Page:NIOSH Manual of Analytical Methods - 5516.pdf/5

2,4- and 2,6-TOLUENEDIAMINE: METHOD 5516, Issue 2, dated 15 August 1994 - Page 5 of 5

James E. Arnold, NIOSH/DPSE and Alexander W. Teass, Ph.D., NIOSH/DBBS.

Place 25 g 1-(2-methoxyphenyl)piperazine (yellowish white solid) in a 250-mL beaker. Add ca. 125 mL pentane. Bring to a boil (CAUTION: Pentane is FLAMMABLE) on a water bath and allow to boil until all but a small amount of yellow oil is in solution. The 1-(2-methoxyphenyl)piperazine will melt as it is warmed in the pentane. Decant the solution into a clean beaker, cover with a watchglass, and cool in the freezer for 2 to 3 h. Collect the resulting white needles in a Buchner funnel using suction filtration and dry them in a vacuum desiccator. The crystals are hygroscopic and melt at 26 to 29 °C. Store them in an airtight container in a refrigerator.

Place 0.5 g of 2,4- or 2,6-toluenediamine in a 250-mL beaker. Add ca. 100 mL of distilled water and warm to dissolve the compound. Filter the solution, if necessary. Chill the solution in an ice bath, then slowly add 5 mL acetic anhydride and stir. After keeping the mixture at least 1 h in the ice bath, collect the solid product by suction filtration. Recrystallize the product from water by dissolving it in boiling water, filtering the hot solution, chilling the filtrate in a refrigerator, and collecting the precipitate by suction filtration. Dry the precipitate in a vacuum desiccator.

2,4-Bisacetamidotoluene recrystallizes as white needles and melts at 230 °C.

2,6-Bisacetamidotoluene recrystallizes as brownish needles and melts at ca. 318 °C. NIOSH Manual of Analytical Methods (NMAM), Fourth Edition