FIELD OF THE DISCLOSURE:
The present disclosure relates to a process for preparing alkylene bis-dithiophosphates. The present disclosure particularly relates to a process for preparing tetra-alkyl alkylene bis-dithiophosphates. 5
PRIOR ART AND PROBLEM TO BE SOLVED:
Various processes are reported in the literature for preparing alkylene bis-dithiophosphates, particularly tetra-alkyl alkylene bis-dithiophosphates. 10
For instance, RO63381 discloses the use of water as a solvent for the preparation of tetraethyl methylene bis-dithiophosphate by reacting sodium salt of O, O' diethyl dithiophosphoric acid and methylene dichloride. The teachings of RO63381 are directed towards facilitation of the reaction of sodium salt of O,O' diethyl dithiophosphoric acid and methylene dichloride in water medium. The reaction of sodium salt of the O,O' diethyl dithiophosphoric acid and methylene dichloride 15 in water is based on the principle of improved solubility of methylene dichloride in water at higher pressure and temperature. JP42004454 discloses the process for preparing tetraethyl methylene bis-dithiophosphate by reacting O, O' diethyl dithiophosphate with methylene dichloride in the presence of bromine or iodine compound as a catalyst and water as a solvent.
The problem with the processes disclosed in RO63381 and JP42004454 is that since it involves 20 the use of water, the full capacity of the manufacturing unit cannot be used efficiently and the process also generates effluent. Further, in JP42004454 process, a catalyst is used to drive the reaction which adds up raw material cost.
Another Romanian patent document RO61710 also discloses the preparation of tetraethyl methylene bis-dithiophosphate by reacting sodium salt of O, O' diethyl dithiophosphoric acid and 25 cyclic methylene sulfate. JP41006735 discloses the preparation of tetraethyl methylene bis-dithiophosphate from O, O' diethyl dithiophosphate and methylene sulfate. However, the reactant cyclic methylene sulfate or methylene sulfate used in the processes is not easily accessible and processing sulfate containing effluent increases the cost of operation.
3
JP09169785 discloses a process for preparing bis(dialkyl dithio phosphato)alkanes by reacting phosphorus pentasulfide, ammonium and dihaloalkane in lower alcohol as a solvent.
US3014058 discloses a process for preparing tetra-alkyl alkylene bis-dithiophosphate by reacting metal salt of O, O diethyl phosphorodithioate and dibromomethane or bromochloromethane in the presence of inert solvent such as alcohol. 5
FR1231107 discloses the preparation of tetra-alkyl alkylene bis-dithiophosphate by reacting ammonoium O, O diethyl phosphorodithioate and dibromomethane in the presence of water as a solvent.
GB845647 discloses the preparation of tetra-alkyl alkylene bis-dithiophosphate by reacting potassium O, O diethyl phosphorodithioate and dibromomethane in the presence of acetone as a 10 solvent.
US2928862 discloses the preparation of 1,4-bis(di-2-butoxyphosphinothioylthio)-2-butene by reacting O, O di-sec-butyl phosphorodithioate and 1,4-dichloro-2-butene in ethanol as a solvent.
Processes disclosed in the above patent literature employ at least one solvent to facilitate the reaction. The use of the solvent reduces the output per unit time period and requires processing 15 of the solvent for reuse, the quantity and the quality of which diminishes after every reuse.
Therefore, there is a need for a process for preparing alkylene bis-dithiophosphates, particularly tetra-alkyl alkylene bis-dithiophosphates using easily and readily available raw materials without using a solvent.
20
OBJECTS / OBJECTIVES OF THE DISCLOSURE:
Some of the objects of the present disclosure, which at least in one embodiment is adapted to provide, are described herein below:
It is an object of the present disclosure to provide a process for preparing alkylene bis-25 dithiophosphates.
4
Another object of the present disclosure is to provide a process for preparing tetra-alkyl alkylene bis-dithiophosphates.
Still another object of the present disclosure is to provide a process for preparing tetra-ethyl methylene bis-dithiophosphate.
Yet another object of the present disclosure is to provide a process for preparing alkylene bis-5 dithiophosphates which is carried out without using a solvent.
Further object of the present disclosure is to provide a process for preparing alkylene bis-dithiophosphates which is efficient and simple.
Other objects and advantages of the invention disclosed in the present disclosure will be more apparent from the following description which is not intended to limit the scope of the invention 10 disclosed in the present disclosure.
SUMMARY OF THE DISCLOSURE:
15
The present disclosure relates to a process for preparing alkylene bis-dithiophosphates, particularly tetra-alkyl alkylene bis-dithiophosphates by reacting corresponding salt of O, O' dialkyl dithiophosphosphate and an alkylene inserting agent.
The prior arts neither disclose nor suggest/teach/motivate to carry the reaction of the salt of O, O' dialkyl dithiophosphosphate and the alkylene inserting agent at high temperature and pressure 20 conditions in the presence of inert gas without using a solvent. One of the advantages of the process of the present disclosure is that since the solvent is not used, the product output per unit time period is improved and the effluent is not generated, thereby improving the economics of the operation. This also makes the process environment friendly.
Further, the starting material used for preparing alkylene bis-dithiophosphates is easily available. 25
5
DETAILED DESCRIPTION OF THE DISCLOSURE:
The present disclosure relates to a process for preparing alkylene bis-dithiophosphates,
particularly tetra-alkyl alkylene bis-dithiophosphates of Formula I.
5
The compound of Formula I is prepared by reacting a compound of Formula IIa or Formula IIb
and an alkylene inserting agent of Formula III. The process steps are described herein after.
The compound of Formula IIa or IIb and the alkylene inserting agent of Formula III are charged
in a container at a temperature ranging from about 10 oC to about 50 oC. The container is then
10 closed/sealed and an inert gas is passed or purged into the container to obtain an initial pressure
in the range of about 0.5 kg/cm2 to about 3.0 kg/cm2. The ratio of the compound of Formula IIa
or IIb to the alkylene inserting agent of Formula III added in the container ranges from about
1:0.5 to about 1:10. Typically, the ratio higher than 1:10 of the compound of Formula IIa or IIb
to the alkylene inserting agent of Formula III can also be employed with diminishing advantages
15 of the reaction process.
6
The mixture in the container is heated at a temperature ranging from about 10 oC to about 120 oC, particularly from 50 oC to about 120 oC, to obtain a pressure ranging from about 2.5 kg/cm2 to about 15 kg/cm2.
A minute amount of a compound of Formula I can be formed at any positive temperature and pressure conditions. To make the reaction commercially and technically viable, the reaction of 5 the compound of Formula IIa or Formula IIb and the alkylene inserting agent of Formula III is carried out at a temperature ranging from about 50 oC to about 120 oC and a pressure ranging from about 2.5 kg/cm2 to about 15 kg/cm2.
The pressure conditions maintained during the reaction are dependent on the temperature conditions employed and the inert gas used to maintain an inert atmosphere. 10
In one of the non-limiting and illustrative embodiments of the present disclosure, the pressure is about 2.5 kg/cm2 when the temperature is about 50 oC. In another non-limiting and illustrative embodiment of the present disclosure, the pressure is about 15 kg/cm2 when the temperature is about 120 oC. However, when the temperature ranges from about 50 oC to about 120 oC it is likely that the pressure can range anywhere from about 2.5 kg/cm2 to about 15 kg/cm2. 15
In one of the preferred embodiments of the present disclosure the reaction of the compound of Formula IIa or Formula IIb and the alkylene inserting agent of Formula III is carried out at a temperature from about 70 oC to about 95 oC and the pressure ranges from about 5 kg/cm2 to about 10 kg/cm2.
Inert atmosphere is achieved by using an inert gas such as nitrogen and argon. 20
The reaction of the compound of Formula IIa or Formula IIb and the alkylene inserting agent of Formula III is carried out for a time period ranging from about 6 to about 15 hours.
In the last step, after the completion of the reaction, the container and the product are cooled and washed with water comprising at least one base. Examples of the base include but are not limited to sodium carbonate, sodium bicarbonate, sodium hydroxide, potassium hydroxide, ammonium 25 hydroxide, potassium carbonate and potassium bicarbonate. An organic layer comprising the compound of Formula I, is separated and distilled to obtain the compound of Formula I. The compound of Formula I obtained by the process of the present disclosure further comprise
7
impurities of Formula IV and Formula V. The amount of the impurity of Formula IV ranges
from 0.05% to 0.5% and Formula V is about 0.05 to 1.0%. The structures of Formula IV and
Formula V are as follows:
5
In order to complete the reaction of the compound of Formula IIa or Formula IIb and the
alkylene inserting agent of Formula III in reduced time at least one catalyst can be added in the
reaction. The catalyst can be added at any stage but necessarily maintaining the inert gas in the
container. The catalyst can be a phase transfer catalyst.
10 Examples of the catalyst useful for the purpose of the present disclosure include but are not
limited to para-toluene sulfonic acid, tertiary butyl ammonium bromide, dimethyl formamide,
sodium bromide, iodine, sodium iodide and combinations thereof.
R1 and R2 in the Formula I is optionally substituted C1-C5 alkyl. C1-C5 alkyl include methyl,
ethyl, propyl, isopropyl, butyl, secondary butyl, isobutyl, tertiary butyl, pentyl, tertiary pentyl,
15 neopentyl, isopentyl, secondary pentyl and 3-pentyl.
In one of the embodiments of the present disclosure, R1 and R2 in the Formula I are C1-C4 alkyl.
C1-C4 alkyl include methyl, ethyl, propyl, isopropyl, butyl, secondary butyl, isobutyl and tertiary
butyl.
In another embodiment of the present disclosure, R1 and R2 in the Formula I are C1-C3 alkyl. C1-
20 C3 alkyl include methyl, ethyl, propyl and isopropyl.
In yet another embodiment of the present disclosure, R1 and R2 in the Formula I are C1-C2 alkyl.
C1-C2 alkyl include methyl and ethyl.
In yet another embodiment of the present disclosure, R1 and R2 in the Formula I are ethyl.
8
R1 and R2 in the Formula I can be same or different. For instance, R1 can be methyl and R2 can be ethyl.
R1 and R2 can be further substituted with a group which include but is not limited to halogen such as Cl, Br, I, OH, CN, NO2, CHO, COOH and COOR1.
R3 and R4 in the Formula I are independently hydrogen or optionally substituted C1-C5 alkyl. C1-5 C5 alkyl include methyl, ethyl, propyl, isopropyl, butyl, secondary butyl, isobutyl, tertiary butyl, pentyl, tertiary pentyl, neopentyl, isopentyl, secondary pentyl and 3-pentyl.
In one of the embodiments of the present disclosure, R3 and R4 are C1-C4 alkyl. C1-C4 alkyl include methyl, ethyl, propyl, isopropyl, butyl, secondary butyl, isobutyl and tertiary butyl.
In another embodiment of the present disclosure, R3 and R4 are C1-C3 alkyl. C1-C3 alkyl include 10 methyl, ethyl, propyl and isopropyl.
In yet another embodiment of the present disclosure, R3 and R4 are C1-C2 alkyl. C1-C2 alkyl include methyl and ethyl.
In yet another embodiment of the present disclosure, R3 and R4 are hydrogen.
R3 and R4 in the Formula I can be same or different. 15
In another embodiment of the present disclosure, R3 in the Formula I is hydrogen and R4 in the Formula I is selected from the group consisting of methyl, ethyl, propyl, isopropyl, butyl, secondary butyl, isobutyl, tertiary butyl, pentyl, tertiary pentyl, neopentyl, isopentyl, secondary pentyl and 3-pentyl.
In another embodiment of the present disclosure, R3 in the Formula I is hydrogen and R4 in the 20 Formula I is selected from the group consisting of methyl, ethyl, propyl, isopropyl, butyl, secondary butyl, isobutyl and tertiary butyl.
In another embodiment of the present disclosure the substituent R3 in the Formula I is hydrogen and the substituent R4 in the Formula I is selected from the group consisting of methyl, ethyl, propyl and isopropyl. 25
In yet another embodiment R3 can be hydrogen and R4 can be methyl.
9
R3 and R4 can further be substituted with a group which include but is not limited to halogen such as Cl, Br, I, OH, CN, NO2, CHO, COOH and COOR1.
R3 and R4 together with the carbon atoms to which they are bound may form a carbocyclic or heterocyclic ring. In an exemplary embodiment, R3 and R4 together with the atoms to which they are bound form a 3- to 8- membered carbocyclic or heterocyclic ring. 5
The denotation “n” in the Formula I is an integer from 1 to 3. In one embodiment, the denotation “n” ranges from 1 to 2. Preferably, the denotation “n” is 1. When the denotation “n” in the Formula I is 2 or 3 then R3 and R4 may attach to the same carbon atom or different carbon atoms.
The compound of Formula I is obtained from the compound of Formula IIa or IIb and the compound of Formula III. The substituents R1 and R2 of the compound of Formula IIa or IIb 10 have the same meaning as described herein before. The denotation “M” in the Formula IIa or IIb is an inorganic cation, or an organic cation.
M in the compound of Formula IIa is selected from the group comprising NH4, and elements in group 1 of the modern periodic table such as Na, and K. M in the compound of Formula IIb is selected from the elements in group 2 to 16 of the modern periodic table such as Mg, Cu, Mn, 15 Fe, Co, Pb, Sn, Pt, Pd, Au, Hg, Al and Si.
R3 and R4 of the compound of Formula III have the same meaning as described herein before. The denotation x1 and x2 are independently selected from the group comprising halogen, mesylate, and triflate. Halogen is selected from chlorine, bromine or iodine. For the purpose of this invention disclosed in the disclosure, when either of or both of R3 and R4 is/are hydrogen 20 then halogen is not bromine.
In one of the embodiments of the present disclosure, the compound of Formula I prepared by the process of the present disclosure has the following definition of the substituents: x1 and x2 are independently halogen; n is 1 to 2; R1 and R2 are optionally substituted C1-C4 alkyl; R3 and R4 are independently selected from the group comprising hydrogen or optionally substituted C1-C3 25 alkyl; when n is greater than 1, x1 and x2 may bound with the same carbon atom or with different carbon atoms, and R3 and R4 may bound with the same carbon atom or with different carbon atoms; and M is an inorganic cation.
10
In one of the embodiments of the present disclosure, the compound of Formula I prepared by the process of the present disclosure has the following definition of the substituents: x1 and x2 are independently chlorine, iodine or fluorine; n is 1; R1 and R2 are C1-C2 alkyl; R3 and R4 are hydrogen; and M is Na or K.
In one of the preferred embodiments, sodium or potassium or ammonium salt of O, O'-diethyl 5 dithiophosphate is reacted with methylene dichloride or methylene diiodide or methylene difluoride to obtain tetraethyl methylene bis-dithiophosphate.
The present disclosure also relates to the compound of Formula I obtained by the process of the present disclosure.
The present disclosure further relates to the compound of Formula I obtained by the process of 10 the present disclosure in a formulation comprising at least one acceptable excipient.
The present disclosure still further relates to the compound of Formula I obtained by the process of the present disclosure in a combination with at least one other agrochemical.
The present disclosure further relates to the compound of Formula I obtained by the process of the present disclosure in a kit comprising a package containing at least one acceptable excipient 15 and optionally at least one agrochemical.
The present disclosure further relates to the use of the compound of Formula I obtained by the process of the present disclosure as an agrochemical.
The term “agrochemical” for the purpose of the present disclosure shall include any chemical capable of being used in protecting or promoting the growth or treating or being used as ancillary 20 in protecting or promoting the growth or treating a plant or plant material or the locus thereof.
The present disclosure further relates to a method of protecting plants or plant materials. The method comprises applying an effective amount of compound of Formula I prepared by the process of the present disclosure to the plant or the plant material to be protected.
The term “plant” is understood here to mean all plants and plant populations, such as desired and 25 undesired wild plants or crop plants (including naturally occurring crop plants). Crop plants can be plants which can be obtained by conventional breeding and optimization methods or by
11
biotechnological and genetic engineering methods or combinations of these methods, including the transgenic plants and including the plant cultivars which are protectable and non-protectable by plant breeders’ rights.
For the purpose of the present disclosure, the term “plant” also includes a living organism of the kind exemplified by trees, shrubs, herbs, grasses, ferns, and mosses, typically growing in a site, 5 absorbing water and required substances through its roots, and synthesizing nutrients in its leaves by photosynthesis.
Examples of “plant” for the purpose of the present disclosure include but are not limited to agricultural crops such as cereals, corn, rice, soybean and other leguminous plants, fruits and fruit trees, nuts and nut trees, citrus and citrus trees, any horticultural plants, cucurbitaceae, 10 oleaginous plants, tobacco, coffee, tea, cacao, sugar beet, sugar cane, cotton, potato, tomato, onions, peppers and vegetables, ornamentals, any floricultural plants and other plants for use of human and animals.
The plant material for the purpose of the present disclosure includes but is not limited to cuttings, leaves, twigs, tubers, flowers, seeds, branches, roots including taproot, lateral roots, root hairs, 15 root apex, root cap, rhizomes, slips, shoots, fruits, fruit bodies, bark, stem, buds, auxillary buds, meristem, nodes, internodes, and locus thereof.
The term "carbocycle or carbocyclic or carbocyclyl" includes "aromatic carbocyclic ring system" and “nonaromatic carbocylic ring system” or polycyclic or bicyclic (spiro, fused, bridged, nonfused) ring compounds in which ring may be aromatic or non-aromatic (where aromatic 20 indicates that the Huckel rule is satisfied and non-aromatic indicates that the Huckel rule is not satisfied).
The term "heterocycle or heterocyclic or heterocyclyl" includes "aromatic heterocycle or heteroaryl ring system" and “nonaromatic heterocycle ring system” or polycyclic or bicyclic (spiro, fused, bridged, nonfused) ring compounds in which ring may be aromatic or non-25 aromatic, wherein the heterocycle ring contains at least one heteroatom selected from N, O, S(O)0-2, and or C ring member of the heterocycle may be replaced by C(=O), C(=S), C(=CR*R*) and C=NR*, * indicates integers (where aromatic indicates that the Huckel rule is satisfied and non-aromatic indicates that the Huckel rule is not satisfied).
12
In one embodiment the process for preparing the compound of Formula I is biphasic.
The process of the present disclosure of reacting the compound of Formula IIa or IIb and the compound of Formula III the reaction is carried out in the absence of solvent/co-solvent.
In one of the embodiments of the present disclosure the process of reacting the compound of Formula IIa or IIb and the compound of Formula III is carried out in the absence of a reagent. 5
In one of the embodiments of the present disclosure the process of reacting the compound of Formula IIa or IIb and the compound of Formula III is carried out in the presence of a reagent.
The present disclosure is further described in the light of the following non-limiting examples which are set forth for illustration purpose only and not to be construed for limiting the scope of the disclosure. 10
EXAMPLES
Example 1:
General Process:
The compound of Formula IIa or IIb and the alkylene inserting agent of Formula III were 15 charged in an autoclave at 25 oC to obtain a mixture. The autoclave was closed and inert gas was purged into the autoclave till a pressure of 1 to 2 kg/cm2 was attained in the autoclave. The mixture in the autoclave was heated to a temperature of 50 to 120 oC during which the pressure increased to 3 to 15 kg/cm2. The reaction was held at 50 to 120 oC for 6 to 15 hours. After completion of the reaction, heating was stopped, autoclave and the mixture were allowed to cool 20 to room temperature. A product of Formula I along with byproducts and unreacted reactants was washed with aqueous solution of sodium carbonate to obtain organic layer and aqueous layer. The organic layer was separated and distilled to obtain the pure product of Formula I.
The following Table 1 depicts examples for the preparation of the compound of Formula I by the general process depicted above. 25
13
R1 and R2 is ethyl, M is sodium in Sr. No. 1-16 and M is NH4 in Sr. No. 17, n is 1, x1 and x2 are
chlorine, R3 and R4 are hydrogen.
5 Table 1:
Sr.
No
Formula
IIa
Formula
III
Initial
N2
pressure
(kg/cm2)
Catalyst Reaction
pressure
(kg/cm2)
Temp.
°C
Reaction
time
(hrs)
GC %
Ratio of Formula
IIa: Formula III
(MDC)
(Formula
I)
1 1 0.5 2.0 - 8.5 85-90 10 81.40
2 1 0.5 1.0 - 7.0 85-90 10 81.00
3 1 1 1.0 - 5.0 85-90 10 78.10
4 1 0.5 1.0 - 2.5 50 10 71.90
5 1 0.5 1.0 - 3.0 60 15 71.96
6 1 0.7 1.0 - 5.0 85-90 10 54.73
7 1 0.5 0.0 - 5.0 85-90 10 54.73
8 1 0.5 1.0 - 15.0 120 10 53.43
9 1 4 1.0 - 8.0 85-90 10 52.66
10 1 2 1.0 - 6.0 85-90 10 52.52
11 1 0.5 2.0 - 3.0 50 10 45.00
12 1 10 1.0 - 10.0 85-90 10 26.97
13 1 4 1.0 - 2.5 60 10 24.33
14 1 0.5 1.0 - 1.0 25-30 24 8.48
14
15 1 11 1.0 - 2.0 40 10 4.21
16 1 0.5 - - 3.8 85-90 15 54.73
17 1 0.5 1.0 - 7.0 85-90 12 5
From the above table, it can be concluded that
- inert atmosphere is required for completion of the reaction and to limit the impurity
formation. In other words, inert atmosphere induces high product selectivity and yield,
5 - though reaction is workable at 50 to 120 oC, the optimal results are obtained at 80 to 90
oC, and
- the process of the present disclosure is effective at 2.5 to 15 kg/cm2 pressure.
Example 2:
10 Plurality of compounds of Formula I can be prepared by the following process:
The compound of Formula IIa and the alkylene inserting agent of Formula III were charged in an
autoclave at 25 oC to obtain a mixture. The autoclave was closed and nitrogen gas was purged
into the autoclave till a pressure of 1 to 2 kg/cm2 was attained in the autoclave. The mixture in
the autoclave was heated to a temperature of 85-95 oC during which the pressure increased to 3
15 to 15 kg/cm2. The reaction was held at 85-95 oC for 10 hours. After completion of the reaction,
heating was stopped, autoclave and the mixture were allowed to cool to room temperature. A
product of Formula I along with byproducts and unreacted reactants was washed with aqueous
solution of sodium carbonate to obtain organic layer and aqueous layer. The organic layer was
separated and distilled to obtain the pure product of Formula I.
20
15
The embodiments herein and the various features and advantageous details thereof are explained with reference to the non-limiting embodiments in the description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein be practiced and to further enable those 5 of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic 10 concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments 15 herein can be practiced with modification within the spirit and scope of the embodiments as described herein.
Any discussion of documents, acts, materials, devices, articles and the like that has been included in this specification is solely for the purpose of providing a context for the disclosure. It is not to be taken as an admission that any or all of these matters form a part of the prior art base or were 20 common general knowledge in the field relevant to the disclosure as it existed anywhere before the priority date of this application.
The numerical values mentioned in the description and the foregoing claims though might form a critical part of the invention of the present disclosure, any deviation from such numerical values shall still fall within the scope of the present disclosure if that deviation follows the same 25 scientific principle as that of the invention disclosed in the present disclosure.

We Claim:
1. A process for preparing a compound of Formula I; said process comprising a step of
reacting a compound of Formula IIa or Formula IIb and an alkylene inserting agent of
Formula III at a temperature ranging from 10 to 120 oC, a pressure ranging from 2.5 to 15
5 kg/cm2 and under inert atmosphere,
wherein,
x1 and x2 are independently selected from the group comprising halogen,
mesylate, and triflate,
10 n is 1 to 3;
R1 and R2 are independently optionally substituted C1-C5 alkyl;
R3 and R4 are independently hydrogen or optionally substituted C1-C5 alkyl, or
R3 and R4 together with the carbon atoms to which they are bound form a 3- to 8-
membered carbocylic or heterocylic ring;
15 M is an inorganic cation or an organic cation; and
17
when n is greater than 1, x1 and x2 may bound with the same carbon atom or with different carbon atoms, and R3 and R4 may bound with the same carbon atom or with different carbon atoms.
2. The process as claimed in claim 1, wherein the temperature ranges from 50 to 120 oC. 5
3. The process as claimed in claim 1, wherein
a. the ratio of the compound of Formula IIa or IIb to the alkylene inserting agent of Formula III ranges from 1:0.5 to 1:10,
b. the temperature ranges from 70 to 95 oC and the pressure ranges from 5 to 10 kg/cm2, 10 and
c. the inert atmosphere is maintained by using at least one inert gas selected from the group consisting of nitrogen and argon.
4. The process as claimed in claim 1, wherein 15
x1 and x2 are independently halogen, the halogen being selected chlorine, bromine, iodine, provided that when R3 and/or R4 are/is hydrogen, halogen is not bromine;
n is 1 to 2;
R1 and R2 are independently optionally substituted C1-C4 alkyl; 20
R3 and R4 are independently hydrogen or optionally substituted C1-C3 alkyl;
18
when n is greater than 1, x1 and x2 may bound with the same carbon atom or with different carbon atoms, and R3 and R4 may bound with the same carbon atom or with different carbon atoms; and
M is an inorganic cation.
5
5. The process as claimed in claim 1, wherein
x1 and x2 is independently chlorine, iodine or fluorine,
n is 1,
R1 and R2 are C1-C2 alkyl,
R3 and R4 are hydrogen, and 10
M is Na or K.
6. The process as claimed in claim 1, wherein the compound of Formula I is tetraethyl methylene bis-dithiophosphate, the compound of Formula IIa is selected from sodium or potassium salt of O, O'-diethyl dithiophosphate and the compound of Formula III is 15 selected from the group of methylene dichloride, methylene diiodide and methylene difluoride.
7. The process as claimed in claim 1, comprises pre-steps of charging the compound of Formula IIa or IIb and the alkylene inserting agent of Formula III at a temperature 20 ranging from 10 to 50 oC in a container and closing the container, passing an inert gas to obtain a pressure in the range of 0.5 to 3.0 kg/cm2 and heating a mixture in the container.
19
8. The process as claimed in claim 1, wherein the substitutents of the alkyl group are
selected from the group consisting of Cl, Br, I, OH, CN, NO2, CHO, COOH and COOR1.
9. The compound of Formula I obtained by the process as claimed in claim 1, comprise the
5 compound of Formula IV in the range of from 0.05 to 0.5% and the compound of
Formula V in the range of from 0.05 to 1.0%,
10. The compound of Formula I obtained by the process as claimed in claim 1.