US3981883A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Manufacture of 3-amino-2,1-benzisothiazoles
Assignee: BASF SE
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Filing: 1975-03-06
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Granted: 1976-09-21
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Expires: 1995-03-06
Abstract
Abstract Process for the manufacture of 3-amino-2,1-benzisothiazoles by oxidative ring closure of o-aminothiobenzamides, comprising the improvement of conducting the reaction in about 85 to 110% sulfuric acid which serves as solvent and oxidizing agent. 3-Amino-2,1-benzisothiazoles are important diazo components for blue azo dyes.
Inventors
- 👤 Rolf Niess
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 22:55
CPC Classifications
C; C07; C07D; C07D275/00; C07D275/04; C09; C09B; C09B29/00; C09B29/0025; C09B29/0074; C09B29/0077; C09B29/0081; C09B29/06; C09B29/08; C09B29/0805; C09B29/0807; C09B29/0809; C09B29/0811
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
99 words
In a process for the manufacture of 3-amino-2,1-benzisothiazoles of the formula ##SPC3## wherein the ring A is unsubstituted or substituted by chloro, bromo, nitro, C 1 - to C 4 -alkyl, benzyl, phenyl, amino, C 1 - to C 4 -alkylamino or -dialkylamino, phenylamino, acetyl, benzoyl, hydroxy, methoxy, ethoxy, phenoxy, sulfamoyl, C 1 - to C 4 -mono- or di-alkyl-substituted sulfamoyl, phenylsulfamoyl, methylsulfonyl, ethylsulfonyl or phenylsulfonyl, by oxidative ring closure of a thioamide of the formula ##SPC4## the improvement which comprises effecting the ring closure in about 85 to 110% sulfuric acid at temperatures of about 10° to 160°C.
Claim 2
Dependent Claim
99 words
In a process for the manufacture of 3-amino-2,1-benzisothiazoles of the formula ##SPC3## wherein the ring A is unsubstituted or substituted by chloro, bromo, nitro, C 1 - to C 4 -alkyl, benzyl, phenyl, amino, C 1 - to C 4 -alkylamino or -dialkylamino, phenylamino, acetyl, benzoyl, hydroxy, methoxy, ethoxy, phenoxy, sulfamoyl, C 1 - to C 4 -mono- or di-alkyl-substituted sulfamoyl, phenylsulfamoyl, methylsulfonyl, ethylsulfonyl or phenylsulfonyl, by oxidative ring closure of a thioamide of the formula ##SPC4## the improvement which comprises effecting the ring closure in about 85 to 110% sulfuric acid at temperatures of about 10° to 160°C.
Claim 3
Dependent Claim
12 words
The process according to claim 1 using 95 to 102% sulfuric acid.
Claim 4
Dependent Claim
13 words
The process according to claim 1 using a temperature between 40° and 90°C.
Claim 5
Dependent Claim
18 words
The process according to claim 1 wherein a catalytic amount of bromine is added to accelerate the reaction.
Claim 6
Dependent Claim
21 words
The process according to claim 1 using a 3 to 15-fold amount of sulfuric acid based on the weight of thioamide.
Claim 7
Dependent Claim
38 words
The process according to claim 1 using a 95 to 102% sulfuric acid in an amount of about 3 to 15 times the amount by weight of the thioamide and using a temperature of between 40° and 90°C.
Claim 8
Dependent Claim
32 words
The process according to claim 1 using a 96 to 100% sulfuric acid and a temperature of 60° to 100°C., the ring closure reaction being maintained for about 1 to 5 hours.
Claim 9
Dependent Claim
37 words
The process according to claim 1 wherein an oxidizing agent is added to the sulfuric acid reaction medium to accelerate the ring closure and the reaction is carried out at a temperature of about 10° to 60°C.
Claim 10
Dependent Claim
14 words
The process according to claim 8 using a temperature of about 20° to 45°C.
Claim 11
Dependent Claim
29 words
The process according to claim 8 using an added oxidizing agent selected from the group consisting of hydrogen peroxide, peracetic acid, perbenzoic acid, perphthalic acid, sulfuryl chloride and bromine.
References Cited (Backward Citations)
DE1445547A1
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-09-21 | 1980-03-22 | 1980-09-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-09-21 | 1984-03-22 | 1984-09-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-09-21 | 1988-03-22 | 1988-09-21 | $7700.00 | Window Closed / Lapsed |