GB2027700A - Process for the Preparation of Tricyclazole - Google Patents
Process for the Preparation of Tricyclazole Download PDFInfo
- Publication number
- GB2027700A GB2027700A GB79257520A GB7925752A GB2027700A GB 2027700 A GB2027700 A GB 2027700A GB 79257520 A GB79257520 A GB 79257520A GB 7925752 A GB7925752 A GB 7925752A GB 2027700 A GB2027700 A GB 2027700A
- Authority
- GB
- United Kingdom
- Prior art keywords
- formic acid
- tricyclazole
- reaction
- aromatic hydrocarbon
- xylene
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D513/00—Heterocyclic compounds containing in the condensed system at least one hetero ring having nitrogen and sulfur atoms as the only ring hetero atoms, not provided for in groups C07D463/00, C07D477/00 or C07D499/00 - C07D507/00
- C07D513/02—Heterocyclic compounds containing in the condensed system at least one hetero ring having nitrogen and sulfur atoms as the only ring hetero atoms, not provided for in groups C07D463/00, C07D477/00 or C07D499/00 - C07D507/00 in which the condensed system contains two hetero rings
- C07D513/04—Ortho-condensed systems
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Nitrogen And Oxygen Or Sulfur-Condensed Heterocyclic Ring Systems (AREA)
- Thiazole And Isothizaole Compounds (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
- Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)
Abstract
A process for preparing 5-methyl- 1,2,4-triazolo[3,4-b]benzothiazole, effective in controlling rice blast, involves the reaction of 2-hydrazino- 4-methylbenzothiazole and excess formic acid and utilizes an aromatic hydrocarbon during work-up.
Description
SPECIFICATION
Process for the Preparation of Tricyclazole
This invention relates to an improved process of preparing tricyclazole, tricyclazole being the generic name for 5-methyl-l ,2,4-triazolo-[3,4b]benzothiazole.
U.S. Patent Specification No. 4,064,261 discloses that various triazolobenzoxazoles and triazolobenzothiazoles, including tricyclazole, are effective in the control of plant pathogenic organisms, especially the organism which causes rice blast. One of the methods described in that patent Specification for the preparation of the triazolo compounds involves the reaction of a 2hydrazinobenzothiazole or benzoxazole with a carboxylic acid. Tricyclazole is prepared by the reaction of 2-hydrazino-4-methylbenzothiazole with formic acid.
Heretofore, a portion of the excess formic acid employed has been recovered by distillation.
Isopropyl alcohol was added to the residue from the distillation to convert the remaining formic acid to the isopropyl ester and to precipitate the desired tricyclazole.
The recovery of tricyclazole in this manner using isopropyl alcohol suffers from several disadvantages. Firstly, only about 40 percent of the excess formic acid and 75 percent of the isopropyl alcohol can be recovered and reused.
Secondly, the tricyclazole product is contaminated with 2 1/2 to 3 percent of 2,2'hydrazobis(4-methylbenzothiazole) and 2,2'azobis(4-methylbenzothiazole). These impurities impart undesirable color to the product. The
Applicants have now discovered an improvement in the process for the preparation of tricyclazole from 2-hydrazino-4-methylbenzothiazole and formic acid which comprises adding an aromatic hydrocarbon solvent to the reaction mixture at the completion of the reaction and removing excess formic acid by azeotropic distillation, followed by crystallization and isolation of tricyclazole from the solvent. The yield and the purity of tricylazole are improved and the consumption of formic acid is reduced by about 40 percent.The two impurities, 2,2'-hydrazobis(4methylbenzothiazole) and 2,2'-azobis(4methylbenzothiazole), are presenf in the tricyclazole product in quantities of less than about 0.4 percent. Waste streams are also reduced.
This invention is an improvement in the process for the manufacture of tricyclazole by the reaction of 2-hydrazino-4methylbenzothiazole with formic acid. The improvement comprises using an aromatic hydrocarbon solvent rather than isoproyl alcohol in the workup of the reaction mixture. The aromatic hydrocarbon solvent is preferably selected from benzene, toluene and xylene.
Xylene is most preferred. At the completion of the reaction sufficient solvent is added to azeotropically remove the excess formic acid while keeping the tricyclazole product in solution
or in an easily handled slurry. Upon cooling the
mixture after the azeotropic distillation, the
tricyclazole which precipitates is recovered by
filtration, centrifugation or similar technique.
The aromatic hydrocarbon solvent may be
added upon completion of the reaction and all the
excess formic acid removed as an azeotrope.
However, it is preferred to first remove a portion sof the formic acid by distillation, then add the solvent and remove the remaining formic acid as
an azeotrope. Following the latter procedure,
enough formic acid is left after the initial
distillation to maintain a liquid mixture.
The reaction of 2-hydrazino-4 methylbenzothiazoie with formic acid is well
known; however, for completeness, it will be described below. To effect the reaction, the
reactants are contacted with one another. The
reaction consumes the reactants in equimolar amounts, producing tricyclazole and water.
Excess formic acid is used as the reaction
medium. The formic acid used is 80 percent or stronger, preferably 85 to 90 percent. The reaction goes forward under a wide range of temperatures, such as from about 500 to about 1 500C. It is convenient and preferred to conduct the reaction at the reflux temperature of the reaction mixture. The tricylcazole product is then
recovered in accordance with the improved procedure.
The improved process of the invention will be illustrated by the following non-limitative
Examples. The xylene utilized was "solvent-grade xylene" containing 18% of the para-isomer, 18% of the ortho-isomer, 38-42% of the meta-isomer and 2024% of the ethyl isomer.
Example 1
In a 500 ml. 3-neck flask equipped with an agitator, thermometer and condenser were places 66.5 g. of 2-hydrazino-4-methylbenzothiazole, 110.7 g. of 98% formic acid and 93.4 g. of recovered formic acid (78%). The mixture was heated under reflux at 110 C. for two hours.
Formic acid was removed by distillation to a pot temperature of 1 300C. The mixture was cooled to 800C and 200 ml. of toluene was added. The temperature dropped to 450C but no crystallization occurred. An azeotrope of formic acid and toluene was removed by distillation to a pot temperature of 11000. The mixture was allowed to cool to room temperature with crystallization occurring at about 550C. The slurry became too thick to stir at this temperature and an additional 50 ml. of toluene was added. The mixture was filtered and the filter cake was washed with 100 ml. of 12% sodium bicarbonate solution. The filter cake then was washed with 1 50 ml. of water followed by 50 ml. of toluene and was dried in vacuo over night at 650C. The yield of tricyclazole was 64.6 g. (92.3%) and assayed 1.98% impurities.The melting point was 183-1850C.
Example 2
In a 500 ml. 3-neck flask equipped with an agitator, thermometer and condenser were placed 66.5 g. of 2-hydrazino-4-methylbenzothiazole, 110.7 g. of 98% formic acid and 93.4 g of recovered formic acid (78%). The reaction mixture was heated under reflux for 2 hours at 11 00C.
Formic acid was removed by distillation to a pot temperature of 1 400C. and 150 ml. of xylene was added. An azeotrope of formic acid and xylene was removed by distillation to a pot temperature of 141 OC. Another 1 50 ml. of xylene was added and the mixture was cooled to room temperature.
Crystallization occurred at 1000C. just after the second 1 50 ml. of xylene was added. The tricyclazole product was removed by filtration and was washed with 50 ml. of xylene and dried in vacuo overnight at 650C. The yield was 59.7 g.
(91.1%) and impurities assayed at 0.56%. The melting point was 181-1850C.
Example 3
In a 2 1. 3-neck flask equipped with an agitator, thermometer and condenser were placed 199.5 g. of 2-hydrazino-4-methylbenzothiazole and 534 ml. of 86.7% formic acid. The mixture was heated under reflux for 2 hours at 1 090C.
During the heating between 900C and 1 090C crystals formed and then dissolved. The 2 hour reflux time began at the time of solution of the crystals. After refluxing, formic acid was removed by distillation to a pot temperature of 1300 C. The first 1 63 ml. removed was held apart from the rest of the distillate. The reaction mixture was cooled to 1000C. and 450 ml. of xylene was added. The remaining formic acid was removed azeotropically over a 3 hour period. The formic acid recovered in this manner was added to the second portion of formic acid recovered by distillation, giving a total of 363 ml. of recovered acid to be recycled.An additional 1 50 ml. of xylene was added to the residue from the distillation while maintaining the temperature at 1 35 0--1 400C. The mixture was allowed to cool to room temperature. Crystallization occured at 123"C. causing an exotherm to 1 250C. The product was recovered by filtration and washed with 1 50 ml. of xylene. The volume of combined filtrate and washings was 690 ml. The filter cake was dried in vacuo overnight at 850C. The yield was 180.6 g. (89.5%, corrected for purity); impurities assayed 0.47%. The melting point was 183-1 88.50C.
The combined filtrate and washing were distilled to recover 450 ml. of xylene to be recycled to the next reaction and 1 25 ml. of xylene to be added at the end of the azeotropic
distillation of the next reaction. At the end of the
distillation another 23.3 g. of product with an
assay of 53% was recovered.
Example 4
The procedure of Example 3 was repeated except that the formic acid used was obtained by adding 98% formic acid to the 363 ml. of formic acid recovered in Example 3 to give a total volume of 534 ml. of 87.6% formic acid. The 450
ml. of xylene added after distillation of the formic
acid was recovered from Example 3 as was 125
ml. of the 1 50 ml. of xylene added at the
completion of the azeotropic distillation. The yield
of tricyclazole was 1 85 g. (91.7%, corrected) and
impurities assayed 0.6%. The melting point was 182.5-1 880C. An additional 20.4 g. of product with an assay of 51% was recovered from the
mother liquor.
Claims (9)
1. A process for the manufacture of tricyclazole by reaction of 2-hydrazino-4-methylbenzothiazole with excess formic acid, characterized in that the product is recovered by adding an aromatic hydrocarbon solvent to the reaction mixture, azeotropically removing excess formic acid with the aromatic hydrocarbon solvent and recovering the tricyclazole from the solvent.
2, A process according to claim 1 , wherein the aromatic hydrocarbon solvent is selected from benzene, toluene and xylene.
3. A process according to claim 1, wherein the aromatic hydrocarbon solvent is xylene.
4. A process according to claim 1, wherein the aromatic hydrocarbon solvent is toluene.
5. A process according to any of claims 1 to 4, wherein a portion of the excess formic acid is removed by distillation 'prior to the addition of the aromatic hydrocarbon solvent.
6. A process according to any one of claims 1 to 5, wherein the reaction between the benzothiazole and formic acid is effected at a temperature between 50 and 1 500C.
7. Tricyclazole whenever prepared by a process according to any one of claims 1 to 6.
8. A process for preparing tricyclazole according to claim 1, substantially as hereinbefore described with reference to any one of the Examples.
9. Tricyclazole whenever prepared by the process of claim 8.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US93063878A | 1978-08-03 | 1978-08-03 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2027700A true GB2027700A (en) | 1980-02-27 |
| GB2027700B GB2027700B (en) | 1982-11-03 |
Family
ID=25459558
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB79257520A Expired GB2027700B (en) | 1978-08-03 | 1979-07-24 | Process for the preparation of tricyclazole |
Country Status (13)
| Country | Link |
|---|---|
| JP (1) | JPS5522680A (en) |
| BR (1) | BR7904678A (en) |
| CA (1) | CA1134367A (en) |
| DE (1) | DE2928867A1 (en) |
| ES (1) | ES482930A1 (en) |
| FR (1) | FR2432522A1 (en) |
| GB (1) | GB2027700B (en) |
| HU (1) | HU180743B (en) |
| IE (1) | IE48382B1 (en) |
| IL (1) | IL57808A (en) |
| IT (1) | IT1122311B (en) |
| MX (1) | MX5913E (en) |
| PH (1) | PH18848A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0213814A2 (en) * | 1985-08-09 | 1987-03-11 | Eli Lilly And Company | Synthesis of tricyclazole |
| EP1618115A1 (en) * | 2003-01-07 | 2006-01-25 | Indofil Chemicals Company | Industrial process for preparing environmentally safe tricyclazole |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CY1004A (en) * | 1971-10-12 | 1979-08-02 | Lilly Co Eli | Heterocyclic-fused triazole derivatives and their use in controlling plant pathogenic organisms |
| BE789918A (en) * | 1971-10-12 | 1973-04-11 | Lilly Co Eli | BENZOTHIAZOLES IN THE FIGHT AGAINST PHYTOPATHOGENIC ORGANISMS |
| HU165912B (en) * | 1972-10-10 | 1974-12-28 |
-
1979
- 1979-07-16 PH PH22785A patent/PH18848A/en unknown
- 1979-07-16 IL IL57808A patent/IL57808A/en not_active IP Right Cessation
- 1979-07-16 HU HU79EI872A patent/HU180743B/en not_active IP Right Cessation
- 1979-07-17 CA CA000331948A patent/CA1134367A/en not_active Expired
- 1979-07-17 DE DE19792928867 patent/DE2928867A1/en active Granted
- 1979-07-20 FR FR7918832A patent/FR2432522A1/en active Granted
- 1979-07-23 BR BR7904678A patent/BR7904678A/en not_active IP Right Cessation
- 1979-07-24 GB GB79257520A patent/GB2027700B/en not_active Expired
- 1979-07-24 IT IT24615/79A patent/IT1122311B/en active
- 1979-07-26 MX MX798255U patent/MX5913E/en unknown
- 1979-07-27 JP JP9664379A patent/JPS5522680A/en active Granted
- 1979-07-27 ES ES482930A patent/ES482930A1/en not_active Expired
- 1979-08-08 IE IE1415/79A patent/IE48382B1/en not_active IP Right Cessation
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0213814A2 (en) * | 1985-08-09 | 1987-03-11 | Eli Lilly And Company | Synthesis of tricyclazole |
| EP0213814A3 (en) * | 1985-08-09 | 1988-07-20 | Eli Lilly And Company | Synthesis of tricyclazole |
| EP1618115A1 (en) * | 2003-01-07 | 2006-01-25 | Indofil Chemicals Company | Industrial process for preparing environmentally safe tricyclazole |
| EP1618115A4 (en) * | 2003-01-07 | 2007-02-28 | Indofil Chemicals Company | Industrial process for preparing environmentally safe tricyclazole |
Also Published As
| Publication number | Publication date |
|---|---|
| CA1134367A (en) | 1982-10-26 |
| JPS5522680A (en) | 1980-02-18 |
| ES482930A1 (en) | 1980-09-01 |
| IL57808A (en) | 1983-06-15 |
| GB2027700B (en) | 1982-11-03 |
| FR2432522A1 (en) | 1980-02-29 |
| DE2928867A1 (en) | 1980-02-21 |
| IL57808A0 (en) | 1979-11-30 |
| IE791415L (en) | 1980-02-03 |
| BR7904678A (en) | 1980-07-08 |
| PH18848A (en) | 1985-10-14 |
| JPS6252754B2 (en) | 1987-11-06 |
| MX5913E (en) | 1984-08-23 |
| IE48382B1 (en) | 1984-12-26 |
| IT1122311B (en) | 1986-04-23 |
| IT7924615A0 (en) | 1979-07-24 |
| HU180743B (en) | 1983-04-29 |
| DE2928867C2 (en) | 1988-11-17 |
| FR2432522B1 (en) | 1983-11-18 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 19960724 |