US4396766A
Expired / Lapsed
US
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Process for producing sodium and zinc pyrithione
Assignee: Olin Corp
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Filing: 1982-04-28
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Granted: 1983-08-02
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Expires: 2002-04-28
Abstract
Abstract Disclosed is a process for producing a zinc pyrithione product having an acceptable white or off-white color and containing substantially no undesired 2-hydroxypyridine-N-oxide or metal salt complexes thereof, by (1) making sodium pyrithione by reacting a 2-halopyridine-N-oxide with sodium hydrosulfide and sodium carbonate (or a mixture of sodium carbonate and sodium hydroxide) under selected addition temperatures and reaction temperatures and in selected mole ratios; followed by (2) making zinc pyrithione by reacting the sodium pyrithione with a zinc salt.
Inventors
- 👤 Douglas A. Farmer, Jr.
- 👤 Lawrence E. Katz
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 04:38
CPC Classifications
C; C07; C07D; C07D213/00; C07D213/02; C07D213/89
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
162 words
A process for preparing zinc pyrithione comprising the steps: (a) adding sodium hydrosulfide and a base selected from the group consisting of sodium carbonate and sodium hydroxide to an aqueous solution of a 2-halopyridine-N-oxide selected from the group consisting of 2-bromopyridine-N-oxide and 2-chloropyridine-N-oxide, at a temperature below about 70° C. (i) wherein the mole ratio of the sum of moles of said sodium hydrosulfide and said base to said 2-halopyridine-N-oxide is at least about 2:1; (ii) wherein the mole ratio of said sodium hydrosulfide to said 2-halopyridine-N-oxide is at least about 1:1; (iii) wherein the mole ratio of said base to said 2-halopyridine-N-oxide is at least about 0.75:1; and (iv) wherein said base is comprised of at least about 10 mole % of sodium carbonate; (b) heating the resultant mixture of step (a) to about 75° C. to about 105° C. for sufficient time to form sodium pyrithione; and (c) reacting said sodium pyrithione with a zinc salt to form zinc pyrithione.
Claim 2
Dependent Claim
162 words
A process for preparing zinc pyrithione comprising the steps: (a) adding sodium hydrosulfide and a base selected from the group consisting of sodium carbonate and sodium hydroxide to an aqueous solution of a 2-halopyridine-N-oxide selected from the group consisting of 2-bromopyridine-N-oxide and 2-chloropyridine-N-oxide, at a temperature below about 70° C. (i) wherein the mole ratio of the sum of moles of said sodium hydrosulfide and said base to said 2-halopyridine-N-oxide is at least about 2:1; (ii) wherein the mole ratio of said sodium hydrosulfide to said 2-halopyridine-N-oxide is at least about 1:1; (iii) wherein the mole ratio of said base to said 2-halopyridine-N-oxide is at least about 0.75:1; and (iv) wherein said base is comprised of at least about 10 mole % of sodium carbonate; (b) heating the resultant mixture of step (a) to about 75° C. to about 105° C. for sufficient time to form sodium pyrithione; and (c) reacting said sodium pyrithione with a zinc salt to form zinc pyrithione.
Claim 3
Dependent Claim
10 words
The process of claim 1 wherein said 2-halopyridine-N-oxide is 2-chloropyridine-N-oxide.
Claim 4
Dependent Claim
15 words
The process of claim 1 wherein said base is 100 mole % of sodium carbonate.
Claim 5
Dependent Claim
14 words
The process of claim 3 wherein said sodium carbonate is added in solid form.
Claim 6
Dependent Claim
30 words
The process of claim 1 wherein the mole ratio of the sum of moles of said sodium hydrosulfide and base to said 2-halopyridine-N-oxide is from about 2:1 to about 3:1.
Claim 7
Dependent Claim
22 words
The process of claim 1, wherein the mole ratio of said sodium hydrosulfide to 2-halopyridine-N-oxide is from about 1:1 to about 1.25:1.
Claim 8
Dependent Claim
22 words
The process of claim 1, wherein the mole ratio of said base to said 2-halopyridine-N-oxide is from about 1:1 to about 1.2:1.
Claim 9
Dependent Claim
26 words
The process of claim 1, wherein the temperature at which said base and sodium hydrosulfide is added is from about 20° C. to about 65° C.
Claim 10
Dependent Claim
162 words
A process for preparing zinc pyrithione comprising the steps: (a) adding sodium hydrosulfide and a base selected from the group consisting of sodium carbonate and sodium hydroxide to an aqueous solution of 2-chloropyridine-N-oxide at a temperature from about 20° C. to about 65° C. (i) wherein the mole ratio of the sum of moles of said sodium hydrosulfide and said base to said 2-chloropyridine-N-oxide is from about 2:1 to about 3:1; (ii) wherein the mole ratio of said sodium hydrosulfide to said 2-chloropyridine-N-oxide is from about 1:1 to about 1.25:1; (iii) wherein the mole ratio of said base to said 2-chloropyridine-N-oxide is from about 1:1 to about 1.2:1; and (iv) wherein said base is comprised of at least about 10 mole % of sodium carbonate; (b) heating the resultant mixture of step (a) to about 75° C. to about 105° C. for sufficient time to form sodium pyrithione; and (c) reacting said sodium pyrithione with a zinc salt to form zinc pyrithione.
Claim 11
Dependent Claim
162 words
A process for preparing zinc pyrithione comprising the steps: (a) adding sodium hydrosulfide and a base selected from the group consisting of sodium carbonate and sodium hydroxide to an aqueous solution of 2-chloropyridine-N-oxide at a temperature from about 20° C. to about 65° C. (i) wherein the mole ratio of the sum of moles of said sodium hydrosulfide and said base to said 2-chloropyridine-N-oxide is from about 2:1 to about 3:1; (ii) wherein the mole ratio of said sodium hydrosulfide to said 2-chloropyridine-N-oxide is from about 1:1 to about 1.25:1; (iii) wherein the mole ratio of said base to said 2-chloropyridine-N-oxide is from about 1:1 to about 1.2:1; and (iv) wherein said base is comprised of at least about 10 mole % of sodium carbonate; (b) heating the resultant mixture of step (a) to about 75° C. to about 105° C. for sufficient time to form sodium pyrithione; and (c) reacting said sodium pyrithione with a zinc salt to form zinc pyrithione.
Claim 12
Dependent Claim
15 words
The process of claim 9, wherein said base is 100 mole % of sodium carbonate.
Claim 13
Dependent Claim
14 words
The process of claim 10, wherein said sodium carbonate is added in solid form.
Claim 14
Dependent Claim
167 words
In a process for preparing sodium pyrithione which comprises reacting a 2-halopyridine-N-oxide with sodium hydrosulfide and a base to form sodium pyrithione, the improvement which comprises (a) adding said sodium hydrosulfide and a base selected from the group consisting of sodium carbonate and sodium hydroxide to an aqueous solution of a 2-halopyridine-N-oxide selected from the group consisting of 2-bromopyridine-N-oxide and 2-chloropyridine-N-oxide, at a temperature below about 70° C. (i) wherein the mole ratio of the sum of moles of said sodium hydrosulfide and said base to said 2-halopyridine-N-oxide is at least about 2:1; (ii) wherein the mole ratio of said sodium hydrosulfide to said 2-halopyridine-N-oxide is at least about 1:1; (iii) wherein the mole ratio of said base to said 2-halopyridine-N-oxide is at least about 0.75:1; and (iv) wherein said base is comprised of at least about 10 mole % of sodium carbonate; (b) heating the resultant mixture of step (a) to about 75° C. to about 105° C. for sufficient time to form said sodium pyrithione.
Claim 15
Dependent Claim
167 words
In a process for preparing sodium pyrithione which comprises reacting a 2-halopyridine-N-oxide with sodium hydrosulfide and a base to form sodium pyrithione, the improvement which comprises (a) adding said sodium hydrosulfide and a base selected from the group consisting of sodium carbonate and sodium hydroxide to an aqueous solution of a 2-halopyridine-N-oxide selected from the group consisting of 2-bromopyridine-N-oxide and 2-chloropyridine-N-oxide, at a temperature below about 70° C. (i) wherein the mole ratio of the sum of moles of said sodium hydrosulfide and said base to said 2-halopyridine-N-oxide is at least about 2:1; (ii) wherein the mole ratio of said sodium hydrosulfide to said 2-halopyridine-N-oxide is at least about 1:1; (iii) wherein the mole ratio of said base to said 2-halopyridine-N-oxide is at least about 0.75:1; and (iv) wherein said base is comprised of at least about 10 mole % of sodium carbonate; (b) heating the resultant mixture of step (a) to about 75° C. to about 105° C. for sufficient time to form said sodium pyrithione.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1986-08-01 | 1987-01-31 | 1987-08-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-08-01 | 1991-01-31 | 1991-08-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-08-01 | 1995-01-31 | 1995-08-02 | $7700.00 | Window Closed / Lapsed |