Jeffrey M. Njus

Diiminoisoindoline: tautomerism, conformations, and polymorphism.

Two polymorphs of the industrially important compound diiminoisoindoline occur in the amino tautomeric form as a conformational isomorph with a 1 : 1 mixture of the syn- and anti-isomers, and a conformational polymorph containing only the syn-isomer.

Thermally Annealed Solid State Polymerization of 2,3-Dicyano-5,7-Dimethyl-6H-1,4-Diazepine: An NMR Study

ABSTRACT The thermally annealed solid state polymerization of 2,3-dicyano-5,7-dimethyl-6H-1,4-diazepine( A) was studied by 1H, 13C, and 15N CP/MAS solid state NMR spectroscopy, and by a 1H solution state NMR deuterium exchange experiment of A. Collectively, the NMR data suggests that a tautomeric form of the monomer is responsible for the solid state reactivity of the crystalline monomer. The solid state polymerization of crystalline A proceeds as a heterogeneous decomposition of the crystalline lattice resulting in an insoluble, amorphous material. A plausible reaction scheme involving a tautomeric form of A is proposed. The scheme is consistent with the NMR spectra.

Solution and Solid‐State Polymerization of 2,3‐Dicyano‐5,7‐dimethyl‐6H‐1,4‐diazepine

Abstract 2,3‐Dicyano‐5,7‐dimethyl‐6H‐1,4‐diazepine (1) is polymerized to a conjugated structure in solution by both alkaline sugar reagents and butoxide in n‐butanol and in the solid state by thermal annealing. From both infrared and nuclear magnetic resonance spectra, all polymers have a similar chain repeat structure involving polymerization at one of the two cyano groups in the molecular structure of 1. Electronic spectra, gel permeation chromatography (GPC), and thermal analysis further characterize the polymers. The methyl protons of 1 are acidic, and solution polymerization is likely initiated by a delocalized anion derived from 1. This delocalized anion also provides a rationalization for polymerization at only one of the cyano groups of 1 instead of cyclopolymerization. The solid state polymerization leads to an amorphous product in a heterogeneous process. The crystal structure of 1 does not allow formation of an infinite chain. A tautomeric form of 1 likely initiates the solid state polymerization. The tautomerization creates a defect site in the crystal of 1, and the initial addition reaction is likely topochemical.

The Interaction of Cinnamic Acids with 60Co Gamma Radiation

In the interest of expanding our knowledge of the interaction of cinnamic acid and its derivatives with ionizing radiation, (E)-cinnamic acid and several of its chlorinated and brominated derivatives were exposed to 60Co gamma radiation. Dimer yields were estimated from integration of the proton NMR signals of the irradiated material. (E)-Cinnamic acid itself is relatively unreactive. The largest yield of dimer was obtained with p-bromocinnamic acid where exposure to a dose of 116 megarads led to a 24% yield.