Kurze Originalmitteilungen: Synthesen radioaktiv markierter Verbindungen. 48. Mitt. Darstellung von (l-¹⁴C)-Trichloressigsäure

Synthesis of [1,2‐14C]trichloroacetic acid

“…[1,2-14 C]TCA was analysed by GC-MS using the Finnigan MAT ITD 800 (San Jose, USA) mass spectrometer in connection with the gas chromatograph Varian 3400 (Walnut Creek, USA) equipped with a DB-5 capillary column (30 m  0.25 mm ID, film thickness d f 0.25 mm, J&W, Folsom, USA). 3 Synthetic procedure: A 30 ml thick-walled glass ampoule was charged with 0.1 mmol potassium [1,[2][3][4][5][6][7][8][9][10][11][12][13][14] C]acetate in 1 ml methanol, 0.1 mg red phosphorus, 0.1 mg potassium iodide and a solution of 2 mg sulphur in 2 ml benzene. The solvents were removed by lyophilization, resulting in a very fine, homogeneous mixture of the reaction components.…”

“…The residue was dissolved in 2 ml water and distilled on the vacuum line. [1,[2][3][4][5][6][7][8][9][10][11][12][13][14] C]TCA was separated from the aqueous solution by HPLC. The concentration of [1,[2][3][4][5][6][7][8][9][10][11][12][13][14] C]TCA was 2 mmol/ml (7.4 MBq/ml).…”

“…Trichloroacetic acid (TCA) -a secondary air pollutant formed in the atmosphere by photooxidation of C 2 -chlorocarbons -is considered to be an important phytotoxic stress factor which influences the health status of forests. Radioindicator techniques using [1,[2][3][4][5][6][7][8][9][10][11][12][13][14] C]TCA have often been employed to study the behaviour of TCA in the soil and its effects on conifers. [1][2][3] However, [1,[2][3][4][5][6][7][8][9][10][11][12][13][14] C]TCA of high specific activity is not commercially available and the methods described in the literature [4][5][6] Copyright # 2001 John Wiley & Sons, Ltd. do not lend themselves to small (51 mmol) scale synthesis at high specific activity.…”

“…The described synthetic methods 4,5 are multistep syntheses starting from [ 14 C]acetate, [ 14 C]acetylene or [ 14 C]acetaldehyde or they only involve mono-14 C-substitution. 6 Blanchard 7 used photochlorination of [2-14 C]acetic acid of low specific activity with subsequent ion-exchange chromatographic purification.…”

“…Using the publications of Sonia et al 8 and Abrams et al 9 as base and building upon our own experience in synthesizing [ 14 C]bromoacetic acid by direct halogenation of sodium [ 14 C]acetate in the presence of sulphur 10 , we have developed 12 a method for the small-scale synthesis of [1,2-14 C]TCA. Potassium or sodium [1,[2][3][4][5][6][7][8][9][10][11][12][13][14] C]acetate of maximum specific activity reacts almost quantitatively with gaseous chlorine to produce [1,[2][3][4][5][6][7][8][9][10][11][12][13][14] C]TCA in the presence of sulphur, red phosphorus and potassium iodide in a closed system.…”