- 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 0179; 0182-0183; 0193
(2021/04/14)
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- NOVEL PROCEDURE FOR THE FORMATION OF 2H-BENZOTRIAZOLE BODIES AND CONGENERS
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The present invention relates to a process for the preparation of 2H-benzotriazole compounds and congeners, novel 2H-benzotriazole compounds and congeners and their use as UV absorbers in coatings and bulk plastics.
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Page/Page column 26; 27; 33
(2020/07/05)
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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 0062; 0063; 0064; 0065
(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 0041; 0042; 0043; 0044
(2018/03/26)
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- Preparation method of ultraviolet absorbent containing chlorobenzotriazole
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The invention relates to a preparation method of an ultraviolet absorbent containing chlorobenzotriazole. Azobenzene, sodium hydroxide and toluene are stirred and mixed, the temperature is controlled to 60-80 DEG C, water and hydrazine are dropwise added at a constant speed, heat preservation reaction is performed after the completion of dropping, hydrochloric acid is added to perform neutralization to reach the pH of 6-7 after completion of hydrazine reduction, washing is performed, and an oil phase, namely nitrogen oxide, is obtained; the nitrogen oxide solution, alkali, a framework nickel catalyst and a catalyst promoter sodium phosphite are put into an autoclave, and hydrogen is led to perform constant-pressure constant-temperature reaction after nitrogen displacement; after reaction is completed, reaction liquid filtration and washing are performed, an organic phase evaporated solvent is obtained, and recrystallization, filtration and drying are conducted on the methanol and toluene mixed solvent to obtain the ultraviolet absorbent containing chlorobenzotriazole. Compared with an existing synthetic method, the preparation method has the advantages of being good in reaction selectivity, inhibiting a dechlorination phenomenon in the hydrogenation process, producing few by-products and the like and meanwhile does not produce wastewater containing zinc and aluminum, subsequent processing is simple, and the 'three wastes' problem produced in the secondary reduction process is solved.
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Paragraph 0072-0097
(2017/07/20)
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- Preparation method of benzotriazole light stabilizer
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The invention discloses a preparation method of a benzotriazole ultraviolet light stabilizer. 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 stabilizer represented by formula III, wherein the formula I, the formula II and the formula III are respectively shown in the description, and R in the formulas is C(CH3)3 or CH3. The preparation method allows wastewater generated in the invention to be environmentally-friendly.
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Paragraph 0023; 0024
(2017/01/17)
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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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- 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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- 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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- 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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- 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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- 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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- 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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- 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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- 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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p. 8303 - 8306
(2007/10/03)
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- Microbial deoxygenation of N-oxides with Baker's yeast-NaOH
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The microbial deoxygenation of a series of aromatic and heteroaromatic N-oxide compounds, including quinoline N-oxides, isoquinoline N-oxides, 2-aryl-2H-benzotriazole 1-oxides, benzo[c]cinnoline N-oxide and azoxybenzenes, has been performed with bakers'yeast-NaOH.
- Baik, Woonphil,Kim, Dong Ik,Koo, Sangho,Rhee, Jong Uk,Shin, Sung Hee,Kim, Byeong Hyo
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p. 845 - 848
(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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- Process for sulfur containing derivatives of hydroxyphenyl/benzotriazoles
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A composition that, when present in a polymer matrix, reduces the deleterious effect of UV light absorption by the polymer is provided, which comprises a sulfur-containing derivative of hydroxyphenylbenzotriazole having the formula of: STR1 wherein each X is selected from the group consisting of hydrogen, halogens, cyano, alkyl, phenyl group, biphenyl group, arylthio, amine, ketone, aldehyde, alkoxy, hydroxy, carboxylic acid group, oligomer and combinations thereof and can have carbon atoms up to about 20; n is a whole number from 1 to 5; n' is a whole number from 0 to 4; n" is a whole number from 1 to 2 and each n" can be the same or different; q is an integer from 1 to 10; each Y is selected from the group consisting of --S(O) (O)--, --S(O)--, and --S--; each R can be selected from the group consisting of hydrogen, alkyl group, alkenyl group, aralkyl group, alkaryl group, and combinations thereof and can have 0 to about 10 carbon atoms; each OH group can be at either the 2'- or the 6'-position, or both. Also provided are a composition comprising the sulfur-containing derivative, a process for preparing the derivative, a composition comprising a polymer chemically bonded to the derivative, and a process for preparing the composition which comprises a polymer chemically bonded to the derivative.
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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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- 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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- Process for the preparation of benzotriazole derivatives
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Hologenated 2-(2-hydroxyphenyl)-2H-benzotriazoles of the formula STR1 in which X is halogen, 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 corresponding o-nitroazo compound in the presence of a hydrogenation catalyst consisting of 0.1 to 3% of Pt on a support and of an organic amine.
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- Method for preparing 2-phenylbenzotriazoles
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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 alkoxy 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 alkoxy 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 alkoxy 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 at least one selected from the group consisting of primary and secondary alcohol reducing agents 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 defined 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 0.4 to 0.7 mole primary alcohol and/or 0.8 to 1.4 mole secondary alcohol 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 0.4 to 0.7 mole primary alcohol and/or 0.8 to 1.4 mole secondary alcohol 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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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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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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- 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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- 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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- The Reduction of Some o-Nitrophenylazo Dyes with Glucose: A General Synthesis of 2-Aryl-2H-benzotriazole 1-Oxides
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The reduction of some representative o-nitrophenylazo dyes in ethanolic alkali with glucose gives the corrsponding 2-aryl-2H-benzotriazole 1-oxides in excellent yield.These 1-oxides are rapidly reduced to the parent benzotriazoles at room temperature by means of zinc dust/ethanolic alkali.This method provides a convenient preparation for 5-chlorobenzotriazoles, which are otherwise readily dechlorinated by zinc dust under more vigorous conditions
- Rosevear, Judi,Wilshire, John F. K.
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p. 2089 - 2093
(2007/10/02)
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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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- 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 preparation of 2-aryl-2H-benzotriazoles
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A two stage reductive ring closure of o-nitrophenylazophenols produces 2-aryl-2H-benzotriazoles by (a) reacting an organic solvent solution of azophenol with an excess of an aqueous solution of a sulfhydrate or sulfide to form an N-oxide and (b) reducing the N-oxide with an alkali metal hydroxide plus zinc or tin.
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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 manufacture of 2-(2-hydroxyphenyl)benztriazoles
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Process for the manufacture of 2-(2-hydroxyphenyl)benztriazoles of the formula I STR1 wherein R1 denotes hydrogen or halogen, R2 denotes hydrogen, alkyl, alkoxy, alkylsulphonyl, acylamino, --SO3 H, --COOH or halogen, R3 denotes hydrogen, alkyl, cycloalkyl, aralkyl, aryl or halogen, R4 denotes hydrogen, alkyl, alkoxy or --OH and R5 denotes hydrogen, alkyl, cycloalkyl, aralkyl, aryl, carboxyalkyl, alkoxy, acylamino or halogen, characterized in that a 2-(2-hydroxyphenyl)-benztriazole-1 oxide in the formula III STR2 is reacted with 0.5 to 0.6 mol equivalent of hydrazine hydrate at a temperature above 100° C, in a high-boiling ether as the solvent and in the presence of a base.
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- Process for the production of 2-aryl-2H-benzotriazoles
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An improved process for the production of 2-aryl-2H-benzotriazoles by the reduction of o-nitroazobenzene intermediates with zinc in alkaline medium comprises employing a ratio of moles of alkali to moles of o-nitroazobenzene intermediate in the range of 0.2-1.7/1 in the presence of less than 150 ppm of iron based on zinc used. The improved process results in higher yields of high purity products with a concomitant reduction in the amount of undesired cleavage amine by-products and a reduction in effluent pollution problems. The process is carried out in a polar/non-polar solvent mixture.
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- 1-Aza-4-thiacyclohexane-4,4-dioxide derivatives
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New 1-aza-4-thiacyclohexane-4,4-dioxide derivatives are used alone or in combination with other stabilizers for stabilizing organic materials. The new compounds are prepared by reacting substituted diallylsulfides with ammonia, amines or hydrazines.
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