Methyl trichloroacetate, hydrolysis

Dichloroacetic acid is produced in the laboratory by the reaction of chloral hydrate [302-17-0] with sodium cyanide (31). It has been manufactured by the chlorination of acetic and chloroacetic acids (32), reduction of trichloroacetic acid (33), hydrolysis of pentachloroethane [76-01-7] (34), and hydrolysis of dichloroacetyl chloride. Due to similar boiling points, the separation of dichloroacetic acid from chloroacetic acid is not practical by conventional distillation. However, this separation has been accompHshed by the addition of a eotropeforming hydrocarbons such as bromoben2ene (35) or by distillation of the methyl or ethyl ester. 

Meat was homogenized in 0.1 M HCl, heated at 100°C for 1 h, cooled, and adjusted to a pH of 4.5 to 5. The mixture was then subjected to enzymatic hydrolysis with mylase 100 and papain for 4 h at 45 to 50°C. To cleave thiamine to 4-methyl-5-(2-hydroxyethyl)thiazole, NaHSOs or Na2S03 was added, the pH was readjusted to 4 to 5, and the mixture was again heated at 100°C for 2 h. After the addition of trichloroacetic acid (TCA), the mixture was chilled and filtered. The filtrate was adjusted to a pH of 11 to 12 and then extracted with chloroform, which was evaporated to dryness. The residue was taken up in 1 mL internal standard solution and the latter was concentrated to 0.5 mL. The resulting sample was stored for analysis. 

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