DESC:FIELD OF THE INVENTION
The present invention relates to an improved process for preparation of a herbicide compound. The present invention in particular, relates to an improved process for the preparation of Tembotrione of Formula (I) with less expensive and readily available reagents and solvents.

BACKGROUND OF THE INVENTION
Tembotrione is a selective herbicide primarily used for post-emergence control of broadleaf and grassy weeds in crops like corn and others. The development of an improved process for synthesizing tembotrione involves addressing challenges in traditional methods or conventional methods, such as complex reactions, high costs, and environmental concerns. The process aims to reduce production costs, making tembotrione more affordable and competitive in the market. These improvements not only make the production of tembotrione more efficient and sustainable but also help maintain its effectiveness as a selective herbicide for weed control in various crops.
Tembotrione is one of the representative trione with a chemical name 2-{2-chloro-4- (methylsulfonyl)-3-[(2,2,2-trifluoroethoxy)methyl]benzoyl}cyclohexane-1,3-dione and the structural formula as follows:

Structure of Tembotrione of Formula (I)

Tembotrione (I) is a trione herbicide developed by Bayer Corporation in 2007. It is a 4- Hydroxyphenylpyruvate dioxygenase (HPPD) inhibitor. It has been registered in several countries, such as the United States of America (USA), Mexico, Belgium, France (Germany), the Netherlands, Brazil, and Selveya (Spain).

Tembotrione (I) acts by blocking the synthesis of HPPD. This results in a decrease in the conversion of the hydroxyprotein to homogentisinate, a build-up of tyrosine, a decrease in the biosynthesis of Plastoquinone, a decrease in tocopherol biosynthesis, a decrease in carotenoid biosynthesis, and a fade and yellowing of the weeds within two weeks.

Tembotrione (I) has a wide spectrum, quick action and excellent environmental compatibility in corn and maize fields. It has been shown to be effective against resistant weeds and cancerous weeds.
There are different ways and processes to synthesize Tembotrione (I). For example, Wuhan institute of technology's patent application no. CN10394292137A reports that Tembotrione is synthesized by starting with 2-chlorotoluene. However, this process requires expensive reagents, high production cost, and the intermediate state is isolated and treated separately. This makes the process cumbersome, has low rate of reaction, and results in low yield of the final product.

Further, Anhui Jukai agrochem co ltd.'s patent application no. CN10608290A, states the synthetic technology for Tembotrione (I) which involves expensive and large amount of condensing agent, involves reagents which have high synthesis cost.

Furthermore, the currently known method of preparing Tembotrione (I) primarily starts with 2-chlorotoluene and involves esterification, bromination, alkylation, and a reaction with cyclohexane. Nevertheless, the aforementioned technique has the following drawbacks: it produces a lot of contaminants and byproducts; it uses hazardous and highly polluting raw materials, such as liquid bromine and p-toluene sulfonate acid; it generates a lot of waste and low yield overall.

In order to avoid using highly toxic and highly polluting raw materials, it is necessary to develop a production process that overcomes the issues with previous arts, which rely on expensive reagents, hazardous substances like liquid bromine and p-toluene sulfonate acid, and generate high levels of waste and impurities. These traditional or conventional processes suffer from low reaction efficiency, cumbersome isolation of intermediates, and low yields of the final product i.e. Tembotrione.

Therefore, the present invention provides an improved process which uses readily available reagents, has an efficient synthesis step, high reaction efficiency, few impurities, is thereby environmentally friendly process that results in higher yield and purity of the final product i.e. Tembotrione (I) is overall cost-effective, addressing the limitations of the prior art and thereby contributing to a more sustainable production method.

The present invention provides an improved process for preparing Tembotrione(I), which involves m- xylene as a starting material. m-xylene is widely applied to the production of fine chemical including agrochemical products and intermediates. However, its use as a starting material for preparation of Tembotrione (I) resulting in improved, higher yield, along with high purity and stability of Tembotrione (I) has not been found so far.

Thus, the present invention aims to develop an improved process for the preparation of the herbicide compound i.e., Tembotrione (I) in view of the deficiencies of the methods reported in the prior arts, and to improve the process route which uses environment and user-friendly chemicals, reagents instead of high-risk chemicals, reagents from the perspective of production safety. The use of environment and user-friendly chemicals, reagents instead of toxic chemicals, reagents simplify the process, increases the yield, reduces the synthesis cost, reduces the emissions of the wastes, and is suitable for industrial scale-up production on commercial level.

The present invention thus satisfies the existing needs, as well as others, and generally overcomes the deficiencies found in the prior arts.

OBJECTIVE AND ADVANTAGES OF THE INVENTION
The main objective of the present invention is to provide an improved, simple, economically advantageous and cost-effective process for the preparation of Tembotrione of Formula (I), with high purity and yield of Tembotrione (I) on a commercial scale.

Another objective of the present invention is to provide an improved process that involves less expensive and readily available reagents and solvents.

Another objective of the present invention is to provide an improved process for preparing Tembotrione of formula (I), using m-xylene as starting material.

Another objective of the present invention is to provide an improved process for preparing Tembotrione of formula (I), with an improved reaction rate and minimized side reactions or formation of by-products.

Another objective of the present invention is to provide a novel and effective improved process for preparation of Tembotrione of formula (I), with reduced or minimal waste generation.

Another objective of the present invention is to provide an improved process for the preparation of Tembotrione of formula (I), which is industrially and economically robust process with safe operations.

Another objective of the present invention is to provide an improved process for the preparation of Tembotrione of formula (I), which results in an improved yield and purity of product.

Another objective of the present invention is to provide an improved process wherein, less effluent is generated. Another objective of this invention is to obtain a compound (2), i.e 1,3-dichloro-2,4-dimethylbenzene by halogenating compound (1) i,e m-Xylene in the presence of halogenating agent using suitable Lewis acid.

A further object of this invention is to obtain a compound (3), i.e, 2-Bromomethyl-1,3-dichloro-4-methyl-benzene by halogenating compound (2) i.e 1,3-dichloro-2,4-dimethylbenzene in the presence of halogenating agent, free radical initiator and a solvent.

A further object of this invention is to obtain a compound (4), i.e, 1,3-Dichloro-4-methyl-2-(2,2,2-trifluoro-ethoxymethyl)-benzene, by reacting compound (3), i.e, 2-Bromomethyl-1,3-dichloro-4-methyl-benzene with trifluoroethyl alcohol (Trifluoroethanol) in the presence base.

A further object of this invention is to obtain a compound (5), i.e, 2-Chloro-1-methyl-4-methylsulfanyl-3-(2,2,2-trifluoro- ethoxymethyl)-benzene, by reacting compound (4), i.e, 1,3-dichloro-4-methyl-2-(2,2,2-trifluoro-ethoxymethyl)-benzene with sodium thiomethoxide or methyl thiol and a base.

A further object of this invention is to obtain a compound-(6), i.e., 2-Chloro-4- methanesulfonyl-1-methyl-3-(2,2,2-trifluoro-ethoxymethyl)-benzene, by controlled oxidation, of a compound (5), i.e.,
2-Chloro-1-methyl-4-methylsulfanyl-3-(2,2,2-trifluoro- ethoxymethyl)-benzene.

A further object of this invention is to obtain a compound (7), i.e., 1-(bromomethyl)-2- chloro-4-methanesulfonyl-3-[(2,2,2-trifluoroethoxy)methyl]benzene, by halogenating the compound (6), at benzylic position using halogenating reagents in presence of radical initiator.

A further object of this invention is to obtain a compound-(8), i.e., 2-[2-Chloro-4- methanesulfonyl-3-(2,2,2-trifluoro-ethoxymethyl)-benzyl]-cyclohexane-1,3-dione, by reacting the compound (7) with 1,3-Cyclohexadione using a suitable solvent, and in presence of base.

A further object of this invention is to oxidize the compound (8) in the presence of an oxidizing agents to furnish a target compound, i.e., Tembotrione of Formula (I).
Some or all these and other objects of the invention can be achieved by way of the invention described hereinafter.

ADVANTAGES OF THE PRESENT INVENTION:
1. The improved process of the present invention by utilizing m-xylene, a readily available and inexpensive starting material reduces the overall cost of raw materials. This makes the production of Tembotrione of Formula (I) more economically advantageous on a commercial scale.
2. The improved process of the present invention provides higher yields and improved purity of the final product, addressing common issues with low yield and impurities in traditional synthesis methods
3. The improved process of the present invention optimizes reaction conditions, resulting in a higher reaction rate and minimizing side reactions or the formation of by-products. This leads to a more selective and controlled synthesis, which contributes to better overall process efficiency.
4. The improved process of the present invention minimizes the generation of waste materials, making it more environmentally sustainable. This reduction in waste contributes to a cleaner production process, with less impact on the environment and lower disposal costs.
5. The improved process of the present invention utilizes less expensive reagents and solvents, making it more accessible and reducing the overall cost of production.
6. The improved process of the present invention provides a safer and more environmentally friendly approach.
7. The improved process of the present invention minimizes the amount of effluent generated during production contributing to lower environmental impact and making the process more complaint with environmental regulations.

SUMMARY OF THE INVENTION
Accordingly, the main aspect of the present invention is to provides an improved process for the preparation of Tembotrione of Formula (I). Provided herein is simple, cost effective and consistently reproducible process for the preparation of highly pure and stable form of Tembotrione (I).

In another aspect, the present invention provides an improved process for the preparation of Tembotrione of Formula (I), using cost effective and readily available reagents.
In another aspect, the present invention provides an improved process for the preparation of a Tembotrione of formula (I), comprising:
a) reacting a compound m-Xylene (1), with a halogenating agent and in the presence of suitable Lewis acid to obtain a compound 1,3-dichloro-2,4-dimethylbenzene (2);
b) reacting the compound (2) in the presence of halogenating agent, free radical initiator and a solvent, to obtain a compound 2-Bromomethyl-1,3-dichloro-4-methyl-benzene (3);
c) reacting the compound (3) with trifluoroethyl alcohol (Trifluoroethanol) in presence base, to obtain a compound 1,3-Dichloro-4-methyl-2-(2,2,2-trifluoro-ethoxymethyl)-benzene (4);
d) reacting the compound (4) with sodium thiomethoxide or methyl thiol and a base to obtain a compound 2-Chloro-1-methyl-4-methylsulfanyl-3-(2,2,2-trifluoro- ethoxymethyl)-benzene (5);
e) oxidizing the compound (5) in the presence of an oxidizing agent, to obtain a compound 2-Chloro-4-methanesulfonyl-1-methyl-3-(2,2,2-trifluoro-ethoxymethyl)- benzene (6);
f) reacting the compound (6) in the presence of a halogenating agent and a free radical initiator, obtain a compound 1-Bromomethyl-2-chloro-4-methanesulfonyl-3-(2,2,2-trifluoro-ethoxymethyl)-benzene (7);
g) condensing the compound (7), with 1,3-Cyclohexadione using a suitable solvent, and in the presence of base to furnish a compound 2-[2-Chloro-4-methanesulfonyl-3-(2,2,2-trifluoro-methoxymethyl)- benzyl]-cyclohexane-1,3-dione (8);
h) oxidizing the compound-(8) in the presence of an oxidizing agents to yield the target compound, i.e., Tembotrione of Formula (I).

In yet another aspect, the present invention relates to an improved process for the preparation of Tembotrione of Formula (I), which comprises chlorinating the compound m-Xylene (1) with chlorine gas to yield compound 1,3-dichloro-2,4-dimethylbenzene (2), i.e.,

The compound (2), then is brominated in the presence of either aqueous HBr (47-49%) and aqueous hydrogen peroxide or N-bromosuccinimide and a free radical initiator to furnish a compound, 2-Bromomethyl-1,3-dichloro-4-methyl-benzene (3), i.e.,

The compound (3), is treated with trifluoroethyl alcohol (Trifluroethanol)in presence base to furnish a compound, 1,3-Dichloro-4-methyl-2-(2,2,2-trifluoro-ethoxymethyl)-benzene (4), i.e.,

The compound (4), is reacted with sodium thiomethoxide or methyl thiol and a base to give a compound, 2-Chloro-1-methyl-4-methylsulfanyl-3-(2,2,2-trifluoro-ethoxymethyl)-benzene 15 (5), i.e.,

The compound (5), is subjected to controlled oxidation, to provide a compound, 2-Chloro-4- methanesulfonyl-1-methyl-3-(2,2,2-trifluoro-ethoxymethyl)-benzene (6), i.e.,

Thereafter, the compound (6) is brominated in the presence of hydrogen bromide (47-49%) and hydrogen peroxide (H2O2) or N-Bromosuccinimide (NBS) and a free radical initiator to obtain a compound 1-Bromomethyl-2-chloro-4-methanesulfonyl-3-(2,2,2-trifluoro-ethoxymethyl)- benzene (7), i.e.,

The compound (7), is then condensed with 1,3-Cyclohexadione using a suitable solvent, and in the presence of base to furnish a compound 2-[2-Chloro-4-methanesulfonyl-3-(2,2,2-trifluoro-methoxymethyl)-benzyl]- cyclohexane-1,3-dione (8), i.e.,

The compound (8), is then oxidized with oxidizing agents like tert-butyl hydroperoxide, Iodoxybenzoic acid (IBX), Selenium dioxide and alike to yield Tembotrione of (Formula I).

The improved process of the present invention is represented by the following scheme

Scheme 1
In yet another aspect, the present invention provides a process to obtain a compound (2) i.e, 1,3-dichloro-2,4-dimethylbenzene, by halogenating a compound (1), i,e, m-Xylene in the presence of a halogenating agent.

In yet another aspect, the present invention provides a process to obtain a compound (3), i.e., 2-Bromomethyl-1,3-dichloro-4-methylbenzene by halogenating compound (2) i.e 1,3-dichloro-2,4-dimethylbenzene in the presence of halogenating agent, free radical initiator and a solvent.

In yet another aspect, the present invention provides a process to obtain a compound (4) i.e, 1,3-Dichloro-4-methyl-2-(2,2,2-trifluoro-ethoxymethyl)-benzene, by reacting compound (3), i.e, 2-Bromomethyl-1,3-dichloro-4-methylbenzene, with trifluoroethyl alcohol (Trifluroethanol) in the presence a base.

In yet another aspect, the present invention provides a process to obtain a compound (5) i.e 2-Chloro-1-methyl-4-methylsulfanyl-3-(2,2,2-trifluoro-ethoxymethyl)-benzene, by reacting compound (4), i.e, 1,3-Dichloro-4-methyl-2-(2,2,2-trifluoro-ethoxymethyl)-benzene with sodium thiomethoxide or methyl thiol and a base.

In an aspect, the present invention obtains a compound-(6), i.e., 2-Chloro-4-methanesulfonyl- 1-methyl-3-(2,2,2-trifluoro-ethoxymethyl)-benzene, by controlled oxidation, of a compound (5), i.e., 2-Chloro-1-methyl-4-methylsulfanyl-3-(2,2,2-trifluoro-ethoxymethyl)-benzene

In an aspect, the present invention obtains a compound (7), i.e., 1-(bromomethyl)-2-chloro-4- methanesulfonyl-3-[(2,2,2-trifluoroethoxy)methyl]benzene, by halogenating the compound (6), at benzylic position using halogenating reagents in presence of radical initiator.

In an aspect, the present invention obtains a compound-(8), i.e., 2-[2-Chloro-4- methanesulfonyl-3-(2,2,2-trifluoro-ethoxymethyl)-benzyl]-cyclohexane-1,3-dione, by reacting the compound (7) with 1,3-Cyclohexadione using a suitable solvent, and in presence of base.

In an aspect, the present invention provides that the compound (8), is oxidized in the presence of oxidizing agents to furnish the target compound, i.e., Tembotrione of Formula (I).

DETAILED DESCRIPTION OF THE INVENTION
At the very outset of the detailed description, it may be understood that the ensuing description only illustrates a particular form of this invention. However, such a particular form is only exemplary embodiment, and without intending to imply any limitation on the scope of this invention. Accordingly, the description is to be understood as an exemplary embodiment and teaching of the invention and not intended to be taken restrictively.

The technical solutions of the present disclosure will be further described below by way of specific embodiments. It will be apparent to those skilled in the art that the embodiments are merely illustrations of the present disclosure and should not be construed as specific limitations to the present disclosure.
It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the present disclosure.

Certain ranges are presented herein with numerical values being preceded by the term “about”. The term “about” is used herein to provide literal support for the exact number that it precedes, as well as a number that is near to or approximately the number that the term precedes. In determining whether a number is near to or approximately a specifically recited number, the near or approximately unrecited number may be a number which in the context in which it is presented, provides the substantial equivalent of the specifically recited number. In an embodiment, “about” can mean within one or more standard deviations, or within ±30%, 25%, 20%, 15%, 10%, or 5% of the stated value.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the invention belongs. Although any process and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, preferred process is described. For the purposes of the present invention, the following terms are defined below:

The articles “a” and “an” are used herein to refer to one or to more than one (i.e., to at least one) of the grammatical object of the article. By way of example, “an element” means one element or more than one element.

As used herein, the terms, “including”, “includes”, “comprising”, and comprises” mean “including without limitation” and shall not be construed to limit any general statement that it follows to the specific or similar items.

Each embodiment is provided by way of explanation of the invention and not by way of limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made to the process described herein without departing from the scope of the invention. For instance, features illustrated or described as part of one embodiment can be applied to another embodiment to yield a still further embodiment.

While several embodiments of the present invention have been described and illustrated herein, those of ordinary skill in the art will readily envision a variety of other means and/or structures for performing the functions and/or obtaining the results and/or one or more of the advantages described herein, and each of such variations and/or modifications is deemed to be within the scope of the present invention.
Moreover, other than in any operating examples, or where otherwise indicated, all numbers expressing, for example, quantities of materials/ingredients used in the specification are to be understood as being modified in all instances by the term "about". The term "about" shall be interpreted to mean "approximately" or "reasonably close to" and any statistically insignificant variations therefrom.

Traditional or Conventional methods for the preparation of tembotrione are associated with drawbacks such as use of expensive reagents, hazardous substances like liquid bromine and p-toluene sulfonate acid, generation of high levels of waste and impurities. Further, these traditional or conventional processes suffer from low reaction efficiency, cumbersome isolation of intermediates, and low yields.

In an embodiment, the present invention provides an improved process for the preparation of Tembotrione of Formula (I).

In one of the embodiments, the present invention provides an improved process for the preparation of Tembotrione of Formula (I), using cost effective and readily available reagents.

In an embodiment, the present invention provides an improved process for the preparation of a Tembotrione of formula (I), comprising:
a) reacting a compound m-Xylene (1), with a halogenating agent and in the presence of suitable Lewis acid to obtain a compound 1,3-dichloro-2,4-dimethylbenzene (2);
b) reacting the compound (2) in the presence of halogenating agent, free radical initiator and a solvent, to obtain a compound 2-Bromomethyl-1,3-dichloro-4-methyl-benzene (3);
c) reacting the compound (3) with trifluoromethyl alcohol/ trifluoroethanol in presence base, to obtain a compound 1,3-Dichloro-4-methyl-2-(2,2,2-trifluoro-ethoxymethyl)-benzene (4);
d) reacting the compound (4) with sodium thiomethoxide or methyl thiol and a base to obtain a compound 2-Chloro-1-methyl-4-methylsulfanyl-3-(2,2,2-trifluoro-ethoxymethyl)-benzene (5);
e) oxidizing the compound (5) in the presence of an oxidizing agent, obtains a compound 2-Chloro-4-methanesulfonyl-1-methyl-3-(2,2,2-trifluoro-ethoxymethyl)- benzene (6);
f) reacting the compound (6) in the presence of a halogenating agent and a free radical initiator, obtain a compound 1-Bromomethyl-2-chloro-4-methanesulfonyl-3-(2,2,2-trifluoro-ethoxymethyl)-benzene (7);
g) condensing the compound (7), with 1,3-Cyclohexadione using a suitable solvent, and in the presence of base to yield a compound 2-[2-Chloro-4-methanesulfonyl-3-(2,2,2-trifluoro-methoxymethyl)-benzyl]-cyclohexane-1,3-dione (8);
h) oxidizing the compound-(8) in the presence of an oxidizing agent and dried utilizing drying agent to furnish a target compound, i.e., Tembotrione of Formula (I).

In one of the embodiments, the halogenating agent is selected from the group comprising of a chlorinating agent or brominating agent, fluorine, iodine, etc.

In one of the embodiments, the chlorinating agent is selected from the group comprising thionyl chloride, sulfuryl chloride, phosphorous chloride, phosphorous oxychloride, chlorine, hydrogen chloride etc. or combination thereof.

In one of the embodiments, the brominating agent is selected from the group comprising bromine (Br2), hydrogen bromide (HBr), N-bromosuccinimide (NBS), mandelic acid, etc. or combination thereof.,

In one of the embodiments, the halogenating agent is combined with acetic acid, water, phosphorous and/or H2O2, or combination thereof.

In a preferred embodiment, the halogenating agent is selected from the group comprises of a chlorinating agent or brominating agent.

In one of the embodiments, the free radical initiator is selected from the group comprising azobisisobutyronitrile (AIBN), benzoyl peroxide or combination thereof.

In one embodiment, the base is selected from the group comprising isopropylamine, diisopropylamine, diisopropylethylamine, triethylamine, dimethylamine, trimethyl amine, pyridine, N- methylmorpholine, 3-picoline, 2-picoline, 4-picoline, sodium carbonate (Na2CO3), sodium bicarbonate (NaHCO3), potassium carbonate (K2CO3), calcium hydroxide or combination thereof.

In one of the embodiments, the suitable solvent is selected from the group comprising N,N- dimethylformamide (DMF), N-methylpyrrolidene (NMP), methanol, benzene, dichloromethane, 1,2-dichloroethane, chloroform, 1, 4- dioxane, diethyl ether, acetic acid, hydrogen peroxide, o-dichlorobenzene ethylene dichloride (EDC) , carbon tetrachloride, fluorobenzene, chlorobenzene, dichlorobenzene, tetrahydrofuran and acetonitrile, trifluoroethanol, ethyl acetate, Acetone, dimethylsulfoxide (DMSO), cyclohexane, hexane, heptane, toluene, xylene, etc. or combination thereof.

In one of the embodiments, the Lewis acid is selected from the group comprising Zinc chloride (ZnCl2), Aluminium Chloride (AlCl3), Ferric Chloride (FeCl3), Boron Trifluoride (BF3), Boron Trichloride (BCl3), Titanium tetrachloride (TiCl4), Antimony Pentafluoride (SbF5), Copper Chloride (CuCl2) etc. or combination thereof.

In one of the embodiments, the catalyst in the reaction of the present invention is selected from Pd/C or Raney Nickel, Pt/C, PtO2/C, Tetrabutylammonium bromide (TBAB), sodium tungsten dihydrate, Na2WO4.2H2O, (2,2,6,6-Tetramethylpiperidin-1-yl)oxyl or (2,2,6,6-tetramethylpiperidin-1-yl)oxidanyl (TEMPO), Cobalt(II) acetate, Co-napthenate, palladium (II) acetate, triphenyl phosphine, or combination thereof.

In one of the embodiments, the oxidizing agent is selected from the group comprising hydrogen peroxide, tert-butyl hydroperoxide, 2-Iodoxybenzoic acid (IBX), potassium permanganate, potassium dichromate, chlorine, sodium dichromate, chromium trioxide, nitric acid, perchloric acid, osmium tertraoxide, iodine, fluorine, selenium dioxide etc or combination thereof.

In one of the embodiments, the oxidation process of the present invention is executed by utilizing oxidising agent with or without a suitable catalyst.

In one of the embodiments, the drying agent is selected from group comprising sodium sulfate, magnesium sulfate, calcium chloride, silica gel, SiO2, phosphorus pentoxide, anhydrous calcium sulfate, sodium (Na), potassium carbonate, alumina, activated charcoal etc.

In one of the embodiments, a compound (2) i.e, 1,3-dichloro-2,4-dimethylbenzene is obtained by halogenating a compound (1), i,e, m-Xylene in the presence of a halogenating agent.

In an embodiment, the present invention provides a process for preparing a compound (2), i.e., 1,3-dichloro-2,4-dimethylbenzene, comprising addition of a solvent, for instance ethylene dichloride (EDC) to the m-Xylene compound (1) in the presence of Lewis acid such as Ferric Chloride (FeCl3), followed by addition of base such as Isopropyl amine and bubbling a halogenating agent such as Chlorine gas at slow rate at room temperature for 5 hours to 6.5 hours. The mixture is refluxed till completion of the reaction, and is monitored and after completion, the solvent such as ethylene dichloride (EDC) is distilled off under vacuum to yield the desired product compound (2) i.e., 1,3-dichloro-2,4-dimethylbenzene.

In one of the embodiments, a compound (3) i.e 2-Bromomethyl-1,3-dichloro-4-methylbenzene, is obtained by halogenating compound (2) i.e 1,3-dichloro-2,4-dimethylbenzene in the presence of halogenating agent, free radical initiator and a solvent.

In another embodiment, wherein the compound (3) i.e., 2-Bromomethyl-1,3-dichloro-4-methylbenzene, is prepared by two methods, i.e., method A and method B.
In an embodiment, the method A for the preparation of compound (3) i.e 2-Bromomethyl-1,3-dichloro-4-methylbenzene, comprises addition of solvent such as ethylene dichloride (EDC) to the compound (2) i.e, 1,3-dichloro-2,4-dimethylbenzene, to obtain a mixture. The mixture is stirred for 30 minutes, followed by the addition of free radical initiator, for instance azobisisobutyronitrile (AIBN) and halogenating agent, such as aqueous hydrogen bromide (HBr) and aqueous hydrogen peroxide (H2O2) is simultaneously added in a dropwise manner using two different pressure equalizing addition funnels for a period of 80 minutes to 90 minutes to obtain a reaction mass, wherein, the reaction mass is heated to a temperature range of 55oC to 60oC and maintained till completion of the reaction. The reaction is monitored. After completion, the reaction mass is cooled to room temperature and quenched with sodium thiosulfate, to separate the layers, wherein, aqueous layer is washed with ethylene dichloride (EDC) and the combined organic layer is washed with brine, dried over sodium sulfate and filtered. The organic solvent is removed to furnish compound (3) i.e, 2-Bromomethyl-1,3-dichloro-4-methylbenzene.

In another embodiment, the method B for the preparation of compound (3) i.e 2-Bromomethyl-1,3-dichloro-4-methylbenzene, comprises addition of solvent such as acetonitrile to the compound (2) i.e, 1,3-dichloro-2,4-dimethylbenzene to obtain a mixture. The mixture is stirred for 30 minutes, followed by the addition of free radical initiator, for instance azobisisobutyronitrile (AIBN) and brominationg agent such as N-Bromosuccinimide (NBS) in portions over a period of 90 minutes to obtain a reaction mass. Further, the reaction mass is taken to reflux till completion. The reaction is monitored. After completion, the reaction mass is filtered, the filtrate is concentrated, wherein, the residue thus obtained is dissolved in solvent such as ethyl acetate and washed with water, and brine, and dried over sodium sulfate and filtered to remove organic solvent under vacuum to obtain a compound (3), i.e, 2-Bromomethyl-1,3-dichloro-4-methylbenzene.

In one of the embodiments, a compound (4), i.e, 1,3-Dichloro-4-methyl-2-(2,2,2-trifluoro-ethoxymethyl)-benzene, is obtained by reacting compound (3), i.e, 2-Bromomethyl-1,3-dichloro-4-methylbenzene, with trifluoroethyl alcohol (Trifluroethanol) in the presence a base.

In an embodiment, the present invention provides a process for preparing compound (4) i.e, 1,3-Dichloro-4-methyl-2-(2,2,2-trifluoro-ethoxymethyl)-benzene, comprising adding a solvent such as ethylene dichloride (EDC) to the compound (3), i.e, 2-Bromomethyl-1,3-dichloro-4-methylbenzene, to obtain a mixture. The mixture is stirred for 30 minutes, followed by addition of a base such as Potassium carbonate in one lot and catalyst such as Tetrabutylammonium bromide (TBAB). Further, dropwise addition of Trifluoroethanol in a solvent such as ethylene dichloride (EDC) at reflux temperature is performed, to obtain a reaction mass. After completion, the reaction mass is cooled to room temperature. The reaction mass is filtered and the residue is washed with a solvent such as ethylene dichloride (EDC), wherein, the combined organic layer is washed with water, brine, and dried over sodium sulfate, and filtered under reduced pressure to furnish a compound (4), i.e, 1,3-Dichloro-4-methyl-2-(2,2,2-trifluoro-ethoxymethyl) benzene.

In one of the embodiments, a compound (5), i.e, 2-Chloro-1-methyl-4-methylsulfanyl-3-(2,2,2-trifluoro- ethoxymethyl)-benzene, is obtained by reacting compound (4), i.e, 1,3-Dichloro-4-methyl-2-(2,2,2-trifluoro-ethoxymethyl)-benzene with sodium thiomethoxide or methyl thiol and a base.

In an embodiment, the present invention provides a process for preparing a compound (5), i.e, 2-Chloro-1-methyl-4-methylsulfanyl-3-(2,2,2-trifluoro- ethoxymethyl)-benzene, comprising addition of a solvent such as N,N-Dimethylformamide to the compound (4), i.e, 1,3-Dichloro-4-methyl-2-(2,2,2-trifluoro-ethoxymethyl)benzene, to obtain a mixture. The mixture is stirred for 30 minutes, followed by addition of catalyst such as Tetrabutylammonium bromide (TBAB) and dropwise addition of aqueous Sodium thiomethoxide at a temperature range of 60oC to 70oC, to obtain a reaction mass. The reaction mass is heated at a temperature range of 110oC to 120oC. After completion, the reaction mass is cooled to room temperature and poured over ice, extracted with solvent such as ethyl acetate, by which the layers are separated, wherein, the aqueous layer is washed with a solvent such as ethyl acetate and the combined organic layer is washed with water, brine, and dried over sodium sulfate, and filtered under reduced pressure to furnish a compound (5), i.e, 2-Chloro-1-methyl-4-methylsulfanyl-3-(2,2,2-trifluoro-ethoxymethyl)benzene.

In an embodiment, a compound-(6), i.e., 2-Chloro-4-methanesulfonyl-1-methyl-3-(2,2,2- trifluoro-ethoxymethyl)-benzene, is obtained by controlled oxidation, of a compound (5), i.e., 2-Chloro-1-methyl-4-methylsulfanyl-3-(2,2,2-trifluoro-ethoxymethyl)-benzene.

In an embodiment, the present invention provides a process for preparing compound (6) i.e, 2-Chloro-4-methanesulfonyl-1-methyl-3-(2,2,2- trifluoro-ethoxymethyl)-benzene, comprises addition of solvent such as methanol to the compound (5) i.e, 2-Chloro-1-methyl-4-methylsulfanyl-3-(2,2,2-trifluoro-ethoxymethyl)benzene, followed by addition of oxidizing agent such as Sodium tungstate, dihydrate. The reaction mixture is stirred for 20 mins, followed by dropwise addition of hydrogen peroxide (H2O2) at room temperature. The reaction is monitored by TLC and HPLC. After completion, the solid material is filtered and treated as first crop, and filtrate is quenched with sodium thiosulfate and concentrated in vacuo to obtain residue, wherein, the residue thus obtained is dissolved in solvent such as ethyl acetate and washed with water, and brine, and dried over anhydrous sodium sulfate and filtered and concentrated to furnish compound (6) i.e, 2-Chloro-4-methanesulfonyl-1-methyl-3-(2,2,2- trifluoro-ethoxymethyl)-benzene.

In an embodiment, a compound (7), i.e., 1-(bromomethyl)-2-chloro-4-methanesulfonyl-3- [(2,2,2-trifluoroethoxy)methyl]benzene, is obtained by halogenating the compound (6), at benzylic position using halogenating reagents in presence of radical initiator.

In another embodiment, wherein process for the preparation of compound (7) i.e, 1-(bromomethyl)-2-chloro-4-methanesulfonyl-3- [(2,2,2-trifluoroethoxy)methyl]benzene, comprises two methods, Method A and Method B.

In an embodiment, method A for a preparing compound (7) i.e, 1-(bromomethyl)-2-chloro-4-methanesulfonyl-3- [(2,2,2-trifluoroethoxy)methyl]benzene, comprises addition of solvent for instance, ethylene dichloride (EDC) in compound (6) i.e, -Chloro-4-methanesulfonyl-1-methyl-3-(2,2,2-trifluoro-ethoxymethyl)-benzene, followed by the addition of free radical initiator, for instance azobisisobutyronitrile (AIBN). The reaction mixture was stirred for 10 minutes. Then in a dropwise manner, simultaneously added halogenating agent, such as aqueous hydrogen bromide (HBr) and aqueous hydrogen peroxide (H2O2) at a temperature range of 50-55 o C and maintained till completion of reaction. The reaction is monitored by TLC and HPLC. After completion, the reaction mass is diluted with solvent such as ethylene dichloride (EDC), and washed with water, brine, dried over anhydrous sodium sulfate, and filtered and concentrated to furnish compound (7) i.e, 1-Bromomethyl-2-chloro-4-methanesulfonyl-3-(2,2,2-trifluoro-ethoxymethyl)-benzene.

In another embodiment, method B for preparing compound (7) i.e, 1-(bromomethyl)-2-chloro-4-methanesulfonyl-3- [(2,2,2-trifluoroethoxy)methyl]benzene, comprises addition of solvent acetonitrile in compound (6) i.e, -Chloro-4-methanesulfonyl-1-methyl-3-(2,2,2-trifluoro-ethoxymethyl)-benzene followed by addition of free radical initiator, for instance azobisisobutyronitrile (AIBN). The reaction mixture was stirred for 10 minutes. Then portion wise added N-Bromo succinimide (NBS) at a temperature range of 50-55 o C. The reaction is monitored by TLC and HPLC. After completion, the reaction mass is filtered and the filtrate is concentrated under reduced pressure, and the residue is extracted with solvent such as ethylene dichloride (EDC), and the organic layer is washed with water, brine, dried over anhydrous sodium sulfate, filtered and concentrated to furnish compound (7) i.e, 1-Bromomethyl-2-chloro-4-methanesulfonyl-3-(2,2,2-trifluoro-ethoxymethyl)-benzene.

In another embodiment, a compound-(8), i.e., 2-[2-Chloro-4-methanesulfonyl-3-(2,2,2-trifluoro-ethoxymethyl)-benzyl]-cyclohexane-1,3-dione, is obtained by reacting the compound (7) with 1,3-Cyclohexadione using a suitable solvent, and in presence of base.

In an embodiment, the present invention provides a process for preparing a compound (8), i.e, 2-[2-Chloro-4-methanesulfonyl-3-(2,2,2-trifluoro-ethoxymethyl) benzyl]-cyclohexane-1,3-dione, comprises addition of solvent such as N,N-dimethylformamide (DMF) and catalyst such as Tetrabutyl ammonium bromide (TBAB) , followed by addition of 1,3-Cyclohexadione and base potassium carbonate (K2CO3).The reaction mass is stirred for 10 mins and then raised the temperature to 90 o C, then stirred the reaction mass for 45 mins. Then dropwise added mixture of Compound (7) i.e, 1-Bromomethyl-2-chloro-4-methanesulfonyl-3-(2,2,2-trifluoro-ethoxymethyl)-benzene in solvent such as N,N-dimethylformamide (DMF), at the same temperature range of 90 o C . The reaction is monitored by TLC and HPLC. After completion, the reaction mass is filtered, and the filtrate was concentrated under reduced pressure and the residue is extracted with solvent such as ethylene dichloride (EDC), and the organic layer is washed with water, brine, dried over anhydrous sodium sulfate, filtered and concentrated to furnish compound (8) i.e, 2-[2-Chloro-4-methanesulfonyl-3-(2,2,2-trifluoro-ethoxymethyl) benzyl]-cyclohexane-1,3-dione.

In another embodiment, the compound (8), is oxidized in the presence of an oxidizing agent to yield the target compound, i.e., Tembotrione of Formula (I).

In an embodiment, the present invention provides an improved process for preparing a compound of formula (I) i.e, Tembotrione, comprises addition of fluorobenzene and dimethylsulfoxide (DMSO) to the compound (8) i.e, 2-[2-Chloro-4-methanesulfonyl-3-(2,2,2-trifluoro-ethoxymethyl) benzyl]-cyclohexane-1,3-dione, followed by addition of oxidizing agent such as 2-Iodoxybenzoic acid (IBX) in a single portion. The reaction mass is stirred at room temperature for 15 minutes and then refluxed for 12 hrs. The reaction mass is monitored by TLC and HPLC. After completion, the reaction mass is filtered, and the filtrate is diluted with solvent such ethyl acetate, and the organic layer is washed with water, saturated solution of sodium bicarbonate (NaHCO3), water, brine, and dried over anhydrous sodium sulfate, and filtered and concentrated to furnish Tembotrione (I).

In an embodiment, the reaction is carried at a temperature of from 0? to 200? for a period of about 1 hour to about 24 hours and at a pressure of from atmospheric pressure to 50 bar.

The improved process for preparing Tembotrione of formula (I) disclosed according to the present invention yields Tembotrione with purity of around 95% to 99% and a yield of above 80%.

The present invention has the advantage of short residence time of the material, high selectivity, high yield, high purity, less equipment investment, manufacturing cost savings, reduced material consumption, reducing the amount of by-products in the final product.

Accordingly, the present process represents a significant technical improvement over conventional/traditional methods, offering continuous operation, low energy consumption, and an efficient, feasible synthesis of Tembotrione of formula (I). It is simpler, faster, and more industrially viable. As such, this innovation provides a clear technical advancement relative to existing techniques, with notable economic benefits and makes the invention not obvious to a person skilled in the art.

In some embodiments, the purity is determined by high-performance liquid chromatography (HPLC) analysis.

The improved process of the present invention involves m-xylene as a starting material as m-xylene is provides production of fine chemical products and intermediates.

The use of m-xylene as a starting material for preparation of Tembotrione (I) results in an improved production of final product with higher yield, along with high purity and stability of Tembotrione (I).

The improved process of the present disclosure is simple, employs cost effective and less toxic reagents and provides tembotrione with a comparatively high purity and high yield.

According to another aspect, there is provided an improved process for preparing agrochemical composition comprising highly pure and stable Tembotrione obtained as per the process disclosed herein.

Yet in another embodiment, agrochemical compositions comprise at least a bio-active effective amount of highly pure and stable Tembotrione obtained by the improved processes disclosed herein. The agrochemical compositions further contain one or more agrochemically acceptable excipients. Suitable excipients and the amounts to use may be readily determined by the formulation scientist based upon experience and consideration of standard procedures and reference works in the field.

While preferred embodiments and examples have been shown and described, it is to be understood that various further modifications will be apparent to those skilled in the art.

EXAMPLES

Although the content of the present invention is further specifically explained using examples, the present invention is not limited to the following examples as long as the gist of the present invention is not exceeded. The following examples are presented to further explain the invention with experimental conditions, which are purely illustrative and are not intended to limit the scope of the invention.
Tembotrione (Formula I) is synthesized by sequential reactions starting from a compound (1).
The compound (1) is subjected to the chlorination using the chlorinating agents included but not Limited to chlorine gas, N-Chlorosuccinimide (NCS) to furnish compound (2), which in turn subjected to bromination using brominating agents included but not limited to Bromine in acetic acid, Bromine in water, aqueous hydrogen bromide and aqueous hydrogen peroxide , in presence of free radical initiator such as azobisisobutyronitrile (AIBN), using solvents including but not limited to ethylene dichloride, acetonitrile, carbon tetrachloride, chlorobenzene, o-dichlorobenzene to furnish compound (3).The said bromination is carried out at a temperature of from 0oC to 180oC for a period ranging from 1 hour to 24 hours. The more preferred temperature range is from 25oC to 180oC and at a pressure of from an atmospheric pressure to 10 bar.

The compound (3) is then treated with trifluoroethanol in the presence of base to provide a compound (4). The compound (4) when subjected to nucleophilic displacement reaction with sodium thiomethoxide or methyl thiol and appropriate base yields a compound (5).

The compound (5) under controlled oxidation condition provides compound (6). The compound (6) is brominated in the presence of hydrogen bromide (47-49%) and hydrogen peroxide (H2O2) or N-Bromosuccinimide and a free radical initiator to obtain a compound (7). The compound (7), is then condensed with 1,3-Cyclohexadione using a suitable solvent and in the presence of base furnish a compound (8), which in turn is oxidized with oxidizing agents like tert-butyl hydroperoxide, Selenium dioxide, Iodoxybenzoic acid (IBX) and alike to yield Tembotrione (Formula I compound).
The selected starting material is optimally substituted to get desired selectivity and improved yield for the proposed scheme.

Example 1: Preparation of 1,3-dichloro-2,4-dimethylbenzene (2)

A four necked glass reactor (2 Lit) fitted with condenser, thermometer pocket, thermometer, mechanical stirrer was charged with ethylene dichloride (EDC) (575 mL) followed by m-Xylene (242.3 g), Ferric chloride (FeCl3) (36.6 g). Isopropyl amine (2.4 g) was added. Chlorine gas was bubbled at slow rate at room temperature for 6.5 hr. Then the mixture was refluxed till completion of the reaction. The reaction was monitored. After completion, ethylene dichloride (EDC) was distilled off under vacuum to yield the desired product, 1,3-dichloro-2,4-dimethylbenzene (2). After purification, HPLC purity (area): 95%, Yield: 287.2 g, 78 %

Example 2: Preparation of 2-Bromomethyl-1,3-dichloro-4-methylbenzene (3)

Method A:
A four necked glass reactor (2 Lit) fitted with condenser, thermometer pocket, thermometer, mechanical stirrer was charged with ethylene dichloride (EDC) (600 mL) followed by 1,3-dichloro-2,4-dimethylbenzene (2) (285.7 g). The mixture was stirred for 30 minutes. Azobisisobutyronitrile (AIBN) (10.3 g) was added. Aqueous hydrogen bromide (HBr) (48%, 306.6 g) and Aqueous Hydrogen peroxide (H2O2) (30%, 199.4 g) were added simultaneously in a dropwise manner from using two different pressure equalizing addition funnels over a period of 80 minutes to 90 minutes. After complete addition, the reaction mass was taken to 55-60 oC and maintained till completion of the reaction. The reaction was monitored. After completion, the reaction mass was cooled to room temperature and quenched with sodium thiosulfate. The layers were separated. Aqueous layer was washed with ethylene dichloride (EDC) (2 X 100 mL). The combined organic layer was washed with brine, dried over sodium sulfate and filtered. The organic solvent was removed to furnish 2-Bromomethyl-1,3-dichloro-4-methylbenzene (3). After purification, HPLC purity (area): 94%, Yield: 267.3 g, 70 %

Method B:
A four necked glass reactor (2 Lit) fitted with condenser, thermometer pocket, thermometer, mechanical stirrer was charged with Acetonitrile (600 mL) followed by 1,3-dichloro-2,4-dimethylbenzene (2) (189.5 g). The mixture was stirred for 30 minutes. Azobisisobutyronitrile (AIBN) (6.7 g) was added. N-Bromosuccinimide (NBS) (217 g) was added in portions over a period of 90 minutes. After complete addition of N-Bromo succinimide (NBS), the reaction mass is taken to reflux. The reaction was maintained at reflux till completion. The reaction was monitored. After completion, the reaction mass was filtered, the filtrate was concentrated. The residue thus obtained was dissolved in Ethyl acetate and washed with water, brine, dried over sodium sulfate and filtered. Organic solvent was removed under vacuum to provide 2-Bromomethyl-1,3-dichloro-4-methylbenzene (3). After purification, HPLC purity (area): 96%, Yield: 200.6 g, 80 %.

Example 3: Preparation of 1,3-Dichloro-4-methyl-2-(2,2,2-trifluoro-ethoxymethyl)benzene (4)

A four necked glass reactor (2 Lit) fitted with condenser, thermometer pocket, thermometer, mechanical stirrer was charged with Ethylene dichloride (EDC) (570 mL) followed by 2-Bromomethyl-1,3-dichloro-4-methylbenzene (3) (204.3 g). The mixture was stirred for 30 minutes. Potassium carbonate (231.8 g) was added in one lot. Tetrabutylammonium bromide (TBAB) (12.7 g) was added. Trifluoroethanol (80.2 g) in EDC (160 mL) was added dropwise at reflux temperature. The reaction was monitored by HPLC. After completion, the reaction mass was cooled to room temperature. The reaction mass was filtered and the residue was washed with ethylene dichloride (EDC) (2 X 75 mL). The combined organic layer was washed with water, brine, dried over sodium sulfate, and filtered. The organic layer was concentrated under reduced pressure to furnish 1,3-Dichloro-4-methyl-2-(2,2,2-trifluoro-ethoxymethyl) benzene (4). After purification, HPLC purity (area): 95%, Yield: 166.9 g, 86 %.

Example 4: Preparation of 2-Chloro-1-methyl-4-methylsulfanyl-3-(2,2,2-trifluoro-ethoxymethyl)benzene (5)

A four necked glass reactor (2 Lit) fitted with condenser, thermometer pocket, thermometer, mechanical stirrer was charged with N,N-Dimethylformamide (450 mL) followed by 1,3-Dichloro-4-methyl-2-(2,2,2-trifluoro-ethoxymethyl)benzene (4) (168.5 g). The mixture was stirred for 30 minutes. Tetrabutylammonium bromide (TBAB) (9.4 g) was added. Aqueous Sodium thiomethoxide (20%, 248.7 g) was added dropwise at 60-70 oC. After complete addition of sodium thiomethoxide, the reaction mass heated at 110-120 oC. The reaction was monitored by HPLC. After completion, the reaction mass was cooled to room temperature and poured over ice, extracted with ethyl acetate. The layers were separated. The aqueous layer was wished with ethyl acetate (2 X 100 mL). The combined
organic layer was washed with water, brine, dried over sodium sulfate, and filtered. The organic layer was concentrated under reduced pressure to furnish 2-Chloro-1-methyl-4-methylsulfanyl-3-(2,2,2-trifluoro-ethoxymethyl)benzene (5). After purification, HPLC purity (area): 95%, Yield: 125.9 g, 82 %.

Example 5: Preparation of 2-Chloro-4-methanesulfonyl-1-methyl-3-(2,2,2-trifluoro-ethoxymethyl)-benzene (6)

A four necked glass reactor (2 Lit) fitted with condenser, thermometer pocket, thermometer, mechanical stirrer was charged with Methanol (1000 mL) followed by 2-Chloro-1-methyl-4-methylsulfanyl-3-(2,2,2-trifluoro-ethoxymethyl)benzene (5) (279 g). Sodium tungstate, dihydrate (17.2 g) was added. The reaction mixture was stirred for 20 mins. Hydrogen peroxide (411.4 g, 30% Aqueous solution) was added dropwise at room temperature. After complete addition of hydrogen peroxide(H2O2), the reaction mass was stirred at room temperature. The reaction was monitored by TLC and HPLC. After completion, the solid material was filtered and treated as first crop. The filtrate was quenched with sodium thiosulfate and concentrated in vacuo to obtain residue. The residue was dissolved in Ethyl acetate (300 mL), washed with water, brine, dried over anhydrous sodium sulfate, filtered and concentrated to furnish second crop. After purification, HPLC purity (Area): 95%, Yield: 266 g, 95 %

Example 6: Preparation of 1-Bromomethyl-2-chloro-4-methanesulfonyl-3-(2,2,2-trifluoro-ethoxymethyl)-benzene (7)

Method A: HBr, H2O2, AIBN, EDC, 10 oC to reflux
Method B: NBS, ACN, 10 oC to reflux

Method A: A four necked glass reactor (1 Lit) fitted with condenser, thermometer pocket, thermometer, mechanical stirrer was charged with ethylene dichloride (EDC) (450 mL) followed by 2-Chloro-4-methanesulfonyl-1-methyl-3-(2,2,2-trifluoro-ethoxymethyl)-benzene (130.5 g) followed by azobisisobutyronitrile (AIBN) (2.71 g). The reaction mixture was stirred for 10 minutes. Hydrogen bromide (HBr) (48%, 71.8 g) and hydrogen peroxide (H2O2) (30%, 46.6 g) were added dropwise simultaneously at 50-55 oC. The reaction was monitored by TLC and HPLC. After completion, the reaction mass was diluted with ethylene dichloride (EDC), washed with water, brine, dried over anhydrous sodium sulfate, filtered and concentrated to furnish 1-Bromomethyl-2-chloro-4-methanesulfonyl-3-(2,2,2-trifluoro-ethoxymethyl)-benzene (7). After purification, HPLC purity (Area): 95%, Yield: 108.9 g, 74 %.

Method B: A four necked glass reactor (1 Lit) fitted with condenser, thermometer pocket, thermometer, mechanical stirrer was charged with Acetonitrile (450 mL) followed by 2-Chloro-4-methanesulfonyl-1-methyl-3-(2,2,2-trifluoro-ethoxymethyl)-benzene (92.8 g) followed by azobisisobutyronitrile (AIBN) (1.9 g). The reaction mixture was stirred for 10 minutes. N-Bromo succinimide (NBS) (56.5 g) was added portion wise at 50-55 oC. The reaction was monitored by TLC and HPLC. After completion, the reaction mass was filtered. The filtrate was concentrated under reduced pressure. The residue was extracted with ethylene dichloride (EDC). The organic layer was washed with water, brine, dried over anhydrous sodium sulfate, filtered and concentrated to furnish 1-Bromomethyl-2-chloro-4-methanesulfonyl-3-(2,2,2-trifluoro-ethoxymethyl)-benzene (7). After purification, HPLC purity (Area): 95%, Yield: 81.2 g, 76 %.

Example 7: Preparation of 2-[2-Chloro-4-methanesulfonyl-3-(2,2,2-trifluoro-ethoxymethyl) benzyl]-cyclohexane-1,3-dione (8)

A three necked round bottom flask (500 mL) along with condenser, thermometer pocket, thermometer, mechanical stirrer was charged with N,N-dimethylformamide (DMF) (230 mL) followed by Tetrabutyl ammonium bromide (TBAB) (3.93 g), 1,3-Cyclohexadione (28.2 g) and potassium carbonate (K2CO3) (70.5 g). The reaction mixture was stirred for 10 minutes, and then heated to 90 oC. The reaction mass was stirred at this temperature for 45 mins. 1-Bromomethyl-2-chloro-4-methanesulfonyl-3-(2,2,2-trifluoro-ethoxymethyl)-benzene (92.8 g) in N,N-dimethylformamide (DMF) was added dropwise at the same temperature. The reaction was monitored by TLC and HPLC. After completion, the reaction mass was filtered. The filtrate was concentrated under reduced pressure. The residue was extracted with ethylene dichloride (EDC). The organic layer was washed with water, brine, dried over anhydrous sodium sulfate, filtered and concentrated to furnish 2-[2-Chloro-4-methanesulfonyl-3-(2,2,2-trifluoro-ethoxymethyl) benzyl]-cyclohexane-1,3-dione (8). After purification, HPLC purity (Area): 95%, Yield: 72.9 g, 79 %.

Example 8: Preparation of Tembotrione (I)

A three necked round bottom flask (500 mL) along with condenser, thermometer pocket, thermometer, mechanical stirrer was charged with fluorobenzene and dimethylsulfoxide (DMSO) (2:1) (150 mL) followed by 2-[2-Chloro-4-methanesulfonyl-3-(2,2,2-trifluoro-ethoxymethyl)benzyl]-cyclohexane-1,3-dione (51.55 g). 2-Iodoxybenzoic acid (IBX) (103.6 g) was added in a single portion. The reaction mixture was stirred at room temperatute for 15 minutes and then refluxed for 12 hrs. The reaction was monitored by TLC and HPLC. After completion, the reaction mass was filtered. The filtrate was diluted with ethyl acetate. The organic layer was washed with water, saturated solution of sodium bicarbonate (NaHCO3), water, brine, dried over anhydrous sodium sulfate, filtered and concentrated to furnish Tembotrione (I). After purification, HPLC purity (Area): 95 %, Yield: 42.7 g, 87 %.

Although this invention has been disclosed in the context of certain preferred embodiments and examples, it will be understood by those skilled in the art that the present invention extends beyond the specifically disclosed embodiments to other alternative embodiments and/or uses of the invention and obvious modifications and equivalents thereof.

It should be understood that the scope of the present invention is not limited by the examples in any manner. It will be appreciated by any person skilled in this art that the present invention includes the given examples and further can be modified and altered without departing from the novel teachings and advantages of the invention which are intended to be included within the scope of the invention.
,CLAIMS:I/WE CLAIM:
1. An improved process for the preparation of a Tembotrione of formula (I), comprising:
a) reacting a compound m-Xylene (1), with a halogenating agent and in the presence of suitable Lewis acid to obtain a compound 1,3-dichloro-2,4-dimethylbenzene (2);
b) reacting the compound (2) in the presence of halogenating agent, free radical initiator and a solvent, to obtain a compound 2-Bromomethyl-1,3-dichloro-4-methyl-benzene (3);
c) reacting the compound (3) with trifluoroethanol in presence base, to obtain a compound 1,3-Dichloro-4-methyl-2-(2,2,2-trifluoro-ethoxymethyl)benzene (4);
d) reacting the compound (4) with sodium thiomethoxide or methyl thiol and a base to obtain a compound 2-Chloro-1-methyl-4-methylsulfanyl-3-(2,2,2-trifluoro-ethoxymethyl)benzene (5);
e) oxidizing the compound (5) in the presence of an oxidizing agent, obtains a compound 2-Chloro-4-methanesulfonyl-1-methyl-3-(2,2,2-trifluoro-ethoxymethyl)- benzene (6);
f) reacting the compound (6) in the presence of a halogenating agent and a free radical initiator, obtain a compound 1-Bromomethyl-2-chloro-4-methanesulfonyl-3-(2,2,2- trifluoro-ethoxymethyl)-benzene (7);
g) condensing the compound (7), with 1,3-Cyclohexadione using a suitable solvent, and in the presence of base to yield a compound 2-[2-Chloro-4-methanesulfonyl-3-(2,2,2-trifluoro-methoxymethyl)benzyl]cyclohexane-1,3-dione (8);
h) oxidizing the compound-(8) in the presence of an oxidizing agent with or without a suitable catalyst and dried by utilizing drying agent to furnish a target compound, i.e., Tembotrione of Formula (I).

2. The improved process as claimed in claim 1, wherein, the halogenating agent is selected from the group comprising of a chlorinating agent, brominating agent, fluorine, iodine, etc. or combination thereof.

3. The improved process as claimed in claim 2, wherein, the chlorinating agent is selected from the group comprising thionyl chloride, sulfuryl chloride, phosphorous chloride, phosphorous oxychloride, chlorine, hydrogen chloride, etc. or combination thereof.

4. The improved process as claimed in claim 2, wherein, a brominating agent is selected from the group comprising bromine (Br2), hydrogen bromide (HBr), N-bromosuccinimide (NBS) etc. or combination thereof.

5. The improved process as claimed in claims 1-4, wherein, the halogenating agent is combined with acetic acid, water, phosphorous and/or H2O2, or combination thereof.

6. The improved process as claimed in claim 1, wherein, the free-radical initiator is selected from the group comprising azobisisobutyronitrile (AIBN), benzoyl peroxide or combination thereof.

7. The improved process as claimed in claim 1, wherein, the base is selected from the group comprising isopropylamine, diisopropylamine, diisopropylethylamine, triethylamine, dimethylamine, trimethyl amine, pyridine, N- methylmorpholine, 3-picoline, 2-picoline, 4-picoline, sodium carbonate (Na2CO3), sodium bicarbonate (NaHCO3), potassium carbonate (K2CO3), calcium hydroxide or combination thereof.

8. The improved process as claimed in claim 1, wherein, the solvent is selected from the group comprising N,N-dimethylformamide (DMF), N-methylpyrrolidone (NMP), methanol, benzene, dichloromethane, 1,2-dichloroethane, chloroform, 1, 4-dioxane, diethyl ether, acetic acid, hydrogen peroxide, o-dichlorobenzene, ethylene dichloride (EDC), carbon tetrachloride, fluorobenzene, chlorobenzene, dichlorobenzene, tetrahydrofuran and acetonitrile, Trifluoroethanol, ethyl acetate, acetone, dimethylsulfoxide (DMSO), cyclohexane, hexane, heptane, toluene, xylene, water, brine etc. or combination thereof.

9. The improved process as claimed in claim 1, wherein, the Lewis acid is selected from the group comprising Zinc chloride (ZnCl2), Aluminium Chloride (AlCl3), Ferric Chloride (FeCl3), Boron Trifluoride (BF3), Boron Trichloride (BCl3), Titanium tetrachloride (TiCl4), Antimony Pentafluoride (SbF5), Copper Chloride (CuCl2) etc. or combination thereof.

10. The improved process as claimed in claim 1, wherein, the oxidizing agent is selected from the group comprising hydrogen peroxide, tert-butyl hydroperoxide, 2-Iodoxybenzoic acid (IBX), potassium permanganate, sodium tungsten dihydrate, potassium dichromate, chlorine, sodium dichromate, chromium trioxide, nitric acid, perchloric acid, osmium tertraoxide, iodine, fluorine. selenium dioxide etc or combination thereof.

11. The improved process as claimed in claim 1, wherein, the catalyst in the reaction of the present invention is selected from Pd/C or Raney Nickel, Tetrabutylammonium bromide (TBAB), sodium tungsten dihydrate, Pt/C, PtO2/C, Na2WO4.2H2O, (2,2,6,6-Tetramethylpiperidin-1-yl)oxyl or (2,2,6,6-tetramethylpiperidin-1-yl)oxidanyl (TEMPO), Cobalt(II) acetate, Co-napthenate, palladium (II) acetate, triphenyl phosphine, or combination thereofor combination thereof.
12. The improved process as claimed in claim 1, wherein, the drying agent is selected from group comprising sodium sulfate, magnesium sulfate, calcium chloride, silica gel, SiO2, phosphorus pentoxide, anhydrous calcium sulfate, sodium (Na), potassium carbonate, alumina, activated charcoal etc.

13. The improved process as claimed in claim 1, wherein, the reaction is carried at a temperature of from 0? to 200?.

14. The improved process as claimed in claim 1, wherein the reaction is carried out for a period of about 1 hour to about 24 hours and at a pressure of from an atmospheric pressure to 50 bar.

15. An agrochemical composition, wherein the composition comprises at least a bio-active effective amount of highly pure and stable Tembotrione of formula (I) as obtained by the process claimed in claims 1-14.

16. The agrochemical composition as claimed in claim 15, wherein the composition further comprises one or more agrochemically acceptable excipients.

17. A process for preparing the agrochemical composition comprising Tembotrione of formula (I) as claimed in claims 15-16.