Patent US2492085A successfully refreshed from Google Patents.
Patent US4041044A successfully refreshed from Google Patents.
US4041044A
Expired / Lapsed
US
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Process for the production of 2-aryl-2H-benzotriazoles
Assignee: Novartis Corp
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Filing: 1975-10-15
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Granted: 1977-08-09
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Expires: 1995-10-15
Abstract
Abstract 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.
Inventors
- 👤 Howard L. White
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 23:51
CPC Classifications
C; C07; C07D; C07D249/00; C07D249/16; C07D249/18; C07D249/20
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
144 words
An improved process for the production of 2-aryl-2H-benzotriazoles of the formula I ##STR9## wherein R 1 is hydrogen, R 2 is hydrogen or chlorine, R 3 is methyl, sec-butyl, tert-butyl, tert-amyl, tert-octyl, cyclohexyl, chlorine or carboxyethyl, R 4 is hydrogen, and R 5 is chlorine, methyl, tert-butyl, sec-butyl, tert-amyl, tert-octyl or α-methylbenzyl by the reduction at a temperature between about 55° to about 73° C. of the corresponding o-nitroazobenzene intermediate ##STR10## by adding zinc to an aqueous alkali metal hydroxide medium containing said o-nitroazobenzene intermediate wherein the improvement comprises employing an initial ratio of moles of alkali to moles of o-nitroazobenzene intermediate in the range of 0.2 to 0.848/1 in the presence of an amount of iron impurities in the reaction system of less than 150 ppm based on zinc used, and with no additional alkali or o-nitroazobenzene being added during the reduction reaction.
Claim 2
Dependent Claim
144 words
An improved process for the production of 2-aryl-2H-benzotriazoles of the formula I ##STR9## wherein R 1 is hydrogen, R 2 is hydrogen or chlorine, R 3 is methyl, sec-butyl, tert-butyl, tert-amyl, tert-octyl, cyclohexyl, chlorine or carboxyethyl, R 4 is hydrogen, and R 5 is chlorine, methyl, tert-butyl, sec-butyl, tert-amyl, tert-octyl or α-methylbenzyl by the reduction at a temperature between about 55° to about 73° C. of the corresponding o-nitroazobenzene intermediate ##STR10## by adding zinc to an aqueous alkali metal hydroxide medium containing said o-nitroazobenzene intermediate wherein the improvement comprises employing an initial ratio of moles of alkali to moles of o-nitroazobenzene intermediate in the range of 0.2 to 0.848/1 in the presence of an amount of iron impurities in the reaction system of less than 150 ppm based on zinc used, and with no additional alkali or o-nitroazobenzene being added during the reduction reaction.
Claim 3
Dependent Claim
41 words
The process according to claim 1 wherein the ratio of moles of alkali to moles of o-nitroazobenzene intermediate is 0.3-0.7/1 in the presence of an amount of iron impurities in the reaction system less than 100 ppm based on zinc used.
Claim 4
Dependent Claim
42 words
The process according to claim 1 wherein the ratio of moles of alkali to moles of o-nitroazo intermediate is 0.3-0.6/1 in the presence of an amount of iron impurities in the reaction system of less than 50 ppm based on zinc used.
Claim 5
Dependent Claim
19 words
The process according to claim 1 further comprising carrying out the reduction reaction in an aqueous polar/non-polar solvent mixture.
Claim 6
Dependent Claim
15 words
The process according to claim 4 wherein the polar/non-polar solvent mixture is aqueous isopropanol/mineral spirits.
Claim 7
Dependent Claim
11 words
The process according to claim 1 for the production of 2-(2-hydroxy-3,5-di-tert-amylphenyl)-2H-benzotriazole.
Claim 8
Dependent Claim
11 words
The process according to claim 1 for the production of 5-chloro-2-(2-hydroxy-3,5-di-tert-butylphenyl-2H-benzotriazole.
Claim 9
Dependent Claim
11 words
The process according to claim 1 for the production of 5-chloro-2-(2-hydroxy-3-tert-butyl-5-methylphenyl)-2H-benzotriazole.
Claim 10
Dependent Claim
11 words
The process according to claim 1 for the production of 2-(2-hydroxy-3-(α-methylbenzyl)-5-methylphenyl)-2H-benzotriazole.
Claim 11
Dependent Claim
136 words
An improved process for the production of 2-aryl-2H-benzotriazoles of the formula I ##STR11## wherein R 1 is hydrogen, R 2 is hydrogen or chlorine, R 3 is methyl, sec-butyl, tert-butyl, tert-amyl, tert-octyl, cyclohexyl, chlorine or carboxyethyl, R 4 is hydrogen, and R 5 is hydrogen by the reduction at a temperature between about 45° and 75° C. of the corresponding o-nitroazobenzene intermediate ##STR12## by adding zinc to an aqueous alkali metal hydroxide medium containing said o-nitroazobenzene intermediate wherein the improvement comprises employing an initial ratio of moles of alkali to moles of o-nitroazobenzene intermediate in the range of 1.2 to 1.7/1 in the presence of an amount of iron impurities in the reaction system of less than 150 ppm based on zinc used, and with no additional alkali or o-nitroazobenzene being added during the reduction reaction.
Claim 12
Dependent Claim
136 words
An improved process for the production of 2-aryl-2H-benzotriazoles of the formula I ##STR11## wherein R 1 is hydrogen, R 2 is hydrogen or chlorine, R 3 is methyl, sec-butyl, tert-butyl, tert-amyl, tert-octyl, cyclohexyl, chlorine or carboxyethyl, R 4 is hydrogen, and R 5 is hydrogen by the reduction at a temperature between about 45° and 75° C. of the corresponding o-nitroazobenzene intermediate ##STR12## by adding zinc to an aqueous alkali metal hydroxide medium containing said o-nitroazobenzene intermediate wherein the improvement comprises employing an initial ratio of moles of alkali to moles of o-nitroazobenzene intermediate in the range of 1.2 to 1.7/1 in the presence of an amount of iron impurities in the reaction system of less than 150 ppm based on zinc used, and with no additional alkali or o-nitroazobenzene being added during the reduction reaction.
Claim 13
Dependent Claim
41 words
The process according to claim 10 wherein the ratio of moles of alkali to moles of o-nitroazobenzene intermediate is 1.2-1.4/1 in the presence of an amount of iron impurities in the reaction system less than 100 ppm based on zinc used.
Claim 14
Dependent Claim
44 words
The process according to claim 10 wherein the ratio of moles of alkali to moles of o-nitroazo intermediate is 1.2 to 1.3/1 in the presence of an amount of iron impurities in the reaction system of less than 50 ppm based on zinc used.
Claim 15
Dependent Claim
18 words
The process according to claim 10 further comprising carrying out the reduction reaction in an aqueous/aromatic solvent mixture.
Claim 16
Dependent Claim
12 words
The process according to claim 13 wherein the aromatic solvent is toluene.
Claim 17
Dependent Claim
11 words
The process according to claim 10 for the production of 2-(2-hydroxy-5-methylphenyl)-2H-benzotriazole.
Claim 18
Dependent Claim
11 words
The process according to claim 10 for the production of 2-(2-hydroxy-5-tert-octylphenyl)-2H-benzotriazole.
References Cited (Backward Citations)
US3230194A
Cited
US3773751A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-08-08 | 1981-02-07 | 1981-08-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-08-08 | 1985-02-07 | 1985-08-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-08-08 | 1989-02-07 | 1989-08-09 | $7700.00 | Window Closed / Lapsed |