Claims:
1. A process for the preparation of 2-methyl-3- biphenyl methanol [BMA] and cyhalothric acid, Cis-3-(2-chloro-3,3,3-trifluropro-1en-1-yl)-2,2-dimethyl cyclopropane carboxylic acid [MTH acid] comprising:

a) base initiated hydrolysis of bifenthrin residue in presence of suitable organic solvent and
b) isolating compound BMA;
c) colleting the filtrate from step b) and separating organic and aqueous phase;
d) acidifying aqueous phase with acid and
e) isolating MTH acid.

2. The process as claimed in claim 1 wherein in step (a) the base is selected from group of sodium hydroxide, potassium hydroxide, calcium hydroxide, cesium hydroxide, ammonia, sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate or the like, preferably the base used is sodium hydroxide.

3. The process as claimed in claim 1 wherein in step (a) the solvent is alcohol selected from methanol, ethanol, n-propanol, isopropanol, n-butanol or combinations thereof.

4. The process as claimed in claim 1 wherein catalyst is added in step (a) selected from the group consisting of Tetra butyl ammonium bromide [TBAB], Aliquot- 336, Benzene tri ethyl ammonium chloride [TEBA-Cl], Tetra butyl ammonium chloride [TBACl], or Ethyl triphenyl phosphonium bromide.

5. The process as claimed in claim 1 wherein in step (a) comprises treatment of bifenthrin residue at temperature in the range of 50 to 70°C for 2 to 4 hours.

6. The process as claimed in claim 1 wherein said isolation involves cooling the mass to room temperature after treatment in step (a) to obtain BMA.

7. The process as claimed in claim 1 wherein step (d) involves acidifying the aqueous phase with hydrochloric acid to obtain MTH acid.

8. The process as claimed in claim 1 wherein isolation in step (e) involves extraction of the mixture with suitable solvent selected from toluene, hexane, heptane, diisopropyl ether, methyl tertiary butyl ether or mixture thereof to obtain MTH acid.

9. The process as claimed in any one of the preceding claims wherein solvent is continuously recovered from steps (a) to (e) and used in the process of preparation of BMA and MTH acid.

10. The process as claimed in claim 1 wherein 2-methyl-3- biphenyl methanol and cyhalothric acid produced with purity more than 99% are used for preparation of bifenthrin.
, Description:
FIELD OF THE INVENTION

The present invention relates to novel, cleaner process for the environment sustainability that eliminate the incineration of the residue generated during Bifenthrin manufacturing process and produce intermediates for synthesis of bifenthrin.

BACKGROUND OF THE INVENTION

Pyrethroids are known to be active against acarids such as ticks and mites. For a broader pesticidal activity or for enhanced activity of one of the actives, such compounds are often used in combination. Bifenthrin, chemically known as 2-methyl biphenyl-3-ylmethyl-(Z)-(1RS)-suitable-3-(2-chloro-3,3,3-three fluoro-1-propenyl)-2,2-dimethyl cyclopropane carboxylic acid ester, is a pyrethroid insecticide.

Bifenthrin is a highly effective synthetic pyrethroid insecticide and acaricide. Bifenthrin has contact killing and stomach toxicity, without systemic and fumigation activity. Bifenthrin has a fast knockdown speed, a long residual effect, a wide insecticidal spectrum, and a good control effect on mites. It is mainly used to control various lepidopteran larvae, whiteflies, aphids, and herbivorous spider mites.

CN102827004A discloses method for preparing bifenthrin. The method includes performing transesterification between lambda-cyhalothric acid and low-molecular-weight alcohol in the presence of weakly acidic catalysts to obtain lambda-cyhalothric acid ester; and then performing transesterification between lambda acid ester and methyl-3-biphenylmethyanol under the catalysis effect of titanate catalysts to obtain the target product, namely the bifenthrin.

CN104628568A relates to a method for producing bifenthrin with a clean synthesizing process. Lambda-cyhalothric acid and 2-methyl-3-biphenylmethanol are adopted to react in a high-pressure kettle in the presence of a water-borne organic solvent and a catalyst, water generated in the reaction is moved out by the water-borne organic solvent, and a direct esterification reaction is carried out to obtain bifenthrin. The production method has the characteristics of high conversion rate of 2-biphenylmethanol, easily separated and recycled catalyst, small amount of three wastes in the synthesizing process and the like, and can meet the requirement of clean production.

The present invention provides a simple and industrially viable process for preparation of intermediates of bifenthrin in high yield and purity.

OBJECTS OF THE INVENTION

It is an object of the present invention to provide a cleaner and greener process for production of Bifenthrin and its intermediates.

An object of the present invention is to provide simple, cost effective and industrially viable process for preparation of Bifenthrin and its intermediates.

Another object of the present invention is to provide Bifenthrin and its intermediates with purity more than 98%.

It is an object of the present invention to provide a process for the preparation of 2-methyl-3- biphenyl methanol and cyhalothric acid, Cis-3-(2-chloro-3,3,3-trifluropro-1en-1-yl) -2,2-dimethyl cyclopropane carboxylic acid from Bifenthrin residue generated in the process of manufacture of Bifenthrin.

It is another object of the present invention to provide a process for the preparation of 2-methyl-3- biphenyl methanol and cyhalothric acid, Cis-3-(2-chloro-3,3,3-trifluropro-1en-1-yl) -2,2-dimethyl cyclopropane carboxylic acid with purity more than 99%.

It is another object of the present invention to provide to provide a process for the preparation of 2-methyl-3- biphenyl methanol and cyhalothric acid, Cis-3-(2-chloro-3,3,3-trifluropro-1en-1-yl) -2,2-dimethyl cyclopropane carboxylic acid from Bifenthrin residue which is reused into the manufacturing of Bifenthrin.

It is further object of the present invention to provide a process that eliminated the cost of incineration of residue and reduced the capital cost of manufacturing process of bifenthrin.

SUMMARY OF THE INVENTION

According to an aspect of the present invention there is provided a process for the preparation of 2-methyl-3- biphenyl methanol [BMA] and cyhalothric acid, Cis-3-(2-chloro-3,3,3-trifluropro-1en-1-yl)-2,2-dimethyl cyclopropane carboxylic acid [MTH acid] comprising:

a) base initiated hydrolysis of bifenthrin residue in presence of suitable organic solvent and
b) isolating compound BMA;
c) colleting the filtrate from step b) and separating organic and aqueous phase;
d) acidifying aqueous phase with acid and
e) isolating MTH acid.

BRIEF DESCRIPTION OF FIGURES

Figure 1: Flow diagram of the process of the present invention.

Figure 2: Process flow diagram for BMA isolation.

Figure 3: Process flow diagram for MTH Acid isolation

DETAILED DESCRIPTION OF THE INVENTION

The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of exemplary embodiments of the invention. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary.

Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope of the invention. In addition, descriptions of well-known functions and constructions are omitted for clarity and conciseness.

The terms and words used in the following description and claims are not limited to the bibliographical meanings, but, are merely used by the inventor to enable a clear and consistent understanding of the invention. Accordingly, it should be apparent to those skilled in the art that the following description of exemplary embodiments of the present invention are provided for illustration purpose only and not for the purpose of limiting the scope of the invention as defined by the appended claims and their equivalents.

It is to be understood that the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise.

The term “reflux temperature” means the temperature at which the solvent or solvent system reflux or boils at atmospheric pressure.

The term “room temperature” means a temperature from about 10°C to 45°C, preferably 25°C to 30°C.

Features that are described and/or illustrated with respect to one embodiment may be used in the same way or in a similar way in one or more other embodiments and/or in combination with or instead of the features of the other embodiments.

The novel process of the present invention is based on cleaner technology process with environment sustainable and eliminating the residue waste and its incineration from manufacturing of bifenthrin.

Accordingly, the present invention relates to the development of novel cleaner process for the environment sustainability. The present invention relates to a process that eliminates the incineration of the residue generated during Bifenthrin manufacturing process. The present invention more particularly relates to a novel process for the conversion of incineration residue generated during Bifenthrin manufacturing process, into the valuable active ingredients.

The process for manufacture of bifenthrin involves use of intermediate compounds namely, 2-methyl-3- biphenyl methanol [BMA] and cyhalothric acid, Cis-3-(2-chloro-3,3,3-trifluropro-1en-1-yl) -2,2-dimethyl cyclopropane carboxylic acid [MTH acid].

Typically, the process for preparation of Bifenthrin encompasses two step process. The first step comprises chlorination of Biphenyl methyl alcohol using acid and solvent at elevated temperature of about 65°C for 5 to 8 hrs to obtain an intermediate, 2-methyl-3- biphenyl methyl chloride [BPC]. In the second step BPC intermediate is further reacted with potassium salt of MTH acid in presence of phase transfer catalyst and solvent and isolating pure bifenthrin. During this process residue is generated, usually from 1 MT manufacturing of bifenthrin 35 kg residue is generated.

The present invention relates to a novel process for production of these intermediates, 2-methyl-3- biphenyl methanol and cyhalothric acid, Cis-3-(2-chloro-3,3,3-trifluropro-1en-1-yl) -2,2-dimethyl cyclopropane carboxylic acid which are used into the manufacturing of Bifenthrin.

Need of the present invention

In the process for the preparation of bifenthrin the residue is generated which required incineration and add extra cost. Typically, manufacturing of 1 Metric ton (MT) bifenthrin generate about 35 kg of residue in the plant.

This residue generated during the manufacturing process of bifenthrin is in very large quantity and incineration of the residue involves following parameters.

1. Incineration of generated residue increases the environment load and the carbon foot print.
2. Incineration cost is also high and consumes more capital cost of manufacturing process.

Solution provided by the present invention

The present inventors have developed a novel cleaner environment sustainable process for conversion of such residue into valuable active raw materials through retro synthetic approach. The novel process of the present invention gives two valuable raw materials i.e. BMA and MTH acid, which is further reused into the manufacturing of agrochemically active ingredient, particularly Bifenthrin.

The present inventors have found that the novel process of the present inventions have eliminated the residue incineration and hence reduction in large quantity of about 35 Kg of footprints per 1 MT of Bifenthrin manufacturing in the plant and it also provides impact on reduction in environment load.

The present inventors from the process of the present invention have isolated both materials, biphenyl methyl alcohol and cyhalothric acid from the residue and used for preparation of bifenthrin. The present process approximately saving is 40 Rs per one kg of bifenthrin thus making the present process cost effective.

The process of the present invention converted incinerable residue into the valuable active ingredients [Raw materials BMA and MTH acid] that are used in Bifenthrin manufacturing process. Hence, reducing the environment load and avoid incineration of residue as well as saving huge cost. The present invention approximately reduced the 35 kg residue per manufacturing of 1.0 MT bifenthrin making the process environmentally friendly and green process.

Advantageously, the process of the present invention eliminated the entire quantity of residue for incineration hence reduction in environment load and reduction in waste footprint 35 kg per 1MT of Bifenthrin and thus complying with environment regulations.

According to a preferred embodiment of the present invention, the process for preparation of intermediates of bifenthrin comprises the steps of,

a) base initiated hydrolysis of bifenthrin residue in presence of suitable organic solvent and
b) isolating compound BMA;
c) colleting the filtrate from step b) and separating organic and aqueous phase;
d) acidifying aqueous phase with acid and
e) isolating MTH acid

Both the isolated intermediate compounds having more than 99% purity and reused into the manufacturing of Bifenthrin.

The process of present invention also comprising the economic viability. Firstly, eliminated the incineration of the residue and secondly reuse of the isolated active ingredients i.e. BMA and MTH acid. Hence estimated cost saving up to 40 Rs per kg of manufacturing of bifenthrin.

The main advantage of the present invention is to provide a novel economic viable process, which is in ease operation and plant friendly and after completion of process no waste residue is generated. Thus, it makes the process simple, cost effective and suitable for industrial scale up.

In an embodiment of the present invention there is provided a process for the preparation of 2-methyl-3- biphenyl methanol [BMA] and cyhalothric acid, Cis-3-(2-chloro-3,3,3-trifluropro-1en-1-yl)-2,2-dimethyl cyclopropane carboxylic acid [MTH acid] from Bifenthrin residue comprising the step of:

a) treating Bifenthrin residue with base in the presence of base and solvent to get 2-methyl-3-biphenyl methanol;
b) isolating the BMA;
c) separating aqueous layer after isolation of BMA;
d) acidifying the aqueous layer with acid;
e) isolating MTH acid.

The step (a) involves heating the mixture of residue of bifenthrin (BF-20 83.02 % GC area , 72 % w/w bifenthrin content), suitable base, suitable solvent optionally catalyst at temperature in the range from 50 to 70°C, preferably 60 to 65°C for 2 to 4 hours preferably 2-3 hours and isolating BMA having purity more than 99%.

In another embodiment of the present invention there is provided a process for the preparation of 2-methyl-3- biphenyl methanol and cyhalothric acid, Cis-3-(2-chloro-3,3,3-trifluropro-1en-1-yl)-2,2-dimethyl cyclopropane carboxylic acid from Bifenthrin residue comprising the step of:

a) treating Bifenthrin residue with base in the presence of base, catalyst and solvent to get 2-methyl-3-biphenyl methanol;
b) isolating the BMA;
c) separating aqueous layer after isolation of BMA;
d) acidifying the aqueous layer with acid;
e) isolating MTH acid.

Suitable base is selected from sodium hydroxide, potassium hydroxide, calcium hydroxide, cesium hydroxide, ammonia, sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate or the like, preferably the base used is sodium hydroxide. Suitable solvent is alcohol selected from methanol, ethanol, n-propanol, isopropanol, n-butanol or combinations thereof.

The catalyst is phase transfer catalyst. Typically, the phase transfer catalyst is selected from the group comprising Tetra butyl ammonium bromide [TBAB], Aliquot- 336, Benzene tri ethyl ammonium chloride [TEBA-Cl], tetra butyl ammonium chloride [TBACl], ethyl triphenyl phosphonium bromide and the like, preferably Tetra butyl ammonium bromide is used.

In step (b) the solvent can be recovered from the organic layer.

In step (d) isolation involves acidifying the aqueous phase using acid and extracting the mixture with suitable solvent and filtering MTH acid. Suitable solvent for extraction is selected from toluene, hexane, heptane, diisopropyl ether, methyl tertiary butyl ether or mixture thereof, preferably hexane. In step (d) acid used is mineral acid preferably hydrochloric acid.

The process of the present invention involves continuous recovery of solvent at all steps as known to a person skilled in the art and reuse the recovered solvent to make the process economically suitable.

In an embodiment of the present invention the purity of 2-methyl-3- biphenyl methanol and cyhalothric acid is more than 99%.

The scheme of the process of the present invention is as follow:

Advantages of the present invention are:

1. The present invention is clean and green process for manufacturing intermediates of bifenthrin at large scale.
2. It is commercially viable industrial feasible process.
3. The present process provides high purity intermediate compounds.
4. The present invention meets the environment regulations and thus reducing the environment pollution.
5. The present process is a continuous process for preparation of intermediates of bifenthrin with more than 99 % purity and recovery of solvents and recycles the solvents in the process thus enabling to reduce large process cost thereby making the process economically viable.
6. Present invention is environment sustainable, based on retro synthetic approach of hydrolysis of residue.
7. It reduced the environmental load and 35 kg of carbon foot print, due to elimination of residue incineration.
8. It eliminated the cost of incineration of residue and reduced the capital cost of manufacturing process of bifenthrin.
9. Present invention eliminated the incineration of residue, which is generated during the manufacturing process of bifenthrin.

EXAMPLES

The present invention will now be explained in detail by reference to the following examples, which should not be construed as limiting the scope of the present invention.

Example 1
To a 500 Ltr. Reactor, bifenthrin residue (received from second crop of the manufacturing of bifenthrin, BF-20 83.02 % GC area, 72 % w/w of bifenthrin), methanol and optionally catalyst were charged in a reactor and stirred. NaOH solution (16%) was added to the mixture and the mixture was heated to about 64-65°C temperature for 2 to 4 hrs. Methanol was recovered under vacuum and the mass was washed under vacuum. Hexane was added to the mixture and stirred for 1 hrs at 64-65°C temperature. The mixture was then cooled to 28-30°C temperature and filtered the mass to obtain wet cake of BMA. Filtrate was collected and hexane was recovered from the filtrate (Recycle the recovered hexane and residue for incineration). Hexane was added to the separated aqueous layer from the filtrate and mass was acidified with HCL to obtain MTH acid. The mass was fileted to get pure MTH acid and solvent was recovered from the filtrate and reused in subsequent experiments.

Example 2
Step 1:
To a 500 Ltr. Reactor, Bifenthrin Residue [72 % w/w bifenthrin], isopropanol, NaOH solution and catalyst were charged under stirring. The reaction mass was heated to reflux temperature and maintained for 2-3 hrs. After completion of reaction (bifenthrin is less than 0.5%), IPA was recovered from the reaction mass under vacuum. (Temperature – 60-65 & vacuum 600-740 mm/Hg) and recycle recovered IPA in subsequent experiments. The mass was water washed under vacuum and toluene and hexane were charged to reaction mass and stirred for 1 hr at 60-65°C. The mixture was cooled to room temperature (28-30°C) to obtain BMA. The wet cake of BMA was filtered and washed with water lot wise (slurry wash - 30 Kg *2 & 20 Kg *1) followed by hexane and dried to get BMA with high purity (GC A % purity 99.2 %). The filtrate was collected and separated the organic layer and aqueous layer. Solvent was recovered from the organic layer and aqueous layer was used for next step.

Step 2:
In a reactor aqueous layer from above step was charged and stirred at ambient temperature. The reaction mass was acidified with 30% HCl and stirred. The reaction mass was extracted with hexane and MTH Acid wet cake was filtered, washed with water followed by hexane and dried (MTH acid 99.2 % & M/C 0.1 %). Hexane was recovered from separated organic layer and the recovered hexane was recycled in same stage into subsequent experiments and residue for incineration.

Example 3: By using recovered/recycled Hexane, IPA and Catalyst

Bifenthrin residue [bifenthrin 72 % w/w] [200 gm], isopropyl alcohol [200 mL], NaOH solution [140 gm] [16 % concentration] and catalyst [1.0 gm] were charged into three neck kettle with condenser, thermo-pocket and stirred at ambient temperature. The reaction mass was heated at temperature up to 60-65?C and maintaining the reaction mass for 2.0 hrs. After completion of reaction, recover IPA under vacuum at 50-55 C and added recovered hexane from example 2 [250 ml] and water [300 ml] to the reaction mass.

The reaction mass was filtered, BMA solid cake was collected and dried [BMA content 96.0 % GC area and Impurity 3.5%]. The filtrate was collected and organic layer [hexane layer] and water layer was separated. Organic layer [hexane layer] was distilled and recycles in subsequent experiments. Aqueous layer was transferred into kettle and added recovered Hexane [250 ml]. The reaction mass was acidified with HCL to obtain MTH acid. The wet cake was filtered and dried (purity: 99.2 % GC area]. The mother liquor was separated, and hexane was recovered and recycled in subsequent experiments.