Abstract: A method for cultivating Monarda fistulosa for production of thymoquinone includes planting seeds at rates between about 2.5 and about 5 pounds per acre, preferably about 4 pounds per acre. The heavy rate of planting produces plants bearing oil without weed contamination and reduces herbicide use due to production of natural herbicides by the monarda plants. Seeding and mowing the first season, and harvesting in seasons thereafter reduce costs. The method results in increased production of essential oils including thymoquinone and thymohydroquinone at levels up to about 40% or more of recovered oils, and which may be distilled from the plant.
Abstract: The invention relates to kits and methods for assessing the desirability of supplementing the diet of a human with reduced coenzyme Q (CoQH2). The methods involve assessing occurrence in the human's genome of the NQO1*2 polymorphism of the NQO1 gene. Occurrence of a copy of the polymorphism indicates that the human can benefit from dietary supplementation with CoQH2, and occurrence of two copies (i.e., homozygosity) of the NQO1*2 polymorphism indicates that dietary supplementation with CoQH2 can be especially desirable.
Type:
Application
Filed:
March 28, 2006
Publication date:
February 3, 2011
Inventors:
John R. DePhillipo, Robert P. Ricciardi
Abstract: Compounds that may have anti-inflammatory activity are of general formula (I); wherein X1, is H or COR1, and X2 is H or COR2 but X1, and X2 are not both H; R1 and R2 are the same or different and are each C1-4 alkyl substituted with R3, or a four to seven-membered ring which can be optionally substituted with R8 and can contain one or more additional heteroatoms selected from O, S(O)n and NR9; is R3 is F, CF3, OR4, NR5R6 O, S(O)n R7; R4, R5 and R6 are the same or different and are each H or C1-4 alkyl optionally substituted with R3, or NR5R6 is a C4-6 heterocycloalkyl ring containing one or more heteroatoms selected from O, NR8 and S(O)n; each n is 0-2; R7 is C1-4 alkyl; R8 is as defined for R3 or C1-4 alkyl optionally substituted with R3 or halogen; and R9 is H or C1-4 alkyl; or a salt, solvate or hydrate thereof.
Abstract: The present invention discloses a new process for the preparation of 1,4-benzoquiones of formula (II) wherein R1, R2, R3 and R4 are independently selected from the group consisting of branched or unbranched C1-C6 alkyl, phenyl and benzyl, wherein phenyl and benzyl is optionally substituted by one or more substituent independently selected from the group consisting of C1-C6 alkyl and halogen, and wherein C1-C6 alkyl is optionally substituted with one or more halogen susbstituents, and wherein R2 and R3 together can form a C1-C6-alkylene radical, optionally substituted by one or more susbstituents independently selected from the group comprising C1-C6, benzyl, phenyl and halogen. One preferred compound is 2,3-dimethoxy-5-methyl-[1,4]benzoquinone, also known as coenzyme Q0 (CoQ0). Also disclosed are novel compounds and intermediates, and a method for the preparation of coenzyme Qn, preferable the coenzyme Q10.
Abstract: Methods of treating or suppressing mitochondrial diseases, such as Friedreich's ataxia (FRDA), Leber's Hereditary Optic Neuropathy (LHON), mitochondrial myopathy, encephalopathy, lactacidosis, stroke (MELAS), or Kearns-Sayre Syndrome (KSS) are disclosed, as well as compounds useful in the methods of the invention. Energy biomarkers useful in assessing the metabolic state of a subject and the efficacy of treatment are also disclosed.
Abstract: Novel benzoquinone-derived compounds and polymorphs, prodrugs, geometric or optical isomers thereof, and pharmaceutically acceptable esters, ethers, carbamates, oximes of such compounds, polymorphs, prodrugs and isomers are provided. Process for preparation of compounds of the invention and pharmaceutical compositions containing such compounds and their use for reducing or inhibiting activity of lipase gene family for treatment, amelioration or prevention of lipase gene family mediated diseases and conditions including overweight, obesity, hyperlipidemia, hypercholesterolemia, hypertriglyceridemia, pancreatitis, diabetes, atherosclerosis, other cardiovascular diseases, metabolic syndromes, and metabolic disorders are provided. Methods of use of the compounds for skin care, hair care and cosmetics are provided.
Abstract: Novel quinones are provided, as well as compositions comprising these novel quinones. Methods of using the novel quinones in treatment of various indications including cancer are also provided.
Type:
Grant
Filed:
August 2, 2004
Date of Patent:
August 7, 2007
Assignee:
Cellgate, Inc.
Inventors:
Andrei V. Blokhin, Benjamin Frydman, Laurence J. Marton, Karen M. Neder, Jerry Shunneng Sun
Abstract: The present invention relates to a method of conveniently and efficiently producing reduced coenzyme Q10 having excellent qualities which is useful in foods, functional nutritive foods, specific health foods, nutritional supplements, nutrients, drinks, feeds, animal drugs, cosmetics, medicines, remedies, preventive drugs, etc. This method is suitable for industrial production thereof. In a method of synthesizing reduced coenzyme Q10 by reducing oxidized coenzyme Q10, followed by crystallization, at least one species selected from among hydrocarbons, fatty acid esters, ethers and nitrites is used as a solvent. Thus, the reduced coenzyme Q10 can be protected from oxidation, and as a result, the formation of the oxidized coenzyme Q10 as a by-product can be minimized, thereby giving reduced coenzyme Q10 having excellent qualities.
Abstract: A substituted benzoic acid derivative which is represented by the following formula (I) and has an NF-?B inhibiting action (in the formula, R3, R4 and R5 each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon(s) or an alkoxy group having 1 to 6 carbon(s); R9 and R10 each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon(s) or an acyl group having 2 to 11 carbons); R2 represents an optionally-substituted aromatic hydrocarbon group or an optionally-substituted heterocyclic group; and X represents a carboxyl group which may be esterified or amidated)
Abstract: The present invention relates to a method of conveniently and efficiently producing high-quality reduced coenzyme Q10 which is useful as an ingredient in foods, functional nutritive foods, specific health foods, nutritional supplements, nutrients, animal drugs, drinks, feeds, cosmetics, medicines, remedies, preventive drugs, etc. This method is suitable for industrial production thereof. A method of producing a reduced coenzyme Q10 which comprises reducing an oxidized coenzyme Q10 in an aqueous medium with the use of dithionous acid or a salt thereof, said reduction being carried out in the coexistence of a salt and/or under deoxygenated atmosphere, and at pH of 7 or below. Thus, the formation of the oxidized coenzyme Q10 as a by-product due to oxidation can be minimized, thereby giving reduced coenzyme Q10 having excellent qualities in a high yield.
Abstract: The objects of the present invention are an agent (A) for coloring fibers obtained by mixing two components (A1) and (A2), characterized in that component (A1) contains at least one 2-benzothiazolinone hydrazone derivative of formula (I) or a physiologically tolerated salt thereof and component (A2) contains at least one ortho-quinone of formula (II) or a para-quinone of formula (III), a method for coloring hair by use of said agent and a multicomponent kit for coloring hair.
Abstract: Silver-free, aqueous-based direct thermographic materials are designed to have image tone with near neutral density. Without the use of organic silver salts containing reducible silver ions, the image is formed using a color developing agent precursor that releases a color developing agent when heated to a temperature of at least 80° C., a combination of cyan, yellow and magenta dye-forming color couplers that provide cyan, yellow, and magenta dyes, and a substituted or unsubstituted benzoquinone as an oxidizing agent. No silver metal or silver ions are purposely added to these materials. This combination of components provides a means for controlling image tone without reliance upon conventional toning agents.
Abstract: A bioengineered synthesis scheme for the production of quinic acid from a carbon source is provided. Methods of producing quinic acid from a carbon source based on the synthesis scheme as well as conversion of quinic acid to hydroquinone are also provided.
Type:
Grant
Filed:
May 9, 2003
Date of Patent:
February 21, 2006
Assignee:
Board of Trustees Operating Michigan State University
Abstract: An NF-?B inhibitor having as an active ingredient a benzoquinone derivative represented by the general formula (1) wherein R1, R2, and R3 are each independently H, alkyl having 1 to 5 carbons, or alkoxy having 1 to 5 carbons; R4 is H, hydroxymethyl, alkyl, or carboxyl which is optionally esterified or amidated; Z is represented by the formula (A); and, n is an integer from 0 to 6, or its hydroquinone form or a pharmaceutically acceptable salt thereof.
Abstract: The present invention relates to a process for the conversion of phenol to hydroquinone and quinones. More particularly this invention relates to a process for the oxidation of phenol to a mixture of 1,4-benzoquinone and hydroquinone using an oxidant in the presence of titanium superoxide as a reusable catalyst in a liquid phase condition.
Type:
Grant
Filed:
September 29, 2003
Date of Patent:
March 29, 2005
Assignee:
Council of Scientific and Industrial Research
Abstract: A method is described for the simultaneous preparation of p-bromophenols and p-benzoquinones, intermediates useful in the preparation of hydroquinones and 4,4′-dihydroxybiphenyls, respectively. Hydroquinones and 4,4′-dihydroxybiphenyls are useful monomers for the preparation of a variety of polymers. The method also comprises reducing the p-benzoquinone to its corresponding hydroquinone in the presence of the p-bromophenol. Limiting the amount of HBr present in the reaction mixture was shown to control the amount of benzoquinone produced. The method also allows for the recycling of many of the reagents used, thereby reducing the cost of producing each monomer.
Type:
Grant
Filed:
November 7, 2003
Date of Patent:
November 9, 2004
Assignee:
General Electric Company
Inventors:
Ryan Christopher Mills, Eric James Pressman, Timothy Leigh Chuck, John Yaw Ofori
Abstract: A method is described for the simultaneous preparation of 4-bromophenols and p-benzoquinones, intermediates useful in the preparation of hydroquinones and 4,4′-dihydroxybiphenyls respectively. Hydroquinones and 4,4′-dihydroxybiphenyls are useful monomers for the preparation of a variety of polymers. In one example phenol is reacted with in the presence of HBr, a catalytic amount of cupric bromide and a stoichiometric excess of oxygen under relatively mild conditions to provide a mixture of the phenol, 4-bromophenol, and 1,4-benzoquinone. Phenol conversion was 54 percent and selectivities for bromophenol and benzoquinone were 23% and 37% respectively. Limiting the amount of HBr present in the reaction mixture was shown to control the amount of benzoquinone produced.
Type:
Grant
Filed:
April 4, 2003
Date of Patent:
February 17, 2004
Assignee:
General Electric Company
Inventors:
Ryan Christopher Mills, Timothy Leigh Chuck
Abstract: An NF-&kgr;B inhibitor having as an active ingredient a benzoquinone derivative represented by the general formula (1) wherein R1, R2, and R3 are each independently H, alkyl having 1 to 5 carbons, or alkoxy having 1 to 5 carbons; R4 is H, hydroxymethyl, alkyl, or carboxyl which is optionally esterified or amidated; Z is represented by the formula (A); and, n is an integer from 0 to 6, or its hydroquinone form or a pharmaceutically acceptable salt thereof.
Abstract: A bioengineered synthesis scheme for the production of quinic acid from a carbon source is provided. Methods of producing quinic acid from a carbon source based on the synthesis scheme as well as conversion of quinic acid to hydroquinone are also provided.
Type:
Grant
Filed:
October 25, 1999
Date of Patent:
July 29, 2003
Assignee:
Board of Trustees operating Michigan State University
Abstract: Agents potentiating nerve growth factor activity are provided for treating Alzheimer's disease which contain as the active ingredient dodecatrienoic acid derivatives represented by the general formula (I): 1
Abstract: Processes for the stereospecific synthesis of coenzyme Q10, ubiquinone, are disclosed; a total synthetic procedure using geraniol as the starting material. The process of the invention results in high yields of isometrically pure ubiquinone. The synthetic coenzyme Q10 can be used as an antioxidant, a nutritional supplement and as a pharmaceutical in treating many conditions.
Abstract: This invention provides a new class of squaraine dyes having moieties which serve for the covalent attachment to biological substrates and resulting in the fluorescent labeling of the substrates. The labeled substrates are intended for use in analytical techniques for the detection and measurement of biological and clinical compounds of interest.
Abstract: The invention concerns anti-tumour agents of formula (I) wherein each of R1, R2 and R3 has the meanings defined in the specification including hydrogen, (1-4C)alkyl, (3-4)alkenyl, (3-4C)alkynyl, amino, (1-4C)alkylamino and (1-4C)alkoxy; each of R4 and R5 is (1-4C)alkyl; each of R6 and R7 is hydrogen or (1-4C)alkyl; X is oxygen; m is 1 or 2 and each R8 is as defined in the specification; each of Y1 and Y2 is halogeno, (1-4C)alkanesulphonyloxy, benzenesulphonyloxy or phenyl-(1-4C)akanesulphonyloxy; or a pharmaceutically-acceptable salt thereof; provided that at least one of R1, R2 and R3 is other than hydrogen; a process for preparation, pharmaceutical compositions containing them and their use in the production of an anti-proliferative effect.
Abstract: A process for the preparation of 2,3,5-trimethyl-p-benzoquinone by oxidation of 2,3,5- or 2,3,6-trimethylphenol using oxygen or a gas mixture containing oxygen in the presence of a two-phase liquid reaction medium composed of water and a neocarboxylic acid having to 11 carbon atoms with a copper (II) halide-containing catalyst system at elevated temperature.
Abstract: A process for producing an alkyl-substituted hydroquinone, wherein said process comprises reacting a hydroquinone compound represented by the general formula (1)
wherein R1 and R2 independently represent a hydrogen atom or a straight or branched chain alkyl group having 1 to 10 carbon atoms, R independently represent a straight or branched chain alkyl group having 1 to 10 carbon atoms and n represents an integer of 0 to 2, with a monohydric or dihydric alcohol in the presence of a catalyst and under the condition in which said alcohol is in a supercritical state by substitution of at least one hydrogen atom on the aromatic ring in said hydroquinone compound.
Abstract: Electrophotographic photoreceptors for use in photocopiers and laser printers, among other things, possessing high electron mobility and superior photosensitivity properties. The photoreceptors of the invention utilize a photosensitive layer with a carrier transport material containing a compound which exhibits high molecular vibration. The compounds of the invention are electron transfer agents which can be dispersed in a photosensitive layer at a high concentration and can be molecularly designed to have a desired magnitude of molecular vibration.
Type:
Grant
Filed:
March 3, 1999
Date of Patent:
August 28, 2001
Assignees:
Shindengen Electric Manufacturing Co., Ltd., Yamanashi Electronics Co., Ltd.
Abstract: A process for producing 2-methyl-1,4-benzoquinone at a high conversion, a high selectivity and at a low cost by oxidizing m-cresol with oxygen at a low partial pressure in the presence of at least one copper (I) halide catalyst and a mixed solvent of ketone and acetonitrile. The 2-methyl-1,4-benzoquinone is useful as an intermediate compound to produce vitamin K.
Abstract: The present invention provides novel antiviral naphthoquinone compounds, which may be isolated from plants of the genus Conospermum or synthesized chemically, in accordance with the present inventive methods. The antiviral naphthoquionone compounds, derivatives thereof, and prodrugs thereof, may be used alone or in combination with other antiviral agents in compositions, such as pharmaceutical compositions, to inhibit the growth or replication of a virus, such as a retrovirus, in particular a human immunodeficiency virus, specifically HIV-1 or HIV-2, in the treatment or prevention of viral infection.
Type:
Grant
Filed:
May 31, 1995
Date of Patent:
February 9, 1999
Assignee:
The United States of America as represented by the Secretary of the Department of Health and Human Services
Inventors:
Michael R. Boyd, John H. Cardelina, II, Kirk R. Gustafson, Laurent A. Decosterd, Ian Parsons, Lewis Pannell, James B. McMahon, Gordon M. Cragg
Abstract: Disclosed herein are a quinone derivative represented by the following formula: ##STR1## wherein R.sup.1 and R.sup.2 are identical with or different from each other and mean individually a lower alkyl or lower alkoxy group, or may form an aromatic ring together, R.sup.3 denotes a lower alkyl group, n stands for 0 or an integer of 1-9, and a linkage --- is a single or double bond, such as a vitamin K derivative or coenzyme derivative; and a process for the preparation of the quinone derivative at a high yield without forming any geometric isomer; as well as a 1,4,4.sub.a,8.sub.a -tetrahydro-4.sub.a .alpha.-alkenyl-1.alpha.,4.alpha.-methanonaphthalene-5,8-dione derivative which is useful as an intermediate for the preparation of the quinone derivative.
Abstract: The invention provides a novel process to oxidize 1,4-dihydroxy aromatic compounds into the corresponding quinones using sulfuryl chloride as the oxidant. The process is simple and cost effective and provides an efficient way to synthesize hindered quinones.
Abstract: The invention relates to the use of compounds of the formula IR.sup.1.sub.a Re.sub.b O.sub.c (I),where a is from 1 to 6, b is from 1 to 4 and c is from 1 to 14 and the sum of a, b and c is in accordance with the valence of from 5 to 7 of the rhenium, with the proviso that c is not greater than 3.multidot.b, and where R.sup.1 is identical or different and is an aliphatic hydrocarbon radical having from 1 to 10 carbon atoms, an aromatic hydrocarbon radical having from 6 to 10 carbon atoms or an arylalkyl radical having from 7 to 9 carbon atoms, with the radicals R.sup.1 being able, if desired, to be identically or differently substituted independently of one another and, in the case of .sigma.-bonded radicals, at least one hydrogen atom still being bonded to the carbon atom in the .alpha. position, as catalysts for the oxidation of electron-rich aromatic compounds and their derivatives and to a process for the oxidation of electron-rich aromatic compounds which comprises oxidizing electron-rich C.sub.6 -C.sub.
Type:
Grant
Filed:
January 25, 1995
Date of Patent:
April 1, 1997
Assignee:
Hoechst Aktiengesellschaft
Inventors:
Wolfgang A. Herrmann, Joao D. G. Correia, Richard Fischer, Waldemar Adam, Jianhua Lin, Chantu R. Saha-Moller, Masao Shimizu
Abstract: Disclosed herein are a quinone derivative represented by the following formula: ##STR1## wherein E.sup.1 and E.sup.2 are identical with or different from each other and mean individually a lower alkyl or lower alkoxy group, or may form an aromatic ring together, E.sup.3 denotes a lower alkyl group, n stands for 0 or an integer of 1-9, and a linkage ------ is a single or double bond, such as a vitamin K derivative or coenzyme Q derivative; and a process for the preparation of the quinone derivative at a high yield without forming any geometric isomer; as well as a 1,4,4.sub.a,8.sub.a -tetrahydro-4.sub.a .alpha.-alkenyl-1.alpha.,4.alpha.-methanonaphthalene-5,8-dione derivative which is useful as an intermediate for the preparation of the quinone derivative.
Abstract: The present invention relates to novel benzoquinones which are useful as antihyperlipidemic agents. The present invention also provides a process for their preparation, pharmaceutical compositions, and a method for treating birds and mammals in need thereof which comprises administering to said host an effective amount of a benzoquinone of the present invention.
Abstract: An optically active (S)- or (R)-pentane compound of the general formula (11): ##STR1## wherein R.sub.11, R.sub.12 and R.sub.13 independently represent a hydrogen atom or a lower alkyl group having 1 to 4 carbon atoms, R.sub.14 represents a hydroxy, protected hydroxy or oxo group, if R.sub.14 is an oxo group, the ring denoting benzene in the above formula (11) is benzoquinone, R.sub.15 represents a hydrogen atom, hydroxy or acyloxy group, R.sub.16 represents a hydroxy or acyloxy group, and the chiral central carbon marked with a symbol * in said formula (11) alternatively has one of an R-configuration and an S-configuration, is disclosed. Further, intermediate products of the compound of the formula (11) are also disclosed. Still further, a process for manufacturing the above compounds is disclosed. The compound of the formula (11) is easily synthesized from an easily available optically active starting material.
Abstract: 1,4-Benzoquinone derivatives and benzene derivatives having cerebral- and cardiac-blood flow improving activities and preventive activities of cerebral ischema with low toxicities, and thus are useful as activators for cardiac and cebral metabolisms, curing agents for heart failure, cardiac and cerebral blood flow improving agents, as well as anti-allergic agents for slow reacting allergy (IV-type allergy).
Abstract: Method for dyeing keratinous fibres, characterized in that at least one composition (A) containing at least one aminoindole in a medium appropriate for dyeing is applied to these fibres, the application of the composition (A) being preceded or followed by the application of a composition (B) containing, in a medium appropriate for dyeing, at least one quinone derivative chosen from ortho- or para-benzoquinones, ortho- or para-benzoquinone monoimines or diimines, 1,2- or 1,4-naphthoquinones, ortho- or para-benzoquinone sulphonimides, .alpha.,.omega.-alkylene-bis-1,4-benzoquinones, or 1,2- or 1,4-naphthoquinone monoimines or diimines, the aminoindoles and the quinone derivatives being chosen such that the difference in redox potential .DELTA.E between the redox potential E.sub.i of the aminoindoles, determined at pH 7 in a phosphate medium on a vitreous carbon electrode by voltametry, and the redox potential E.sub.
Type:
Grant
Filed:
May 29, 1991
Date of Patent:
January 19, 1993
Assignee:
L'Oreal
Inventors:
Alain Baudry, Alex Junino, Herve Richard
Abstract: Disclosed is a process for removing chlorine-containing impurities from quinone compounds such as p-bezonquinone. The process involves extracting a quinone compound containing 1000 ppm or more chlorine with heptane, cyclohexane or a mixture thereof and separating the quinone compound from the extraction mixture. The process provides a means for obtaining quinone compounds containing 50 ppm or less chlorine.
Abstract: Disclosed is a process for the preparation of quinhydrones by the catalytic oxidation of aromatic diols with a peroxide in the presence of a catalyst system comprising a cerium carboxylate and a cupric carboxylate.
Type:
Grant
Filed:
March 18, 1991
Date of Patent:
September 22, 1992
Inventors:
Michael Bellas, Yeong-Jen Kuo, Fred H. Rash
Abstract: Disclosed is a process for making quinones by oxidation of dihydroxyaromatic compounds in the presence of oxygen using supported platinum catalysts.
Type:
Grant
Filed:
December 13, 1990
Date of Patent:
June 2, 1992
Assignee:
Eastman Kodak Company
Inventors:
Dale E. Van Sickle, Garry L. Myers, William D. Nottingham, Glenn C. Jones
Abstract: The invention relates to a process for the production of phenol or phenol derivatives by oxidation of the aromatic nucleus of benzene or benzene derivatives with nitrous oxide over a zeolite catalyst.
Type:
Grant
Filed:
March 12, 1991
Date of Patent:
May 5, 1992
Assignee:
Institute of Catalysis
Inventors:
Alexandr S. Kharitonov, Gennadii I. Panov, Kazimira G. Ione, Vyacheslav N. Romannikov, Galina A. Sheveleva, Lidia A. Vostrikova, Vladimir I. Sobolev
Abstract: Disclosed is a process for the preparation of quinones by the catalytic oxidation of aromatic diols with a peroxide in the presence of a catalytic amount of ceric trihydroxyhydroperoxide.
Type:
Grant
Filed:
March 18, 1990
Date of Patent:
April 21, 1992
Assignee:
Eastman Kodak Company
Inventors:
Yeong-Jen Kuo, Michael Bellas, Phillip M. Hudnall
Abstract: A series of 2-amino-5,6-dimethyl-1,4-benzoquinone derivatives, inhibitors of cyclooxygenase and lipoxygenase and useful as antiallergic and antiinflammatory agents.
Abstract: Process for dyeing keratinous fibres, comprising the step of applying to these fibres at least one composition A containing, in a medium appropriate for dyeing, at least one mono- or di-hydroxyindole the application of the composition A being preceded or followed by the application of a composition B containing, in a medium appropriate for dyeing, at least one quinone derivative chosen from ortho- or para-benzoquinones, monoimines or diimines of ortho- or para-benzoquinones, 1,2- or 1,4-naphthoquinones, sulphonimides of ortho- or para-benzoquinones, .alpha., .omega.-alkylene-bis-1,4-benzoquinones, or 1,2- or 1,4-naphthoquinone-monoimines or -diimines; the mono- or di-hydroxyindoles and the quinone derivatives being chosen such that the oxidation-reduction potential difference .DELTA.E between the oxidation-reduction potential E.sub.i of the mono- or di-hydroxyindoles, determined at pH 7 in a phosphate medium on a vitreous carbon electrode by voltametry, and the oxidation-reduction potential E.sub.
Type:
Grant
Filed:
December 6, 1989
Date of Patent:
October 1, 1991
Assignee:
L'Oreal
Inventors:
Arnaud De Labbey, Alain Baudry, Daniel Bauer, Pierre Bore
Abstract: There is provided a process of producing p-benzoquinone, wherein hydroquinone and hydrogen peroxide are reacted in water, an aqueous inorganic acid solution, an inert organic polar solvent or a mixture of water with an inert organic polar solvent in the presence of a catalyst selected from the group consisting of iodine, hydrogen iodide, and iodine compounds of metals.According to the process, p-benzoquinone can be obtained from hydroquinone with the yield and the quality of the p-benzoquinone being high without requiring any special facilities, equipments and operations.