US3761474A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Purification of crude cyanuric acid
Assignee: FMC Corp
•
Filing: 1971-03-22
•
Granted: 1973-09-25
•
Expires: 1991-03-22
Abstract
Abstract Crude cyanuric acid obtained by pyrolysis of urea is purified by extracting the impurities with an extraction acid solution. The extraction acid solution containing the impurities can then be digested to convert the impurities to cyanuric acid without any of the difficulties associated with digesting crude cyanuric acid in an acid slurry.
Inventors
- 👤 R Mesiah
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 12:14
CPC Classifications
C; C07; C07C; C07C51/00; C07C51/16; C07C51/21; C07C51/255; C07C51/265
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
27 words
The process of claim 1 in which the extraction solution is present in an amount greater than 200 percent of the weight of the crude cyanuric acid.
Claim 2
Dependent Claim
25 words
The process of claim 1 in which the extraction acid solution is selected from the group consisting of sulfuric, nitric, hydrobromic, hydrochloric and phosphoric acids.
Claim 3
Dependent Claim
24 words
The process of claim 1 in which the extraction solution is an aqueous sulfuric acid solution contained between 10 and 30 percent sulfuric acid.
Claim 4
Dependent Claim
17 words
The process of claim 1 in which the temperature during extraction is between 65* and 75* C.
Claim 5
Dependent Claim
14 words
The process of claim 1 in which the contacting time is about 10 minutes.
References Cited (Backward Citations)
US2768167A
Cited
US2943088A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-09-24 | 1977-03-26 | 1977-09-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-09-24 | 1981-03-26 | 1981-09-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-09-24 | 1985-03-26 | 1985-09-25 | $7700.00 | Window Closed / Lapsed |