Study of 1,4‐bis(propylaminomalonylamino)butane as a model compound for nylons n ,3

We are presently studying n ,3 nylons, which have an unusual hydrogen bonding system. In order to determine their structure with greater precision, we have synthesized and determined by X‐ray diffraction the structure of a dimer of the repeating unit of nylon 4,3, namely, 1,4‐bis(propylaminomalonylamino)butane (pMBMp). This compound crystallizes in the triclinic system, space group P 1 with a = 4,65, b = 4,91, c = 24,47 Å; α = 85,3, β = 89,7 and γ = 61,9°. The malonyl residues of pMBMp are related by an inversion center, with torsional angles about the methylene bonds of each malonyl residue in the range 110–115° (or the equivalent negative values). A. conformation TS̄(T) 3 ST was found for the butylenediamide unit. These results give support to the crystalline structure proposed for nylons n ,3.