GB2330579A

GB2330579A - Resolution of the (+)2,2-dimethyl-3-(2,2-disubstitutedvinyl)-cyclopropane-1- carboxylic acids from its optical Isomers

Info

Publication number: GB2330579A
Application number: GB9809332A
Authority: GB
Inventors: D S Rane; R V Datar; P D Joshi; J R Malwankar; Titirmare Shyam
Original assignee: Gharda Chemicals Ltd
Current assignee: Gharda Chemicals Ltd
Priority date: 1997-10-31
Filing date: 1998-04-30
Publication date: 1999-04-28
Anticipated expiration: 2018-04-30
Also published as: GB2330579B; FR2770519A1; GB9809332D0; FR2770519B1

Abstract

A process for resolving (+)-cis-2,2-dimethyl-3-(2,2-dihalogenovinyl)-cyclopropane-1-carboxylic acids of formula (I), in which X=Fluorine, chlorine or bromine, from a mixture of cis(Œ) or cis(Œ) and trans(Œ) using the salt of the optically active base L-Ephedrine at temperatures ranging between 10-80‹C.

Description

Resolution of the (+) 2 2-dimethyl-3-(2 2-disubstitutedvinyl)- cycloproPane-1-carboxvlic acids from its optical Isomers The invention described herein exemplifies the use of salts of chiral amines as resolving agents for resolving the optical isomers of 2,2-dimethyl-3-(2,2-dihalogenovinyl)-cyclopropane-1-carboxylic acids. The techniques that are currently available and are known to the art are as quoted below.

DE 3013151, which is incorporated herein by reference, discloses the resolution of D,L-cis & D, L-trans-2, 2-dimethyl-3-(2, 2dihalovinyl)cyclopropane-l-carboxylic acid (I). Typically one of the following optically active bases L-ephedrine, D-ephedrine, D-N Methylephedrine, L-N-methylephedrine, D-Pseudodephedrine or Lephedrine was mixed with D,L-cis acid or D,L-trans acid, in a medium selected from ethanol, isopropanol, ethylacetate, dichloroethane, toluene or mixtures of isopropylether and methanol, warmed to 700C, cooled to 200C, giving a crude salt of (T) with the base employed. The salt so formed on hydrolysis gave 96.1% D-cis or D-trans-2,2-dimethyl-3-(2,2-dihalovinyl)cyclopropane-lcarboxylic acid & 3.9% of the L-cis or trans-isomer respectively.

The process talks of resolving the D-cis or D-trans acid of formula (I) from D,L-cis or D,L-trans acid of formula (I) respectively. No mention of resolution of D-cis from a mixture of D,L-cis and D,L- trans has been made. It makes use of free base for the resolution which are commercially available in the market as their salts and hence add up to one more step of isolating free base from the salt.

HU40988, discloses a process for resolving the (+) cis-2,2- dimethyl-3-(2 , 2-disubstitutedvinyl) cyclopropane-l-carboxylic acid or their alkali salt using optically active N-benzyl-2-aminobutanol or with its salt in less than mole equivalent quantity in a media of water or water-organic dissolvent mixture, yielding 40% (+) cis isomer [a5D = + 256. The patent while disclosing the process for produ w isomer from (~)cis-racemic mixture does not disclose the process for producing the (+) cis isomer from a mixture of () cis and trans racemic acid.

US 4229593, discloses a method to prepare (+)-cis-3-(2,2- dichloroethenyl) -2, 2-dimethylcyclopropane carboxylic acid from the (l) cis trans mixture using auinine as the resolving agent. ere again the base used is a free base which is expensive. This patent discloses a process for producing the (t) cis isomer of dichloro derivative of the (I) cis trans mixture.

Thus according to this invention we have a process for resolving (+)-cis-2, 2-dimethyl-3-(2, 2-dihalogenovinyl)-cyclopropane-1- carboxylic acids of formula (I),

in which X=Fluorine, chlorine or brorine, from a mixture of cis (+) or cis (t) and trans (~) using the salt of the optically active base L-Ephedrine at temperatures ranging between 10-800C.

The process also eliminates the direct contact of L-ephedrine, a free base and ethylene dichloride as in the entire process the base is in the form of its salt.

DESCRIPTION OF THE INVENTION The invention described herein is especially about using the salt of a chiral amine for resolving the optical isomers of 2,2 dimethyl-3-(2,2-dihaloge.novinyl)-cyclopropane-l-carboxylic acid of formula (I),

in which, X = Fluorine, chlorine or bromine atom.

An aqueous solution of the resolving agent is added to an aqueous solution of Na-salt of optical isomers of 2,2-dimethyl-3-(2,2- dihalogenovinyl)-cyclopropane-l-carboxylic acid over a period of 34 hrs at 250C. Mass is filtered. Cake so obtained is refluxed in ethylene dichloride, filtered, washed and dried. The dry cake is hydrolysed to yield 34% of (+)-cis-2,2-dimethyl-3-(2,2- dihalogenovinyl)-cyclopropane-l-carboxylic acid, [a] = 400.

All the filtrate and washes are mixed, acidified and layers separated. The aqueous layer containing resolving agent is reused for the next batch by making up to the quantity of resolving agent using fresh resolving agent. The procedure is characterised therein that a salt of the optically active base i.e. L-Ephedrine HC1 is taken in a system selected from acetone, water or alkyl alcohol or a combination of these wherein, the quantity of organic phase in aqueous phase can range anywhere between 0-25%, is reacted with a solution of the salt of an acid of formula (I). The quantity of the base used is < 1.0 m/m of the acid of formula (I).

The temperature used for the resolution is relatively lower than that quoted in the art. The resultant salt formed is filtered, purified, decomposed by acid hydrolysis, extracted in a suitable solvent. The solvent on evaporation yields the required acid.

The specific examples that follow will serve to further illustrate the principles and practice of the present invention.

These examples should not be construed to limit the scope of the present invention.

EXAMPLE 1 In a 5 litre reactor 800 ml water, 209g (lm) (+)-Cis-Cypermethric acid (I) and 263 ml. 4 N NaOH were added and a solution of sodium salt of cis cypermethric acid was prepared. In a beaker 100.5g (0.5m) L-ephedrine Hcl solution was prepared in 920 ml water. The solution of L-ephedrine HCl was added to the sodium-Cypermethric acid solution in about 2 hrs at 30 C. The precipitation of the (+)-cis-L-ephedrine salt started after 20% addition was completed.

The mass was then equilibrated for 9 hrs. The reaction mass was filtered, cake washed with water and dried in oven. The cake was taken in 2.5 litres ethylene dichloride, stirred at reflux for hr, cooled to room temperature, filtered and washed with ethylene dichloride. The wet cake was slurried in 1.0 litres water, acidified with 160 ml HCl (SN) and extracted with ethylene dichloride. Ethylene dichloride layer was concentrated to isolate the (+)-cis-cypermethric acid. Yield of the process after the crystallization = 72% on quantity of (+) cis cypermethric acid present in the starting (f)-cis-cypermethric acid used. Specific rotation of purified product [a]O = 420.

EXAMPLE 2 The work method is similar to the one used in example 1 which was repeated at 45 cm, the mass worked up, and the solids dried. Yield of the process = 62. 58 on L-ephedrine HCl charged. Specific rotation of the purified product [a]0 = 41.360.

EXAMPLE 3 In a 5 litre reactor 263 ml of 4 N NaOH was taken and to it was added 298g (1.0 m) of (+) cis dibromo cypermethric acid. It was stirred at rqom temperature till clear solution. In another beaker 100. 5g (0.5 m) mole of L-Ephedrine Hcl was taken with 350 ml water and 50 ml of acetone, stirred to have a clear solution. This solution was added to (+) cis dibromo cypermethric acid-Na salt solution at 32 to 380c in 2-4 hrs., precipitation was observed during the addition. After the complete addition the slurry was stirred for 2 to 3.5 hrs at 32-380C, filtered, washed by 350 ml water twice. The wet cake was dehydrated in 2.0 litre ethylene dichloride at reflux. After the dehydration it was stirred at reflux for 1 hr. Cooled to room temperature in 6 hrs., filtered, washed by 200 ml ethylene dichloride twice. This wet cake was then taken in 1 litre water, acidified to pH < 2 with conc. HC1 and the solids were extracted in methylene dichloride. The methylene dichloride layer was washed and concentrated to get pure (+) cis dibromo cypermethric acid. Yield - 63% on (+) dibromocypermethric acid present originally in the racemic acid used.

Specific rotation of the purified product [a]0 = + 17.50 (C=2.5, chloroform).

EXAMPLE 4 In 5 litres reactor 263 ml of 4 N NaOH was taken and 209g (1 m) of 80:20 cis: trans (+) cyperemthric acid was added to it. It was stirred at room temperature till a clear solution was obtained. In another beaker a clear solution of L-ephedrine HCl 80.6g (0.4 m) was prepared in 350 ml water. This solution was added to the (+) cis:trans cypermethric acid Na-salt solution at 32-38 c in 2 to 4 hrs. Precipitation was observed during the addition. After the complete addition the slurry was stirred for 2 to 3.5 hrs. at 32 to 38"C, filtered and washed twice with 350 ml water. The wet cake was dehydrated in 2.0 litres ethylene dichloride at reflux. After the dehydration the solution was stirred at reflux for 1 hr.

Cooled to room temperature in 6 hrs, filtered and washed with 200 ml ethylene dichloride twice. This wet cake was then taken in 1.0 litre water, acidified to pH S 2 with conc. HCl and the solids were extracted in Methylene dichloride. The methylene dichloride layer was washed acid free and concentrated to get pure (+) cis cypermethric acid. Yield = 70% on (+) cypermethric acid present in the original charge.

Specific rotation of the purified product [α] = 400 (C = 5, ethylene dichloride).

Claims

We Claim.

1. A process for resolving (+)-cis-2,2-dimethyl-3-(2,2-dihalogenovinyl)-cyclopropane-1-carboxylic acids of formula ),.

in which X= Fluorine, chlorine or bromine, from a mixture of cis (~) or cis (~) and trans(~) using the salt of the optically active base I.-Ephedrine at ternperatures ranging between 10-80 C.

2. A process as per claim I wherein the salt of L-ephedrine employed can be either an organic (viz. Oxalate) or an inorganic salt (viz. hydrochloride, nitrate, sulphate, etc.) 3. A process as per claim 1 or 2 wherein quantity of L-ephedrine.salt employed is between 0.1 to 1.0 ole mole of the quantity of add (I) to be resolved.

.4. X process as per claim 3 wherein the quantity of L-ephedrine.salt employed is preferably between 0.4 to 0.5 mole/mole of the quantity of acid (I) to be resolved.

5. A process as per claim 4 wherein the tenperatule at which the resolution is carried out is in the range of 10-80 C and preferably in the range of 30-50 C.

6. A process as per claim 5 wherein the solvent employed for extraction is selected from halogenated organic solvents such as ethylene dichloride, Methylene dichloride, and their like.

7. A procedure as per claims 6 for the resolution of acides of the formula (), to obtain the most active form of the acid, used in the manufacrure of pyrethroids which are potent, wide spectrum insecticides for a variety of pests. any of 8. A process as per /claims 1-7, substantially herein described and as exemplified with respect to examples 1 to 4.

CLAIMS: 1. A process for resolving (+)-cis-2,2-dimethyl-3-(2,2 dihalogenovinyl) -cyclopropane-l-carboxylic acids of formula (I)

in which X= fluorine, chlorine or bromine, from a mixture of cis (=) or cis (+) and trans (+) using the salt of the optically active base L-ephedrine at temperatures ranging between 10-800C.

2. A process as per claim 1 wherein the salt of Lephedrine employed can be either an organic or an inorganic salt.

3. A process according to claim 2 in which the organic salt is an oxalate.

4. A process according to claim 2 or claim 3 in which the inorganic salt is a hydrochloride, nitrate or sulphate.

5. A process as per any of claims 1 to 4 wherein the quantity of L-ephedrine salt employed is between 0.1 to 1.0 mole/mole of the quantity of acid (I) to be resolved.

6. A process as per claim 5 wherein the quantity of Lephedrine salt employed is between 0.4 to 0.5 mole/mole of the quantity of acid (I) to be resolved.

7. A process as per claim 6 wherein the temperature at which the resolution is carried out is in the range of 30500C.

8. A process as per claim 7 wherein the solvent employed for extraction is selected from halogenated organic solvents.

9. A process according to claim 8, wherein the solvents are ethylene dichloride, methylene dichloride, and their like.

10. A procedure as per claim 8 or claim 9 for the resolution of acids of the formula (I), to obtain the most active form of the acid, used in the manufacture of pyrethroids which are potent, wide spectrum insecticides for a variety of pests.

11. A process as per any of claims 1 to 10, substantially as herein described and as exemplified with respect to examples 1 to 4.