of the present invention is a process for preparing a phenolic resin which comprises preparing a reaction medium containing an unreacted phenol and a peroxidase enzyme and adding a solution of a peroxide to said medium, said solution being added to said reaction medium at a rate which decreases from an initial rate as the concentration of said unreacted phenol in said medium decreases.

DEFINITIONS

The term "phenolic resin" as used herein includes phenolic dimers and trimers as well as oligomers and higher molecular weight species.

A "unit" of peroxidase means the amount of peroxidase which produces a change of 12 absorbance units measured at 1 cm pathlength in one minute at 420 nm when added to a solution containing 100 mM potassium phosphate, 44 mM pyrogallol and 8 mM hydrogen peroxide and having a pH of 6 (Sigma Chemical Co. Peroxidase Bulletin).

DETAILED DESCRIPTION

A variety of peroxidases can be used in the present invention. The most preferred peroxidases are soybean and horseradish peroxidases. However, peroxidases from other legumes are also useful such as peroxidases from peas, guar beans, garbanzo beans, and runner beans. It is also believe that peroxidases from rice and certain malvaceous plants, such as cotton, may be useful.

Peroxidases useful herein are commercially available. Being water soluble they are easily harvested by homogenizing the protein source with water, filtering the homogenate, and retaining the filtrate. The filtrate is treated to remove proteinaceous and lipophilic impurities by adding to the filtrate a solution of a protein fixative or a detergent and forcing the enzyme to precipitate by the addition of a non-solvent for the peroxidase such as acetone or isopropanol. Useful purification techniques are described in the above-referenced patent application.

Legume hulls such as soybean hulls are biocatalytically active and can be used directly in some cases. It is not clear whether the peroxidase is being extracted by the reaction solvent medium or whether the peroxidase reacts similar to an immobilized enzyme. A combination of both mechanisms may occur.

The amount of hulls used will depend on their reactivity. For preparation of soybean hulls and suggested reaction amounts see the above-referenced patent application.

The amount of the enzyme used to make the phenolic resin will depend on its activity. The enzyme is not consumed in the reaction but gradually loses activity during the course of reaction. For practical purposes, the enzyme can be reacted in an amount of about 500 to 500,000 and more typically 1000 to 5000 units per 100 grams phenol.

The peroxide used is typically hydrogen peroxide, but other peroxides are also useful. Examples of other potentially useful peroxides include methyl peroxide, ethyl peroxide, etc.

The peroxide is reacted in a total amount of about 0.1 to 2.5 moles per mole phenol (or other oxidizable substrate) and, more typically, about 0.1 to 1.0 mole per mole phenol. Depending upon its nature, it is reacted neat or as a solution. In the preferred embodiments, hydrogen peroxide, is dissolved in water in a concentration of about 1 mM to 10 M and added to the reaction medium as described next.

The initial rate of addition (moles/min) of the peroxide solution is set at about twice the average reaction rate. Typically, the peroxide is initially added at a rate of about 2 to 3 millimolar/min. Thereafter, the reaction rate of the peroxide is downwardly adjusted for the decrease in the rate of reaction which accompanies the reaction of the phenol and the lower phenol concentrations. The rate of downward adjustment is controlled such that the peroxide concentration does not exceed 3 to 12 and more preferably about 3 to 5 millimolar.

The phenols can be reacted in a water-miscible or a water-immiscible solvent. Representative examples of useful water-immiscible solvents include hexane, trichloromethane, methyl ethyl ketone, ethyl acetate, and butanol. Examples of useful water-miscible solvents include ethanol, methanol, dioxane, tetrahydrofuran (THF), dimethyl formamide, methyl formate, acetone, n-propanol, isopropanol, ethanol, t-butyl alcohol. The reaction is typically carried out at phenol concentrations of about 1 to 100 g per 100 ml solvent.

A number of different procedures may be used to react the phenol or other oxidizable substrate. Solutions of the phenol and enzyme may be individually prepared and metered into a reaction vessel, or solutions of the phenol and enzyme may be pre-mixed. Alternatively, the enzyme and the phenol may be dissolved in a common solvent. However, the preferred reaction system is a mixture of water and a solvent.

The organic-aqueous system formed upon mixing the phenol, enzyme and peroxide may contain water and an organic solvent in a volumetric ratio (water:organic) in the range of about 1:10 to 10:1, more typically, 1:2 to 2:1. The most preferred ratio will vary with the solubility characteristics of the phenolic monomer(s) that is (are) polymerized and the resin which is produced.

Reaction temperatures will vary with the substrate and the enzyme. Enzymes are generally quite temperature sensitive and a temperature is selected which does not denature the enzyme, lower its reactivity or otherwise inhibit the reaction. The reaction of the phenol proceeds at room temperature, but temperatures of about 0 to 70 C. can be used. The enzymes can lose their activity if the reaction temperature becomes much higher. However, some latitude exists, depending upon the solvent system which is used. Certain solvents appear to stabilize the enzyme and thereby permit the use of higher temperatures. There is evidence in the literature that temperatures up to 100 C. may be useful with some peroxidases.

The activity of peroxidases is pH dependent. The oxidative reactions are typically carried out at a pH in the range of 4 to 12 and, preferably, 4 to 9, and, more preferably, about 6. A pH may be selected at which the enzyme is highly active. This will vary with the nature of the enzyme and its source. Buffers can be used to maintain pH, but are not usually required. One example of a useful buffer is a potassium phosphate buffer.

While reference is herein made to the bulk pH of the reaction system, those skilled in the art will appreciate that it is the pH in the micro-environment of the enzyme that is critical. Thus, where the phenol is dissolved in a water- immiscible solvent and the enzyme solution is dispersed in the solution of the phenol, it is the pH of the enzyme solution which is critical.

Phenolic resins prepared in accordance with the present invention are useful in a variety of applications depending on the nature of the phenol and the molecular weight distribution of the resin. Among other factors affecting molecular weight are solvent selection, phenol selection, and reaction conditions. The resins are often mixtures of dimers, trimers, and higher molecular weight oligomers. Phenolic resins useful as developers in recording materials such as carbonless copy paper, heat-sensitive recording paper, electrothermographic recording paper are preferably para-substituted and may range from about 500 to 5000 in molecular weight. The phenols used in adhesives need not be para-substituted. These resins typically range from about 1000 to 15,000 in molecular weight but molecular weights up to at least 30,000 are attainable.

Phenols which are preferred for reaction in the present invention are represented by the Formula (I): ##STR1## wherein Y and Z are selected from the group consisting of a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, an aryl group, an allyl group, a phenylalkyl group, a --COOR group, a --NR1 R2 group, where R represents a hydrogen atom or a lower alkyl group, and R1 and R2 represent a hydrogen atom, an alkyl group, or a phenylalkyl group or Z in conjunction with the adjacent meta position forms a condensed benzene ring. Since polymerization proceeds via the ortho or para positions, when Y is at the ortho or para position, at least one of Y and Z must be a hydrogen atom or Z must form a condensed benzene ring. Y is preferably para to the phenolic hydroxyl group. U.S. Pat. No. 4,900,671 contains a discussion of phenolic substitution which may be used in this invention.

Specific examples of phenols which can be polymerized in accordance with the process of the present invention are phenol, 4-t-butylphenol, 4-n-butylphenol, 4-ethylphenol, cresol, p-phenylphenol, p-octylphenol, p-nonylphenol, p-hydroxybenzoate, bisphenol A, etc.

In addition to being useful in reacting phenols, the method of this invention is also useful in the reaction of other oxidizable substrates such as aromatic amines. Examples of other oxidizable substrates are disclosed in the above-referenced patent application.

The invention is illustrated in more detail by the following non-limiting examples.

COMPARATIVE EXAMPLE

1800 ml of acetone is added to a 5000 ml jacketed, 3-necked, round bottom flask. The jacket is used to maintain the temperature of the flask at 15 C. The acetone is mixed with a mechanical stirrer at 300 RPM and 500 g bisphenol A is added After the bisphenol A is dissolved, 1078 ml distilled water is added with 122.0 ml of a horseradish peroxidase enzyme solution containing 25,000 total purpurogallin units. A 15% hydrogen peroxide solution is then added using a peristaltic pump at a constant rate of 1 ml/min. until 500 ml have been added. A resin containing 23.43% residual monomer and having Mn=4410 and Mw=7992 was obtained.

EXAMPLE 1

360 ml of acetone is placed in a 1000 ml jacketed, 3-necked, round bottom flask. The jacket is used to maintain the temperature of the flask at 15 C. The acetone is mixed using a mechanical stirrer at 300 RPM and 100 g bisphenol A is added. After the bisphenol A is dissolved, 215 ml distilled water and 25 ml horseradish peroxidase enzyme solution containing 5,000 total purpurogallin units are added. A 15% hydrogen peroxide solution is metered into the reaction medium using a peristaltic pump at a ramped rate starting at 0.6 ml/min. and decreasing at a constant ramped rate until the rate is 0.0 ml/min. after 6 hrs. A total of 107 ml hydrogen peroxide solution is added. The resin contained less than 1% residual monomer and had Mn=4966 and Mw=9097.

EXAMPLE 2

302 ml of isopropyl alcohol was added to a 1000 ml jacketed, 3-necked, round bottom flask. The jacket was maintained at a temperature of 55 C. The alcohol was stirred with a mechanical stirrer at 350 RPM and 100 g t-butylphenol was added. After the phenol dissolved 285.2 ml distilled water and 16.8 ml soy enzyme soluton containing 2515 total purpurogallin units was added. When the contents of the flask reached 50 C the peroxide addition was begun. 35% hydrogen peroxide solution was added by use of a computer controlled peristaltic pump at a ramped rate over a 2 hour period. The initial rate was set to 0.76 ml/min. and at the end of 2 hours the rate was zero.

Having described the invention in detail and by reference to preferred embodiments thereof, it will be apparent that modifications and variations are possible without departing from the scope of the invention defined in the appended claims.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US4657856 *Sep 17, 1981Apr 14, 1987Kyowa Hakko Kogyo Co., Ltd.Fermentation of mucor, blocking agents, fluorescent reagent
US4900671 *Jul 8, 1987Feb 13, 1990The Mead CorporationBiocatalytic process for preparing phenolic resins using peroxidase or oxidase enzyme
US5110740 *Sep 6, 1989May 5, 1992The Mead CorporationOxidation with peroxidase and peroxy compound; polymerization to water insoluble polymer
US5112752 *May 22, 1991May 12, 1992The Mead CorporationPurification of enzymes, precipitation from solution
US5147793 *Oct 18, 1990Sep 15, 1992The Mead CorporationBiocatalytic oxidation using soybean peroxidases
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US5780104 *Dec 18, 1996Jul 14, 1998Mitsui Chemicals, Inc.Coating interior with oil repellent solution containing oxidatively coupled bisphenolic adduct or polymer
US6306991Aug 11, 2000Oct 23, 2001Rohm And Haas CompanyTwo part coating composition with two containers, oxidative polymers with crosslinkable functional groups
US7705075Apr 15, 2008Apr 27, 2010Polnox Corporationantioxidant for preventing oxidation in a polyolefin, and phosphorus stabilizer; increase longer shelf life
US7705176Oct 27, 2006Apr 27, 2010Polnox Corporationfor use in food, plastics, elastomers, composites and petroleum based products; heat resistance
US7705185Mar 24, 2006Apr 27, 2010Polnox Corporationalkylating 3,5-bis(1,1-dimethylethyl)-4-hydroxy-N-(4-hydroxy)-benzenepropanamide with decyl bromide in presence of acetone solvent to form alkylated product; better thermal stability
US7767853Oct 17, 2007Aug 3, 2010Polnox CorporationAntioxidants and methods of making and using the same
US7799948Feb 22, 2006Sep 21, 2010Polnox CorporationNitrogen and hindered phenol containing dual functional macromolecular antioxidants: synthesis, performances and applications
US7902317Dec 2, 2005Mar 8, 2011Polnox CorporationSynthesis of aniline and phenol-based antioxidant macromonomers and corresponding polymers
US7923587May 28, 2008Apr 12, 2011Polnox CorporationAnti-oxidant macromonomers and polymers and methods of making and using the same
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US8008423May 28, 2010Aug 30, 2011Polnox CorporationStabilized polyolefin compositions
US8039673Jan 5, 2009Oct 18, 2011Polnox CorporationMacromolecular antioxidants comprising differing antioxidant moieties: structures, methods of making and using the same
US8080689Aug 11, 2010Dec 20, 2011Polnox CorporationNitrogen and hindered phenol containing dual functional macromolecular antioxidants: synthesis, performances and applications
US8242230May 17, 2011Aug 14, 2012Polnox CorporationMacromolecular antioxidants based on sterically hindered phenols and phosphites
US8252884Aug 24, 2011Aug 28, 2012Polnox CorporationStabilized polyolefin compositions
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US8598382Aug 13, 2012Dec 3, 2013Polnox CorporationMacromolecular antioxidants based on sterically hindered phenols and phosphites
US8691933Jul 1, 2013Apr 8, 2014Polnox CorporationStabilized polyolefin compositions
US8710266Nov 17, 2011Apr 29, 2014Polnox CorporationNitrogen and hindered phenol containing dual functional macromolecular antioxidants: synthesis, performances and applications
Classifications
U.S. Classification435/156, 435/192, 435/190, 435/132
International ClassificationC12P7/22
Cooperative ClassificationC12P7/22
European ClassificationC12P7/22
Legal Events
DateCodeEventDescription
Jun 16, 2005FPAYFee payment
Year of fee payment: 12
May 27, 2003ASAssignment
Owner name: MEADWESTVACO CORPORATION, CONNECTICUT
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:MEAD CORPORATION, THE;REEL/FRAME:014066/0963
Effective date: 20021231
Owner name: MEADWESTVACO CORPORATION ONE HIGH RIDGE PARKSTAMFO
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:MEAD CORPORATION, THE /AR;REEL/FRAME:014066/0963
Jun 18, 2001FPAYFee payment
Year of fee payment: 8
Jun 18, 1997FPAYFee payment
Year of fee payment: 4