Description:FIELD OF THE INVENTION
[001] The present invention relates to a process for the preparation of high purity 2-Chloro-4-fluoro-5-nitrobenzoate derivatives. The present invention further relates to a single pot process for the preparation of high purity Methyl 2-Chloro-4-fluoro-5-nitrobenzoate from 2-Chloro-4-fluoro Toluene.

BACKGROUND OF THE INVENTION
[002] 2-Chloro-4-fluoro-5-nitrobenzoate derivatives, especially Methyl 2-Chloro-4-fluoro-5-nitrobenzoate is an intermediate of Saflufenacil , a herbicide of the pyrimidine dione chemical class used for the pre-plant burn down and selective pre-emergence dicot weed control in different field crops.

[003] Synthesis of 2-Chloro-4-fluoro-5-nitrobenzoate derivatives, in particular Methyl 2-Chloro-4-fluoro-5-nitrobenzoate, is known in the art. Some of the routes for synthesis of these 2-Chloro-4-fluoro-5-nitrobenzoate derivatives, in particular Methyl 2-Chloro-4-fluoro-5-nitrobenzoate are discussed herein. One such process is described in CN106866684A. Herein, 2-Chloro-4-fluoro-benzoic acid is reacted with sulfuric acid + nitric acid to obtain 2-Chloro-4-fluoro-5-nitrobenzoic acid. However, the starting product is a solid, and hence not so easily handled compared to a liquid compound at room temperature. Furthermore, the nitration requires significant volumes of sulfuric acid and nitration of 2-chloro-4-fluorobenzoic acid leads to the production of considerable amounts of unwanted by-product impurities.

[004] WO2006090210 discloses nitration and hydrolysis of 2-Chloro-4-fluoro-1-(trichloromethyl) benzene using Oleum + sulfuric acid and nitic acid. However, due to isolation at each stage, huge amount of effluent is generated. Also, the process is lengthy and multiple equipment is required.

[005] IN 254982 discloses nitration of 2-Chloro-4-fluoro-1-(trichloromethyl) benzene using 30% Oleum and 99% HNO3 followed by hydrolysis using H2SO4 + H2O.

[006] WO2018141642 discloses production of Methyl 2-Chloro-4-fluoro-5- nitrobenzoic acid using Sulfuric acid, Fuming nitric acid Water. However, the process is complicated since it requires isolation at nitration and hydrolysis stage and results in more than 5% isomer formation and with a yield of 87 – 89%

[007] Thus, the existing processes have several limitations such as the process results in isomer formation, impurities being generated and low yield.

[008] Thus, there is a need for a one-pot process for the preparation of 2-Chloro-4-fluoro-5-nitrobenzoate derivatives, in particular Methyl/Ethyl 2-Chloro-4-fluoro-5-nitrobenzoate with higher yield and purity, while at the same time being environment-friendly, less complex, economical, and minimizes or eliminates the generation of impurities and isomers.

SUMMARY OF THE INVENTION
[009] In an aspect the present invention relates to a single pot process for the preparation of 2-Chloro-4-fluoro-5-nitrobenzoate derivatives of formula (I) comprising subjecting compound of formula (II) to nitration and hydrolysis to obtain compound of formula (III),
? reacting the compound of formula (III) with R1OH followed by esterification to obtain a compound of formula (I):

(II) (III) (I)
wherein,
R = CCl3, CBr3, CN, CHO, COOH, COOR1, CONH2. CONR2 or CON+R3 and
R1 = C1 to C10 straight chain or branched alkyl, C1 to C10 cycloalkyl, or
Aliphatic diols having formula HO-R2-OH, where R2 is C1-C6 alkyl.

[010] The invention also relates to a single pot process for the preparation of Methyl or ethyl 2-Chloro-4-fluoro-5-nitrobenzoate comprising the steps of chlorination of 2-chloro-4-fluoro toluene followed by the nitration and hydrolysis of obtained 2-chloro-4-fluoro benzotrichloride to obtain the acid which is the in-situ reacted with methanol or ethanol to obtain Methyl or Ethyl 2-Chloro-4-fluoro-5-nitrobenzoate.

IIa IIIa Ia
BRIEF DESCRIPTION OF THE DRAWINGS
[011] Reference will be made to embodiments of the invention, examples of which may be illustrated in accompanying figures. These figures are intended to be illustrative, not limiting. Although the invention is generally described in context of these embodiments, it should be understood that it is not intended to limit the scope of the invention to these particular embodiments.
[012] Figure 1 shows a flow-chart illustrating the process for preparation of 2-Chloro-4-fluoro-5-nitrobenzoate derivatives in accordance with an embodiment of the invention.

DESCRIPTION OF THE INVENTION
[013] The present invention provides a single pot process for the preparation of 2-Chloro-4-fluoro-5-nitrobenzoate derivatives of formula (I), in particular Methyl 2-Chloro-4-fluoro-5-nitrobenzoate. The single pot in-situ process starts from 2-Chloro 4-Fluoro toluene and ends with the final product i.e. 2-Chloro-4-fluoro-5-nitrobenzoate derivatives of formula (I).

[014] In an embodiment, the scheme 1 discloses a one-pot reaction scheme wherein (i) the 2-Chloro-4-Fluoro compound of formula (II) is subjected to nitration and hydrolysis to obtain the in-situ intermediate of formula (III), and the in-situ intermediate of formula (III) is reacted with alcohol R1OH to obtain the 2-Chloro-4-fluoro-5-nitrobenzoate derivatives of formula (I).

(II) (III) (I)
wherein,
R = CCl3, CBr3, CN, CHO, COOH, COOR1, CONH2. CONR2 or CON+R3 and
R1 = C1 to C10 straight chain or branched alkyl, C1 to C10 cycloalkyl, or
Aliphatic diols having formula HO-R2-OH, where R2 is C1-C6 alkyl.

[015] In the present context, “one-pot” refers to the synthesis of 2-Chloro-4-fluoro-5-nitrobenzoate derivatives of formula (I), as above, in a series of steps that are performed in a single apparatus or reaction vessel. The one-pot procedure eliminates the need for isolation (e.g., purification) of the intermediates, while reducing the number of synthetic steps.

[016] In an embodiment, the present invention process is a green process or is environment friendly. In the present context, “environment-friendly” refers to the process being capable of substantially reducing the requirement of recovering the hazardous and troublesome effluents in comparison with the state-of-the-art or commercially used processes.

[017] The nitration was conducted with various nitrating agents as mentioned in the literature. However, the reaction with solvent takes more time for conversion in the nitration reaction and hence in an embodiment, the reaction was carried out without solvent. In the embodiment where nitration is carried out in solvent, the reagents used, in particular were nitrate salts of alkaline earth metals and transition metals in suitable solvents. Alternatively, concentrated nitric acid in neat conditions or in chlorinated solvent systems like dichloromethane, chloroform, carbon tetra chloride, dichloroethane, tetrachloro ethane, chlorobenzenes or their mixtures therein. Another method to introduce nitro group in the said molecule is by conducting the nitration in nitrating mixture where H2SO4: HNO3 molar ratio with respect to the substrate remains in the range of 1:0.5-10: 1- 12 more precisely the ratio remains in the range of 1:3-7: 1-4. H2SO4: HNO3 weight by weight ratio with respect to substrate remains in the range of 1:0.2-4: 0.26-3, more precisely the ratio remains in the range of 1:1-5:0.35-2. In other words, concentration of HNO3 (by weight) remains in the range of ~ 17-38% in the reaction mass, more precisely the concentration is maintained between 5-25% (by weight). The 2-Chloro-4-fluoro benzotrichloride is contacted with nitrating mixture maintaining above mentioned concentrations at a temperature ranging from -5 to 30 º C more precisely between 0 to 15 º C, over a period of 0.5- 10 hrs more precisely between 1 to 6 hrs.

[018] The reaction mass yields mixture containing nitro benzotrichloride as a major component above 98 % as indicated by HPLC. The reaction mass after nitration process, is extracted with suitable solvents in batch mode or continuous or semi-continuous process. The solvents used comprise etheral solvents such as dialkyl ethers R-O-R’ where 1) R = R’ = C1 to C7 aliphatic alkyl (straight chain, branched or cyclo alkyl) like, Diethyl ether, Diisopropyl ether, Dipropyl ether, dipentyl ether Di tert. butyl ether, Dicyclhexyl ether, Dicyclopentyl ether, etc., & 2) R and R’ can exist in combinations of C1 to C7 aliphatic alkyl - straight chain, branched or cyclo alkyl groups. or their mixtures therein;
Cyclic ethers like tetrahydrofuran (THF), Methyl –THF, etc., or their mixtures therein;
Halogenated aliphatic hydrocarbons with C1- C10 eg., dihalomethane, chloroform, carbon tetrahalides, dihalomethane, tetrahalo ethane, halo propanes, halo pentanes and higher analogues or their mixtures therein;
Halogenated aromatic hydrocarbons like mono or multi halo benzenes, or their mixtures therein, eg., mono, di, tri, quatra, penta - chloro, bromo, iodo and fluoro benzenes or their alkyl, haloalkyl substituted analogues; or their mixtures therein;
Aliphatic Hydrocarbons include (straight chain, branched and cyclic) with C4- C10 eg., pentane, hexane, cyclohexane; or their mixtures therein
Aromatic hydrocarbons with C6-C12 eg., benzene, toluene, Xylenes (all isomers and mixtures), tri-methylbenzenes (all isomers and mixtures), cumenes (all isomers and mixtures) etc., or their mixtures therein. The solvent layer is separated and used for next step of hydrolysis. The spent acid can be recycled back into the process after adjusting the strength of 1) nitric acid using fresh concentrated HNO3 and 2) Sulfuric acid using oleum.

[019] In another embodiment, the hydrolysis step was carried out using concentrated acids individually or in their proportionate combinations as follows -
Hydrochloric acid having strength 32-35% w/w;
Hydrofluoric acid having strength 35-80% w/w;
Sulphur based acids, which includes acids like Sulfurous acid (H2SO3), sulfinic acid (RHSO2), sulfuric acid H2SO4, having strength in the range of 80-100% w/w. or their mixtures therein;
Oleum SO3 having strengths ~0.1-25%;
Per chloric acid HClO4 with strength of 10-75% w/w;
Phosphorous based acids, which includes acids like phosphorous acid (H3PO3), Phosphoric acid H3PO4, having strength in the range of 80-100% w/w. or their mixtures therein;
Aliphatic Sulphonic acid having formula RSO3H where R= straight chain or branched alkyl group with C1 – C10; Aromatic Sulphonic acid having formula ArSO3H where Ar= benzene, alkyl benzene or other substituted benzenes group with C6 – C15;

[020] The 2-Chloro-4-fluoro-5-nitro benzene derivative of formula (II) was subjected to hydrolysis in acidic conditions at temperature ranging from 10 to 100 º C, more precisely between 40 to 90 º C, preferably at 80-90 º C, over a period of 0.5- 10 hrs more precisely between 1 to 5 hrs, with simultaneous distillation of solvent used for extraction of previous step nitro intermediate. The recovered solvent can be recycled back in the process thus making the process more cost competitive. HCl gas released during the reaction is scrubbed in water to generate conc. HCl (~25-32 %). The reaction mass after maintaining at above parameters, ends up to a mixture containing corresponding derivative of nitro benzoic acid as a major component above 97 % as indicated by HPLC.

[021] In an embodiment, the esterification of 2-Chloro-4-fluoro-5-nitro benzoic acid of formula (III) was initiated in situ by treating the reaction mass with aliphatic alcohols at the boiling point of respective alcohol. The alcohols include
a) alkyl R1-OH where 1) R1 = C1 to C10 aliphatic alkyl
b) R1 = Straight chain like Methyl, ethyl, propyl, butyl, pentyl, hexyl, septyl, heptyl and higher analogues Branched alcohols like isopropyl, isobutyl, tert butyl and higher analogues
c) R1 = Cyclo alkyl like, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl and higher analogues,
d) R1 = Aliphatic diols having formula HO-R1-OH, where R1 is alkyl group with C1-C6.

The reaction mass after being maintained at above parameters, results in a mixture containing corresponding derivative of nitro benzoate ester as a major component above 98 % as indicated by HPLC.

[022] In an embodiment of the invention, the reaction mixture is now subjected to recovery using any tool favourable for distillation of excess alcohol. Under reduced pressure keeping temperature below 100 ºC, the residual mass is now subjected to batch mode / semi continuous / continuous extraction in any suitable solvent in hot avoiding the crystallization of ester. The solvents used for the extraction of 2-Chloro-4-fluoro-5-nitrobenzoate derivatives are selected on the bases of its solubility in the solvent and ay include –
Ethereal solvents such as di alkyl ethers R-O-R’ (where 1) R = R’ = C1 to C7 aliphatic alkyl (straight chain, branched or cyclo alkyl) like, Diethyl ether, Diisopropyl ether, Dipropyl ether, dipentyl ether Ditert-butyl ether, Dicyclohexyl ether, Dicyclopentyl ether, etc., & 2) R and R’ can exist in combinations of C1 to C7 aliphatic alkyl - straight chain, branched or cyclo alkyl groups. or their mixtures therein;
Cyclic ethers like tetrahydrofuran (THF), Methyl –THF, etc., or their mixtures therein;
Halogenated aliphatic hydrocarbons with C1-C10 eg., dihalomethane, chloroform, carbontetrahalides, dihalomethane, tetrahalo ethane, halopropanes, halopentanes and higher analogues or their mixtures therein;
Halogenated aromatic hydrocarbons like mono or multi halo benzenes, or their mixtures therein, eg., mono, di, tri, quatra, penta - chloro, bromo, iodo and fluoro benzenes or their alkyl, haloalkyl substituted analogues; or their mixtures therein;
Aliphatic Hydrocarbons with C4- C10 (straight chain, branched and cyclic) eg., pentane, hexane, heptane, cyclohexane, cyclopropane, cyclopentane and higher analogues; or their mixtures therein;
Aromatic hydrocarbons with C6-C12 eg. benzene, toluene, Xylenes (all isomers and mixtures); tri-methylbenzenes (all isomers and mixtures), cumenes (all isomers and mixtures) etc., or their mixtures therein.

[023] The solvent used for the extraction remains in the range of 5-15 times of the substrate, more precisely solvent is used in the range of ~8-13 times of the substrate. The solvent layer containing the 2-Chloro-4-fluoro-5-nitrobenzoate derivative is separated in hot from the spent acid layer. The organic layer is then washed with dilute 2-5 % sodium bicarbonate aqueous solution to get rid of traces of unreacted carboxylic acid. The separation of spent acid is necessary before hydrolysis step for the following reasons/benefits
a) to attain recyclable value of spent acid after top up of nitric acid in next subsequent nitration reaction. This will advantageously reduce the effluents.
b) Avoiding frothing at hydrolysis step: -
? In case of substituents R= CCl3 or CBr3, HCl or HBr are the by-products which cause heavy frothing if the nitration reaction mass along with spent acid is carried ahead for next step of hydrolysis. This will increase the load on effluents considerably due to entire spent acid getting carried forward in hydrolysis.

? In case of substituents R= CN, CONH2. CONR2 or CON+R3, ammonia or substituted ammonia will be by-products which will neutralize the acid required for hydrolysis and thus increase the effluents in the form of salts.

? In case of R= COOH we get the desired nitro substitution after nitration and subsequent esterification with alcohol will lead to desired ester

? In case of R= COOR1 we get the desired nitro substitution after nitration and subsequent hydrolysis esterification play the role of purification to yield desired ester with high purity.

[024] The organic layer is subjected to partial recovery of solvent at temperature below 100ºC, more preferably below 70ºC under reduced pressure. The solvent recovered can be recycled back to the process, thus helping the economics of overall process. After attaining ~ 50 % recovery of solvent product is crystallized out from the reaction mixture using the skills in the art of crystallization with respect to stirrer design, reactor dimensions and RPM during crystallization. The Reaction mass is cooled and equilibrated to 0-30ºC, preferably 5-15ºC for 2-5 hrs. The product is isolated by filtration followed by washing with solvent and then dried under vacuum till loss on drying remains below 1%. The dry product, 2-Chloro-4-fluoro-5-nitrobenzoate derivative indicated +99% purity with any unknown impurity below 0.1% in HPLC analysis.

[025] In another embodiment, the invention relates to a single pot process for the preparation of Methyl or Ethyl 2-Chloro-4-fluoro-5-nitrobenzoate. The process involves 2-Chloro-4-Fluorotoluene as a key starting material which is converted into Methyl 2-Chloro-4-fluoro-5-nitrobenzoate through multistep reactions and in situ intermediates. The 2-Chloro-4-Fluorotoluene is subjected to chlorination to obtain 2-Chloro-4-fluoro benzotrichloride of formula IIa, followed by nitration and hydrolysis to obtain the acid of formula IIIa, which is then subjected to reaction with CH3OH or C2H5OH to obtain the final product of formula Ia

IIa IIIa Ia

[026] In an embodiment, the 2-Chloro-4-Fluorotoluene is subjected to chlorination using UV catalyzed chlorination using inbuilt UV lamp having capacity of 50-1000 watts, more precisely of 200-600 watts at temperature of 30-150 ºC, more precisely between 40 to 80 ºC. The reaction is conducted with stirrer designed for gas liquid mixing keeping RPM range of 50- 200, more precisely between 50 to 100. Alternatively, the chlorination can be free radical initiated chlorination using free radical initiator like Azobisisobutyronirile AIBN, benzoyl peroxide etc., at the concentration level of 0.05- 50% w/w in the reaction system at the temperature of 30-150 ºC, more precisely between 40 to 80 ºC in presence or absence of UV light. Another method of chlorination is by purging chlorine in the reaction mass at such a rate that maximum chlorine is consumed in the reaction and by-product of HCl gas along with escaped chlorine is absorbed in the scrubber. The escaped chlorine could be recycled back in the process reducing the consumption of chlorine. The chlorine purging is continued in the reaction mass till almost quantitative conversion to benzotrichloride derivative is achieved. After the completion, the reaction mass is purged with nitrogen to drag out dissolved HCl and chlorine.

[027] Advantageously, the present invention process can be carried out in a single reactor vessel without isolation and recovery of the intermediates. Furthermore, it is also feasible to practice the present invention as batch, semi-continuous or continuous process. Further, the process of the present invention is clean and environment friendly and can be carried out in a single reaction vessel, i.e., one-pot. Process involves efficient recovery and recycle of solvents thus reducing the waste effluent per kg of final product considerably. Solvent recoveries involve simple distillations. Additionally, the process is less complex, economical with minimum generation of impurities. High purity Methyl or Ethyl 2-Chloro-4-Fluoro-5-nitrobenzoate with any single unknown impurity less than 0.1% can be achieved from this process.

EXAMPLES

[028] Procedure for synthesis of Methyl 2-Chloro-4-fluoro-5-nitrobenzoate
600 gm 2-chloro-4-Fluoro toluene was charged in Photochlorinator, at room temperature and was heated at 50-60 ºC with slow to moderate stirring. UV lamp was turned on. Feeding of chlorine gas started with quantified rate. The rate of chlorine gas is adjusted in such a way that the more than 90% of chlorine got consumed in the reaction. 888 gm chlorine gas was allowed to pass through the reaction mass over several hours controlling the exotherm of reaction below 100 ºC. Completion of the reaction conversion was ensured by GC analysis. Reaction mass was cooled to 50-60 ºC was purged with nitrogen gas to drag out dissolved chlorine.
The reaction mass was then contacted with 1275 gm sulfonitrating mixture (with ~ 10-11% HNO3 strength) at temperature 0-5 ºC. After maintaining the reaction mass at 0-5 ºC. for several hrs, the reaction completion was ensured by HPLC analysis. After the reaction completion, product (2-chloro-4-fluoro-5-nitrobenzotrichlorde) is extracted in THF to separate spent acid which can be recycled back in the process after adjustment of its strength.
Organic layer containing 2-chloro-4-fluoro-5-nitrobenzotrichlorde was now heated to ~100 ºC and was contacted with 366 gm phosphoric acid with simultaneous recovery of solvent. Reaction mass was maintained for few hours till it shows the complete reaction conversion by HPLC analysis.
Reaction mass was cooled to 60-70 ºC and reacted with 244 gm methanol at 60-70 ºC. Reaction mass was equilibrated at this temperature for few hours till reaction conversion completion was ensured by HPLC analysis.
Reaction mass was cooled to 50-55 ºC and was subjected to distillation under reduced pressure to recover unreacted alcohol, which can be recycled back in the process. The residual mass was extracted with the suitable solvent based on solubility of ester. In this case the methyl ester is extracted in mixture of THF and Heptane. The spent acid is separated and Organic layer is washed with 8% sodium bicarbonate solution to get rid of unreacted 2-Chloro-4-fluoro-5-nitrobenzoic acid.
[029] Organic layer was subjected to distillation under reduced pressure to recover the solvent partly at atmospheric pressure or under reduced pressure below 50 ºC till ~ 1.5-2 vol of heptane remains in the residual mass. Further reaction mass was cooled to 0-10 ºC and the product was isolated by filtration, followed by washing. The product was then dried at 45°C to 50°C temperature under vacuum to yield 820 g of high purity of Methyl 2-Chloro-4-Fluoro-5-nitrobenzoate with molar yield of ~84 % having 99.5+% HPLC purity and any unknown impurity less than 0.1%.

[030] The foregoing description of the invention has been set merely to illustrate the invention and is not intended to be limiting. Since the modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to the person skilled in the art, the invention should be construed to include everything within the scope of the disclosure.

, Claims:WE CLAIM

1. A single pot process for the preparation of 2-Chloro-4-fluoro-5-nitrobenzoate derivatives of formula (I) comprising
? subjecting compound of formula (II) to nitration and hydrolysis to obtain compound of formula (III),
? reacting the compound of formula (III) with R1OH followed by esterification to obtain a compound of formula (I):

(II) (III) (I)
wherein,
R = CCl3, CBr3, CN, CHO, COOH, COOR1, CONH2. CONR2 or CON+R3 and
R1 = C1 to C10 straight chain or branched alkyl, C1 to C10 cycloalkyl, or
Aliphatic diols having formula HO-R2-OH, where R2 is C1-C6 alkyl.

2. The single pot process as claimed in claim 1, wherein the nitration was carried out by nitrate salts of alkaline earth metals or transition metals or concentrated nitric acid or using nitrating mixture of H2SO4: HNO3. in chlorinated solvent systems like dichloromethane, chloroform, carbon tetra chloride, dichloromethane, tetrachloro ethane, chlorobenzenes or their mixtures therein in suitable solvents.

3. The single pot process as claimed in claim 1, wherein the nitration is carried out at a temperature ranging from -5 to 30?C over a period of 0.5- 10 hrs.

4. The single pot process as claimed in claim 1, wherein reaction mass obtained after nitration process comprising 2-Chloro-4-fluoro-5-nitro benzene derivative is extracted with solvents in batch mode continuous or semi-continuous process.

5. The single pot process as claimed in claim 4, wherein solvent selected for the extraction is selected from Etheral solvents, Cyclic ethers, halogenated aliphatic hydrocarbons, Halogenated aromatic hydrocarbons, Aliphatic Hydrocarbons and Aromatic hydrocarbons.

6. The single pot process as claimed in claim 1, wherein solvent layer extracted after nitration is subjected to hydrolysis with simultaneous solvent recovery acid to obtain nitro benzoic acid derivative.

7. The single pot process as claimed in claim 6, wherein the acid is selected from Hydrochloric acid having strength 32-35% w/w, Hydrofluoric acid having strength 35-80% w/w, Sulphur based acids having strength in the range of 80-100% w/w, Oleum SO3 having strength ~0.1-25%, Per chloric acid HClO4 with strength of 10-75% w/w, Phosphorous based acids having strength in the range of 80-100% w/w, Aliphatic Sulphonic acid and Aromatic Sulphonic acid and mixtures thereof.

8. The single pot process as claimed in claim 6, wherein the hydrolysis is carried out at temperature ranging from 10 to 100 deg over a period of 0.5- 10 hrs.

9. The single pot process as claimed in claim 1, wherein the nitro benzoic acid of formula (III) is reacted with R1OH to obtain a reaction mass comprising the compound of Formula (I).

10. The single pot process as claimed in claim 9, wherein the reaction mass is subjected to batch mode, semi continuous or continuous extraction in a solvent selected from Etheral solvents, Cyclic ethers, Halogenated aliphatic hydrocarbons, Halogenated aromatic hydrocarbons, Aliphatic Hydrocarbons or Aromatic hydrocarbons or their mixtures thereof.

11. The single pot process as claimed in claim 1, wherein the compound of formula (I) is Methyl or Ethyl 2-Chloro-4-fluoro-5-nitrobenzoate.

12. The single pot process as claimed in claim 11, wherein compound of formula (II) where R = CCl3 is obtained by chlorination of 2-Chloro-4-Fluoro Toluene.