FORM 2
THE PATENT ACT, 1970
(39 of 1970)
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
(See section 10 and rulel3) l.TITLE OF THE INVENTION:
A NOVEL PROCESS FOR THE PURIFICATION OF 2-CYANO- 3,3-DIARYLACRYLATES USING ADSORPTION CHROMATOGRAPHY"
2. APPLICANT
(a) NAME: GALAXY SURFACTANTS LTD.
(b) NATIONALITY: An Indian Company incorporated under the Indian
Companies ACT, 1956
(c) ADDRESS: C-49/2, TTC Industrial Area, Pawne,
Navi Mumbai-400703 Maharashtra, India
3. PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner in which it is to be performed.

FIELD OF INVENTION
The present invention relates to a cost effective and energy saving process for the purification of 2-Cyano-3,3-diarylacrylates using adsorption chromatography. The method is simple, the adsorbent can be used repetitively thus making the technique cost-effective. The invention enables to achieve high yield with high purity of 2-Cyano-3,3-diarylacrylates.
BACKGROUND OF INVENTION
2-Cyano-3,3-diaryIacrylates, with structural Formula I, are widely used in creams and lotions as a Sun protection factor (SPF) booster. The extended conjugation of the acrylate portion of the molecule absorbs UVB and short-wave UVA (ultraviolet) rays with wavelengths from 280 to 320 nm.

2-Cyano-3,3-diarylacrylates are generally prepared by the Knoevenagel condensation of either 1) Cyanoacetic ester with Arylketone or 2) Alkyl cyanoacetate with Arylketone followed by transesterification with long chain alcohol.
For purification of 2-Cyano-3,3-diarylacrylates, in general, the technique preferred is distillation under reduced pressure where in, the crude product obtained after removal of unreacted starting material, is distilled under reduced pressure to get desired quality of 2-Cyano-3,3-diarylacrylates.

The patent EP0430023 and US5047571 disclose the process where the product obtained after Knoevenagel reaction, is purified by carrying out wipe film evaporation. Patent US5451694 and EP2008/000372 describes the means of purification as distillation whereby purity of 98% is obtained.
The drawback of this technique is high temperature distillation (temperature above 200°C) which is generally done under highly reduced pressure. This involves high energy consumption and thus process becomes costly. The process though gives good colour, is generally not devoid of inevitable impurities like Diarylcyanoacryl amide and Diarylcyanoacrylic acid. These impurities exhibit boiling point similar to 2-Cyano-3,3-diarylacrylates under reduced pressure and thus cannot be removed by distillation. This, in turn affects the purity of final product. There is always a huge distillation loss too due to formation of tarry material at high temperature from which 2-Cyano-3,3-diarylacrylates cannot be recovered by further distillation.
Distillation at higher temperature under reduced pressure -incurs huge energy consumption. In today's scenario, where the concern is high about carbon foot print and energy conservation, it is one's social responsibility to come up with the technique which lowers the carbon foot print and leads to energy saving.
Hence, there is a need to develop a novel, efficient and industrially viable process for purification of 2-Cyano-3,3-diarylacrylates.
The inventors of present invention have developed a novel purification process to purify 2-Cyano-3,3-diarylacrylates using adsorption chromatography technique. Further, the purification process gives advantages over distillation technique in terms of lowering of inevitable impurities like Diarylcyanoacryl amide and Diarylcyanoacrylic acid. The purification process is cost effective, operationally

simple, energy saving, exploits cheap and commercially available, recyclable adsorbents with very good yield and a control over unwanted impurities.
OBJECT OF INVENTION
i) An object of the present invention is to provide a novel process for the purification of 2-Cyano-3,3-diarylacrylates.
ii) Another object of the present invention is to provide an efficient purification process for the manufacturing of 2-Cyano-3,3-diaryIacrylates with good yields and high purity of 2-Cyano-3,3-diarylacrylates.
iii) Another object of the present invention is to provide an efficient purification process for the preparation of 2-Cyano-3,3-diarylacrylates wherein individual impurities like Diarylcyanoacryl amide and Diarylcyanoacrylic acid are less than 0.05%.
iv) Another object of the present invention is to provide simple, economic and industrially viable purification process for the manufacturing of high purity 2-Cyano-3,3-diarylacrylates.
v) Yet another object of the present invention is to provide purification process for the manufacturing of 2-Cyano-3,3-diarylacrylates with gardner colour of less than 6.0.
SUMMARY OF INVENTION
According to an aspect of the present invention, there is provided a novel process for the purification of 2-Cyano-3,3-diarylacrylates of Formula I


in which
Ar =Ar' = Phenyl or substituted phenyl
R = C4-C12alkyl
According to another aspect of the present invention, there is provided a novel and improved process, Process A for the purification of 2-Cyano-3,3-diarylacrylates of Formula I comprising the steps of
(i) removing unreacted starting materials from the crude 2-Cyano-3,3-diaryl
acrylate by vacuum distillation; (ii) maintaining temperature of the mass between 50-60°C; (iii) passing the crude material of step (ii) through the column containing
adsorbent at 50-60°C; (iv) obtaining the pure 2-Cyano-3,3-diaryIacrylate.
According to another aspect of the present invention, there is provided an alternative process, Process B for the purification of 2-Cyano-3,3-diarylacrylates of Formula I comprising the steps of
(a) removing unreacted starting materials from the crude 2-Cyano-3,3-diaryl acrylate by vacuum distillation;
(b) adding organic solvent to the crude material of step (a);
(c) passing the crude material of step (b) through the column containing adsorbent at 20-40°C;

(d) obtaining the pure 2-Cyano-3,3-diarylacrylate after removal of organic solvent under reduced pressure at temperature of less than 80°C.
In particular, the present invention relates to the novel and improved process for the purification of 2-Cyano-3,3-diarylacrylates of Formula I containing individual impurities such as Diar ylcyanoacryl amide and Diarylcyanoacrylic acid less than 0.05% of impurities.
DETAILED DESCRIPTION OF INVENTION
The present invention provides the novel and improved processes for the purification of 2-Cyano-3,3-diarylacrylates of Formula I.

The compound of Formula I can be obtained by reaction of cyanoacetic ester of Formula II with Arylketone of Formula III using conventional processes reported in literature.


In another embodiment of the present invention, there is provided an improved processes, process A and process B for the purification of 2-Cyano-3,3-diarylacrylates of Formula I..
Process A comprises the steps of
(i) removing unreacted starting materials from the crude 2-Cyano-3,3-diaryl
acrylate by vacuum distillation; (ii) maintaining temperature of the mass between 50-60°C; (iii) passing the crude material of step (ii) through the column containing
adsorbent at 50-60°C; (iv) obtaining the pure 2-Cyano-3,3-diarylacrylate.
Process B comprises the steps of
(a) removing unreacted starting materials from the crude 2-Cyano-3,3-diaryl acrylate by vacuum distillation;
(b) adding organic solvent to the crude material of step (a);
(c) passing the crude material of step (b) through the column containing adsorbent at 20-40°C;
(d) obtaining the pure 2-Cyano-3,3-diarylacrylate after removal of organic solvent under reduced pressure at temperature of less than 80°C.
The process of the present invention for purification of 2-Cyano-3,3-diarylacrylates of Formula I is depicted in flow diagram (Figure 1)


According to an embodiment, the adsorbents are activated carbon, silicates like zeolites and silica, synthetic resins, activated alumina, preferably silica is used.
According to another embodiment, the adsorbent is washed and recycled repeatedly.
According to another embodiment of the present invention, the mesh size of silica used for the purification is of 100-300 mesh size, preferably 100-200 mesh size.
According to another embodiment of the present invention, crude 2-Cyano-3,3-diarylacrylates is introduced fro m the top or through the bottom of the column, preferably through the bottom entry.
According to yet another embodiment of the present invention, the crude 2-Cyano-3,3-diarylacrylates is passed through column containing silica gel maintaining temperature between 20-100°C, more preferably 20-60°C.

In yet another embodiment, the organic solvents used in step (b) is selected from hydrocarbons like hexane, cyclohexane, toluene, xylene, or polar solvents like ethanol, glycerine, methanol, preferably hexane or cyclohexane.
In yet another embodiment, the total impurities are less than 0.2%, with individual impurities like Diarylcyanoacryl amide and Diarylcyanoacrylic acid less than 0.05%.
In another embodiment of the present invention, the Gardner colour of the final product achieved is less than 6.
The inventors of the present invention have observed that keeping the temperature of the input material between 20-100°C, in particular between 50-60°C in case of Process A (without solvent process) or 20-40°C in case of Process B (with solvent process) and pressure between 0.1-8 kg/cm2 , preferably 3-7 kg/cm , makes the mass less viscous and more flowable through the column containing silica of 100-200 mesh, especially while passing material from bottom of the column, with the proper rate and complete utilization of column efficiency. If the material (without solvent) is passed from the top of the column, under reduced pressure preferably 100-450 mm of Hg A maintaining temperature between 20-100°C, in particular between 20-60°C, it is also possible to achieve the desired improvement but there is a decrease in efficiency in comparison to the process where the material is passed from the bottom as the chances of channeling are less.
In another embodiment, the invention relates to the product comprising 2-Cyano-3,3-diarylacrylates of Formula I


wherein, the 2-Cyano-3,3-diarylacrylate is at least 99.8% min. and total impurities are less than 0.2%.
In another embodiment, the invention relates to a composition comprising 2-Cyano-3,3-diarylacrylates of Formula I

wherein the purity of 2-Cyano-3,3-diarylacrylate is at least 99.8% and individual impurities like Diarylcyanoacryl amide and Diarylcyanoacrylic acid are less than 0.05%.
The details of the invention provided in the following examples are given by the way of illustration only and should not be construed to limit the scope of the present invention.

EXAMPLES AND COMPARATIVE EXAMPLES
Comparative Example
Purification of 2-Ethylhexyl-3,3-biphenvl cyanoacrylate according to the prior art
A 5000 mL four neck round bottom flask, equipped with a mechanical stirrer, a thermometer, Dean and Stark set up and a condenser, was charged with 2-ethylhexyl cyanoacetate (1735 g, 8.8 gmol), benzophenone (1000 g, 5.5 gmol), acetic acid (825 g, 13.75 gmol), ammonium acetate (155g, 2.0 gmol) and 1000 mL Cyclohexane. The stirred reaction mass was then heated to 85-90°C. The water formed was removed cautiously azeotropically. The reaction was continued till the Gas chromatographic analysis showed no further decrease in benzophenone concentration in reaction mass. The loss of acetic acid was continuously adjusted by adding the corresponding acetic acid. The acetic acid and solvent was then recovered from the mass. The excess reactants were recovered under reduced pressure to the best possible level. The HPLC analysis of reaction mass showed Biphenylcyanoacryl amide content 0.48%, Biphenylcyano acrylic acid 0.2%, unreacted benzophenone 0.032% in the crude mass.
The above 1386 g of crude mass obtained was then taken in distillation set up having packed column and reflux head. The distillation was carried out under reduced pressure of 0.1 mm of Hg A and bottom temperature above 220°C, to yield 1293 g of 2-Ethylhexyl 3,3-biphenyl cyanoacrylate of purity 99.36%, Biphenylcyanoacryl amide 0.42% and Biphenylcyano acrylic acid 0.16%.
Experimental Example 1
Purification of 2-Ethvlhexyl-3.3-biphenyl cyanoacrylate according to present invention using Silica as adsorbent (with solvent)

A 5000 mL four neck round bottom flask, equipped with a mechanical stirrer, a thermometer, Dean and Stark set up and a condenser, was charged with 2-ethylhexyl cyanoacetate (1735 g, 8.8 gmol), benzophenone (1000 g, 5.5 gmol), acetic acid (825 g, 13.75 gmol), ammonium acetate (155g, 2.0 gmol) and 1000 mL Cyclohexane. The stirred reaction mass was then heated to 85-90°C. The water generated was then continuously removed azeotropically. The reaction was continued till the Gas chromatographic analysis showed no further decrease in benzophenone concentration in reaction mass. The loss of acetic acid was continuously adjusted by adding the corresponding acetic acid. The acetic acid and solvent were then recovered from the mass. The excess reactants were recovered under reduced pressure to the best possible level. The HPLC analysis of reaction mass showed Biphenylcyanoacryl amide content 0.46%, Biphenylcyano acrylic acid 0.2%, unreacted benzophenone 0.032% in the crude mass.
Purification of crude 2-Ethvlhexyl-3,3-biphenvl cyanoacrylate
The above 1390 g of crude mass was then stored in the stainless steel reservoir equipped with the heating system to attain desired temperature. The material was allowed to attain temperature between 55-60°C and passed through silica column containing 280 g of silica of mesh size 100-200, under nitrogen pressure 6-7 kg/cm2 from bottom of the silica column maintaining temperature 50-60°C (the design of column is as given in the Figure 1). The material left in the column was then recovered using minimum amount of solvent like cyclohexane and recycled
The total quantity of crude 2-Ethyl hexyl-3,3,-diphennylcyanoacrylate passed through the silica column was 1390 g. The material recovered was 1113 g with 99.7% purity, Gardener colour <6, Biphenylcyanoacryl amide content 0.03%, Biphenylcyano acrylic acid content below detection level (<0.005%) and benzophenone 60 ppm.

Experimental Example 2
Purification of 2-Ethylhexvl-3,3-biphenyl cyanoacrylate according to present invention using silica as adsorbent (without solvent)
A 5000 mL four neck round bottom flask, equipped with a mechanical stirrer, a thermometer and a condenser, was charged with 2-ethylhexyl cyanoacetate (1735 g, 8.8 gmol), benzophenone (1000 g, 5.5 gmol), acetic acid (825 g, 13.75 gmol), ammonium acetate (155g, 2.0 gmol). The stirred reaction mass was then heated to 85-90°C. Azeotrope of acetic acid/water mixture was distilled off over a period of 16 h. under reduced pressure from 400-420 mm of Hg A till the Gas chromatographic analysis showed no further decrease in benzophenone concentration in reaction mass. The loss of acetic acid was continuously adjusted by adding the corresponding acetic acid. The acetic acid was then recovered under reduced pressure (30-60 mm of Hg A).
The HPLC analysis of reaction mass showed Biphenylcyanoacryl amide content 0.43%, Biphenylcyano acrylic acid 0.24%, unreacted benzophenone 0,026% in the crude mass.
Purification of crude 2-Ethvlhexyl-3,3-biphenyl cyanoacrylate
The above 1589 g of crude mass was then stored in the stainless steel reservoir equipped with the heating system to attain desired temperature. The material was allowed to attain temperature between 55-60°C and passed through silica column containing 320 g of silica of mesh size 100-200, under nitrogen pressure 7-8 kg/cm2 from bottom of the silica column (the design of column is as given in the Figure 1)
The total quantity of crude 2-Ethyl hexyl-3,3,-biphennylcyanoacrylate passed through the silica column was 1589 g. The material recovered was 1287 g of 2-Ethylhexyl-

3,3-biphenyl cyanoacrylate of purity 99.86%, with Biphenylcyanoacryl amide content 0.03%, Biphenylcyano acr ylic acid content below detection level (<0.005%) and benzophenone 80 ppm.
Experimental Example 3
Purification of 2-Ethvlhexyl-3.3-biphenvl cyanoacrylate according to present invention using silica as adsorbent and solvent
A 5000 mL four neck round bottom flask, equipped with a mechanical stirrer, a thermometer and a condenser, was charged with 2-ethylhexyl cyanoacetate (1735 g, 8.8 gmol), benzophenone (1000 g, 5.5 gmol), acetic acid (825 g, 13.75 gmol), ammonium acetate (155g, 2.0 gmol). The stirred reaction mass was then heated to 85-90°C. Azeotrope of acetic acid/water mixture was distilled off over a period of 16 h. under reduced pressure from 400-420 mm of Hg A till the Gas chromatographic analysis showed no further decrease in benzophenone concentration in reaction mass. The loss of acetic acid was continuously adjusted by adding the corresponding acetic acid. The acetic acid was then recovered under reduced pressure (30-60 mm of Hg A).
The HPLC analysis of reaction mass showed Biphenylcyanoacryl amide content 0.46%, Biphenylcyano acrylic acid 0.21%, unreacted benzophenone 0.06% in the crude mass.
Purification of crude 2-Ethylhexyl-3,3-diphenyl cyanoacrylate
The above 1594 g of crude mass was then mixed with 160 g of cyclohexane and stored in the stainless steel reservoir equipped with the heating system to attain desired temperature. The material was passed through silica column containing 320 g of silica of mesh size 100-200 at temperature between 25-30°C, under nitrogen

pressure 4-6 kg/cm from bottom of the silica column (the design of column is as given in the Figure 1)
The total quantity of crude 2-Ethyl hexyl-3,3,-diphennylcyanoacrylate passed through the silica column was 1594 g along with 160 g of cyclohexane. The material recovered was 1413 g which on recovery of cyclohexane yielded 1283 g of 2-Ethyl hexyl-3,3,-diphennylcyanoacrylate of purity 99.86%, with Biphenylcyanoacryl amide content 0.024%, Biphenylcyano acrylic acid content below detection level (<0.005%) and benzophenone 94 ppm.

We claim
1. A novel process for the purification of 2-Cyano-3,3-diarylacrylates of Formula I by adsorption chromatography

in which
Ar =Ar' = Phenyl or substituted phenyl R = C4-C12alkyl
2. The process as claimed in claim 1 comprising the steps of
(i) removing unreacted starting materials from the crude 2-Cyano-3,3-diaryl
acrylate by vacuum distillation; (ii) maintaining temperature of the mass between 50-60°C; (iii) passing the crude material of step (ii) through the column containing
adsorbent at 50-60°C; (iv)obtaining the pure 2-Cyano-3,3-diarylacrylate.
3. The process as claimed in claim 1 comprising the steps of
(a)removing unreacted starting materials from the crude 2-Cyano-3,3-diaryI
acrylate by vacuum distillation; (b)adding organic solvent to the crude material of step (a); (c) passing the crude material of step (b) through the column containing
adsorbent at 20-40°C;

(d) obtaining the pure 2-Cyano-3,3-diarylacrylate after removal of organic solvent under reduced pressure at temperature of less than 80°C.
4. The process as claimed in claim 3, wherein the solvent used in step (b) is selected from hydrocarbons like hexane, cyclohexane, toluene, xylene, or polar solvents like ethanol, glycerine, methanol, preferably hexane or cyclohexane.
5. The process as claimed in claim 1,2 and 3, wherein the adsorbent is silica.
6. Silica claimed in claim 5 has the mesh size 100-300, preferably 100-200 mesh.
7. The process as claimed in claim 1, 2 and 3, wherein the pressure is between 0.1-8 kg/cm2.
8. The process as claimed in claim 1, 2 and 3, wherein the purity of 2-Cyano-3,3-diarylacrylate is at least 99.8% .
9. The process as claimed in claim 1, 2 and 3, wherein the total impurities are less than 0.2%.
10. The process as claimed in claim 1, 2 and 3, wherein the individual impurities like Diarylcyanoacryl amide and Diarylcyanoacrylic acid are less than 0.05%.
11. The process as claimed in claim 1, 2 and 3, wherein the colour of 2-Cyano 3,3-diarylacrylates on Gardner scale achieved is less than 6.

12. The process as claimed in claim 1, wherein 2-Cyano-3,3-diaryIacrylate of Formula I is 2-Ethylhexyl-3,3-diphenyl cyanoacrylate.