DESC:FORM 2
THE PATENT ACT 1970
(39 of 1970)
&
THE PATENT RULES, 2003
COMPLETE SPECIFICATION
(See section 10 and rule 13)

“A PROCESS FOR PREPARATION OF 4-CHLORO-2,2-DIMETHYL-1,3-DIOXOLANE”

SRF LIMITED, AN INDIAN COMPANY,
SECTOR 45, BLOCK-C, UNICREST BUILDING,
GURGAON – 122003,
HARYANA (INDIA)

The following specification particular describe the invention and the manner in which it is to be performed.

FIELD OF THE INVENTION
The present invention provides a process for preparation of 4-chloromethyl-2,2-dimethyl-1, 3-dioxolane.

BACKGROUND OF THE INVENTION
The 4-chloromethyl-2,2-dimethyl-1,3-dioxolane is an important building block for organic synthesis.
Chinese patent application no. 114195754 provides a process for preparation of S-(-)-4-chloromethyl-2,2-dimethyl-1,3-dioxolane by ring-opening condensation reaction on S-epichlorohydrin in presence of high molar ratio of catalyst selected from aluminium chloride, zinc chloride, iron trichloride and titanium isopropoxide.
Chinese patent no. 102532089 provides a process for preparation of glycerol acetonide via condensation of acetone and epichlorohydrin in presence of Lewis acid selected from aluminium chloride, boron trifluoride ethyl ether complex and iron trichloride or columbium pentachloride.
The processes involve aqueous treatment of the reaction mass that results in degradation of the dioxolane ring that is highly susceptible to ring opening in presence of water.
Chinese patent no. 111138421 provides a process for preparation of 4-chloromethyl-2,2-dimethyl-1,3-dioxolane from epichlorohydrin using boron trifluoride etherate catalyst in acetonitrile solvent. The process is using high amount of catalyst and solvent to obtain product.
Industrial & Engineering Chemistry Research (2013), 52(18), 6129-6137 provides a process for preparation of 4-chloromethyl-2,2-dimethyl-1,3-dioxolane from epichlorohydrin using Cesium tungsten hydroxide oxide phosphate (Cs2.5W12(OH)0.5O35.5(PO4)).
All the processes known are use large quantities of solvent and catalyst and require multiple operations for isolation of product.
Hence, there is a need in the art to develop a cost-effective process for preparation of 4-chloromethyl-2,2-dimethyl-1,3-dioxolane that gives the titled compound in good yield without compromising on product quality.
The present invention provides a process for preparation 4-chloromethyl-2,2-dimethyl-1,3-dioxolane in non-aqueous conditions with limited quantity of reagents and simple operations.
OBJECT OF THE INVENTION
The present invention provides a process for preparation 4-chloromethyl-2,2-dimethyl-1,3-dioxolane in non-aqueous conditions.
SUMMARY OF THE INVENTION
In an aspect, the present invention provides a process for preparation of 4-chloromethyl-2,2-dimethyl-1,3-dioxolane comprising the steps of:
i) reacting epichlorohydrin and acetone in presence of catalyst at 40-75?;
ii) quenching the reaction mixture using a solid base; and
iii) distilling the reaction mixture to obtain 4-chloromethyl-2,2-dimethyl-1,3-dioxolane.
DETAIL DESCRIPTION OF THE INVENTION
In an embodiment, the catalyst is selected from a group consisting of tin dichloride, tin tetrachloride, cobalt chloride, aluminium chloride, zinc chloride, titanium iso-propoxide, boron trifluoride ethyl ether complex, ferric chloride and columbium pentachloride or the like.
In a preferred embodiment, the catalyst is selected from a group consisting of aluminium chloride, zinc chloride, tin dichloride, ferric chloride and tin tetrachloride.
In another embodiment, the molar ratio of catalyst to epichlorohydrin is in the range from 0.01-0.1 and more preferably in the range of 0.01-0.05.
In another embodiment, the molar ratio of acetone to epichlorohydrin is selected in the range from 1-4 and preferably in the range from 1.2- 3.1.
In another embodiment, the reaction of epichlorohydrin and acetone is carried out at a temperature selected in the range of 40? to 75? and more preferably at a temperature range of 50? to 70?.
In an embodiment, the solid base is selected from a group consisting of metal carbonates and metal bicarbonates such as sodium carbonate, sodium hydrogen carbonate, potassium carbonate, potassium hydrogen carbonate, cesium carbonate and magnesium carbonate or the like.
The molar ratio of base to epichlorohydrin is selected in the range from 0.01 to 0.05. The solid base also refers to a powder form of base.
In an embodiment, the solid base is directly added in the step i) reaction mixture.
In another embodiment, the solid base may be added in the step i) reaction mixture in lots under stirring.
The present invention is avoiding use of aqueous basic solution for quenching.
In an embodiment, the present invention process is carried out in non-aqueous conditions.
In an embodiment, solid potassium carbonate is directly added in the step i) reaction mixture.
In an embodiment, basified reaction mixture is distilled to obtain 4-(chloromethyl)-2,2-dimethyl-1,3-dioxolane.
The distillation is carried out at temperature range of 70-110? under vacuum and preferably at 70-90? under vacuum.
In an embodiment, the yield of 4-(chloromethyl)-2,2-dimethyl-1,3-dioxolane is greater than 90% and purity is greater than 95%.
In an embodiment, 4-(chloromethyl)-2,2-dimethyl-1,3-dioxolane is used for preparation of 2,2-dimethyl-4-methylene-1,3-dioxolane.
In an embodiment, epichlorohydrin and acetone are reacted in presence of tin dichloride and reaction mass is quenched using solid potassium carbonate.
In an embodiment, epichlorohydrin and acetone are reacted in presence of ferric chloride and reaction mass is quenched using solid potassium carbonate, wherein the molar ratio of ferric chloride is 0.01 and molar ratio of acetone is 1.2 eq. w.r.t epichlorohydrin.
In an embodiment, epichlorohydrin and acetone are reacted in presence of aluminium chloride and reaction mass is quenched using solid sodium carbonate, wherein molar ratio of aluminium chloride is 0.01 and molar ration of acetone is 2 eq. with w.r.t epichlorohydrin.
In an embodiment, epichlorohydrin and acetone are reacted in presence of tin tetrachloride and reaction mass is quenched using solid potassium carbonate, wherein molar ratio of tin tetrachloride is 0.01 and molar ration of acetone is 2 eq. with w.r.t epichlorohydrin.
In an embodiment, epichlorohydrin and acetone are reacted in presence of tin dichloride and reaction mass is quenched using sodium carbonate to isolate 4-chloromethyl-2,2-dimethyl-1,3-dioxolane, which was further used for preparation of 2,2-dimethyl-4-methylene-1,3-dioxolane.
In an embodiment, epichlorohydrin and acetone are reacted in presence of ferric chloride and reaction mass is quenched using potassium carbonate to isolate 4-chloromethyl-2,2-dimethyl-1,3-dioxolane, which was further used for preparation of 2,2-dimethyl-4-methylene-1,3-dioxolane.
In an embodiment, epichlorohydrin and acetone are reacted in presence of zinc chloride and reaction mass is quenched using potassium carbonate to isolate 4-chloromethyl-2,2-dimethyl-1,3-dioxolane, which was further used for preparation of 2,2-dimethyl-4-methylene-1,3-dioxolane.

EXAMPLES
Example 1: Preparation of 4-chloromethyl-2,2-dimethyl-1,3-dioxolane.
Acetone (2 eq.) and tin dichloride (0.01 eq.) were added in a reactor and heated to a temperature of 40?. Epichlorohydrin (1 eq.) was added while heating and the addition was completed in 40-50 minutes. After completion of addition, the reaction mass temperature was raised to 50?, and further heated to 70? and stirred the reaction mass for 2 hours at same temperature. Potassium carbonate (0.3 eq.) was added in the reaction mass and stirred for additional 30 minutes. The reaction mass quenched and distilled under reduced pressure to obtain 4-chloromethyl-2,2-dimethyl-1,3-dioxolane. GC purity (%): 97.5%, Yield: 91%
Example 2: Preparation of 4-chloromethyl-2,2-dimethyl-1,3-dioxolane.
Acetone (1.2 eq.) and ferric chloride (0.01 eq.) were added in a flask and heated to 40-45?. Epichlorohydrin (1eq) was added while heating and completed the addition in 40-50 minutes at 45-60?. At completion of addition, the reaction mass temperature was raised to 50?, and further heated to 60? to 70? and stirred for 30 minutes. Potassium carbonate (0.3 eq.) was added in the reaction mass and stirred for additional 30 minutes. The reaction mass was quenched and distilled under vacuum to obtain 4-chloromethyl-2, 2-dimethyl-1, 3-dioxolane. Yield: 94%
Example 3: Preparation of 4-chloromethyl-2,2-dimethyl-1,3-dioxolane.
Acetone (1.2 eq.) and ferric chloride (0.02 eq.) were added in a flask and heated to a temperature of 40-45?. Epichlorohydrin (1 eq.) was added while heating for 40-50 minutes at 45-60?. After completion of addition, the reaction mass temperature was raised to 50?, and further heated to 60? to 70? and stirred the reaction mass for 30 minutes. Potassium carbonate (0.3 eq.) was added in the reaction mass and stirred for additional 30 minutes. The reaction mass was quenched and distilled under reduced pressure to obtain 4-chloromethyl-2,2-dimethyl-1,3-dioxolane. Yield: 91 %
Example 4: Preparation of 4-chloromethyl-2,2-dimethyl-1,3-dioxolane.
Acetone (2 eq.) and tin tetrachloride (0.01 eq.) were added in a flask and heated to 45?. Epichlorohydrin (1 eq.) was added while heating for 40-50 minutes at 45-60?. After completion of addition, the reaction mass temperature was raised to 50?, and further heated to 60? to 70? and stirred the reaction mass for 2 hours. Potassium carbonate (0.3 eq.) was added in the reaction mass and stirred for additional 30 minutes. The reaction mass was quenched and distilled under reduced pressure to obtain 4-chloromethyl-2,2-dimethyl-1,3-dioxolane. GC purity (%): 99.1%, Yield: 89%
Example 5: Preparation of 4-chloromethyl-2,2-dimethyl-1,3-dioxolane.
Acetone (2 eq.) and aluminium chloride (0.01 eq.) were added in a flask and heated to 40?. Epichlorohydrin (1 eq.) was added while heating for 40-50 minutes at 45-60?. After completion of addition, the reaction mass temperature was raised to 50?, and further heated to 60? to 70? and stirred the reaction mass for 2 hours. Sodium carbonate (0.3 eq.) was added in the reaction mass and stirred for additional 30 minutes. The reaction mass was quenched and distilled under reduced pressure to obtain 4-chloromethyl-2,2-dimethyl-1,3-dioxolane. GC purity (%): 97.9%, Yield: 91%
Example 6: Preparation of 4-chloromethyl-2,2-dimethyl-1,3-dioxolane.
Acetone (2eq.) and zinc chloride (0.01 eq.) were added in a flask and heated to 40?. Epichlorohydrin (1 eq.) was added while heating for 40-50 minutes at 45-60?. After completion of addition, the reaction mass temperature was raised to 50?, and further heated to 60? to 70? and stirred the reaction mass for 2 hours. Sodium carbonate (0.3 eq.) was added in the reaction mass and stirred for additional 30 minutes. The reaction mass was quenched and distilled under reduced pressure to obtain 4-chloromethyl-2,2-dimethyl-1,3-dioxolane. GC purity (%): 97%, Yield: 91%

Comparative examples:
1. Preparation of 4-chloromethyl-2,2-dimethyl-1,3-dioxolane.
Acetone (2eq.) and tin dichloride (0.005eq) were added in a flask and heated to 40?. Epichlorohydrin (1eq) addition was started along with heating and completed addition in 40-50 minutes. At termination of addition, the reaction mass temperature was 50?, which further heated to 70? and stirred the reaction mass for 4 hours. The reaction sample was analysed on gas chromatography.
Conversion: 10%

,CLAIMS:

WE CLAIM:
1. A process for preparation of 4-chloromethyl-2,2-dimethyl-1,3-dioxolane comprising the steps of:
i) reacting epichlorohydrin and acetone in presence of a catalyst at 40-75?;
ii) quenching the reaction mixture using a solid base; and
iii) distilling the reaction mixture to obtain 4-chloromethyl-2,2-dimethyl-1,3-dioxolane.
2. The process as claimed in claim 1, wherein the catalyst is selected from a group consisting of tin dichloride, tin tetrachloride, cobalt chloride, aluminium chloride, zinc chloride, titanium iso-propoxide, boron trifluoride ethyl ether complex, ferric chloride and columbium pentachloride.
3. The process as claimed in claim 1, wherein the molar ratio of catalyst to epichlorohydrin is in the range from 0.01-0.1.
4. The process as claimed in claim 1, wherein the molar ratio of acetone to epichlorohydrin is selected in the range from 1-4.
5. The process as claimed in claim 1, wherein the reaction of epichlorohydrin and acetone is carried out at a temperature range of 40? to 75?.
6. The process as claimed in claim 1, wherein the solid base is selected from a group consisting of metal carbonates and metal bicarbonates selected from sodium carbonate, sodium hydrogen carbonate, potassium carbonate, potassium hydrogen carbonate, cesium carbonate and magnesium carbonate.
7. The process as claimed in claim 1, wherein the molar ratio of base to epichlorohydrin is selected in the range from 0.01 to 0.05.
8. The process as claimed in claim 1, wherein the preparation of 4-chloromethyl-2,2-dimethyl-1,3-dioxolane is carried out in non-aqueous conditions.

9. The process as claimed in claim 1, wherein the 4-(chloromethyl)-2,2-dimethyl-1,3-dioxolane is obtained with a yield greater than 90% and purity greater than 95%.
Dated this 20th day of December 2022.