20541-87-1Relevant academic research and scientific papers
Preparations, Crystal Structures, and Unusual Proton NMR Characteristics of Some Phthalimides
Barrett, Dawn M. Y.,Kahwa, Ishenkumba A.,Mague, Joel T.,McPherson, Gary L.
, p. 5946 - 5953 (1995)
Protection of NH2 groups as phthalimides using a mixture of acetic acid, phthalic anhydride,and the relevant polyamine can take unusual routes.For diethylenetriamine the major product is diphthalimidodiethylammonium-hydrogen phthalate (DPDAH-HP).For triethylenetetraamine, ethylene migration products N,N-bis(2-phthalimidoethyl)piperazine (2) and N,N',N''-(nitrilotriethylene)trisphthalimide (3) were obtained from room temperature and refluxing reaction mixtures, respectively.The crystal structures of 2, 3, and DPDAH-HP were determined and reveal a series of stabilizing complementary interactions for these favored products (i.e., offset ?-? stacking and C-H...O and possibly C-H...N hydrogen bonds (2), electrostatic interactions between the amine and pyrrolic functionalities (3), and offset ?-? stacking and N-H...O hydrogen bonding (DPDAH-HP).The DPDAH-HP units stack along a screw axis parallel to the b-direction to yield a striking n motif and are linked in the a and c directions by N-H...O bonds.Solution 1H NMR studies of 3 reveal unusual temperature (178-420 K) evolution of sharp aromatic proton resonances in various solvents.Typically, the spectra exhibit a spectacular temperature evolution from a sharp doublet of quartets at high temperature to complex second-order behavior and then a singlet.As the temperature is further lowered, a complex second order spectrum reappears followed by a doublet of quartets.The phthalimide-amine interaction energy, determined from temperature dependent NMR studies, is ca. 20 kJ/mol.Solid state 13C aromatic resonances are broadened by ?-? interactions in 2 and DPDAH-HP while two sets of 13C resonances are found for 3 as expected from the solid state structures.The hydrogen phthalate anion in DPDAH-HP exchanges rapidly with free phthalic acid (equilibrium constant, K ca. 4E2 L/mol); this phthalate exchange exhibits almost temperature independent behavior indicating that it is predominantly entropy driven.
The Reaction of Phthalic Anhydride with Diethylenetriamine and Triethylenetetramine. A Literature Correction
Onopchenko, Anatoli,Harrison, James J.,Chan, Carrie Y.
, p. 717 - 721 (2007/10/03)
A report that phthalic anhydride reacts with diethylenetriamine in acetic acid to form hydrogen phthalate salt of bis-(2-phthalimidoethyl)amine predominantly was reinvestigated. The major product that we obtained was bis(2-phthalimidoethyl)amine, some amide, and very little of the salt. With linear triethylenetetramine, we did not obtain N,N'-bis(2-phthalimidoethyl)ethylenediamine, nor the rearranged tris(2-phthalimidoethyl)amine or 1,4-bis(2-phthalimidoethyl)piperazine reported. A novel amide - 2-{N-2-phthalimidoethyl-N-[2-(2-phthalimidoethyl)aminoethyl]carbamoyl}benzoic acid - was formed as the major product instead. The products reported in the literature are attributed to branched and cyclic amines in their triethylenetetramine, and not to rearrangement reactions. Such possibility is supported by analysis of triethylenetetramine from the same supplier (ca. 65% linear), and our failure to duplicate the results with an authentic triethylenetetramine. Several reported compounds were prepared from pure amines, with no evidence of isomerization.
