SEPARATION OF ISOMERS OF CYCLOPROPANE CARBOXYLIC ACIDS

Abstract: Separation of the geometrical isomers of cyclopropane carboxylic acids of formula (I), wherein R represents alkyl having 1 to 4 carbon atoms or halogen.

Description: Separation of isomers of cyclopropane carboxylic acids The invent io n rela tes to the separat ion of the geomet rical isomers of cyclopropane ca rboxylic acids of f ormula ( i) wherein R represents alkyl having 1 to 4 carbon atoms or halogen. The separated geometrical isomers compared with the isomeric mixtures may be used as starting materials of novel pyrethroids having very favourable insecticidal properties. It is known that many of the insecticidal pyrethroids, which have a substituted cyclopropane carboxylic acid skeleton, are the mixtures of geometri¬ cal and optical isomers. In the recent decades the search and development were directed to the more effective isomers and to their preparation, respective¬ ly, since relation between the structure and the effectiveness has been found. The above fact may be explained beside the greater biological activity also with fulfilling toxicological, environmental and optionally economical requirements. The isomeric ratio of the synthetic, substituted cyclopropane was adjusted to the advantageous value in many ways. E.g. in the most usual synthesis of the cyclopropane ring formation (cycloaddition) the methylene transfer catalysts were varied. First of all copper and copper compounds (θ.An Chem. Soc, 74, 5376 (1952); D. Am. Chem. Soc. 73, 5301, [1951]; Chem. Ber. 99, 2355 C1966] ; Bull. Chem. Soc. dap. 40, 2392 [1967]), organic metal complexes (Chem. Com. p. 1373 [1958J; 0. Org. Chem. .15, p. 30 [19S9J ; 0. Org. Chem. 23, p. 215 [1970]; Chem. Com. p. 1199 [19S7] ; Che. Com. p. 1220 [1970], 0. Org. Chem. 22^ C 39 [1970] were used. In case of the formation of the substituted base skeleton the mass production of the desired favourable isomers is not, however, a feasable way from industrial, technological and economical point of view and this is also valid for the cyclopropane carboxylic acid derivatives (GB-PS 1,446,304, CJ. Org. Chem. JL7, 381 [19521, GB-PS 1,413,491). For the separation of the stereoiso eric (cis, trans) mixtures of substituted cyclopropane carboxylic acids the fractionated crystallization is suggested most widely in the literature (Coll. Czech. Chem. Com. 24, 2230 [1959]; .Pestic. Sci. 1974, 532; Pes ic, Sci. 1974 ' 791 ) • The efficiency and economicalness of these processes is generally not satisfactory. The separations on the basis of solvent selectivi¬ ty are also not suitable. According to these processes e.g. in case of chrysanthemic acid and permethrinic acid medium yields are obtained, besides great amount of benzene, petrolether is used for the recrystallization or digeration is performed (Coll. Czech. Chem. Com. 24, 2230 [1959]) . The same may be stated for other processes based on solvent selectivity (Pestic. Sci. 1971, 245; DE-OS 2,439,177). A new and witty solution is described (DE-PS 2.800.922) according to which two moles of cyclopropane carboxylic acid sodium salt are reacted with one mole of racemic alpha-phenyletilamin whereafter the phenyl- ethyla in salt of the cis isomer may be separated from the sodium salt of the trans isomer. After extraction with ether from the aqueous phase the isomeric purity is, however, only 80/20 and 20/80, respectively. The disadvantage of this process is also that higher isomeric purity may be obtained by recrystallization from petrolether. This means a fractionated recrystalli¬ zation with a SO % conversion calculated from the material balance. The invention is based on the recognition that the geometrical isomers of the cyclopropane carboxylic acids of formula (i) may be separated with great selectivity through their salts of formula (IV) formed with the in a suitable buffered aqueous medium. The invention is characterized by a) preparing from a cyclopropane carboxylic acid of formula (i) wherein R represents alkyl having 1 to 4 carbon atoms or halogen with a compound of formula (il) wherein R 1 and R2 are irideoendently hydrogen, straight or branched chained alkyl having 1 to 5 carbon atoms, straight or branched chained alkenyl having 2 to 5 carbon at oms, phenyl, aralkyl having 7 to 9 carbon atoms, or R 1 and R2 together form a nitrogen or oxygen contain¬ ing heterocyclic group containing 4 or 5 carbon atoms, a> compound of formula (IV) whe rein R, R 1 and R2 have the same meanings as define d above, in aqueous or aqueous-organic solvent medium, the format ion of which is promot ed by adding a salt of formula ( ill) wherein R 1 and R2 have the same meanings as defined above and X represents chloride, bromide, carbonate, sulfate, nitrate, phosphate, acetate or formiate anion and n is 1, 2 or 3. - 5 - said salt of formula (ill) having buffer effect, filtering the resulting salt of formula (IV), optional¬ ly recrystallizing or mixing out, thereafter setting free the cis-cyclopropane carboxylic acid of formula (i) with an aπount of a mineral or organic acid calculated corresponding to the cis isomer content or with an amount of the acid, which is less not more than 10 % than the above calculated amount, in a manner known er se, or b) adding to the sodium or potassium salt of a compount of formula (i) wherein R has the same meaning as defined above, a + salt of formula (ill), wherein R 1, R2, X and n have the same meanings as defined above, having buffer effect in an amount of 100 to 300 mole% in aqueous medium, filtering the resulting salt of formula (IV) wherein defined above, and optionally recrystallizing there¬ after setting free the cis-cyclopropane carboxylic acid or formula (i) with an amount of a mineral or organic acid calculated corresponding to the cis isomer content or with an amount of the acid, which is less not more than 10 % than the above calculated amount, in a manner known per se, and isolating the trans isomer of the compounds of formula (i) by selective acidification followed by filtration. Example 1 In 800 ml of water containing 1.1 mole of ammonium hydroxyde 1 mole of cis/trans permethrinic acid (40/60) is dissolved at 50 to 55 °C then the solution of 2 mole ammonium acetate is 150 ml of water is added and the resulting reaction mixture is filtered off after having been cooled to 15 °C and washed with suitably cold ammonium acetate solution. The nutsch-wet salt is dissolved in 800 ml of watercf 50 to 55 °C then the pH of the solution -is adjust¬ ed to 1.5 to 2 with 2 N hydrochloric acid under gradual stirring and cooling. The resulting substance is filtered off, washed with water and recrystallized from 100 ml aq eous methanol mixture. 58 g (81.6 %) of cis-permethrinic acid are obtained, m.p. 86 to 87° . The mother liquor of the above ammonium salt is acidified with 2.5 N hydrochloric acid to pH = = 3.5, the resulting substance is filtered off, washed and dried. 128 g permethrinic acid are obtained having an isomeric ratio of 10 to 15 % cis/85 to 90 % trans. Example 2 In 500 ml of water containing 1.1 mole of sodium hydroxyde 1 mole of cis/trans permethrinic acid (40/60) is dissolved at 45 to 50 °C then the solution of 2 moles of ammonium chlorid in 300 ml of water is added. The resulting crystals are filtered off after having been cooled to 15 °C, washed with cold ammonium chlorid solution and if desired dried. About 90 g cis-ammonium per ethrinate are obtained having an isomeric ratio of 85 to 90/10 to 15. Further the process of Example 1 is followed or an other acid is used and so the separated geometrical isomers may be obtained. Isomeric mixtures of other cyclopropane carboxylic acids may be separated in the same way.

Claims: CLAIMS 1. Process for the separation of the geometri¬ cal isomers of the cyclopropane carboxylic acids of formula (i) where in R represents alkyl having 1 to 4 carbon atoms or halogen, which comprises a) preparing from a cyclopropane carboxylic acids of formula (i) whe rein R represents alkyl having 1 to 4 carbon atoms or halogen with a compound of formula (il) wherein R 1 and R2 are independently hydrogen, straight or branched chained alkyl having 1 to 5 carbon ato. s, straight or branched chained alkenyl having 2 to 5 carbon atoms, phenyl, aralkyl - 9 - having 7 to 9 carbon atoms, or R 1 and R2 together form a nitrogen or oxygen contain¬ ing heterocyclic group containing 4 or 5 carbon atoms, a compound of formula (IV) wherein defined above, in aqueous or aqueous-organic solvent medium, the formation of which is promoted by adding a salt of formula (ill) wherein R 1 and R2 have the same meanings as defined above and X represents chloride, bromide, carbonat e, sulfate, nitrate, phosphate, acetate or formiate anion and n is 1, 2 or 3, said salt of formula (ill) having buffer effect, filtering the resulting salt of formula (IV), optionally recrystallizing or mixing out, thereafter setting free the cis-cyclopropane carboxylic acid of formula (i) with an amount of a mineral or organic acid calculated corresponding to the cis isomer content or with an amount of the acid, which is less not more than 10 % than the above calculated amount, in a manner known per se, or b) adding to the sodium or potassium salt of a compound of formula (l) wherein R has the same meaning as defined above, a salt of formula (ill) wherein R 1, R2, X and n have the same meanings as defined above, having buffer effect in an amount of 100 to 300 mole% in aqueous medium, filtering the resulting salt of formula (IV) wherein R, R 1 ' , R2 have the same meanin Rgs as defined above, and optionally recrystallizing, thereafter setting free the cis-cyclopropane carboxylic acid of formula (i) with an amount of a mineral or organic acid calculated corresponding to the cis isomer content or with an amount of the acid, which is less not more than 10 % than the above calculated amount, in a manner known per se, and isolating the trans isomer of the compounds of formula (i) by selective acidification followed by filtration. 2. Process according to claim 1 which comprises using aqueous-ethanolic or aqueous-acetonic medium as aqueous-organic solvent medium. 3. Process according to claim lb) which comprises using the salt of formula III) , wherein R 1, R2, X and n have the same meanings as defined in claim 1, having a buffer effect in a quantity of from 200 to 300 mole%.

Inventors: BALOGH GYULA, BOROS LASZLONE, GAJARY ANTAL, HIDASI GYOERGY, RAKOCZI JOZSEF, RAPPI ANDRAS, SOOS RUDOLF, SZEKELY ISTVAN, ZOLTAN SANDOR, BALOGH, GYULA, BOROS, LASZLONE, GAJARY, ANTAL, HIDASI, GYOERGY, RAKOCZI, JOZSEF, RAPPI, ANDRAS, SOOS, RUDOLF, SZEKELY, ISTVAN, ZOLTAN, SANDOR
Applicants: CHINOIN GYOGYSZER ES VEGYESZET, CHINOIN GYOGYSZER ES VEGYESZETI TERMEKEK GYARA RT.
Application year: 1985
Main classification: C07C61
IPC codes: C07C51, C07C61