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

Definitions

• This invention provides a new and perticularly efficient environmentally Safe process for preparing 5- methyl-1.2,4 triazolo[3,4-b] benzothiazole in aqueous slurry form with either elimination or prevention of biproduct impurities like Azo ( A ) , Hydrazo ( B ) , & Triazolo benzothiazolo amino ( C ) compounds by the use of p-Toluene Sulphonic acid as a efficient acid catalyst during process .
• Tricyclazole is described and claimed in US publications . 4, 064, 261 issued 20 sept. 1977 . 984,288 issued 22 Jan. 1980 in Korean patent .
• Taiwanese patent 132 issued 7 Aug. 1976 in Taiwanese patent .
• Japan Kokai JP 8 267,586 issued in 1982 Japan Kokai JP 8 267,586 issued in 1982 .
• Japan Kokai JP 8 267,586 issued in 1982 Japan Kokai JP 8 267,586 issued in 1982 .
• Patent USP 764,026 has mentioned a method of production Of Tricyclazole from 2- amino - 4-methyl benzothiazole in one step without isolating Hydrazino intermediate in same reactor in 86- 93.1 % yield of 98.7 % Purity .
• p-Toluene sulphonic acid is utilised as a Effective acid promotor catalyst and is generally preferred to sulphuric acid because it is less damaging to the reactants and is solid ( handling ) to give highly pure product free from potential by- product impurities .
• p- Toluene sulphonic acid has been extensively used as Viscosity Reducer , surfactant , acid promotor , accelarator and cyclodehydration catalyst .
• Method of this invention is an industrial useful method that does not Possess the above defects .
• catalyst is used in the reaction , the entire product remains in the suspention form even after complete removal of xylene solvent in the final stages of the process and can be conveniently pumped into water to separate the final product in slurry form which can be easily filtered or centrifused. Further use of efficient catalyst has minimised or eliminated impurities formation .
• Detailed description of the invention . .
• This invention is concerned with the production of agrochemical namely 5- methyl - 1,2,4 triazolo [ 3,4-b ] benzothiazole , well known systemic Fungicide for the control of piricularia Oryzae , the causative organism of rice blast from raw material 2- Amino 4- methyl benzothiazole .
• the improved process involves one pot reaction involving two steps .
• 2- amino - 4-methyl benzothiazole is reacted with 80 % commercial Hydrazine hydrate in the presence of hydrochloric acid and Ethylene glycol .
• the concentration of AMBT is approximately 1 gm mole Per 700 ml of ethylene glycol and 3 gm mole of Hydrazine hydrate .
• the reaction Mixture is heated under reflux at 115- 120° C for 3- 4 hrs.
• the reaction is monitered by Gas chromatography for the absence of raw material AMBT . when reaction has gone as far as is desired , the reaction mixture is cooled to 90° C and Xylene in the range of 400 ml per gm mole of AMBT is added .
• the mixture is further cooled to 30 ° C . Agitation is stopped. The layers are seperated . Ethylene glycol layer is seperated and recycled in the later batch . Recycled ethylene glycol is analysed for Hydrazine hydrate and Hydrochloric acid contents and taken into account when recycle process is used . 2- Hydrazino- 4- methyl benzothiazole containing Xylene layer is then washed with water. Xylene layer is neutralised with sodium carbonate.
• the neutralised mixture is distilled to remove water and ethylene glycol. Seperated Xylene is returned to the reaction mixture . Xylene -water mixture is removed at atm. Press, at 100- 110 ° C . While Xylene - Ethylene glycol is isolated under reduced pressure at about 100 ° C . Recovered ethylene glycol is reused in future Process .
• the contents of the vessel is cooled somewhat and 200-250 ml of Xylene per gram mole of product is added
• the mixture is reheated and azeotropic distillation is carried out to remove Substancially remaining formic acid to final liquid temp, of about 135-140 c C at ambient pressure . at this temp, heating is continued till all Xylene being distilled out.
• ethylene glycol , Xylene , Most of the excess Hydrazine hydrate and Hydrochloric acid can be recycled .
• Formic acid recovered from the process can be reconstituted with 98 % commertial formic acid to be used in future lots.
• the yield will be about 94-96 % of the theoritical yield based on the amount of AMBT & product will be 98- 99 % pure .
• the mixture is cooled to 90 ° C and 300 lit. of Xylene is added .
• the agitator is stopped . and allowed to stand 1 hrs.
• Lower Ethylene Glycol layer is removed to be recycled in subsequent batch .
• the mixture is cooled to 100 ° C and 150-200 lit.
• of Xylene is added distillation is continued till temp, of about 140 ° C and maintained till time when condensate is substantially pure Xylene .
• Most of the xylene is removed for recycling process .
• the heating is continued till no more Xylene distills out .
• reaction mass is cooled to 120 ° C and molton slurry is pumped into another suitable agitated vessel containing about 500 lit. of precooled water.
• the mixture is stirred for 1-2 hrs. at ambient temp, to dissolve all inorganic impurities .
• the slurry is filtered through basket centrifuge to collect solid product.
• the product is washed with 2 x 100 lit. water and some Xylene .
• Wet Tricylazole is dried in rotary vaccume evaporator at 100° C to get dried mass having ⁇ 0.5 % moisture content .

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)
• Catalysts (AREA)

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• 2003
  • 2003-01-07 WO PCT/IN2003/000005 patent/WO2004060897A1/en not_active Application Discontinuation
  • 2003-01-07 AU AU2003230185A patent/AU2003230185A1/en not_active Abandoned
  • 2003-01-07 EP EP03723042A patent/EP1618115A4/de not_active Withdrawn

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