Process for the preparation of cypermethrine isomers

Details Process for the preparation of cypermethrine isomers Process for the preparation of cypermethrine isomers

1990-10-19

1992-10-06

Brust, Joseph Paul

Organic compounds -- part of the class 532-570 series

Organic compounds

Nitriles

558355, 558407, C07C25332, C07C25334, C07C25532

Patent

active

051533499

DESCRIPTION:

BRIEF SUMMARY
The present invention is directed to the preparation of enantiomer mixtures of .alpha.-cyano-3-phenoxybenzyl-3-(2,2-dichlorovinyl)-2,2-dimethyl-cycloprop ane-carboxylate (referred to hereinafter as cypermethrin of the formula (I) ##STR2## of given isomer ratio by asymmetric transformation.
In the disclosure the steric configuration of the substituents related to the chiral carbon atom (indicated as .alpha. in the formula) is characterized by the symbols S and R. The terms "cis" and "trans" are used to indicate the position of the substituents on the 3.sup.rd carbon atom of the cyclopropane ring, and the absolute steric configuration of the substituent of the 1.sup.st carbon atom is given as premember 1R and 1S. The following abbreviations are used to indicate the various enantiomers and enantiomer pairs:
The present invention is directed to such isomer mixtures of cypermethrine of the formula (I) ##STR3## which contains out of the theoretically possible 8 isomers of cypermethrin at least 95% of 1RtransS and 1StransR (Ib) isomer pair or only the mixture of 1RcisS and 1ScisR (Ia) and (Ib) isomer pairs at a ratio of (Ia):(Ib)=55:45-25:75 by an asymmetric transformation of II. order in the presence of an amine base and a solvent starting from a cypermethrin isomer mixture containing in addition to the (Ib) isomer pair cis and other trans isomers or the isomer pair of (Ia)+(Ib) at an undesired ratio and the process is carried out by least 90% by weight purity containing at least 60% of trans isomers or cis:trans isomers at a ratio of 65:35-15:85 at a temperature of 0.degree.-25.degree. C. in a system containing up to 0.5% moisture with 0.1-0.5 parts by weight of triethyl amine or 0.0005-0.01 parts by weight of 1,5-diazabicyclo[4.3.0]non-5-ene (DBN) or 1,5-diazabicyclo[5.4.0]undecene (DBU) related to the weight of the starting isomer mixture under intensive stirring, in the presence of propanol at the saturation point of the isomer mixture of the desired ratio while adding to the mixture simultaneously with the epimerization reaction propanol and optionally triethyl-amine so that the ratio of propanol related to cypermethrin is at the end of the reaction 0.5-2 parts by weight and while under optional gradual cooling a crystalline product precipitates, and mass is treated with an aqueous acid solution and/or dissolved in the presence of an organic water-inmiscible solvent at 0.degree.-70.degree. C. or melted without any solvent at 60.degree.-70.degree. C. and washed with an aqueous acid solution and the organic layer is washed with water optionally containing salts or acids and/or the raw product is recrystallized from a solvent containing organic acid and of the operation sequence, whereas optionally reactors by forming a reactor chain by connecting into series 2-10 reactors, which can be cooled and heated and contains a mixer and the elements next to each other are adjusted within a temperature range of (+)30.degree.-(-)25.degree. C. to at most 10.degree. C. temperature difference, and at the beginning 1 part by weight of a desired end product crystal and optionally up to 0.4 parts by weight base are added to each reactor element and the mixtures in each reactor are optionally diluted with an additional 0.4 parts by weight of protic solvent whereafter to the first reactor 1 part by weight of raw isomer mixture of the formula (I) of at least 90% purity and optionally a further amount of base is added to result in 0.4 parts by weight, and optionally up to 0.4 parts by weight of protic solvent is added, the mixture is stirred and the reaction mixture or a part thereof is introduced to the second and subsequent reactors where the addition of the protic solvent and base and the stirring is optionally repeated several times, while the raw cypermethrin is repeatedly added continuously or discontinuously to the first reactor together with up to 0.4 parts by weight of protic solvent and/or a base while the reaction mixture passes in order through all reactors under the above treatment, and the crystals are optionally is

REFERENCES:
patent: 4308279 (1981-12-01), Smeltz
patent: 4512931 (1985-04-01), Robson
patent: 4681969 (1987-07-01), Williams et al.
patent: 4845126 (1989-07-01), Hidasi et al.
patent: 4997970 (1991-03-01), Ager, Jr.

Affiliated with

Also associated with

Rating

Process for the preparation of cypermethrine isomers does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Process for the preparation of cypermethrine isomers, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for the preparation of cypermethrine isomers will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-1190536