Synthesis and structural studies of tris-2-chlorobenzylamine and tris-2-bromobenzylamine

The tris-2-chloro and 2-bromotribenzylamines are prepared from aqueous ammonia and 2-chlorobenzyl chloride and 2-bromobenzyl bromide, respectively, in ethanol. Recrystallization yielded colorless cubes of each product. The crystal structures are each solved in space group P1̄, and are isostructural. The tris-2-chloro compound, 1, has a = 7.4226(5) Å, b = 9.0825(7) Å, c = 14.529(1) Å, α = 78.279(1)°, β = 82.389(1)°, γ = 84.661(1)°, and V = 948.41(12) ų with Z = 2, and d _calc = 1.368 Mg/m³. The tris-2-bromo analog, 2, has a = 7.6569(11) Å, b = 9.0922(13) Å, c = 14.614(2) Å, α = 79.286(2)°, β = 81.777(2)°, γ = 85.401(2)°, and V = 987.9(2) ų with Z = 2, and d_calc = 1.762 Mg/m ³. Lithium-halogen exchange experiments conducted in tetrahydrofuran at -78°C using n-butyl lithium revealed that no exchange occurred for the tris-2-chloro compound, but did occur for the tris-2-bromo analog to yield tribenzylamine upon quench and work-up.