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US4035379A
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Process for the production of 2-amino-benzothiazoles
Assignee: Lonza AG
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Filing: 1976-01-22
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Granted: 1977-07-12
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Expires: 1996-01-22
Abstract
Abstract A process for the production of a 2-amino-benzothiazole having the formula: ##STR1## wherein R 1 , R 2 , R 3 and R 4 are the same or different and are hydrogen, halogen, alkyl or alkoxy. A phenylthiourea having the formula: ##STR2## wherein R 1 , R 2 , R 3 and R 4 are defined as above, is added to a cyclization agent in the absence of a solvent and allowing the phenylthiourea to cyclize to form 2-amino-benzothiazole in salt form. Filtering the salt of the 2-amino-benzothiazole out of the reaction mixture.
Inventors
- 👤 Rudolf Fuchs
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 23:32
CPC Classifications
C; C07; C07D; C07D277/00; C07D277/60; C07D277/62; C07D277/68; C07D277/82
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
175 words
A process for the production of a salt of a 2-amino-benzothiazole having the formula: ##STR5## wherein R 1 , R 2 , R 3 and R 4 are the same or different and are hydrogen, halogen, alkyl having 1 to 10 carbon atoms or alkoxy having 1 to 10 carbon atoms, which comprises (a) adding a phenylthiourea having the formula: ##STR6## wherein R 1 , R 2 , R 3 and R 4 are defined as above, to a cyclization agent in the absence of a solvent and allowing said phenylthiourea to cyclize to form said 2-amino-benzothiazole in salt form, said cyclization step (a) being conducted for between 1 and 10 hours at a temperature between 30° and 100° C., said cyclization agent being a halogen, a sulfur halide, a sulfoxy halide, SbI 5 , SbF f or SbCl 5 , and said cyclization agent being present in an amount which is at least 6 times its stoichiometric amount, and (b) filtering said salt of said 2-amino-benzothiazole out of the reaction mixture of step (a).
Claim 2
Dependent Claim
175 words
A process for the production of a salt of a 2-amino-benzothiazole having the formula: ##STR5## wherein R 1 , R 2 , R 3 and R 4 are the same or different and are hydrogen, halogen, alkyl having 1 to 10 carbon atoms or alkoxy having 1 to 10 carbon atoms, which comprises (a) adding a phenylthiourea having the formula: ##STR6## wherein R 1 , R 2 , R 3 and R 4 are defined as above, to a cyclization agent in the absence of a solvent and allowing said phenylthiourea to cyclize to form said 2-amino-benzothiazole in salt form, said cyclization step (a) being conducted for between 1 and 10 hours at a temperature between 30° and 100° C., said cyclization agent being a halogen, a sulfur halide, a sulfoxy halide, SbI 5 , SbF f or SbCl 5 , and said cyclization agent being present in an amount which is at least 6 times its stoichiometric amount, and (b) filtering said salt of said 2-amino-benzothiazole out of the reaction mixture of step (a).
Claim 3
Dependent Claim
23 words
A process as described in claim 1 wherein said cyclization of step (a) is conducted at a temperature between 50° and 60° C.
Claim 4
Dependent Claim
15 words
A process as described in claim 1 wherein said cyclization agent is a sulfur halide.
Claim 5
Dependent Claim
14 words
A process as described in claim 1 wherein said cyclization agent is disulfur dichloride.
Claim 6
Dependent Claim
26 words
A process as described in claim 1 wherein said cyclization agent is present in an amount which is between 10 and 12 times its stoichiometric amount.
Claim 7
Dependent Claim
25 words
A process as described in claim 1 wherein said salt of said 2-amino-benzothiazole, after step (b) is purified and placed in the free compound form.
Claim 8
Dependent Claim
75 words
A process as described in claim 1 wherein (i) said salt of said 2-amino-benzothiazole, after step (b) is washed with a solvent for said cyclization agent to remove any cyclization agent from said 2-amino-benzothiazole, (ii) said salt of said 2-amino-benzothiazole from step (i) is dissolved in water, (iii) the solution of step (ii) is neutralized with a basic agent, said 2-amino-benzothiazole precipitating in crystalline form, and (iv) removing said 2-aminobenzothiazole precipitate from said neutralized solution.
Claim 9
Dependent Claim
34 words
A process as described in claim 7, wherein, between steps (ii) and (iii) said solution (ii) is treated with activated charcoal to bleach and clarify said solution (ii) containing said salt of said 2-amino-benzothiazole.
Claim 10
Dependent Claim
21 words
A process as described in claim 7 wherein said basic agent is sodium or potassium carbonate or hydroxide in aqueous solution.
Claim 11
Dependent Claim
16 words
A process as described in claim 7 wherein said basic agent is an aqueous ammonia solution.
Claim 12
Dependent Claim
19 words
A process as described in claim 7 wherein said removal of step (iv) is achieved by filtration or centrifugation.
Claim 13
Dependent Claim
33 words
A process as described in claim 1 wherein R 1 , R 2 , R 3 and R 4 are the same or different and are alkyl having 1 to 4 carbon atoms.
Claim 14
Dependent Claim
33 words
A process as described in claim 1 wherein R 1 , R 2 , R 3 and R 4 are the same or different and are alkoxy having 1 to 4 carbon atoms.
Claim 15
Dependent Claim
100 words
A process as described in claim 1 wherein said cyclization agent is disulfur dichloride, bromine, chlorine, fluorine, iodine, sulfur monochloride, S 2 Br 2 , sulfur dichloride SCl 2 , SCl 4 , S 2 F 2 , SF 4 , S 2 F 10 , SF 6 , SO 2 Cl 2 , S 2 O 5 Cl 2 , SO 2 F 2 , SO 2 ClF, SOBr 2 , SOCl 2 , SOF 2 , SOClF, S 2 OCl 4 , S 2 O 3 Cl 4 , SbI 5 , SbF 5 or SbCl 5 .
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-07-11 | 1981-01-10 | 1981-07-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-07-11 | 1985-01-10 | 1985-07-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-07-11 | 1989-01-10 | 1989-07-12 | $7700.00 | Window Closed / Lapsed |