Additions to the azomethine group
Addition and hydrogenation reactions of azomethines in chemistry of carbon-nitrogen bond, emphasizing Schiff bases
Harada, K.↗
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Surface analyses of carbon fibers produced from polyacrylonitrile fibers at low carbonization temperatures
A process for producing carbon fibers from polyacrylonitrile at low carbonization temperatures was studied. The bulk and surface properties of fibers obtained after reaction with benzoic acid, air and carbonizing in nitrogen or a dilute acetylene atmosphere are discussed. All fiber products had different surface and internal compositions. Samples produced at temperatures up to 950 C and carbonized in nitrogen contained substantial quantities of nitrogen and oxygen at the surface. During carbonization, the surface nitrogen converted into two new forms, possibly nitrile and an azo or a new carbon-nitrogen bond. Samples carbonized in acetylene contained a carbon-rich surface stable to oxidation.
Cagliostro, D. E.↗
Low-Temperature Gas-Phase Formation of Methanimine (CH 2 NH; X 1 A')–the Simplest Imine–under Single-Collision Conditions
The D1-methanimine molecule (CHDNH; X 1 A') – the simplest (deuterated) imine – has been prepared through the elementary reaction of the D1-methylidyne (CD; X 2 Π) with ammonia (NH 3 ; X 1 A 1 ) under single collision conditions. As a highly reactive species with a carbon-nitrogen double bond and a key building block of biomolecules like amino acids and nucleobases, methanimine is of particular significance in coupling the nitrogen and carbon chemistries in the interstellar medium and in hydrocarbon-rich atmospheres of planets and their moons. However, the underlying formation mechanisms of methanimine in these extreme environments are still elusive. Here, the directed, low-temperature gas-phase formation of D1-methanimine will deepen our fundamental understanding of low-temperature molecular growths processes via carbon-nitrogen bond coupling. Considering the recent detection of the interstellar D1-methylidyne radical, the investigation of the CD–NH 3 system also suggests a promising pathway for future astronomical observations of D1-methanimine as a molecular tracer of gas phase deuterium-enrichment in deep space.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Prospects for Forming C–N Bonds from Dinitrogen
The formation of C–N bonds from molecular dinitrogen (N 2 ) offers a synthetic route to value-added nitrogen-containing compounds without relying on prefunctionalized nitrogen sources. Here, this Perspective highlights recent advances in forming C–N bonds from N 2 with homogeneous transition metal complexes. After discussing how transition metal complexes activate N 2 through various coordination modes, we focus on the reactivity of reduced nitrogen intermediates with different kinds of carbon sources. Carbon electrophiles and nucleophiles enable C–N bond formation via insertion, substitution, or radical pathways. Cycloaddition reactions, particularly involving polarized N 2 ligands and unsaturated carbon electrophiles, offer routes to more complex products. We describe efforts to achieve catalytic turnover and emphasize the remaining obstacles to catalytic C–N bond construction.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗