Description:FORM 2
THE PATENT ACT, 1970
(39 OF1970)
AND
THE PATENT RULES, 2003
PROVISIONAL/COMPLETE SPECIFICATION
(See section 10; rule 13)
1) TITLE OF THE INVENTION: A GREEN PROCESS FOR PREPARING P-BENZOQUINONE
2) APPLICANT(S):
a) Name: SUDARSHAN FARM CHEMICALS INDIA PVT. LTD.
b) Nationality: India
c) Address: Plot no D-14/3, Near Gopinath Dairy, Village Rekunda, Turbhe Belapur Road, MIDC Turbhe, Navi Mumbai- 400 705, Maharashtra, India
3) PREAMBLE TO THE DESCRIPTION
PROVISIONAL
The following specification particularly describes the invention. COMPLETE
The following specification particularly describes the invention and the manner in which it was to be performed.

FIELD OF INVENTION:
The invention relates to a green process for preparing p-Benzoquinone.

BACKGROUND OF THE INVENTION:
p-Benzoquinone is a yellow, crystalline (sand-like) solid with a Chlorine-like odor. It is a six-membered ring compound is the oxidized derivative of 1,4-hydroquinone.

p-Benzoquinone
It exhibits properties of a ketone, being able to form oximes; an oxidant, forming the dihydroxy derivative; and an alkene, undergoing addition reactions, especially those typical for a,ß-unsaturated ketones. It is very useful compound and find many applications for various purposes for example it is used as a fungicide, as a reagent in photography, and to make dyes and other chemicals.
US2,343,768 published in 1941 and US2,731,478 published in 1956 disclosed the methods for preparing p-benzoquinone which involve steam distillation of p-benzoquinone. The steam distillation of p-benzoquinone creates large excess of aqueous effluent as vapor pressure of p-benzoquinone is low and hence large amount of steam is required to evaporate p-benzoquinone. Further, the aniline gets co-distilled with product. Separation of aniline from distillate is problematic considering solubility of aniline in water. Thus, the product gets contaminated with aniline after filtration which affects the colour and purity of isolated p-benzoquinone. It is economically costly process. Also, the tailor-made plant machinery is required to carry out operation for isolation of p-benzoquinone. Isolation by crystallization after cooling give partial isolation of p-benzoquinone thus yield in hand during crystallization is low. Filtrate after removal of p-benzoquinone is normally coloured and still contains p-benzoquinone at trace level. Therefore, it needs special effluent treatment to treat the filtrate.
The steam distillation is laborious, risky, very expensive and nonspecific method for isolation of p-benzoquinone. It generates large quantity of effluent containing p-benzoquinone and residual manganese salt. The quality of the product obtained through this process is also poor and doesn’t meet even the desired colour specification. The product fails in terms of purity and colour for further use in pharma and agro industries. It shows presence of hydroquinone to the extent of 1.5% to 2.5% which is difficult to remove and hence need specialized repurification for industrial acceptance which again incur additional cost making the process economically challenging.
US2,343,768 does not explains the treatment or the conversion of manganese salts and ammonia salts obtained in the process. Isolation of unconverted low purity manganese dioxide also need to be treated before releasing to environment.
Thus, there was a need of a process for preparing a p-benzoquinone in which the by-product hydroxyquinone generation will be minimum and the isolation of the product shall be easy, economic and safe. Further, the by-product processing before releasing them to environment was another concern to be addressed. Current invention tries to address these needs by providing a simple, safe and economic process for preparing p-benzoquinone with negligible amount of hydroxyquinone. It follows the green chemistry approach and also enables recycling of the raw material and conversion of by-product in to a useful substance.

SUMMARY OF INVENTION:
The invention in first aspect relates to a process for preparing p-benzoquinone comprising
a) simultaneously adding a solution containing aniline in 20% sulphuric acid, and about 2.3 to 2.8 m/m MnO2 to a mixture containing about 0.2 m/m MnO2 in 50% sulphuric acid to obtain a reaction mixture;
b) stirring said reaction mixture till absence of aniline;
c) filtering the reaction mixture to obtain a filtrate and a cake;
d) subjecting the obtained cake to solvent extraction using solvent(s) selected from organic aliphatic solvents, organic aromatic solvents, organic aliphatic chlorinated solvents and organic aromatic chlorinated solvents to isolate p-benzoquinone in said solvent(s) and get MnO2 in the remaining cake.
In the second aspect of the invention, the MnO2 got in step d) is re-used in step a) of the next reaction cycle. For this purpose, the MnO2 got in step d) is added with fresh MnO2 and then re-used in step a) of the next reaction cycle. Preferably the fresh MnO2 has purity 84% to 86% to keep molar stoichiometry in the range of about 2.3m/m to 2.8m/m.
In the third aspect of the invention, the filtrate obtained in abovementioned step c) is given lime treatment to obtain aqueous solution of MnSO4 which can be further converted into manganese carbonate by treating with sodium carbonate. This obtained manganese carbonate can be isolated by simple filtration. The process releases ammonia and gives calcium sulphate too.

BRIEF DESCRIPTION OF THE DRAWINGS:
The embodiments herein will be better understood from the following detailed description with reference to the drawings, in which:
FIGURE 1 is the chromatogram showing the 99.84% purity of p-benzoquinone and only 0.08% hydroxyquinone according to the inventive process using fresh MnO2 and extracted using ethylene dichloride in the example no. 1;
FIGURE 2 is the chromatogram showing the 99.84% purity of p-benzoquinone and only 0.08% hydroxyquinone according to the inventive process using recycled MnO2 and extracted using ethylene dichloride in the example no. 1;
FIGURE 3 is the chromatogram showing the 99.85% purity of p-benzoquinone and only 0.07% hydroxyquinone according to the inventive process using fresh MnO2 and extracted using toluene in the example no. 2;
FIGURE 4 is the chromatogram showing the 99.87% purity of p-benzoquinone and only 0.05% hydroxyquinone according to the inventive process using recycled MnO2 and extracted using toluene in the example no. 2;
FIGURE 5 is the chromatogram showing the 99.83% purity of p-benzoquinone and only 0.09% hydroxyquinone according to the inventive process using fresh MnO2 and extracted using monochlorobenzene in the example no. 3;
FIGURE 6 is the chromatogram showing the 99.85% purity of p-benzoquinone and only 0.07% hydroxyquinone according to the inventive process using recycled MnO2 and extracted using monochlorobenzene in the example no. 3;
FIGURE 7 is the chromatogram showing the 99.86% purity of p-benzoquinone and only 0.06% hydroxyquinone according to the inventive process using fresh MnO2 and extracted using dichloromethane in the example no. 4; and
FIGURE 8 is the chromatogram showing the 99.86% purity of p-benzoquinone and only 0.05% hydroxyquinone according to the inventive process using recycled MnO2 and extracted using dichloromethane in the example no. 4;

DETAILED DESCRIPTION OF THE INVENTION:
As mentioned, there remained a long felt need to provide a process for preparing a
p-benzoquinone in which the by-product hydroxyquinone generation will be minimum and the isolation of the product shall be easy, economic and safe. The present invention not only provide such a simple, safe and economic process for preparing p-benzoquinone with negligible amount of hydroxyquinone but it also enables recycling of the raw material and conversion of by-product in to a useful substance. It follows the green chemistry approach.
In the first aspect of the invention, it provides a process for preparing p-benzoquinone comprising
a) simultaneously adding a solution containing aniline in 20% sulphuric acid, and about 2.3 to 2.8 m/m MnO2 to a mixture containing about 0.2 m/m MnO2 in 50% sulphuric acid to obtain a reaction mixture;
b) stirring said reaction mixture till absence of aniline;
c) filtering the reaction mixture to obtain a filtrate and a cake;
d) subjecting the obtained cake to solvent extraction using solvent(s) selected from organic aliphatic solvents, organic aromatic solvents, organic aliphatic chlorinated solvents and organic aromatic chlorinated solvents to isolate p-benzoquinone in said solvent(s) and get MnO2 in the remaining cake.
The reaction mixture in step c) can be filtered using any suitable filter and more preferably a filter selected from a nutch filter, a filter press and a rosenmund filter.
As mentioned, the solvents that can be used in step d) are the organic aliphatic solvents, the organic aromatic solvents, the organic aliphatic chlorinated solvents and the organic aromatic chlorinated solvents. The non-limiting exemplary list for the organic aliphatic solvents is C-9 fraction, heptane and hexane; for the organic aromatic solvents is toluene, xylene, ortho xylene and mesitylene; for organic aliphatic chlorinated solvents is dichloromethane and ethylene dichloride. The example of most preferred organic aromatic chlorinated solvent for use in step d) of this invention is monochlorobenzene.
In the preferred embodiments the solvent used in step d) is one or more selected from ethylene dichloride, toluene, monochlorobenzene and dichloromethane.
P-benzoquinone isolated in said solvent(s) system can be separated by simply evaporating said solvent(s).
In the second aspect of the invention, the MnO2 got in step d) is re-used in step a) of the next reaction cycle. For this purpose, the MnO2 got in step d) is added with fresh MnO2 and then re-used in step a) of the next reaction cycle. Preferably the fresh MnO2 has purity 84% to 86% to keep molar stoichiometry in the range of about 2.3m/m to 2.8m/m.
In the third aspect of the invention, the filtrate obtained in abovementioned step c) is given lime treatment to obtain aqueous solution of MnSO4 which can be further converted into mangnese carbonate by treating with sodium carbonate.
More specifically, the filtrate obtained in step c) is given lime treatment to obtain aqueous solution of MnSO4, heated to reflux for expelling off the ammonia, filtered to remove calcium sulphate and treated with sodium carbonate under heating to obtain mangnese carbonate. The mangnese carbonate can be isolated by simple filtration.
By giving heat treatment the ammonia is expelled off from the reaction mass and is directly released in the environment. The calcium sulphate obtained is of around 95% purity. It finds application in effluent treatment and making of plaster of paris etc. The mangnese carbonate obtained is of around 96% purity and finds its application in many industries such as its use as fertilizer, in ceramic as glaze colorant etc.
It shows the simplicity, safety, economy and environment friendly nature of the current invention. And examples mentioned hereinafter are the testimony of these facts.
The invention can be further understood with the examples mentioned below. The examples mentioned below are the best method of performing the invention which was known to the applicant. They in no way construed to limit the scope of invention to the mentioned ingredients only or to their specific quantities only.

Examples:
Example -1
Aniline 93 g (1m) is added to an aqueous sulfuric acid of 20% strength 1263g (2.57m) to get clear solution at a temperature range of 20-30° C.
In another assembly containing 337g of 50% sulfuric acid charge 20.7g (0.2m) MnO2 of 84% purity at 0-5° C under stirring. To this add simultaneously Aniline solution in 20% sulfuric acid prepared above and fresh MnO2 289.7g (2.8m) over a period of 12 hr in equal lots.
After completion of addition hydroquinone content in reaction mass was found to be 0.06% and absence of aniline. Reaction mass was then filtered over buckner funnel and cake washed by 100ml water.
Wet cake thus obtained was subjected for extraction using 1.2 lit ethylene dichloride. The solvent extract was concentrated to isolate 100 gm (0.92m) of parabenzoquinone (Yield- 92%) with hydroquinone content 0.08%. The cake after extraction was dried at 60-65°C under reduce pressure.
The purity of MnO2 was 55.3% (94g, 0.6m) which was subjected for recycle. Analysis for purity is in accordance with (BIS IS 1472:2004)

Recycle of MnO2
Aniline 93 g (1m) was added to an aqueous sulfuric acid of 20% strength 1263g (2.57m) to get clear solution at a temperature range of 20-30° C.
MnO2 obtained after filtration 94g of purity 55.3% is mixed with fresh MnO2 225.5g of 84% purity. Total wt is 319.5g.
In another assembly containing 337g of 50% sulfuric acid charge 20.7g (0.2m) MnO2 of 84% purity at 0-5° C under stirring. To this add simultaneously Aniline solution in 20% sulfuric acid prepared above and mixture of MnO2 mentioned above 319.5g (2.81m) over a period of 12 hr in equal lots.
After completion of addition hydroquinone content in reaction mass was found to be 0.5 to 0.6% and absence of aniline. Reaction mass was then filtered over Buckner funnel and cake washed by 100ml water.
Wet cake thus obtained was subjected for extraction using 1.2 lit ethylene dichloride. The solvent extract was concentrated to isolate 95 gm (0.88m) of parabenzoquinone (Yield- 88%) with hydroquinone content 0.08%.
Cake after extraction was dried (wt. 283 g, 1.44m) and found MnO2 content was 44% by BIS IS 1472:2004 method.

Isolation of MnCO3
Mixed both filtrates and analysed for MnSO4 content. (MnSO4 content was 18 – 22 %w/w). To the filtrate added lime 211g (71% purity, 2.02m) and heated to reflux. At reflux temperature ammonia was expelled off in the scrubber. After completion of ammonia evolution, reaction mass was filtered to remove calcium sulphate of 95% purity. (Wt – 286g). The filtrate was treated with sodium carbonate to neutralize MnSO4 and heated to 60°C. MnCO3 was isolated by filtration.
Wt obtained 540g with 96.8% purity. (4.55m).
Balance of Manganese – 98%
Analysis was carried out with procedure mentioned in BIS IS 1473:2004

Example - 2
Aniline 93 g (1m) is added to an aqueous sulfuric acid of 20% strength 1263g (2.57m) to get clear solution at a temperature range of 20-30° C.
In another assembly containing 337g of 50% sulfuric acid charge 20.7g (0.2m) MnO2 of 84% purity at 0-5° C under stirring. To this add simultaneously Aniline solution in 20% sulfuric acid prepared above and fresh MnO2 238g (2.30m) over a period of 12 hr in equal lots.
After completion of addition hydroquinone content in reaction mass was found to be 0.6% and absence of Aniline. Reaction mass was then filtered over Buckner funnel and cake washed by 100ml water.
Wet cake thus obtained was subjected for extraction using 1.5 lit toluene The solvent extract was concentrated to isolate 98 gm (0.90m) of parabenzoquinone (Yield- 90%) with hydroquinone content 0.07%
The cake after extraction was dried at 60-65°C under reduce pressure. The purity by MnO2 content was 58.1% (90g, 0.6m) which was subjected for recycle.

Recycle of MnO2
Aniline 93 g (1m) is added to an aqueous sulfuric acid of 20% strength 1263g (2.57m) to get clear solution at a temperature range of 20-30° C.
MnO2 obtained after filtration 94g of purity 58.1% is mixed with fresh MnO2 170.9g of 84% purity. Total wt is 254.9g.
In another assembly containing 337g of 50% sulfuric acid charge 20.7g (0.2m) MnO2 of 84% purity at 0-5° C under stirring. To this add simultaneously Aniline solution in 20% sulfuric acid prepared above and mixture of MnO2 mentioned above 254.9g over a period of 12 hr in equal lots.
After completion of addition Aniline was found to be absent in the reaction mass. Reaction mass was then filtered over Buckner funnel and cake washed by 100ml water.
Wet cake thus obtained was subjected for extraction using 1.2 lit toluene. The solvent extract was concentrated to isolate 95gm (0.88m) of parabenzoquinone (Yield- 88%) with hydroquinone content 0.05%
Cake after extraction was dried (wt. 283 g, 1.44m) and found MnO2 content was 44%.

Example – 3
Aniline 93 g (1m) is added to an aqueous sulfuric acid of 20% strength 1263g (2.57m) to get clear solution at a temperature range of 20-30° C.
In another assembly containing 337g of 50% sulfuric acid charge 20.7g (0.2m) MnO2 of 84% purity at 0-5° C under stirring. To this add simultaneously Aniline solution in 20% sulfuric acid prepared above and fresh MnO2 259g (2.5m) over a period of 12 hr in equal lots. After completion of addition hydroquinone content in reaction mass was found to be 0.08% and absence of Aniline. Reaction mass was then filtered over Buckner funnel and cake washed by 100ml water.
Wet cake thus obtained was subjected for extraction using 1.8 lit monochlorobenzene. The solvent extract was concentrated to isolate 98 gm (0.90m) of parabenzoquinone (Yield- 90%) with hydroquinone content 0.09%.The cake after extraction was dried at 60-65°C under reduce pressure. The purity by MnO2 content was 58% (90g, 0.6m) which was subjected for recycle.

Recycle of MnO2
Aniline 93g (1m) is added to an aqueous sulfuric acid of 20% strength 1263g (2.57m) to get clear solution at a temperature range of 20-30° C.
MnO2 obtained after filtration 90g of purity 58.0% is mixed with fresh MnO2 170.9g of 84% purity. Total wt is 254.9g.
In another assembly containing 337g of 50% sulfuric acid charge 20.7g (0.2m) MnO2 of 84% purity at 0-5° C under stirring. To this add simultaneously Aniline solution in 20% sulfuric acid prepared above and mixture of MnO2 mentioned above 193.8 g over a period of 12 hr in equal lots.
After completion of addition Aniline was found to be absent in the reaction mass. Reaction mass was then filtered over Buckner funnel and cake washed by 100ml water.
Wet cake thus obtained was subjected for extraction using 1.2 lit monochlorobenzene. The solvent extract was concentrated to isolate 95 gm (0.88m) of parabenzoquinone (Yield- 88%) with hydroquinone content 0.07%

Example – 4
Aniline 93 g (1m) is added to an aqueous sulfuric acid of 20% strength 1263g (2.57m) to get clear solution at a temperature range of 20-30° C.
In another assembly containing 337g of 50% sulfuric acid charge 20.7g (0.2m) MnO2 of 84% purity at 0-5° C under stirring. To this add simultaneously Aniline solution in 20% sulfuric acid prepared above and fresh MnO2 254g (2.45m) over a period of 12 hr in equal lots.
Wet cake thus obtained was subjected for extraction using 1.8 lit dichloromethane. The solvent extract was concentrated to isolate 95 gm (0.87m) of parabenzoquinone (Yield- 87%) with hydroquinone content 0.06%.
The cake after extraction was dried at 60-65°C under reduce pressure. The purity by MnO2 content was 58% (90g, 0.6m) which was subjected for recycle.

Recycle of MnO2
Aniline 93 g (1m) is added to an aqueous sulfuric acid of 20% strength 1263g (2.57m) to get clear solution at a temperature range of 20-30° C.
MnO2 obtained after filtration 90g of purity 58.0% is mixed with fresh MnO2 189.4g of 84% purity. Total wt is 279.4g.
In another assembly containing 337g of 50% sulfuric acid charge 20.7g (0.2m) MnO2 of 84% purity at 0-5° C under stirring. To this add simultaneously Aniline solution in 20% sulfuric acid prepared above and mixture of MnO2 mentioned above 279.4 g over a period of 12 hr in equal lots.
After completion of addition Aniline was found to be absent in the reaction mass. Reaction mass was then filtered over Buckner funnel and cake washed by 100ml water.
Wet cake thus obtained was subjected for extraction using 1.2 lit dichloromethane. The solvent extract was concentrated to isolate 95 gm (0.88m) of parabenzoquinone (Yield- 88%) with hydroquinone content 0.05%.

, Claims:Claims:
I/We claim:
1. A process for preparing p-benzoquinone comprising
a) simultaneously adding a solution containing aniline in 20% sulphuric acid, and about 2.3 to 2.8 m/m MnO2 to a mixture containing about 0.2 m/m MnO2 in 50% sulphuric acid to obtain a reaction mixture;
b) stirring said reaction mixture till absence of aniline;
c) filtering the reaction mixture to obtain a filtrate and a cake;
d) subjecting the obtained cake to solvent extraction using solvent(s) selected from organic aliphatic solvents, organic aromatic solvents, organic aliphatic chlorinated solvents and organic aromatic chlorinated solvents to isolate p-benzoquinone in said solvent(s) and get MnO2 in the remaining cake.

2. The process as claimed in claim 1, wherein in step c) the reaction mixture is filtered using a filter selected from a nutch filter, a filter press and a rosenmund filter.

3. The process as claimed in claim 1, wherein in step d) said organic aliphatic solvents are selected from C-9 fraction, heptane and hexane; said organic aromatic solvents are selected from toluene, xylene, ortho xylene and mesitylene; said organic aliphatic chlorinated solvents are selected from dichloromethane and ethylene dichloride; and said organic aromatic chlorinated solvent is mono chlorobenzene.

4. The process as claimed in claim 1, wherein in step d) said solvent is one or more selected from ethylene dichloride, toluene, mono chlorobenzene and dichloromethane.

5. The process as claimed in claim 1, wherein in step d) the p-benzoquinone isolated in said solvent(s) system is separated by evaporating said solvent(s).

6. The process as claimed in claim 1, wherein the MnO2 got in step d) is re-used in step a) of the next reaction cycle.

7. The process as claimed in claim 6, wherein the MnO2 got in step d) is added with fresh MnO2 of purity 84% to 86% to keep molar stoichiometry in the range of about 2.3m/m to 2.8m/m and then re-used in step a) of the next reaction cycle.

8. The process as claimed in claim 1, wherein the filtrate obtained in step c) is given lime treatment to obtain aqueous solution of MnSO4 which is converted into manganese carbonate by treating with sodium carbonate.

9. The process as claimed in claim 1, wherein the filtrate obtained in step c) is given lime treatment to obtain aqueous solution of MnSO4, heated to reflux for expelling off the ammonia, filtering to remove calcium sulphate and treating with sodium carbonate under heating to obtain manganese carbonate.

10. The process as claimed in claim 9, wherein the obtained manganese carbonate is isolated by filtration.
Dated this 23rd day of May, 2022
Signature: To be digitally signed by-
Name: Mr. Parag M. More
OF INTELLECTUAL PLATFORM®
Patent Agent for applicant
Patent Agent Regn. No. IN/PA-1688
On behalf of applicant