US3852161A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Distillation of pentachlorophenol
Assignee: Dow Chemical Co
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Filing: 1973-07-05
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Granted: 1974-12-03
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Expires: 1993-07-05
Abstract
Abstract Purified pentachlorophenol is recovered in good yield by distilling the commercially available grade under reduced pressure in the presence of distillation residues from the Reimer-Tiemann preparation of salicylaldehyde. Preferably water is also added to the material to be distilled. The purified product is nearly colorless and nonblooming and it is essentially free of polychlorinated dibenzo-p-dioxins and phenoxyphenols.
Inventors
- 👤 M Yoshimine
- 👤 E Kobel
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 09:31
CPC Classifications
C; C07; C07C; C07C37/00; C07C37/68; C07C37/70; C07C37/74; C07C37/88
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
128 words
A PROCESS FOR PURIFYING IMPURE PENTACHLOROPHENOL WHICH COMPRISES DISTILLING SAID PENTACHLOROPHENOL AT SUBATMOSPHERIC PRESSURE FROM ITS MIXTURE WITH ABOUT 0.05-3 PERCENT BASED ON THE WEIGHT OF PENTACHLOROPHENOL OF THE DISTILLATION RESIDUE REMAINING FROM THE REIMER-TIEMANN PREPARATION OF SALICYLALDEHYDE WHEREIN SAID DISTILLATION RESIDUE IS THAT OBTAINED BY HEATING A REACTION MIXTURE OF PHENOL WITH AT LEAST ABOUT AN EQUIVALENT AMOUNT OF CHLOROFORM AND AQUEOUS SODIUM HYDROXIDE IN SUBSTANTIAL MOLAR EXCESS OVER THE CHLOROFROM AT ABOUT 50*C. TO THE BOILING POINT OF SAID REACTION MIXTURE UNTIL THE REACTION IS SUBSTANTIALLY COMPLETE, ACIDIFYING THE RESULTING REACTION MIXTURE WITH A STRONG MINERAL ACID, THEREBY FORMING AN OIL LAYER, AND DISTILLING SAID OIL LAYER UNTIL SUBSTANTIALLY A ALL OF THE PRODUCT SALICYALDEHYDE HAS BEEN SEPARATED BY DISTILLATION FROM THE THEREBY FORMED DISTILLATION RESIDUE.
Claim 2
Dependent Claim
128 words
A PROCESS FOR PURIFYING IMPURE PENTACHLOROPHENOL WHICH COMPRISES DISTILLING SAID PENTACHLOROPHENOL AT SUBATMOSPHERIC PRESSURE FROM ITS MIXTURE WITH ABOUT 0.05-3 PERCENT BASED ON THE WEIGHT OF PENTACHLOROPHENOL OF THE DISTILLATION RESIDUE REMAINING FROM THE REIMER-TIEMANN PREPARATION OF SALICYLALDEHYDE WHEREIN SAID DISTILLATION RESIDUE IS THAT OBTAINED BY HEATING A REACTION MIXTURE OF PHENOL WITH AT LEAST ABOUT AN EQUIVALENT AMOUNT OF CHLOROFORM AND AQUEOUS SODIUM HYDROXIDE IN SUBSTANTIAL MOLAR EXCESS OVER THE CHLOROFROM AT ABOUT 50*C. TO THE BOILING POINT OF SAID REACTION MIXTURE UNTIL THE REACTION IS SUBSTANTIALLY COMPLETE, ACIDIFYING THE RESULTING REACTION MIXTURE WITH A STRONG MINERAL ACID, THEREBY FORMING AN OIL LAYER, AND DISTILLING SAID OIL LAYER UNTIL SUBSTANTIALLY A ALL OF THE PRODUCT SALICYALDEHYDE HAS BEEN SEPARATED BY DISTILLATION FROM THE THEREBY FORMED DISTILLATION RESIDUE.
Claim 3
Dependent Claim
16 words
The process of claim 1 wherein water is also present in the pentachlorophenol-salicylaldehyde preparation residue mixture.
Claim 4
Dependent Claim
15 words
The process of claim 2 wherein the penta-chlorophenol distillation pressure is below 100 mm Hg-absolute.
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) | 1977-12-02 | 1978-06-03 | 1978-12-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-12-02 | 1982-06-03 | 1982-12-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-12-02 | 1986-06-03 | 1986-12-03 | $7700.00 | Window Closed / Lapsed |