2.4- Dichlorophenoxyacetyl chloride

Dissolve 0 01 g. equivalent of the amino acid in 0 03 g. equivalent of N sodium hydroxide solution and cool to 5° in a bath of ice. Add, with rapid stirring, 0 -01 g. equivalent of 2 4-dichlorophenoxyacetyl chloride dissolved in 5 ml. of dry benzene at such a rate (5-10 minutes) that the temperature of the mixture does not rise above 15° if the reaction mixture gels after the addition of the acid chloride, add water to thin it. Remove the ice bath and stir for 2-3 hours. Extract the resulting mixture with ether, and acidify the aqueous solution to Congo red with dilute hydrochloric acid. Collect the precipitate by filtration and recrystallise it from dilute alcohol. 

Commercial 2 4-dichlorophenoxyacetic acid may be recrystallised from benzene m.p. 139-140°. Reflux 10 g. of the acid with 15 ml. of thionyl chloride on a steam bath for 1 hour, distil off the excess of thionyl chloride at atmospheric pressure and the residue under reduced pressure 2 4-dichlorophenoxyacetyl chloride (8 g.) passes over at 155-157°/22-23 mm. It occasionally crystallises (m.p. 44-5-45-5°), but usually tends to remain as a supercooled liquid. 

Dichlorophenoxyacetyl chloride i4)was prepared by addition of 110.0 g (0.498 moles) of 2,4-dichlorophenoxyacetic acid in 250 ml of benzene and 7 ml of N,N-dimethylformamide (DMF) into a one liter, 3-necked roundbottomed flask equipped with mechanical stirrer, addition funnel, thermometer and condenser connected to a caustic scrubber. After heating to reflux, a solution of... 

Amino acids react with 2,4-dichlorophenoxyacetyl chloride to give crystalline derivatives ... 

---

See also in sourсe #XX -- [ ]

---