Hydrochloric Acid → Permethric acid

Temperature

30 °C

1.0 g of ethyl (±)-cis-2,2-dimethyl-3-(2,2-dichlorovinyl)cyclopropane carboxylate of formula (II), in which X represents chlorine atom and R represents ethyl group, was added to the medium above and the mixture was allowed to react with shaking at 30° C. for 40 hours. After the reaction was over, the pH of the reaction mixture was adjusted to 2 or lower with concentrated hydrochloric acid and the mixture was subjected to extraction with methyl isobutyl ketone. Next, an internal standard (dimethyl phthalate) was added to the extract and the mixture was analyzed by gas chromatography (column: 3% Thermon 3000, 1.1 m, 140° C.). Then, the yield of 2,2-dimethyl-3-(2,2-dichlorovinyl)cyclopropane carboxylic acid [in formula (I), X is Cl and R is H] and the recovery rate of the ethyl 2,2-dimethyl-3-(2,2-dichlorovinyl)cyclopropane carboxylate used as the starting material were calculated by comparing their peak areas with that of dimethyl phthalate. It was found that all of the remaining ethyl 2,2-dimethyl-3-(2,2-dichlorovinyl)cyclopropane carboxylate which was not converted to 2,2-dimethyl-3-(2,2-dichlorovinyl)cyclopropane carboxylic acid was recovered. After that, the extract was mixed with IN sodium hydroxide solution to extract 2,2-dimethyl-3-(2,2-dichlorovinyl)cyclopropane carboxylic acid as sodium salt into the aqueous layer. Next, the pH of the aqueous layer was adjusted to 2 or lower with HCl solution to liberate 2,2-dimethyl-3-(2,2-dichlorovinyl)cyclopropane carboxylic acid which was then extracted by using methyl isobutyl ketone. After that, the extract was concentrated and evaporated to dryness to obtain substatially pure 2,2-dimethyl-3-(2,2-dichlorovinyl)cyclopropane carboxylic acid.

1. additionwas added to the medium above and the mixture
2. customto react
3. extractionthe mixture was subjected to extraction with methyl isobutyl ketone
4. additionNext, an internal standard (dimethyl phthalate) was added to the
5. extractionextract
6. customwas analyzed by gas chromatography (column: 3% Thermon 3000, 1.1 m, 140° C.)
7. customwas recovered
8. additionAfter that, the extract was mixed with IN sodium hydroxide solution
9. extractionto extract 2,2-dimethyl-3-(2,2-dichlorovinyl)cyclopropane carboxylic acid as sodium salt into the aqueous layer
10. extractionwas then extracted
11. concentrationAfter that, the extract was concentrated
12. customevaporated to dryness

ORD record

ord-1e72b98f271d46769360cd972d90559d

Source dataset

uspto-grants-1993_01

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US05180671