- Reductive cyclization of o-nitrophenylazobenzenes to 2-aryl-2H- benzotriazoles by SmI2
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In a mild reaction with SmI2, ortho-nitro substituted phenylazobenzenes have been converted into 2-aryl-2H-benzotriazoles.
- Kim, Byeong Hyo,Kim, Sun Kyong,Lee, Yoon Seok,Jun, Young Moo,Baik, Woonphil,Lee, Byung Min
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Read Online
- Preparation method of benzotriazole ultraviolet light absorber
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The invention relates to a preparation method of a benzotriazole ultraviolet absorbent. The method comprises the following steps: under the action of a magnesium oxide supported metal catalyst, carrying out transfer hydrogenation reaction on an azo intermediate shown in a formula I and a hydrogen donor to obtain a target product shown in a formula III. The method provided by the invention is small in catalyst dosage, the raw material conversion rate can reach 100%, and the target product selectivity is 90% or above.
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Paragraph 0092; 0096-0098; 0102-0104; 0108-0110; 0114-0116
(2021/04/14)
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- Hydrogenation of Substituted Benzenes Containing Nitro and Azo Groups over Skeletal Nickel in Aqueous Solutions of 2-Propanol
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Abstract: An analysis is made of the kinetic characteristics of the hydrogenation of 4-nitro- and 2-nitro-2'-hydroxy-5'-methylazobenzenes, 4-nitroaniline and 4-aminoazobenzene over skeletal nickel in neutral azeotropic 2-propanol–water mixture and in the same solvent in the presence of acetic acid or sodium hydroxide. It is found that the selectivity of the hydrogenation of these isomers to the intermediate products depends on the composition and nature of the solvent, and is determined by the rate of reactive group conversion. Compared to the process in the presence of sodium hydroxide, which suppresses the route leading to the predominant hydrogenation of the nitro group, the contribution from the transformation of azo group is considerably greater in the hydrogenation of 4-nitro-2'-hydroxy-5'-methylazobenzene in the presence of acetic acid. Adding a base to the solvent during the hydrogenation of 2-nitro-2'-hydroxy-5'-methylazobenzene accelerates the rate of nitro group conversion and the intramolecular cyclization of the intermediate compound, increasing the selectivity towards the products containing the benzotriazole cycle (particularly 2-(2-hydroxy-5-methylphenyl)benzotriazole-N-oxide). The almost linear correlation between the selectivity of the catalytic hydrogenation of isomers of nitro-2'-hydroxy-5'-methylazobenzene and the kinetic characteristics of the hydrogenation of nitro and azo groups in compounds containing a single reactive substituent at different values of medium’s pH is estimated.
- An’, Khoang,Belova, A. V.,Lefedova, O. V.,Nemtseva, M. P.
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p. 720 - 724
(2020/04/24)
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- The Continuous Synthesis of 2-(2'-Hydroxy-5'-Methylphenyl)Benzotriazole over Cu/γ-Al2O3
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Abstract: The samples of 20% Cu/γ-Al2O3, 20% Co/γ-Al2O3 and 20% Ni/γ-Al2O3 were prepared as hydrogenation catalysts for continuous synthesis of 2-(2'-hydroxy-5'-methylphenyl)benzotriazole. The best yield (86.62%) was afforded by the 20% Cu/γ-Al2O3 catalyst. The characterizations results obtained for the 20% Cu/γ-Al2O3 sample confirmed that Cu particles are evenly distributed over the surface of γ-Al2O3. A reduction of acid sites in the catalyst favored the selectivity to 2-(2'-hydroxy-5'-methylphenyl)benzotriazole. Furthermore, the effect of Cu content, reaction temperature, hydrogen pressure and liquid hourly space velocity was studied. Finally, 2-(2'-hydroxy-5'-methylphenyl)benzotriazole in 86.62% yield was attained under the optimized conditions.
- Yan,Si,Tao,Liu,Wang,Li
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p. 635 - 641
(2019/10/19)
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- A benzo triazole ultraviolet absorbing agent preparation method (by machine translation)
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The invention discloses a benzo triazole ultraviolet absorbing agent preparation method, including the raw material compound and alkali is dissolved in the solvent, is configured to raw material is added to the reaction device; then the Fe3 O4 /Catalyst is added to the raw material liquid in the graphene, access hydrogen, keeping the pressure 0.1 - 5 mpa, temperature 40 - 120 °C; in the reaction process using high performance liquid chromatography to real-time monitoring of the reaction solution, after the reaction, cooling, the restoration of normal pressure and recovering the catalyst after treatment, be benzo triazole ultraviolet absorbent. The method of this invention simple process, environmental protection, low cost, mild reaction conditions, product yield and quality is high, is suitable for industrial production, Fe used therein3 O4 /Graphene catalyst economic and environmental protection, stable properties, is recycled. (by machine translation)
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Paragraph 0044-0057
(2018/06/15)
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- A benzotriazole compound synthesis method (by machine translation)
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The invention discloses a synthetic method of a benzotriazoles compound. The synthetic method comprises the following steps: loading a bifunctional catalyst of hydrogenation-solid alkali into a fixed bed reactor; continuously leading a solution of a compound represented by the formula (I) into the fixed bed reactor, leading hydrogen, and performing heating; enabling the reaction liquid to continuously flow out from a lower end of the fixed bed reactor; cooling the effluent reaction liquid to the room temperature; performing gas-liquid separation, liquid filtration, and filtrate condensation to remove the solvent; and performing purification to obtain the benzotriazoles compound represented by the formula (II). The bifunctional catalyst of hydrogenation-solid alkali is adopted for catalytic hydrogenation to synthesize the benzotriazoles compound. The bifunctional catalyst has catalytic performance of solid alkali during catalytic hydrogenation, so that insufficient addition of alkali liquor is effectively avoided in the prior art. The bifunctional catalyst is high in catalytic activity and is convenient to recycle and reuse. Post-treatment of synthesizing the benzotriazoles compound is simplified, and the problem of environmental pollution resulting from post-treatment of the alkali liquor is effectively avoided. The synthetic method is efficient, and is low in cost and easy and simple to operate.
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Paragraph 0032; 0033; 0034; 0035
(2018/03/26)
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- Preparation method of ultraviolet absorbent
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The invention belongs to the field of macromolecules, and particularly relates to a preparation method of an ultraviolet absorbent. The preparation method of the ultraviolet absorbent adopts rutheniumphosphide as a catalyst, the formula I has catalytic hydrogenation reaction with the ruthenium phosphide to prepare the ultraviolet absorbent, and the structural formula of the ultraviolet absorbentis formula II, wherein (shown in the description), R is H or Cl; R1 is (CH3)3 or H, R2 is CH3, (CH3)3 or t-C8H17. The preparation method of the ultraviolet absorbent solves the technical problems in the prior art that the environment is polluted, the operation is complicated, the atom utilization rate is low, and the cost is higher.
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Paragraph 0033; 0036; 0037; 0038; 0040; 0042; 0044
(2018/11/03)
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- Catalytic hydrogenation of 2-nitro-2′-hydroxy-5′-methylazobenzene over solid base-hydrogenation bifunctional catalysts: Effect of alkali metals on Pd/γ-Al2O3
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Alkali metals doped Pd solid base-hydrogenation bifunctional catalysts were prepared, characterized, and employed in the hydrogenation of 2-nitro-2′-hydroxy-5′-methylazobenzene. The results indicated that the basicity of catalyst endowed by the alkali met
- Si, Leilei,Wang, Bowei,Chen, Shipeng,Hou, Jingru,Yan, Xilong,Li, Yang,Chen, Ligong
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- Preparation method of ultraviolet light absorber UV-P
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The invention discloses a preparation method of an ultraviolet light absorber UV-P. The preparation method includes the following steps that an azo intermediate shown in the formula (I) is reduced into nitric oxide shown in the formula (II) through a reducing agent, nitric oxide is reduced into a product shown in the formula (III) through the reducing agent, and the reducing agent is formed by sintering metal powder and an adsorbent, wherein the formula (I), the formula (II) and the formula (III) are shown in the description. The preparation method has the advantages that the use amount of the metal powder is small, environmental pollution is low, operation is convenient and easy, and the yield of the product is high.
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Paragraph 0022; 0023; 0024; 0025; 0026; 0027
(2017/07/21)
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- Preparation method of benzotriazole ultraviolet light absorber
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The invention discloses a preparation method of a benzotriazole ultraviolet light absorber. The method comprises the following steps: adding an azo dye intermediate represented by formula I to hydrazine hydrate, carrying out reduction to form an intermediate nitrogen oxide represented by formula II, and reducing the intermediate nitrogen oxide represented by formula II with hydrogen to prepare the benzotriazole ultraviolet light absorber represented by formula III, wherein the formula I, the formula II and the formula III are respectively shown in the description. The preparation method allows wastewater generated in the invention to be environmentally-friendly.
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Paragraph 0021; 0022
(2017/01/19)
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- Reductive cyclization of 2-nitro-2′-hydroxy-5′-methylazobenzene to benzotriazole over K-doped Pd/γ-Al2O3
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A series of Pd/γ-Al2O3 catalysts modified by potassium salts were prepared and evaluated in the reductive cyclization of 2-nitro-2′-hydroxy-5′-methylazobenzene without additional base. These solid base-hydrogenation bifunctional catalysts were characterized and the results demonstrated that potassium salts could have an important impact on the properties and catalytic performance of Pd/γ-Al2O3.
- Wang, Bowei,Si, Leilei,Yuan, Yanyan,Li, Yang,Chen, Ligong,Yan, Xilong
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p. 16766 - 16771
(2016/02/20)
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- COLOR DEVELOPING COMPOSITION CONTAINING MOLECULAR COMPOUND, AND RECORDING MATERIAL
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Provided is a color-developing composition containing a molecular compound which has as a component compound a compound represented by formula (I) [wherein Y represents a C1-C12 hydrocarbon group which is chained or branched and saturated or unsaturated, or a C1-C8 hydrocarbon group which is chained or branched, saturated or unsaturated and has an ether or thioether bond; R1, R2, R3 and R4 each independently represent a C1-C6 alkyl group or C2-C6 alkenyl group; n, p, q and r each represents any integer of 0 to 4; and m represents any integer of 0 to 2]. Also provided is a recording material with a sufficient color-forming sensitivity, superior storage stability, and especially with an extremely little background fogging in a heat resistance test.
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- One-pot synthesis of benzotriazoles and benzotriazole 1-oxides by reductive cyclization of o-nitrophenylazo compounds with benzyl alcohol
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Reductive cyclization of 2-[(2-nitrophenyl)azophenols 1 with benzyl alcohol and sodium hydroxide afforded 2-(2H-benzotriazol- 2-yl)phenols 3 and their 1-oxide 2 in good to excellent yields.
- Farkas, Renata,Toerincsi, Mercedes,Kolonits, Pal,Alonso, Oscar Jimenez,Novak, Lajos
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experimental part
p. 2579 - 2588
(2010/04/27)
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- Preparation of 2-aryl-2H-benzotriazoles by zinc-mediated reductive cyclization of o-nitrophenylazophenols in aqueous media without the use of organic solvents
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Zinc powder-mediated reductive cyclization of o-nitrophenylazophenols in alkaline solution affords the corresponding 2-aryl-2H-benzotriazoles in high yields under mild reaction conditions. No organic solvents are used in the reaction and only minimal amounts in the work-up.
- Liu, Guo-Bin,Zhao, Hong-Yun,Yang, Hong-Jie,Gao, Xiang,Li, Miao-Kui,Thiemann, Thies
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p. 1637 - 1640
(2008/02/11)
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- Mono- and biphotonic photochemistry in glass matrices
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Photochemistry in hard glassy solvent matrices gives different results than in gas matrices. It is performed at 83, 77, and ≥10 K by continuous irradiation and by pulsed multi MW cm-2 peak intensity excitation for those systems that do not react monophotonically. The highly structured matrix spectra should be taken as a basis for the interpretation of transient spectra to avoid ambiguities. Numerous [2.2]paracyclophanes are photolyzed. Most of them give stable diradical and quinodimethane spectra in addition to fluorescence and phosphorescence. Some benzylic diradicals undergo chemiluminescence after their photochemical generation. Matrix isolation spectroscopy is at variance with common interpretations in the lepidopterene case. A [2+4]-photocycloreversion of a substituted cyclohexene at 83 K leads to diene stereoisomers/rotamers that isomerize upon further irradiation. E/Z-photoequilibria are obtained in MTHF matrix from both sides with ω-nitrostyrene and α-benzylidene-γ-butyrolactone at 83 K, the latter stereoisomerization was also successfully studied at 10 K. Pulsed irradiation of technical photostabilizers at 10 K leads to stable zwitterion formation by proton migration that cannot be seen by continuous excitation. Inter- and intramolecular donor acceptor systems provide stable charge separation at 15 or 77 K upon pulsed laser irradiation and radicalanion spectra are recorded. Biphotonic photochemistry at ≥10 K allows for the formation of new ring systems such as dioxathiirane (cyclo-SO2), several aryldioxaziridines, and an electron rich triaziridine, compounds that revert upon thawing and could not be obtained by continuous irradiation, except cyclo-SO2 that can also be formed after absorption of the long lived SO2 triplet by another two-photon process.
- Kaupp, Gerd
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p. 140 - 156
(2007/10/03)
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- Synthesis of new ultraviolet light absorbers based on 2-aryl-2H- benzotriazoles
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A procedure for the synthesis of some new ultraviolet absorbers of the benzotriazole series is reported. The compounds bear a carboxylic or a formyl group para to the hydroxy group, and these functionalities impart to the absorbers improved compatibility with certain disperse dyes on polyester fibers.
- Koutsimpelis, Aristides G.,Screttas, Constantinos G.,Igglessi-Markopoulou, Olga
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p. 1393 - 1401
(2007/10/03)
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- Process for the preparation of benzotriazoles
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A process for the preparation of compounds of formula (I): wherein the general symbols are as defined in claim 1, which comprises reacting a compound of formula (V): wherein R1, R2, R3, R4, R5, R6, R7, R8, R9 and R18 are as defined in claim 1, and R18 is especially nitro, chlorine or bromine, with an azide compound of formula (IX): wherein M and n are as defined in claim 1, especially with sodium azide.
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- Liquid-phase hydrogenation of 2-nitro-2′-hydroxy-5′- methylazobenzene on raney nickel at low temperatures
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The character of changes in the concentrations of intermediate products at the initial stage of the hydrogenation of 2-nitro-2′-hydroxy-5′- methylazobenzene (I) on Raney nickel at 275 K and the reasons for their dependence on the composition of the solvent were determined. The smallest amount of I and the largest yield of substituted benzotriazole N-oxide were obtained when the reaction was conducted in a 2-propanol-water solvent containing sodium hydroxide. Conversely, the addition of acids to the solvent sharply increased the yield of the nitrohydrazo derivative. The selectivity of hydrogenation with respect to the substituted benzotriazole was determined by the ratio between the rates of hydrogenation of the nitro and azo groups in the initial compound and intramolecular homogeneous rearrangements of intermediate products.
- Zuenko,Nemtseva,Lefedova,Nikolaev
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p. 877 - 881
(2007/10/03)
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- Hydrogenation kinetics of 2′-hydroxy-5′ -methyl-2-nitroazobenzene under quasisteady conditions
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The kinetics of the liquid-phase hydrogenation of 2′-hydroxy-5′ -methyl-2-nitroazobenzene on skeletal nickel in propan-2-ol and its mixtures with water and sodium hydroxide was studied under quasisteady conditions ensured by a measured substrate feed into a reaction vessel. 2-(2-Hydroxy-5-methylphenyl)benzotriazole N-oxide, 2′-hydroxy-5′ -methyl-2-nitrohydrazobenzene, and aromatic amines were found to be the major reaction intermediates under both steady and quasi-steady conditions, provided the compositions of the solvents are the same. The highest reaction selectivity for the target product, namely, 2-(2-hydroxy-5-methylphenyl)benzotriazole, can be reached at low concentrations of the starting reagent in a chemisorbed layer and high rates of cyclization of 2′-hydroxy-5′ -methyl-2-nitrohydrazobenzene into 2-(2-hydroxy-5-methylphenyl)benzotriazole N-oxide.
- Lefedova
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p. 1266 - 1269
(2007/10/03)
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- The effect of the amount of raney nickel and hydrogen pressure on the rate and selectivity of liquid-phase hydrogenation of 2-nitro-2′-hydroxy-5′-methylazobenzene
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An increase in the content of Raney nickel and hydrogen pressure accelerated the hydrogenation of 2-nitro-2′-hydroxy-5′-methylazobenzene and increased the yield of substituted benzotriazole because of a more complete conversion of intermediate substituted benzotriazole N-oxide. The total selectivity with respect to compounds containing the benzotriazole ring increased when sodium hydroxide was introduced into the aqueous-alcoholic solvent and the amount of the catalyst was decreased. Changes in the selectivity of the reaction were caused by changes in the ratio between the rates of homogeneous benzotriazole cyclization and heterogeneous stages of the complex multistage process of 2-nitro-2′-hydroxy-5′-methylazobenzene hydrogenation.
- Nemtseva,Lefedova,Gostikin,Zuenko
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p. 917 - 921
(2007/10/03)
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- METHOD FOR PREPARING 2-(2-HYRDROXYPHENYL)-2H-BENZOTRIAZOLE
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This invention provides a method for preparing 2-(2-hydroxyphenyl)-2H-benzotriazole of formula (I) below, consisting of steps of a) performing a first reduction in which hydrazine hydrate is added to a compound of formula (II) below with or without a phase transition catalyst in the presence of solvents which include a nonpolar solvent, water, and an alkaline compound, thereby preparing a compound of formula (III) below, and b) performing a second reduction in which water is added to the compound of formula (III) prepared in step a), and then zinc powder and sulfuric acid are added thereto with or without the phase transition catalyst, wherein, X is halogen or hydrogen, R is hydrogen, C1-C12 alkyl, C5-C8 cycloalkyl, phenyl, or phenyl-C1-C4 alkyl; and R' is C1-C12 alkyl, C5-C8 cycloalkyl, phenyl, or phenyl-C1-C4 alkyl
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- Low-emulsifier or emulsifier-free systems of the oil-in-water type with a content of stabilizers and an amino-substituted hydroxybenzophenone
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Cosmetic or dermatological preparations which represent finely disperse systems of the oil-in-water type, comprising a) an oil phase, b) a water phase, c) one or more stabilizers, d) at most 2.00% by weight of one or more emulsifiers, and e) an amino-substituted hydroxybenzophenone of the formula I
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- Processes for the preparation of benzotriazole UV absorbers
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Provided is a process for preparing 2H-benzotriazole UV absorbers containing a perfluoroalkyl moiety at the 5-position of the benzo ring, for example a trifluoromethyl group, which involves diazotizing the perfluoroalkyl substituted o-nitroaniline using concentrated sulfuric acid plus sodium nitrite or nitrosylsulfuric acid to form the corresponding monoazobenzene intermediate via the diazonium salt intermediate which is reduced to the corresponding 5-perfluoroalkyl substituted 2H-benzotriazole UV absorber compound by conventional reduction means. Also provided is a novel one-pot, multiphase reaction for the preparation of 2(2-nitrophenylazo) substituted phenols, which are precursors for 2H-benzotriazole UV absorbers.
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- 2-(2′-hydroxyphenyl)benzotriazoles used as U.V. stabilizers
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2-(2′-hydroxyphenyl)benzotriazoles having general formula (I). The above 2-(2′-hydroxyphenyl)benzotriazoles are useful as light stabilizers for organic polymers.
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- 2-(2′-hydroxyphenyl) benzotriazoles containing a 2,4-imidazolidinedione group and process for their preparation
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2-(2′-hydroxyphenyl)benzotriazoles having general formula (I). The above 2-(2′-hydroyzphenyl)benzotriazoles having general formula (I) are useful as heat, oxygen and light stabilizers for organic polymers. In particular they are useful as UV stabilizers for organic polymers.
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- The reactivity of nitro and azo groups in liquid-phase hydrogenation of 2-nitro-2′-hydroxy-5′-methylazobenzene
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The hydrogenation of 2-nitro-2′-hydroxy-5′-methylazobenzene can proceed by the addition of hydrogen at either the nitro group or the azo group of the initial compound. The product of hydrogen addition at the azo group identified as 2-nitro-2′-hydroxy-5′-methylhydrazobenzene can transform into substituted ben-zotriazole N-oxide in solution. The ratio between the rates of intermediate product hydrogenation and rearrangement to benzotriazole determines the yield of the desired product and depends on the nature and composition of the solvent in which the reaction is conducted.
- Lefedova,Gostikin,Ulitin
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p. 1433 - 1437
(2007/10/03)
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- Liposomogenic UV absorbers
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PCT No. PCT/EP96/00959 Sec. 371 Date Sep. 15, 1997 Sec. 102(e) Date Sep. 15, 1997 PCT Filed Mar. 7, 1996 PCT Pub. No. WO96/29302 PCT Pub. Date Sep. 26, 1996There are described liposomogenic UV absorbers, comprising a hydrophilic head group (=Z), a spacer (=W), a UV chromophore (Q) having an absorption in the range from 285 to 400 nm and at least one hydrophobic tail group (=A) of the formula (1), in which A1 and A2, independently of one another, are a hydrophobic radical, Q is a UV chromophore, W is an organic radical, Z1 and Z2, independently of one another, are a hydrophilic radical, n1 and n2, independently of one another, are a number from 0 to 4, n1=n2=0 not being additionally included, p is 1 or 2, q is a number from 0 to 3, r1 is 1 or 2, r2 is 0 or 1, and s1 is a number from 1 to 3. The liposomogenic UV absorbers according to the invention are preferably used as sunscreen agents in cosmetic preparations. They are capable of self-organization into bimolecular layers, and can thereby penetrate into the stratum corneum to a high extent and behave there in an extremely wash-resistant manner.
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- Electrochemical synthesis of 2-aryl-2H-benzotriazoles and their N-oxides by controlled potential cathodic electrolysis
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Using a divided cell, reductive cyclizations of o-nitrophenylazo dyes (1) toward 2-aryl-2H-benzotriazole-1-oxides (2) or 2-aryl-2H-benzotriazoles (3) were successfully accomplished by the controlled potential cathodic electrolysis reactions. 1 was transformed to 2 under neutral conditions while 1 was transformed to 3 under basic conditions.
- Kim, Byeong Hyo,Lee, Doo Byung,Kim, Dae Ho,Han, Rongbi,Jun, Young Moo,Baik, Woonphil
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p. 841 - 850
(2007/10/03)
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- Photostimulated reductive cyclization of o-nitrophenylazo dyes using sodium hydroxide in isopropyl alcohol. A new synthesis of 2-aryl-2H- benzotriazoles
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o-Nitrophenylazo dyes with NaOH were irradiated in isopropyl alcohol to give the corresponding benzotriazoles. The photostimulated reductive cyclization proceeds through the formation of N-oxides as an intermediate.
- Baik, Woonphil,Yoo, Chang Hyun,Koo, Sangho,Kim, Hern,Hwang, Yong Hyun,Kim, Byeong Hyo,Lee, Seok Woo
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p. 1779 - 1783
(2007/10/03)
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- Phosphites and their production and use
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Phosphites represented by the general formula (I): STR1 wherein R1, R2, R4 and R5 independently represent a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, a cycloalkyl group having 5 to 8 carbon atoms, an alkylcycloalkyl group having 6 to 12 carbon atoms, an aralkyl group having 7 to 12 carbon atoms or a phenyl group; R3 and R6 independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms; X1 is a dihydric alcohol residue, wherein HO--X1 --OH defines the corresponding dihydric alcohol from which residue X1, is obtained; and X2 is a direct bond or an alkylene group having 1 to 8 carbon atoms; and the phosphites are useful as stabilizers for organic materials.
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- 2-bromo-2-nitropropane/zn promoted reductive cyclizations of ortho-carbonyl, imino, or azo substituted nitrobenzenes
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Under the mild conditions, reductive cyclizations of 2-nitrobenzaldehydes, 2'-nitroacetophenone, and N-(2-nitrobenzylidene)anilines were accomplished in the presence of 2-bromo-2-nitropropane/Zn in methanolic solution. Under the similar conditions in MeOH/CH2Cl2, o-nitro-substituted phenylazobenzenes have been converted into 2-aryl-2H-benzotriazoles via reductive cyclizations that are widely used as UV absorbers. Synthesis and mechanistic details are discussed.
- Kim, Byeong Hyo,Lee, Yoon Seok,Kwon, Woong,Jin, Youngoo,Tak, Jung Ae,Jun, Young Moo,Baik, Woonphil,Lee, Byung Min
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p. 2581 - 2592
(2007/10/03)
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- Piperidine compound, a process for producing the same and a stabilizer using the same
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2-Methyl-3-(2,2,6,6-tetramethyl-4-piperidylamino)-N-(2,2,6,6-tetramethyl-4-piperidyl)-propionamide represented by the following formula, a process for producing the same and a stabilized organic material composition containing the same wherein the piperidine compound imparts excellent properties, such as light stability or thermal stability to the organic materials. STR1
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- COMBINED SYNTHESIS AND ISOLATION OF 2-(2'-HYDROXY-5'-METHYLPHENYL)BENZOTRIAZOLE IN A DIAPHRAGM ELECTROLYZER
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A possibility has been shown of isolating 2-(2'-hydroxy-5'-methylphenyl)benzotriazole from a solution of its sodium salt in the anode chamber of a filter-press diaphragm electrolyzer, of combining the synthesis and isolation in the same electrolyzer, and of recycling the solution in the synthesis-isolation cycles.
- Sitner, E. Ya.,Rapoport, Yu. M.,Gorbunov, B. N.,Feotkistov, L. G.,Kilimnik, A. B.
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p. 457 - 460
(2007/10/03)
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- Process for the preparation of benzotriazoles
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2-(2-Hydroxyphenyl)-2H-benzotriazoles of the formula STR1 in which R is hydrogen, C1 -C12 alkyl or C1 -C4 alkoxy, R1 is hydrogen, C1 -C12 alkyl, C5 -C6 cycloalkyl, phenyl or phenyl-C1 -C4 alkyl and R2 is C1 -C12 alkyl, C5 -C6 cycloalkyl, phenyl, phenyl-C1 -C4 alkyl or a group --Cn H2n --COOR3, in which n is 0 to 4 and R3 is hydrogen or C1 -C12 alkyl, can be prepared particularly advantageously by catalytic hydrogenation of a suitable o-nitroazo compound in the presence of a Pt, Pd, Pt/Pd or Rh hydrogenation catalyst and an alkylenediamine or an acyclic or cyclic polyalkylene polyamine in a halogenated or nonhalogenated aromatic hydrocarbon as solvent.
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- Method of preparing 2-phenyl benzotriazoles
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A method of preparing 2-phenylbenzotriazoles expressed by Formula I: STR1 (wherein R1 denotes a hydrogen or chlorine atom, a lower alkyl group having 1 to 4 carbon atoms, a lower alkoxyl group having 1 to 4 carbon atoms, a carboxyl group or a sulfonic acid group; R2 denotes a hydrogen or chlorine atom, a lower alkyl group having 1 to 4 carbon atoms or a lower alkoxyl group having 1 to 4 carbon atoms; R3 denotes a hydrogen or chlorine atom, an alkyl group having 1 to 12 carbon atoms, a lower alkoxyl group having 1 to 4 carbon atoms, a phenyl group, a phenyl group substituted by an alkyl group having 1 to 8 carbon atoms, a phenoxy group or a phenylalkyl group with an alkyl part having 1 to 4 carbon atoms; R4 denotes a hydrogen or chlorine atom, a hydroxyl group or an alkoxyl group having 1 to 4 carbon atoms; and R5 denotes a hydrogen atom, an alkyl group having 1 to 12 carbon atoms or a phenylalkyl group with an alkyl part having 1 to 4 carbon atoms) comprises reduction with hydrogen of o-nitroazobenzene derivatives expressed by Formula II: STR2 (wherein R1, R2, R3, R4 and R5 each denote the same as in Formula I), the reduction being effected in a solvent containing water.
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- SYNTHESIS OF SOME BENZOTRIAZOLES BY DEOXYGENATION OF o-NITROPHENYLAZO COMPOUNDS BY TERTIARY AMINES AND CO
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NEt3 promotes the deoxygenation of specific ortho-nitrophenylazo compounds affording benzotriazoles in good yields and selectivities. The role of the amine is examined in the deoxygenation process with CO as the final oxygen acceptor.
- Pizzotti, Maddalena,Ragaini, Fabio,Cenini, Sergio
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p. 683 - 686
(2007/10/02)
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- Method of preparing 2-phenyl benezothriazoles
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A method of preparing 2-phenylbenzotriazoles expressed by Formula I: STR1 (wherein R1 denotes a hydrogen or chlorine atom, a lower alkyl group having 1 to 4 carbon atoms, a lower alkoxyl group having 1 to 4 carbon atoms, a carboxyl group or a sulfonic acid group; R2 denotes a hydrogen or chlorine atom, a lower alkyl group having 1 to 4 carbon atoms or a lower alkoxyl group having 1 to 4 carbon atoms; R3 denotes a hydrogen or chlorine atom, an alkyl group having 1 to 12 carbon atoms, a lower alkoxy group having 1 to 4 carbon atoms, a phenyl group, a phenyl group substituted by an alkyl group having 1 to 8 carbon atoms, a phenoxy group or a phenylalkyl group with an alkyl part having 1 to 4 carbon atoms; R4 denotes a hydrogen or chlorine atom, a hydroxyl group or an alkoxyl group having 1 to 4 carbon atoms; and R5 denotes a hydrogen atom, an alkyl group having 1 to 12 carbon atoms or a phenylalkyl group with an alkyl part having 1 to 4 carbon atoms) comprises reducing with hydrogen 2-phenylbenzotriazole-N-oxides expressed by Formula II: STR2 (wherein R1, R2, R3, R4 and R5 each denotes the same as in Formula I).
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- Method for preparing 2-phenylbenzotriazoles and 2-phenylbenzotriazole-N-oxides
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This invention relates to a method for preparing 2-phenylbenzotriazoles having the formula I, STR1
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- Method for preparing 2-phenylbenzotriazoles and 2-phenylbenzotriazole-N-oxides
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A method for preparing a 2-phenylbenzotriazole of formula I wherein R1 is H, Cl, C1-4alkyl, C1-4alkoxy, COOH or SO3H; R2 is H, Cl, C1-4alkyl or C1-4alkoxy; R3 is H, Cl, C1-12alkyl, C1-4alkoxy, phenyl, (C1-8alkyl)phenyl, phenoxy or phenyl(C1-4alkyl); R4 is H, Cl, OH or C1-4alkoxy; and R5 is H, C1-12alkyl or phenyl(C1-4alkyl), comprises reducing a nitroazobenzene of formula III = wherein R1, R2, R3, R4 and R5 are as defined above, with a saccharide in the presence of a hydrogen transfer catalyst and base. This method can be conducted in one or two steps. The individual steps, the first from the nitroazobenzene to a 2-phenylbenzotriazole-N-oxide of formula II and the second (II→I) are independent aspects of the invention.
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- Method for preparing 2-phenylbenzotriazoles and 2-phenylbenzotriazole-N-oxides
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This invention relates to a method for preparing a 2-phenylbenzotriazole of formula I, STR1 (wherein R1 represents hydrogen or chlorine atom, a lower alkyl group having a carbon number of 1 to 4, a lower alkoxyl group having a carbon number of 1 to 4, carboxyl group, or sulfonic acid group; R2 represents hydrogen or chlorine atom, a lower alkyl group having a carbon number of 1 to 4, or a lower alkoxyl group having a carbon number of 1 to 4; R3 represents hydrogen or chlorine atom, an alkyl group having a carbon number of 1 to 12, a lower alkoxyl group having a carbon number of 1 to 4, phenyl group, a phenyl group substituted with an alkyl group having a carbon number of 1 to 8, phenoxy group, or a phenylalkyl group, the alkyl part of which has a carbon number of 1 to 4; R4 represents hydrogen or chlorine atom, hydroxyl group, or a lower alkoxyl group having a carbon number of 1 to 4; and R5 represents hydrogen atom, an alkyl group having a carbon number of 1 to 12, or a phenylalkyl group, the alkyl part of which has a carbon number of 1 to 4), which comprises reducing an o-nitroazobenzene of formula III, STR2 (wherein R1, R2, R3, R4 and R5 are as defined above) with an aldehyde reducing agent in the presence of an aromatic ketone catalyst and base. This invention further relates to a method for preparing a 2-phenylbenzotriazole of formula I as derfined above, which comprises reducing 1 mole 2-phenylbenzotriazole-N-oxide of formula II, STR3 (wherein R1, R2, R3, R4 and R5 are as defined above) with 1 to 4 mole aldehyde in the presence of an aromatic ketone catalyst and base. This invention still further relates to a method for preparing a 2-phenylbenzotriazole-N-oxide of formula II as defined above, which comprises reducing 1 mole o-nitroazobenzene of formula III as defined above with 1 to 2 mole aldehyde in the presence of an aromatic ketone catalyst and base.
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- Method for preparing 2-phenylbenzotriazoles and 2-phenylbenzotriazole-N-oxides
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A method for preparing a 2-phenylbenzotriazole of formula I wherein R1 is H, Cl, C1-4alkyl, C1-4alkoxy, COOH or SO3H; R2 is H, Cl, C1-4alkyl or C1-4alkoxy; R3 is H, Cl, C1-12alkyl, C1-4alkoxy, phenyl, (C1-8alkyl)phenyl, phenoxy or phenyl(C1-4alkyl); R4 is H, Cl, OH or C1-4alkoxy; and R5 is H, C1-12alkyl or phenyl(C1-4alkyl), comprises reducing a nitroazobenzene of formula III wherein R1, R2, R3, R4 and R5 are as defined above, with an aldehyde, in the presence of an aromatic ketone and base. This method can be conducted in one or two steps. The individual steps, the first from the nitroazobenzene to a 2-phenylbenzotriazole-N-oxide of formula II and the second (II→I) are independent aspects of the invention.
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- Long-acting pyrethrum/pyrethroid based pesticides with silicone stabilizers
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Pesticidal compositions based on nontoxic, naturally unstable insecticides (pyrethrum, synthetic pyrethroids and mixtures thereof) include a liquid alkyl aryl silicone polymer which stabilizes the insecticide to provide an extended effective killing life. The compositions additionally include a synergist to provide an immediate killing action and an antioxidant to protect the insecticide against destruction by oxygen. Ultraviolet protectants and insect repellents may also be included. Applications include control of insect pests to animals and plants and general purpose insect control. Exemplary formulations are given for compositions to be applied as sprays, dips, powdered or dusts, foggers and shampoos.
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- Preparation of 2-(2H-Benzotriazol-2-yl)phenols by the Reduction of 2-phenols with Thiourea S,S-Dioxide
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The reduction of 2-phenols 1 with thiourea S,S-dioxide and sodium hydroxide in a mixture of isopropyl alcohol and water at reflux provides 2-(2H-benzotriazol-2-yl)phenols 3 in excellent yields.
- Tanimoto, Shigeo,Kamano, Takayoshi
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p. 647 - 649
(2007/10/02)
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- Preparation of Some 2-(2' H-Benzotriazol-2'-yl)phenol Ultraviolet Absorbers: Application of the Transalkylation Reaction
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When 2-(2' H-benzotriazol-2'-yl)phenols containing t-alkyl substituents are warmed in toluene solution with an aluminium chloride/nitromethane catalyst, the t-alkyl groups are transferred to the solvent (toluene).This transalkylation reaction has been used to prepare not readily accessible or previously inaccessible 2-(2' H-benzotriazol-2'-yl)phenols, a class of ultraviolet absorbers widely used in industry.
- Rosevear, Judi,Wilshire, John F.K.
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p. 1163 - 1176
(2007/10/02)
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- The Reduction of Some o-Nitrophenylazo Dyes with Thiourea S,S-Dioxide (Formamidinesulfinic Acid): a General Synthesis of 2-Aryl-2H-benzotriazoles and Their 1-Oxides
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Thiourea S,S-dioxide (formamidinesulfinic acid) reacts with o-nitrophenylazo dyes in ethanolic alkali to give, depending on the reaction conditions, either the corresponding 2-aryl-2H-benzotriazoles or their 1-oxides.The reagent is particularly effective for preparing in high yield 2-(2'H-benzotriazol-2'-yl)phenols, which are important ultraviolet absorbers.The corresponding reductions involving ammonium sulfide and sodium dithionite were also examined.The former reagent was unsatisfactory; the latter reagent behaved erratically and was a less effective reducing reagent than thiourea dioxide.Nevertheless, conditions were established whereby sodium dithionite furnished the 2-(2'H-benzotriazol-2'-yl)phenols in high yield and purity.
- Rosevear, Judi,Wilshire, John F. K.
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p. 2489 - 2497
(2007/10/02)
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- High molecular weight piperidine derivatives as UV stabilizers
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Substituted high molecular weight hindered spiropiperidine compounds and polymer compositions stabilized by these compounds. The spiropiperidine compounds are prepared by reacting hindered 4-piperidinone hydrochloride with an activated benzene, such as resorcinol, in an acid medium.
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- Process for the preparation of 2-aryl-2H-benzotriazoles
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A process for producing benzotriazoles of the formula I STR1 wherein R1 is hydrogen or chlorine, R2 is hydrogen, chlorine, C1 -C4 alkyl, C1 -C4 alkoxy, C2 -C9 alkoxycarbonyl, carboxyl or sulfo, R3 is C1 -C12 alkyl, C1 -C4 alkoxy, phenyl, (C1 -C8 alkyl)-phenyl, C5 -C6 cycloalkyl, C2 -C9 alkoxycarbonyl, chlorine, carboxyethyl or C7 -C9 phenylalkyl, R4 is hydrogen, C1 -C4 alkyl, C1 -C4 alkoxy, chlorine or hydroxyl, and R5 is hydrogen, C1 -C12 alkyl, chlorine, C5 -C6 cycloalkyl or C7 -C9 phenylalkyl, which process comprises treating a benzotriazole-N-oxide of the formula II STR2 wherein R1, R2, R3, R4 and R5 have the above meanings, at a temperature of 20°-150° C., with an amine; or treating an o-nitroazobenzene of the formula III STR3 wherein R1, R2, R3, R4 and R5 have the above meanings, at a temperature of 20°-150° C., with an amine.
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- Process for the production of 2-aryl-2H-benzotriazoles
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A process for the production of 2-aryl-2H-benzotriazoles comprises reducing and cyclizing the corresponding o-nitroazobenzenes with hydrogen at a temperature in the range of about 20° C. to about 100° C. and at a pressure in the range of about 15 psia (1 atmosphere) to about 1000 psia (66 atmospheres) in an organic solvent mixture containing an organic amine at a pH over 10 in the presence of noble metal hydrogenation catalyst, preferably palladium. High yields of pure product are obtained with a concomitant reduction of undesired by-products and a reduction in effluent pollution problems.
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- Process for the production of 2-aryl-2H-benzotriazoles
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A process for the production of 2-aryl-2H-benzotriazoles comprises reducing and cyclizing the corresponding o-nitroazobenzenes with hydrogen at a temperature in the range of about 20° C. to about 100° C. and at a pressure in the range of about 15 psia (1 atmosphere) to about 1000 psia (66 atmospheres) in an alkaline medium at a pH over 10 in the presence of a nickel catalyst, preferably molybdenum-promoted Raney nickel. High yields of pure product are obtained directly with a concomitant reduction of undesired by-product and a reduction in effluent pollution problems.
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