Page:NIOSH Manual of Analytical Methods - 5522.pdf/6

 ISOCYANATES: METHOD 5522, Issue 2, dated 15 January 1998 - Page 6 of 6 APPENDIX: PREPARATION OF TRYPTAMINE DERIVATIVE Dissolve 0.00250 mole (0.41 g) of tryptamine (>99% purity) in 300 mL of toluene. Heat the solution to "60 C while stirring until much of the tryptamine is dissolved. Dissolve 0.001 mole (150-300 mg) of isocyanate in 20 mL of toluene. Add the isocyanate solution to the tryptamine solution. The tryptamine derivative will precipitate as a white gel. Collect the precipitate in a fritted-glass funnel by suction filtration. For the tryptamine derivatives of HDI and MDI, dissolve the precipitate in 100 mL (for HDI) or 450 mL (for MDI) of hot n-propanol. Filter the solution and allow it to cool. Collect the crystals. For the tryptamine derivatives of 2,4- and 2,6-TDI, dissolve the precipitate in 50 mL of hot n-propanol. Filter the solution and allow to cool. Add heptane (175 mL for 2,4-TDI and 100 mL for 2,6-TDI) and collect the precipitate in a fritted-glass funnel " by suction filtration. For all derivatives, dry in a vacuum oven at 60 C to remove solvent. TRYPTAMINE DERIVATIVES Diisocyanate

Tryptamine Derivative

MP ( C)

MW (g/mol)

2,4-TDI

2,4-TDI-tryptamine

216-219

494.60

2,6-TDI

2,6-TDI-tryptamine

298-301

494.60

MDI

MDI-tryptamine

~270

570.70

HDI

HDI-tryptamine

201-201.5

488.64

NIOSH Manual of Analytical Methods (NMAM), Fourth Edition