Description:PROCESS FOR PREPARING CRYSTALLINE FORM OF SULFENTRAZONE
Field of the Invention
The present invention relates to a process for the preparation of crystalline form SJDM-1 of sulfentrazone, characterized by PXRD, DSC and FTIR and use of the prepared form to prepare the agrochemical compositions.
Background of the Invention
Sulfentrazone having CAS name N-(2,4-dichloro-5-(4-(difluoromethyl)-4,5-dihydro-3-methyl-5-oxo-1H-1,2,4-triazol-1-yl) phenyl) methanesulfonamide belongs to the group of protophyrinogen oxidase inhibitors herbicide. It is an important commercial herbicide in agriculture and is used for pre-plant incorporated or pre-emergence control of annual broad-leaved weeds, some grass weeds and Cyperus spp. in soybeans, sugarcane and tobacco.
A number of processes for the preparation of sulfentrazone are already known from the literature such as U.S. Patents 4,818,275; 5,990,315 and 7,169,952. The commercially available sulfentrazone also known as technical sulfentrazone is usually manufactured by the process described in these patent literature is in amorphous state as described in WO 2017/197909, whereas WO2018/118621 describe that commercial available technical sulfentrazone comprise of mixture of polymorphic forms although no details of these forms were provided whether these are crystalline or amorphous. It has been established in prior arts/patent literature (WO 2017/197909 and WO2018/118621) that sulfentrazone of amorphous state or available in prior arts is not suitable for preparing agrochemical compositions/formulations.
The efforts to prepare the crystalline form of sulfentrazone is reported in PCT publication WO 2017/197909 wherein crystalline modification I is prepared from amorphous form using solvent xylene and diethyl ketone in a lengthy process. The PCT publication WO2018/118621 also reports the crystalline form - 1 which is prepared from form 2 of sulfentrazone using the alcoholic solvent in a lengthy process.
It has been surprisingly found by the inventors of present invention that a novel crystalline form of sulfentrazone can be prepared by a simple, cost-effective and environment friendly process which is not only the commercial viable but also produces the novel crystalline form in higher assay content, high yield and high purity without using organic solvent.
Object of the Invention
It is the foremost object of the present invention to provide a simple, cost-effective and environment friendly process for the preparation of crystalline form of sulfentrazone, named as SJDM-1, without using any organic solvent.
Another objective of present invention is to provide a process for the preparation of crystalline form SJDM-1 by exposing the technical sulfentrazone in a specific drying temperature upto certain period.
Yet another objective of present invention is to provide a process for the preparation of crystalline form SJDM-1 in higher assay content by dissolving the technical sulfentrazone in an acetone and drying the resulted product under specific drying temperature upto certain period.
Summary of the Invention
Accordingly, the present invention provides a simple, cost-effective and environment friendly process for the preparation of crystalline form SJDM-1 without using any organic solvent.
Accordingly, the present invention provides a process for the preparation of crystalline form SJDM-1 by exposing the technical sulfentrazone in a specific drying temperature upto certain period comprising the steps of:
a) reacting 2-(5-amino-2,4-dichlorophenyl)-4-(difluoromethyl)-2,4-dihydro-5-methyl-3H-1,2,4-triazol-3-one with methanesulfonyl chloride and pyridine in toluene solvent;
b) washing the obtained product of step a) with toluene; and
c) drying the obtained product of step b) at 60-90 oC under vaccum for 24-60 hours;
Accordingly, the present invention provides a process for the preparation of crystalline form SJDM-1 in higher assay content comprising the steps of:
a) reacting 2-(5-amino-2,4-dichlorophenyl)-4-(difluoromethyl)-2,4-dihydro-5-methyl-3H-1,2,4-triazol-3-one with methanesulfonyl chloride and pyridine in toluene solvent;
b) washing the obtained product of step a) with toluene;
c) dissolving the product obtained in step b) in solvent acetone;
d) optionally distilling the solvent;
e) adding a water to the step d) mixture;
f) isolating the product of step e); and
g) drying the obtained product of step f) at 60-90 oC under vaccum for 24-60 hours;
Brief Description of the Drawings
FIGURE 1 shows the powder X-ray diffraction pattern of SJDM-1 prepared according to present invention.
FIGURE 2 shows the Differential scanning calorimetry (DSC) of SJDM-1 prepared according to present invention.
FIGURE 3 shows the FTIR spectrum of SJDM-1 prepared according to present invention.
FIGURE 4 shows the powder X-ray diffraction pattern of SJDM-1 having higher assay content and prepared according to present invention.
FIGURE 5 shows the Differential scanning calorimetry (DSC) of SJDM-1 having higher assay content and prepared according to present invention.
FIGURE 6 shows the FTIR spectrum of SJDM-1 having higher assay content and prepared according to present invention.
Detailed description of the Invention
The definitions provided herein for the terminologies used in the present disclosure are for illustrative purpose only and in no manner limit the scope of the present invention disclosed in the present disclosure.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by a person of ordinary skill in the art to which the invention pertains. Although other methods and materials similar, or equivalent, to those described herein can be used in the practice of the present invention, the preferred materials and methods are described herein.
It is to be noted that, as used in the specification and the appended claims, the singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise. It should also be noted that the term “or” is generally employed in its sense including “and/or” unless the content clearly dictates otherwise.
As used herein, the terms "comprises", "comprising", "includes", "including", or any other variation thereof, are intended to cover a non-exclusive inclusion, subject to any limitation explicitly indicated.
The term ‘assay’ as used in present invention represents a quantitative measurement of the major components in agrochemical substance. It refers to content or potency to provide an exact result which allows an accurate statement on the content or potency of the analyte in a sample.
As used herein "Crystalline form SJDM-1" means a crystalline sulfentrazone having X-ray diffraction pattern, DSC and FTIR that substantially correspond to as given in figures 1- 6.
As used herein "substantially corresponds" means it covers differences or variations in the pattern that would not be understood by the person skilled in the art to represent a difference in a crystal structure, but rather differences in techniques, sample preparation and instrument etc.
The term “technical sulfentrazone” as used herein can generically refer to any form of sulfentrazone such as amorphous form, solvates, polymorph forms, pseudo polymorph forms, crystalline form, mixture of crystalline forms or mixture of amorphous and crystalline form, or the sulfentrazone obtained from the conventional process/prior art process or the sulfentrazone known in art by the name of technical sulfentrazone. Specifically it is the amorphous form but in the case commercial technical sulfentrazone defined otherwise it is include in the scope of present invention. For the purpose of present invention “technical sulfentrazone” can be procure from the commercial source and used to prepare the crystalline form SJDM-1. Specifically for the purpose of present invention “technical sulfentrazone” is prepared by following the processes as per the prior art such as US patent no. 5,990,315 and is typical of the procedures used herein to prepare technical sulfentrazone, with possible variations related to processing conditions such as mole equivalent, batch size, time, temperature and the like.
Accordingly, the present invention provides a simple, cost-effective and environment friendly process for the preparation of crystalline form SJDM-1 without using any organic solvent. Specifically the present invention provides process for the preparation of crystalline sulfentrazone form SJDM-1 without using any organic solvent.
In an embodiment, the present invention provides a process for the preparation of crystalline form SJDM-1 by exposing the technical sulfentrazone in a specific drying temperature upto certain period comprising the steps of:
a) reacting 2-(5-amino-2,4-dichlorophenyl)-4-(difluoromethyl)-2,4-dihydro-5-methyl-3H-1,2,4-triazol-3-one with methanesulfonyl chloride and pyridine in toluene solvent;
b) washing the obtained product of step a) with toluene; and
c) drying the obtained product of step b) at 60-90 oC under vaccum for 24-60 hours;
In one aspect of the embodiment the 2-(5-amino-2,4-dichlorophenyl)-4-(difluoromethyl)-2,4-dihydro-5-methyl-3H-1,2,4-triazol-3-one can be prepared by using the prior art processes or procured from commercial sources.
In one other aspect of the embodiment reaction of step a) and b) can be performed as per the prior art processes and is typical of the procedures used herein to prepare technical sulfentrazone, with possible variations related to processing conditions such as mole equivalent, batch size, time, temperature and the like.
In one another aspect of the embodiment the product obtained in step b) dried at a temperature of 60-90 oC under vaccum for 24-60 hours to obtain the crystalline form SJDM-1.
In one other aspect of the embodiment the product obtained in step b) preferably dried at a temperature 80-85 oC and the drying time preferably is 38-60 hours to obtain the crystalline form SJDM-1.
In one other embodiment the present invention provides a process for the preparation of crystalline form SJDM-1 in higher assay content comprising the steps of:
a) reacting 2-(5-amino-2,4-dichlorophenyl)-4-(difluoromethyl)-2,4-dihydro-5-methyl-3H-1,2,4-triazol-3-one with methanesulfonyl chloride and pyridine in toluene solvent;
b) washing the obtained product of step a) with toluene;
c) dissolving the product obtained in step b) in solvent acetone;
d) optionally distilling the solvent;
e) adding a water to the step d) mixture;
f) isolating the product of step e); and
g) drying the obtained product of step f) at 60-90 oC under vaccum for 24-60 hours;
In one aspect of the embodiment the 2-(5-amino-2, 4-dichlorophenyl)-4-(difluoromethyl)-2,4-dihydro-5-methyl-3H-1,2,4-triazol-3-one can be prepared by using the prior art processes or procured from commercial sources.
In one other aspect of the embodiment reaction of step a) and b) can be performed as per the prior art processes and is typical of the procedures used herein to prepare technical sulfentrazone, with possible variations related to processing conditions such as mole equivalent, batch size, time, temperature and the like.
In one another aspect of the embodiment the solvent acetone used in step c) is in the range of 0.2 volume to 20 volumes.
In other aspect of the embodiment the solvent used in step d) is optionally distilled. In the process if solvent acetone is distilled then distillation can be done more than 85% of used solvent amount. Generally the quality of product of step b) will be the deciding factor of distillation. It is observed that as per example 1 of present invention wherein solvent is not distilled yield is low, wherein when the solvent acetone is distilled upto 90% the yield of product is increased.
In one other aspect of the embodiment, the water used in step e) is in the range of 0.1 volume to 100 volumes.
In one other aspect of the embodiment, the product formed in step e) can be isolated in step f) by a suitable technique known in the art such as filtration, centrifugation, decantation and the like. Typically, the product is isolated by filtration. The isolation can be optionally done under the nitrogen atmosphere by providing a blanket of nitrogen.
In one other aspect of the embodiment, the product obtained in step f) dried at a temperature of 60-90 oC under vaccum for 24-60 hours to obtain the crystalline form SJDM-1.
In one other aspect of the embodiment the product obtained in step b) preferably dried at a temperature 80-85 oC and the drying time preferably is 38-60 hours to obtain the crystalline form SJDM-1.
In another embodiment of the present invention, the product obtained in step f) found crystalline as per characterization techniques used in art for the crystalline product.
In one another embodiment of the present invention, the crystalline form SJDM-1 is employed to prepare the agrochemical compositions using the agrochemically acceptable excipients and can be prepared in any formulation type generically described in prior art, specifically the agrochemical compositions/formulations by using the SJDM-1 can be prepared by techniques and methods as known in prior art for preparing the agrochemical compositions/formulations with amorphous or technical sulfentrazone.
In one other aspect of the embodiment the agrochemical compositions comprising the crystalline form SJDM-1 may further comprise other compatible agrochemical actives to provide the broad spectrum of weed control.
In one another embodiment of the present invention, the crystalline form SJDM-1 is obtainable by the process as substantially as described in Example 2-7.
In one another embodiment of the present invention the crystalline form SJDM-1 is obtainable by exposing the wet cake of toluene containing the technical sulfentrazone under the disclosed condition of temperature and time period.
The crystalline form SJDM-1 are characterized by their X-ray powder diffraction pattern. Thus, the X-ray diffraction patterns were measured on Bruker Axs X-Ray Diffractometer equipped with goniometer of ?/? configuration and LynxEye (PSD electronic window -5°) detector. The Cu-anode X-ray tube was operated at 30kV and 10mA. The experiments were conducted over the 2? range of 3.0°- 40.0°. One with ordinary skills in the art understand that experimental differences may be arise due to difference in the instrument, sample preparation and other factors.
The DSC measurements were carried out on DSC 8000 Perkin Elmer instrument. The experiments were performed at heating rate of 10.0 °C/min over a temperature range of 30 °C to 430 °C purging with nitrogen at a flow rate of 20ml/min.
The IR spectrum was measured on Shimadzu instrument in the range of 400-4000 cm-1 with the resolution of 4 cm-1 and with the number of scans of 16.
In one another embodiment of the present invention, the crystalline form SJDM-1 is characterized by PXRD as shown in figure 1 and 4. In particular PXRD peaks is observed at 2-theta+0.2°at 6.388, 6.884, 10.557, 11.205, 12.175, 13.747, 14.875, 16.458, 17.286, 17.611, 18.197, 18.565, 19.08, 19.566, 21.180, 21.473, 22.491, 22.697, 22.968, 23.368, 24.561, 28.387, 28.800, particularly the peak at 2-theta+0.2°: 19.08 and 23.368 is observed.
In one another embodiment of the present invention, the crystalline form SJDM-1 is characterized by DSC as shown in figure 2 and 5. In particular DSC shows onset of melting in the range of from about 128 °C to about 135 °C. Specifically as shown in figure 2 the DSC profile having an endothermic melting peak with onset at 128.81°C and peak maximum at 130.58°C with melting enthalpy 61.9740J/g. Similarly as shown in figure 5 the DSC profile having an endothermic melting peak with onset at 131.23°C and peak maximum at 133.40°C with melting enthalpy 58.9275J/g.
In one another embodiment of the present invention, the crystalline form SJDM-1 is characterized by FTIR spectrum as shown in figure 3 and 6. FTIR spectrum comprising a peak, in terms of wavenumber, at about 3458.37, 3255.84, 2931.80, 1737.86, 1610.56, 1490.97, 1327.03, 1159.22, 970.19 and 823.60 as shown in Figure 3. In one other aspect of embodiment of the present invention, FTIR spectrum comprising a peak, in terms of wavenumber, at about 3458.37, 3255.84, 2931.80, 1737.86, 1610.56, 1490.97, 1327.03, 1159.22, 968.27, 823.60 as shown in figure 6.
The foregoing description of the embodiments has been provided for purposes of illustration and not intended to limit the scope of the present disclosure. Individual components of a particular embodiment are generally not limited to that particular embodiment, but, are interchangeable. Such variations are not to be regarded as a departure from the present disclosure, and all such modifications are considered to be within the scope of the present disclosure.
The present disclosure is further described in light of the following experiments which are set forth for illustration purpose only and not to be construed for limiting the scope of the disclosure. The following experiments are scalable to industrial/commercial process.

Examples
Example 1: Preparation of Technical sulfentrazone
53.9 g (0.174 mole) of 2-(5-amino-2, 4-dichlorophenyl)-4-(difluoromethyl)-2,4-dihydro-5-methyl-3H-1,2,4-triazol-3-one, (2.9 g, 0.036 mole) of pyridine and 108 g of toluene was taken in round bottomed flask. The mixture was heated to reflux and (34.99 g, 0.306 mole) of methanesulfonyl chloride was added dropwise over 30 minutes. The solution was heated at reflux for 8-12 hours. After completion of reaction, the reaction mixture was diluted with 431 mL of toluene, then transferred to a 1-L round bottomed flask equipped with a mechanical stirrer. The mixture was warmed to 80 °C and washed twice with 108 mL portions of water with the washes being removed via layer separation. The organic layer was allowed to cool slowly to room temperature and the resulting slurry stirred for 2-3 hours. The slurry was then cooled using an ice bath for 2.5 hours, the product collected by filtration, and the filter cake was washed with a total of 162 mL of cold toluene and dried in a vacuum oven at 50-60 oC to provide 1-[2,4-dichloro-5-(N-methylsulfonylamino)phenyl]-3-methyl-4-difluoromethyl-?2-1,2,4-triazolin-5-one as a tan solid in 56 g (83% yield) with assay 93.91%.
Preparation of crystalline form SJDM-1
Example 2:
Technical sulfentrazone, as prepared in example 1 was dried at 80 oC under vacuum for 48 hours, which gives the crystalline form SJDM-1 and was characterized using PXRD, DSC and FTIR.
Yield 80%; Assay 96.94% and Purity 98.99% by HPLC
PXRD: at 2-theta+0.2°at 6.388, 6.884, 10.557, 11.205, 12.175, 13.747, 14.875, 16.458, 17.286, 17.611, 18.197, 18.565, 19.08, 19.566, 21.180, 21.473, 22.491, 22.697, 22.968, 23.368, 24.561, 28.387, 28.800 as shown in figure 1.
DSC: as shown in figure 2 the DSC profile having an endothermic melting peak with onset at 128.81°C and peak maximum at 130.58°C with melting enthalpy 61.9740J/g.
FTIR Cm-1: 3458.37, 3255.84, 2931.80, 1737.86, 1610.56, 1490.97, 1327.03, 1159.22, 970.19 and 823.60 as shown in figure 3.
Example 3:
Technical sulfentrazone, as prepared in example 1 (10 gm on dry basis) was taken in acetone (10 ml) and stirred the reaction mass and added water (50 ml). Heat the reaction mass at 80-85 oC. Stirred for 1-2 hours, cool to room temperature and filtered the product, wash the product with water (20 gm) and dried at 80 oC for 50-60 hours to get crystalline form SJDM-1 and was characterized using PXRD, DSC and FTIR.
Crystalline form SJDM-1: Yield=90%; HPLC Purity=98.82%; Assay >97% by HPLC.
Technical Sulfentrazone: HPLC Purity=97.73%; assay=93.91% by HPLC.
Example 4:
Technical Sulfentrazone, as prepared in example 1 (25 gm on dry basis) was taken in acetone (85 gm) and stirred at 50 oC. Solvent was distilled out under vacuum up to 90%. Heat the reaction mass at 60-65 oC and water (125 gm) was added and maintained for 1 hour and cool to room temperature, filtered and washed with water (25 gm) and dried at 80 oC for 45-55 hours and was characterized using PXRD, DSC and FTIR.
Crystalline form SJDM-1: Yield=92.8%; HPLC Purity=99.32%; Assay=98.01% by HPLC.
Technical Sulfentrazone: HPLC Purity=97.29%; Assay=94.37% by HPLC.
PXRD: at 2-theta+0.2°at 6.388, 6.884, 10.557, 11.205, 12.175, 13.747, 14.875, 16.458, 17.286, 17.611, 18.197, 18.565, 19.08, 19.566, 21.180, 21.473, 22.491, 22.697, 22.968, 23.368, 24.561, 28.387, 28.800 as shown in figure 4.
DSC: as shown in figure 5 the DSC profile having an endothermic melting peak with onset at 131.23°C and peak maximum at 133.40°C with melting enthalpy 58.9275J/g.
FTIR Cm-1: 3458.37, 3255.84, 2931.80, 1737.86, 1610.56, 1490.97, 1327.03, 1159.22, 968.27, 823.60 as shown in figure 6.
Example 5:
Technical Sulfentrazone, as prepared in example 1 (25 gm on dry basis) was taken in acetone (85 gm) and stirred at 50 oC. Solvent was distilled out under vacuum up to 90%. Heat the reaction mass at 60-65 oC and water (125 gm) was added, cool to room temperature, stirred, filtered and washed with water (25 gm) and dried at 85 oC for 40-50 hours and was characterized using PXRD, DSC and FTIR.
Crystalline form SJDM-1: Yield=91%; HPLC Purity=99.29%; Assay=97.95% by HPLC.
Technical Sulfentrazone: HPLC Purity=97.29%; Assay=94.37% by HPLC.
Example 6:
Technical Sulfentrazone (25 gm on dry basis) was taken in Acetone (125 ml) and stirred at 60-70 oC. Solvent acetone distilled out completely under atmospheric pressure. Heat the reaction mass at 60-70 oC for 30 minutes. Charged Acetone (17 gm) in it and cool it to 25-35 oC. Water (125 gm) was added and maintained for 1 hour, filter, washed with water (25 gm), dried at 80 oC for 38-45 hours and was characterized using PXRD, DSC and FTIR.
Crystalline form SJDM-1: Yield: 90.8%; HPLC purity=98.79; Assay 97.67% by HPLC.
Technical Sulfentrazone: HPLC Purity: 98.24%; Assay=95.43% by HPLC.
Example 7:
Technical Sulfentrazone (15 gm on dry basis) was taken in Acetone (75 ml) and stirred at 40-50 oC. Solvent was distilled out completely under vacuum. Charged Acetone (10.2 gm) in it and cool it to 25-35 oC. (Filtered Mother Liquor of similar process batch containing acetone-water Mother Liquor) (125 gm) was added and maintain for 1 hour, filter, washed with water (15 gm), dried at 80 oC for 45-55 hours and was characterized using PXRD, DSC and FTIR.
Crystalline form SJDM-1: Yield: 93.14%; HPLC purity=98.75%; Assay 97.03% by HPLC.
Technical Sulfentrazone: HPLC Purity: 98.24%; Assay=95.43% by HPLC.
Crystalline form SJDM-1 obtained in example 3 and 5-7 was characterized and complied as described in above example.
Technical advancement
The process to prepare SJDM-1 according to the present invention has the following advantages over the known prior art,
• The present invention provides the process to prepare the SJDM-1 without using any organic solvent.
• The process of the present invention requires the minimum wet operations which proves economical and efficient on a commercial scale.
• The process of the present invention is environment friendly process as it minimize the solvent effluent load in environment.
• The process of the present invention donot require any crystallization or recrystallization process hence minimize the process steps.
• The process of the present invention donot require the seeding and other similar process to accelerate the crystallization hence simplify the process to prepare the crystal form of sulfentrazone.
• The process of the present invention is simple and cost-effective.
• The process of the present invention is commercially viable.
• The process of the present invention provides the crystalline form SJDM-1 with higher assay.
Thus, from the foregoing description, it will be apparent to one of the person skilled in the art that many changes and modifications can be made thereto without departing from the scope of the invention as set forth in the description. Accordingly, it is not intended that the scope of the foregoing description be limited to the description set forth above, but rather that such description be construed as encompassing such features that reside in the present invention, including all the features and embodiments that would be treated as equivalents thereof by those skilled in the relevant art.
, Claims:We Claim:
1. A process for the preparation of crystalline form SJDM-1, comprising:
a) reacting 2-(5-amino-2,4-dichlorophenyl)-4-(difluoromethyl)-2,4-dihydro-5-methyl-3H-1,2,4-triazol-3-one with methanesulfonyl chloride and pyridine in toluene solvent;
b) washing the obtained product of step a) with toluene; and
c) drying the obtained product of step b) at 60-90 oC under vaccum for 24-60 hours;
wherein the obtained product of step c) exhibits PXRD values at the 2? + 0.2 of 6.388, 6.884, 10.557, 11.205, 12.175, 13.747, 14.875, 16.458, 17.286, 17.611, 18.197, 18.565, 19.08, 19.566, 21.180, 21.473, 22.491, 22.697, 22.968, 23.368, 24.561, 28.387, 28.800 and differential scanning calorimeter (DSC) thermogram having an endothermic melting peak with onset at 128.81°C and peak maximum at 130.58°C and assay not less than 95%.
2. The process as claimed in claim 1 wherein in step c) the drying temperature is 60-90 oC, preferably the drying temperature is 80-85 oC and the drying time is 24-60 hours preferably the drying time is 38-60 hours.
3. A process for the preparation of crystalline form SJDM-1, comprising:
a) reacting 2-(5-amino-2,4-dichlorophenyl)-4-(difluoromethyl)-2,4-dihydro-5-methyl-3H-1,2,4-triazol-3-one with methanesulfonyl chloride and pyridine in toluene solvent;
b) washing the obtained product of step a) with toluene;
c) dissolving the product obtained in step b) in solvent acetone;
d) optionally distilling the solvent;
e) adding a water to the step d) mixture;
f) isolating the product of step e); and
g) drying the obtained product of step f) at 60-90 oC under vaccum for 24-60 hours;
wherein the obtained product of step g) exhibits PXRD values at the 2? + 0.2 of 6.388, 6.884, 10.557, 11.205, 12.175, 13.747, 14.875, 16.458, 17.286, 17.611, 18.197, 18.565, 19.08, 19.566, 21.180, 21.473, 22.491, 22.697, 22.968, 23.368, 24.561, 28.387, 28.800 and differential scanning calorimeter (DSC) thermogram having endothermic melting peak with onset at 131.23°C and peak maximum at 133.40°C and assay not less than 97%.
4. The process as claimed in claim 3 wherein in step c) the solvent acetone is used in the range of 0.2 volume to 20 volumes.
5. The process as claimed in claim 3 wherein in step d) the solvent acetone is distilled more than 85% of used solvent amount.
6. The process as claimed in claim 3 wherein in step e) the water is used in the range of 0.1 volume to 100 volumes.
7. The process as claimed in claim 3 wherein in step g) the drying temperature is 60-90 oC preferably the drying temperature is 80-85 oC and the drying time is 24-60 hours preferably the drying time is 38-60 hours.
8. The process as claimed in claim 3 wherein in step g) the obtained product has assay more than 97%.
9. A crystalline form SJDM-1 characterized by PXRD values at the 2? + 0.2 of 6.388, 6.884, 10.557, 11.205, 12.175, 13.747, 14.875, 16.458, 17.286, 17.611, 18.197, 18.565, 19.08, 19.566, 21.180, 21.473, 22.491, 22.697, 22.968, 23.368, 24.561, 28.387, 28.800 with characteristic values at 19.08 and 23.368.
10. A crystalline form SJDM-1 as claimed in claim 9 further characterized by differential scanning calorimeter (DSC) thermogram having an endothermic melting peak with onset at 128.81°C and peak maximum at 130.58°C as shown in figure 2 and endothermic melting peak with onset at 131.23°C and peak maximum at 133.40°C as shown in figure 5.