A solid phase organic synthesis method has been developed for the preparation of substituted methylene
malonamic acids and malonic ester mono acids 5. Two substituents are introduced into the core molecule
5 by preparation of unsymmetrical malonic acid derivatives 2, followed by Knoevenagel condensation with
aromatic or aliphatic aldehydes, giving resin-bound 4. Evaluation of the scope of these reactions led to the
preparation of a 96-member library from a set of eight amines/alcohols (seven amines and one alcohol) and
11 aldehydes leading to 88 substituted methylene malonamic/malonate mono acids 5 and eight unsymmetrical
malonamic/malonate mono acids 3. Structural validation and quantitation for every member of the library
was obtained by evaluation of 1H NMR and HPLC, respectively. The 1H NMR data were obtained using
automated delivery of DMSO solutions of every library member from a 96-deep well microtiter plate to a
flow probe-equipped NMR spectrometer. HPLC data were used for determination of the extent of conversion
of malonamic/malonate esters 2 to the products 5 by an external standard method. Summary information
from the 1H NMR and HPLC data is viewed as plate diagrams for analysis of the final library.
Solid-state 13C and 15N NMR spectroscopy
was used to study the structure and thermochemistry of nylon-6,6. Experiments were performed on samples of
nylon-6,6 heated in the presence of
labeled adipic acid and hexamethylenediamine (HMD) monomers as well as
labeled bis(hexamethylenetriamine) (BHMT), a molecule previously implicated as a potential nylon
cross-linker. The uptake and
subsequent reaction of labeled materials were characterized by a
variety of solid-state NMR techniques.
Reaction of the central (α) nitrogen of BHMT to form an amide
occurs very rapidly. With time,
transamidation causes this position to become indistinguishable from
the bulk amide nitrogen in nylon.
Rotational-echo double resonance (REDOR), a solid-state NMR
experiment that permits the quantitative
measurement of 13C−15N labeled chemical
bonds, was used to detect the formation and breaking of
carbon−nitrogen bonds due to polymerization and transamidation. The
reaction of adipic acid and hexamethylenediamine (HMD) and the transamidation reaction between the resulting
oligomers and bulk nylon
were studied by heating nylon-6,6 in the presence of
[13C]adipic acid and [15N]HMD and
characterizing
the resulting polymers with REDOR. The combination of stable
isotope labeling and NMR spectroscopy
illustrated in this work should be applicable to the study of a wide
variety of polymers.
Differential thermal analysis has been used to reexamine the stable and metastable solid phases of cyclooctanone and the phase transitions. N M R and dielectric measurements were used to characterize the extent of molecular motions in each phase. Rotor phase I can be supercooled into a glassy crystal, I,. A single orientationally ordered phase, 11, is stable at low temperatures. Another phase, 11', is always metastable with respect to phase 11. The activation energies of self-diffusion and molecular reorientation in I are reported.
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