CA1221701A - Process for preparing 2-(2'-hydroxyphenyl)- benzotriazoles from 2-nitro-2"-hydroxyazobenzenes - Google Patents
Process for preparing 2-(2'-hydroxyphenyl)- benzotriazoles from 2-nitro-2"-hydroxyazobenzenesInfo
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Abstract
Abstract Process for preparing 2-(2'-hydroxyphenyl)-benzo-triazoles of the formula from 2-nitro-2'-hydroxyazobenzenes of the formula
Description
~;~2~L7~
3-14451/=
The present invention relates to a process for pro-paring 2-(2'-hydroxyphenyl)-benzotriazoles from nutria-
3-14451/=
The present invention relates to a process for pro-paring 2-(2'-hydroxyphenyl)-benzotriazoles from nutria-
2'-hydroxyazobenzenes.
The reduction of 2-nitro-2'-hydroxyazobenzenes to 2-(2'-hydroxyphenyl)-benzotriazoles in a basic alcoholic mod-sum us known In addition to an aromatic dihydroxy or Dixie compound being present as the catalyst, this reduction how-ever also requires the presence of reducing agents such as 10 zinc, ammon;um swilled, alkali metal sulfide, ammonium ho-drogensulfide, alkali metal hydrogen sulfide, alkali metal d;th;onite or hydrazine hydrate (Japanese Patent Applique-ton No. 63379/78)~ And it is technically complicated to remove the oxides produced on reducing with metals such as 15 zinc and furthermore to prevent these oxides from pollute no the waste water. The sulfur-containing reducing agents are inferior to the metals and leave behind in the products sulfur impurities which are difficult to remove. Hydrazine hydrate is admittedly a powerful reducing agent but because 2û of its high toxicity its handling constitutes a safety risk.
In the processes for reducing 2-nitro-2'-hydroxy-azobenzenes to 2-(2'-hydroxyphenyl)-benzotriazoles which have been described to date, alcohols so far as they were used at all, served as solvents. Moreover, to date it has 25 been the general experience that vitro groups are not attacked by basic alcohol solutions (see GRGANIKUM CPracti-eel Organic Chemistry, published by VEX Dicier Verlag don Wissenschaften, Berlin 1976, pave 604). The search for a more economical and environmentally more acceptable pro-. r ~L2~L71:3~
-- Swiss has now led to the discovery of reaction conditions by which 2-nitro-2'-hydroxyazobenzenes can after all be reduced with basic alcohol solutions whose alcohol has more than one carbon atom to form 2-(2'-hydroxyphenyl)-benzotri-5 Azores.
The present invention accordingly provides a pro-cuss for preparing 2 (2'-hydroxyphenyl)-benzotriazoles from 2-nitro-2'-hydroxyazobenzenes, which comprises reducing a 2-nitro~2'-hydroxyazobenzene compound in a strongly basic 10 medium in the presence of an aromatic dihydroxy or Dixie compound as catalyst and of an alcohol having more than one carbon atom.
The process according to the invention us prefer-ably used for preparing, from compounds of the formula II, 15 compounds of the formula I
! 1 HO ~R3
The reduction of 2-nitro-2'-hydroxyazobenzenes to 2-(2'-hydroxyphenyl)-benzotriazoles in a basic alcoholic mod-sum us known In addition to an aromatic dihydroxy or Dixie compound being present as the catalyst, this reduction how-ever also requires the presence of reducing agents such as 10 zinc, ammon;um swilled, alkali metal sulfide, ammonium ho-drogensulfide, alkali metal hydrogen sulfide, alkali metal d;th;onite or hydrazine hydrate (Japanese Patent Applique-ton No. 63379/78)~ And it is technically complicated to remove the oxides produced on reducing with metals such as 15 zinc and furthermore to prevent these oxides from pollute no the waste water. The sulfur-containing reducing agents are inferior to the metals and leave behind in the products sulfur impurities which are difficult to remove. Hydrazine hydrate is admittedly a powerful reducing agent but because 2û of its high toxicity its handling constitutes a safety risk.
In the processes for reducing 2-nitro-2'-hydroxy-azobenzenes to 2-(2'-hydroxyphenyl)-benzotriazoles which have been described to date, alcohols so far as they were used at all, served as solvents. Moreover, to date it has 25 been the general experience that vitro groups are not attacked by basic alcohol solutions (see GRGANIKUM CPracti-eel Organic Chemistry, published by VEX Dicier Verlag don Wissenschaften, Berlin 1976, pave 604). The search for a more economical and environmentally more acceptable pro-. r ~L2~L71:3~
-- Swiss has now led to the discovery of reaction conditions by which 2-nitro-2'-hydroxyazobenzenes can after all be reduced with basic alcohol solutions whose alcohol has more than one carbon atom to form 2-(2'-hydroxyphenyl)-benzotri-5 Azores.
The present invention accordingly provides a pro-cuss for preparing 2 (2'-hydroxyphenyl)-benzotriazoles from 2-nitro-2'-hydroxyazobenzenes, which comprises reducing a 2-nitro~2'-hydroxyazobenzene compound in a strongly basic 10 medium in the presence of an aromatic dihydroxy or Dixie compound as catalyst and of an alcohol having more than one carbon atom.
The process according to the invention us prefer-ably used for preparing, from compounds of the formula II, 15 compounds of the formula I
! 1 HO ~R3
3 I I
R2 . \~2 it on which R1 us hydrogen or halogen, R2 is hydrogen, alkyd, alkoxy or halogen, R3 is hydrogen, alkyd, cycloalkyl9 anal-20 Kyle or aureole, and Al us hydrogen, alkyd, cycloalkyl~ anal-Kyle aureole or alkoxy.
In earlier processes the alcohol, so far as it was used at all, only had a solvent function. It always had to be added on addition to a reducing agent. In the pro-25 cuss according to the ;nvent;on, by contrast, the alkalis a twofold function, acting as solvent and reducing agent. This does away with one raw material, compared with the earlier processes. Since, moreover, no reducing agents such as zinc, sulfide, hydrogensulf;de, d;thionite or hydra-I
-- Sweeney hydrate are required any longer, the above mentioned disadvantages concerning work load and environmental and safety aspects also disappear. There is no longer a need for the laborious separating processes required in part-5 cuter in the case of metallic reducing agents. At the endow the process the reaction product is precipitated in each case and is readily isolated. The yields are high The novel process is thus more economical and environmentally more acceptable.
The process according to the invention is portico-laxly preferably used for preparing, from compounds of the formula II, compounds of the formula I in which R1 is hydra-gun or chlorine, R2 is hydrogen, alkyd having 1 to 5 carbon atoms, alkoxy having 1 to 4 carbon atoms or chlorine, R3 is 15 hydrogen, alkyd having 1 to 12 carbon atoms, cycloalkyl have in 5 to 8 carbon atoms, aralkyl having 7 to 9 carbon atoms or phenol, and R4 is hydrogen alkyd having 1 to 12 car-bun attunes cycloalkyl having 5 to 8 carbon atoms, aralkyl having 7 to 9 carbon atoms, phenol or alkoxy having 1 to 12 20 carbon atoms.
Halogen R1 and I can be chlorine. Alkyd R2 can be for example methyl, ethyl, propel, isopropyl, n-butyl, left.-bottle, Amy or left. Amelia Alkoxy R2 can be for example methoxy, ethics or n-butoxy. Alkyd R3 and I can be for 25 example methyl, ethyl sec.-butyl, left. bottle, tert.-amyl, tert.-octyl or n-dodecyl. Cycloalkyl R3 and R4 can be for example cyclopentyl, cyclohexyl or cyclooctyl. Aralkyl R3 and R4 can be for example bouncily, -methylbenzyl or YO-YO-dimethylbenzylr Aureole R3 and R4 can be phenol. Alkoxy R4 30 can be for example methoxy, ethics, propoxy, buttocks, ponytail ox, isobutoxy, octyloxy or dodecyloxy.
Typical compounds of the formula I are prepared in the examples.
Suitable alcohols for the process according to the 35 invention have more than one carbon atom. The upper limit of the number of carbon atoms is governed by the require-mint that the alcohol used must still be liquid at room I
temperature The alcohol can be in particular a primary alkanol, a secondary alkanol, an aralkanol, a glycol or a glycol monoalkyl ether. Examples of preferred primary alkanols are ethanol, n-propanol, n-butanol, n-octyl alcohol 5 and n-dodecanol. Examples of preferred secondary alkanols are ;sopropanol, sec.-butanol, sec.-octanol and sec.-dode-carol. An example of a preferred aralkanol is bouncily Alcoa hot. Examples of preferred glycols are 1,2-ethanediol, 1,3-propanediol and 1,4-butanediol. Examples of preferred 10 glycol monoalkyl ethers are ethylene glycol monomethyl ether, ethylene glycol monthly ether and ethylene glycol monobutyl ether. Secondary alkanols are particularly pro-fireball. Isopropanol and sec.~butanol are very particularly preferable.
The strongly basic medium in the process according to the invention can be produced by adding an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide, preferably sodium hydroxide, or an alkali metal such as sodium or potassium, preferably sodium, to one of the Alcoa 20 hots defined above. Said alkali metal hydroxides and alkali metals can be used in at least one preferably two mole equivalents relative to the substrate to be reduced The function of catalyst in the process according to the invention is performed by aromatic dihydroxy or art-25 matte Dixie compounds.
Aromatic d;hydroxy compounds can be benzodiols, for example 1,2-benzodiols and 1,4-benzodiols~ or naphthodiols, for example 1,2-naphthodiols, 1,4-naphthodiols and 2,6-naphthodiols. The aromatic nuclei can be unsubstituted or 30 be completely or partially substituted by alkyd or halogen Unsubstituted benzodiols are preferred.
Aromatic Dixie compounds can be benzoquinones or naphthoquinones. The benzoquinones can be unsubstituted or completely or partially alkyd-, such as methyl-, or halogen-, 35 such as chlorine-, substituted 1,2-benzoquinones and 1,4-benzoquinones. The benzoquinones take second preference to unsubstituted or substituted naphthoquinones~ such as .
~2~7~
1,2~naphthoquinones, 1,~-naphthoquinones or I naphtho-quinines. Substituted nude; are substituted by halogen, hydroxyl, alkyd, d;alkylam;no, piper;dino or morphol;no~
Preferred ~,4-naphthoqu;nones have the formula III
1 1 it / \ / OR
on Shea R5 us hydrogen, halogen or hydroxyl, and R6 us hydrogen, halogen, alkali d;alkylam;no, pardon or morn felon.
Particularly preferred compounds have the formula 10 III on which R5 us hydrogen chlorine or hydroxyl, and R6 us hydrogen, chlorine, alkyd having 1 to 12 carbon atoms, d;alkylamino having 2 to 24 carbon atoms, pardon or morpholino.
Alkyd R6 can be for example methyl, ethyl, n-15 bottle, sec.-butyl, n-octyl or n-dodecyl. Dialkylam;no R6 can be dimethylamino, diethylam;no, d;butylam;no, ductile-amino or dldodecylam;no~
The process according to the invention is very par-ocularly preferably carried out with 1,4-naphthoquinone, 20 2,3-d;chloronaphthoquinone, 2-chloronaphthoquinone, 2-hydroxy-3-methylnaphtho~u;none or 2-chloro-3-dimethylamino-naphthoquinone.
The aromatic d;hydroxy or Dixie compounds acting as the catalyst can be used, for example, on amounts of 1-20 25 mole %, on particular 5-10 mole %, relative to the substrate to be reduced.
The process according to the invention is preferably carried out with a cocatal~st being used on addition to the catalyst. Suitable cocatalysts are alkali metal bisulfites 30 and ammonium bisulfite. Sodium bisulfite used in amounts of, for example 1-20 mole %, in particular 5-10 mole %, relative to the substrate to be reduced is preferred.
The process according to the invention can be car-rued out at about 20C to about 120C, on particular at . :
about 40C to about 100C, and especially at about 50C
to about 80C.
In the process according to the ;nvent;on, the water content of the reaction medium should be less than 15% by 5 volume. The reduction is preferably carried out in an an-hydrous medium.
The compounds of the formula I are known stabilizers for organic materials, for example organic polymers The compounds of the formula II are known for use as starting 10 materials.
The following examples describe the invention in more detail.
Example 1: A 750 ml sulfonating flask is charged with 200 9 of isopropanol, 1 9 of sodium bisulfite and 2.3 g of 2,3-15 dichloronaphthoquinone. The mixture is reflexed or manhour and is then cooled down to 60C, when 25.6 g of so-drum hydroxide and 38.35 g of 2-nitro-2'-hydroxy-3',5'-bis-tert.-amylazobenzene are added. The mixture is stirred at 70-75C for one to two hours, and owe ml of water are 20 then added. The precipitated crystals are filtered off, are washed with water and are dried at 60-70C in vacua.
The product is a high yield of 2,4-di-tert.-amyl-6-~2'-benzotriazolyl3-phenol.
Example 2: A suspension of 9.2 9 of sodium in 400 9 of 25 isopropanol is reflexed in a 1.5 lithe sulfonating flask until a solution is formed. To this are added, at 60C, 3.2 9 of 1,4-naphthoquinone, 2.1 9 of sodium bisulfite and 71 9 of2-nitro-2'-hydroxy-3'~5'-b;s-tert.-butylazobenzenee. The mixture is stirred at 6ûC for between half an hour and a 30 full hour. 20 9 of 17 per cent by volume aqueous sulfuric acid and 100 ml of warm water at 60-70C are then added drops. The precipitated crystals are filtered and are washed with warm 60 per cent by weight aqueous methanol and with warm water. Drying at 70 80C in vacua produces Dow-35 tert.-butyl-6-(2'-benzotriazolyl)-phenol in a high yield.
Example 3: A 75D ml sulfonating flask is charged with 220 9 of sec.-butanol, 34.7 g of 2-nitro-4-chloro-2'-hydroxy-3'-Lo tert.-butyl-5-methylazobenzene~ 2.3 g of 2,3-dichloronaph-thoquinone and 26 g of sun per cent by weight aqueous sodium hydroxide solution. The mixture is stirred at 40-45C for two hours and at 70-75C for three hours. 500 ml of water 5 are added drops. The precipitated crystals are filtered off, are washed with water, and are dried at 60-70C in vacua. The product is a high yield of 2-tert.-butyl-4-methyl-6~t4'-chloro-2'-benzotriazolyl)-phenol.
Example 4: A 750 ml sulfonating flask is charged with 300 10 g of cyclohexanol~ 35.S g of 2-nitro-2'-hydroxy-3',5'-bis-tert.-butylazobenzene~ 2.3 9 of 2,3-dichloronaphthoqui-none and 25.6 g of sodium hydroxide. The mixture is stirred at 70~75C for three hours and is brought to pi 1.5 with 5 per cent by volume aqueous hydrochloric acid. The aqueous phase is separated off and discarded 15 The organic phase is washed with water and cooled down to -5C. A high yield of 2,4-di-tert.-butyl-6-(2'-benzotri-azolyl)-phenol crystallizes out.
5: 200 g of isopropanol are heated to 60C in a 20 750 ml sulfonating flask, and 1 g of sodium bisulfite, 1.6 g of 1,4-naphthoquinone, 14 g of sodium hydroxide and 35.5 9 of 2-n;tro-2'-hydroxy-3',5'-b;s-tert.-butylazobenzenee are then added The mixture us stirred at 75-80C for two hours and 18 9 of 17 per cent by volume aqueous sulfuric acid 25 and 50 ml of warm water are then added drops. The pro-cip;tated crystals are washed with warm methanol and then with warm water The product is a high yield of Dow-tert.-butyl-6~ benzotriazolyl)-phenol.
R2 . \~2 it on which R1 us hydrogen or halogen, R2 is hydrogen, alkyd, alkoxy or halogen, R3 is hydrogen, alkyd, cycloalkyl9 anal-20 Kyle or aureole, and Al us hydrogen, alkyd, cycloalkyl~ anal-Kyle aureole or alkoxy.
In earlier processes the alcohol, so far as it was used at all, only had a solvent function. It always had to be added on addition to a reducing agent. In the pro-25 cuss according to the ;nvent;on, by contrast, the alkalis a twofold function, acting as solvent and reducing agent. This does away with one raw material, compared with the earlier processes. Since, moreover, no reducing agents such as zinc, sulfide, hydrogensulf;de, d;thionite or hydra-I
-- Sweeney hydrate are required any longer, the above mentioned disadvantages concerning work load and environmental and safety aspects also disappear. There is no longer a need for the laborious separating processes required in part-5 cuter in the case of metallic reducing agents. At the endow the process the reaction product is precipitated in each case and is readily isolated. The yields are high The novel process is thus more economical and environmentally more acceptable.
The process according to the invention is portico-laxly preferably used for preparing, from compounds of the formula II, compounds of the formula I in which R1 is hydra-gun or chlorine, R2 is hydrogen, alkyd having 1 to 5 carbon atoms, alkoxy having 1 to 4 carbon atoms or chlorine, R3 is 15 hydrogen, alkyd having 1 to 12 carbon atoms, cycloalkyl have in 5 to 8 carbon atoms, aralkyl having 7 to 9 carbon atoms or phenol, and R4 is hydrogen alkyd having 1 to 12 car-bun attunes cycloalkyl having 5 to 8 carbon atoms, aralkyl having 7 to 9 carbon atoms, phenol or alkoxy having 1 to 12 20 carbon atoms.
Halogen R1 and I can be chlorine. Alkyd R2 can be for example methyl, ethyl, propel, isopropyl, n-butyl, left.-bottle, Amy or left. Amelia Alkoxy R2 can be for example methoxy, ethics or n-butoxy. Alkyd R3 and I can be for 25 example methyl, ethyl sec.-butyl, left. bottle, tert.-amyl, tert.-octyl or n-dodecyl. Cycloalkyl R3 and R4 can be for example cyclopentyl, cyclohexyl or cyclooctyl. Aralkyl R3 and R4 can be for example bouncily, -methylbenzyl or YO-YO-dimethylbenzylr Aureole R3 and R4 can be phenol. Alkoxy R4 30 can be for example methoxy, ethics, propoxy, buttocks, ponytail ox, isobutoxy, octyloxy or dodecyloxy.
Typical compounds of the formula I are prepared in the examples.
Suitable alcohols for the process according to the 35 invention have more than one carbon atom. The upper limit of the number of carbon atoms is governed by the require-mint that the alcohol used must still be liquid at room I
temperature The alcohol can be in particular a primary alkanol, a secondary alkanol, an aralkanol, a glycol or a glycol monoalkyl ether. Examples of preferred primary alkanols are ethanol, n-propanol, n-butanol, n-octyl alcohol 5 and n-dodecanol. Examples of preferred secondary alkanols are ;sopropanol, sec.-butanol, sec.-octanol and sec.-dode-carol. An example of a preferred aralkanol is bouncily Alcoa hot. Examples of preferred glycols are 1,2-ethanediol, 1,3-propanediol and 1,4-butanediol. Examples of preferred 10 glycol monoalkyl ethers are ethylene glycol monomethyl ether, ethylene glycol monthly ether and ethylene glycol monobutyl ether. Secondary alkanols are particularly pro-fireball. Isopropanol and sec.~butanol are very particularly preferable.
The strongly basic medium in the process according to the invention can be produced by adding an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide, preferably sodium hydroxide, or an alkali metal such as sodium or potassium, preferably sodium, to one of the Alcoa 20 hots defined above. Said alkali metal hydroxides and alkali metals can be used in at least one preferably two mole equivalents relative to the substrate to be reduced The function of catalyst in the process according to the invention is performed by aromatic dihydroxy or art-25 matte Dixie compounds.
Aromatic d;hydroxy compounds can be benzodiols, for example 1,2-benzodiols and 1,4-benzodiols~ or naphthodiols, for example 1,2-naphthodiols, 1,4-naphthodiols and 2,6-naphthodiols. The aromatic nuclei can be unsubstituted or 30 be completely or partially substituted by alkyd or halogen Unsubstituted benzodiols are preferred.
Aromatic Dixie compounds can be benzoquinones or naphthoquinones. The benzoquinones can be unsubstituted or completely or partially alkyd-, such as methyl-, or halogen-, 35 such as chlorine-, substituted 1,2-benzoquinones and 1,4-benzoquinones. The benzoquinones take second preference to unsubstituted or substituted naphthoquinones~ such as .
~2~7~
1,2~naphthoquinones, 1,~-naphthoquinones or I naphtho-quinines. Substituted nude; are substituted by halogen, hydroxyl, alkyd, d;alkylam;no, piper;dino or morphol;no~
Preferred ~,4-naphthoqu;nones have the formula III
1 1 it / \ / OR
on Shea R5 us hydrogen, halogen or hydroxyl, and R6 us hydrogen, halogen, alkali d;alkylam;no, pardon or morn felon.
Particularly preferred compounds have the formula 10 III on which R5 us hydrogen chlorine or hydroxyl, and R6 us hydrogen, chlorine, alkyd having 1 to 12 carbon atoms, d;alkylamino having 2 to 24 carbon atoms, pardon or morpholino.
Alkyd R6 can be for example methyl, ethyl, n-15 bottle, sec.-butyl, n-octyl or n-dodecyl. Dialkylam;no R6 can be dimethylamino, diethylam;no, d;butylam;no, ductile-amino or dldodecylam;no~
The process according to the invention is very par-ocularly preferably carried out with 1,4-naphthoquinone, 20 2,3-d;chloronaphthoquinone, 2-chloronaphthoquinone, 2-hydroxy-3-methylnaphtho~u;none or 2-chloro-3-dimethylamino-naphthoquinone.
The aromatic d;hydroxy or Dixie compounds acting as the catalyst can be used, for example, on amounts of 1-20 25 mole %, on particular 5-10 mole %, relative to the substrate to be reduced.
The process according to the invention is preferably carried out with a cocatal~st being used on addition to the catalyst. Suitable cocatalysts are alkali metal bisulfites 30 and ammonium bisulfite. Sodium bisulfite used in amounts of, for example 1-20 mole %, in particular 5-10 mole %, relative to the substrate to be reduced is preferred.
The process according to the invention can be car-rued out at about 20C to about 120C, on particular at . :
about 40C to about 100C, and especially at about 50C
to about 80C.
In the process according to the ;nvent;on, the water content of the reaction medium should be less than 15% by 5 volume. The reduction is preferably carried out in an an-hydrous medium.
The compounds of the formula I are known stabilizers for organic materials, for example organic polymers The compounds of the formula II are known for use as starting 10 materials.
The following examples describe the invention in more detail.
Example 1: A 750 ml sulfonating flask is charged with 200 9 of isopropanol, 1 9 of sodium bisulfite and 2.3 g of 2,3-15 dichloronaphthoquinone. The mixture is reflexed or manhour and is then cooled down to 60C, when 25.6 g of so-drum hydroxide and 38.35 g of 2-nitro-2'-hydroxy-3',5'-bis-tert.-amylazobenzene are added. The mixture is stirred at 70-75C for one to two hours, and owe ml of water are 20 then added. The precipitated crystals are filtered off, are washed with water and are dried at 60-70C in vacua.
The product is a high yield of 2,4-di-tert.-amyl-6-~2'-benzotriazolyl3-phenol.
Example 2: A suspension of 9.2 9 of sodium in 400 9 of 25 isopropanol is reflexed in a 1.5 lithe sulfonating flask until a solution is formed. To this are added, at 60C, 3.2 9 of 1,4-naphthoquinone, 2.1 9 of sodium bisulfite and 71 9 of2-nitro-2'-hydroxy-3'~5'-b;s-tert.-butylazobenzenee. The mixture is stirred at 6ûC for between half an hour and a 30 full hour. 20 9 of 17 per cent by volume aqueous sulfuric acid and 100 ml of warm water at 60-70C are then added drops. The precipitated crystals are filtered and are washed with warm 60 per cent by weight aqueous methanol and with warm water. Drying at 70 80C in vacua produces Dow-35 tert.-butyl-6-(2'-benzotriazolyl)-phenol in a high yield.
Example 3: A 75D ml sulfonating flask is charged with 220 9 of sec.-butanol, 34.7 g of 2-nitro-4-chloro-2'-hydroxy-3'-Lo tert.-butyl-5-methylazobenzene~ 2.3 g of 2,3-dichloronaph-thoquinone and 26 g of sun per cent by weight aqueous sodium hydroxide solution. The mixture is stirred at 40-45C for two hours and at 70-75C for three hours. 500 ml of water 5 are added drops. The precipitated crystals are filtered off, are washed with water, and are dried at 60-70C in vacua. The product is a high yield of 2-tert.-butyl-4-methyl-6~t4'-chloro-2'-benzotriazolyl)-phenol.
Example 4: A 750 ml sulfonating flask is charged with 300 10 g of cyclohexanol~ 35.S g of 2-nitro-2'-hydroxy-3',5'-bis-tert.-butylazobenzene~ 2.3 9 of 2,3-dichloronaphthoqui-none and 25.6 g of sodium hydroxide. The mixture is stirred at 70~75C for three hours and is brought to pi 1.5 with 5 per cent by volume aqueous hydrochloric acid. The aqueous phase is separated off and discarded 15 The organic phase is washed with water and cooled down to -5C. A high yield of 2,4-di-tert.-butyl-6-(2'-benzotri-azolyl)-phenol crystallizes out.
5: 200 g of isopropanol are heated to 60C in a 20 750 ml sulfonating flask, and 1 g of sodium bisulfite, 1.6 g of 1,4-naphthoquinone, 14 g of sodium hydroxide and 35.5 9 of 2-n;tro-2'-hydroxy-3',5'-b;s-tert.-butylazobenzenee are then added The mixture us stirred at 75-80C for two hours and 18 9 of 17 per cent by volume aqueous sulfuric acid 25 and 50 ml of warm water are then added drops. The pro-cip;tated crystals are washed with warm methanol and then with warm water The product is a high yield of Dow-tert.-butyl-6~ benzotriazolyl)-phenol.
Claims (8)
1. A process for preparing 2-(2'-hydroxyphenyl)-benzo-triazoles from 2-nitro-2'-hydroxyazobenzenes, which compri-ses reducing a 2-nitro-2'-hydroxyazobenzene compound in a strongly basic medium in the presence of an aromatic di-hydroxy or dioxo compound as catalyst and of an alcohol having more than one carbon atom.
2. The process according to claim 1, wherein there are prepared, from compounds of the formula II, compounds of the formula I
I
II
in which R1 is hydrogen or halogen, R2 is hydrogen, alkyl, alkoxy or halogen, R3 is hydrogen, alkyl, cycloalkyl, aral-kyl or aryl, and R4 is hydrogen, alkyl, cycloalkyl, aral-kyl, aryl or alkoxy.
I
II
in which R1 is hydrogen or halogen, R2 is hydrogen, alkyl, alkoxy or halogen, R3 is hydrogen, alkyl, cycloalkyl, aral-kyl or aryl, and R4 is hydrogen, alkyl, cycloalkyl, aral-kyl, aryl or alkoxy.
3. The process according to claim 1, wherein there are prepared, from compounds of the formula II, compounds of the formula I in which R1 is hydrogen or chlorine, R2 is hydrogen, alkyl having 1 to 5 carbon atoms, alkoxy having 1 to 4 carbon atoms or chlorine, R3 is hydrogen, alkyl hav-ing 1 to 12 carbon atoms, cycloalkyl having 5 to 8 carbon atoms or aralkyl having 7 to 9 carbon atoms, and R4 is hydrogen, alkyl having 1 to 12 carbon atoms, cycloalkyl hav-ing 5 to 8 carbon atoms, aralkyl having 7 to 9 carbon atoms, phenyl or alkoxy having 1 to 12 carbon atoms.
4. The process according to claim 1, wherein the alkali metal hydroxides or alkali metals are used in amounts of at least 1 mole equivalent relative to the substrate to be reduced.
5. The process according to claim 1, wherein the alco-hol is isopropanol or sec.-butanol.
6. The process according to claim 1, wherein the aro-matic dihydroxy compound acting as catalyst is a benzodiol which is unsubstituted or substituted by alkyl or halogen and the aromatic dioxo compound acting as catalyst is a naphthoquinone which is unsubstituted or substituted by halogen, hydroxyl, alkyl, dialkylamino, piperidino or morpholino.
7. The process according to claim 1, wherein the reduction is carried out in a medium which contains at most 15 % by volume of water, if any.
8. The process according to claim 1, wherein an alkal; metal bisulfite or ammonium bisulfite is used as a cocatalyst in addition to the catalyst.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000455004A CA1221701A (en) | 1984-05-24 | 1984-05-24 | Process for preparing 2-(2'-hydroxyphenyl)- benzotriazoles from 2-nitro-2"-hydroxyazobenzenes |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000455004A CA1221701A (en) | 1984-05-24 | 1984-05-24 | Process for preparing 2-(2'-hydroxyphenyl)- benzotriazoles from 2-nitro-2"-hydroxyazobenzenes |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1221701A true CA1221701A (en) | 1987-05-12 |
Family
ID=4127923
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000455004A Expired CA1221701A (en) | 1984-05-24 | 1984-05-24 | Process for preparing 2-(2'-hydroxyphenyl)- benzotriazoles from 2-nitro-2"-hydroxyazobenzenes |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1221701A (en) |
-
1984
- 1984-05-24 CA CA000455004A patent/CA1221701A/en not_active Expired
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