US4033986A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for the preparation of 4-bromo-1,8-naphthalic acid anhydride
Assignee: CNA Holdings LLC
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Filing: 1976-02-11
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Granted: 1977-07-05
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Expires: 1996-02-11
Abstract
Abstract A novel method for the preparation of 4-bromo-1,8-naphthalic acid anhydride is disclosed. This method is carried out by the bromination, with alkali metal bromide or molecular bromine in the presence of a hypohalite, of a di-alkali metal salt of 1,8-naphthalic acid in aqueous solution at a pH of between 6.5 and 9.5 and at a temperature of between 0° and 30° C. to a di-alkali metal salt of 4-bromo-1,8-naphthalic acid and cyclizing to produce 4-bromo-1,8-naphthalic acid anhydride. This novel direct bromination method produces the desired product in good yields and high purity. 4-Bromo-1,8-naphthalic acid anhydride is a valuable intermediate for the preparation of dyestuffs, pigments and optical brighteners.
Inventors
- 👤 Richard L. Castenson
- 👤 James R. Hazen
- 👤 Rex Y. Tien
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 06:00
CPC Classifications
C; C07; C07C; C07C63/00; C07C63/68; C07C63/72; C07C51/00; C07C51/347; C07C51/363
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
74 words
A process for the preparation of 4-bromo-1,8-naphthalic acid anhydride which comprises brominating a di-alkali metal salt of 1,8-naphthalic acid in an aqueous solution at a pH between 6.5 and 9.5 to the di-alkali metal salt of 4-bromo-1,8-naphthalic acid with a brominating agent comprising (1) an alkali metal bromide, or (2) molecular bromine, in the presence of either (a) a hypochlorite, or (b) chlorine gas and alkali, at a temperature between 0° and 30° C.
Claim 2
Dependent Claim
74 words
A process for the preparation of 4-bromo-1,8-naphthalic acid anhydride which comprises brominating a di-alkali metal salt of 1,8-naphthalic acid in an aqueous solution at a pH between 6.5 and 9.5 to the di-alkali metal salt of 4-bromo-1,8-naphthalic acid with a brominating agent comprising (1) an alkali metal bromide, or (2) molecular bromine, in the presence of either (a) a hypochlorite, or (b) chlorine gas and alkali, at a temperature between 0° and 30° C.
Claim 3
Dependent Claim
16 words
The process as defined in claim 1 wherein the temperature is between 20° and 25° C.
Claim 4
Dependent Claim
16 words
The process as defined in claim 1 wherein the di-alkali metal salt is the potassium salt.
Claim 5
Dependent Claim
29 words
The process as defined in claim 1 wherein the pH is between 7.2 and 7.8 and the brominating agent is sodium or potassium bromide and sodium or potassium hypochlorite.
Claim 6
Dependent Claim
41 words
The process as defined in claim 1 wherein the di-alkali metal salt of 1,8-naphthalic acid is the di-sodium salt, the pH is between 7.2 and 7.8 and the brominating is carried out by successive addition of molecular bromine and sodium hypochlorite.
Claim 7
Dependent Claim
43 words
The process as defined in claim 1 wherein the di-alkali metal salt of 1,8-naphthalic acid is the di-potassium salt, the pH is between 8.5 and 9.0 and the brominating is carried out by successive addition of molecular bromine and sodium or potassium hypochlorite.
Claim 8
Dependent Claim
19 words
The process as defined in claim 1 wherein the brominating is carried out in the presence of calcium hypochlorite.
Claim 9
Dependent Claim
20 words
The process as defined in claim 1 wherein the brominating is carried out in the presence of chlorine and alkali.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-07-04 | 1981-01-03 | 1981-07-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-07-04 | 1985-01-03 | 1985-07-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-07-04 | 1989-01-03 | 1989-07-05 | $7700.00 | Window Closed / Lapsed |