N-H Functional Groups

The N—H functional group of amines is also easy to spot in the IR, with a characteristic absorption in the 3300 to 3500 cm-1 range. Although alcohols absorb in the same range, an N—H absorption is much sharper and less intense than an O-H band. 

The widely used hindered phenol and aryl amine antioxidants contain reactive 0-H and N-H functional groups capable of reacting with oxy radicals by transfer of hydrogen (4). Electron transfer is also a possibility, and some antioxidants, or their reaction products, may function as traps for alkyl radicals. The hydrogen donation mechanism is capable of terminating two kinetic chains ... 

PBI is one of the most highly studied high temperature polymers in miscible blends. The fundamental reason for the observation of miscibility in PBl-based systems is the presence of the N-H functional group that can interact with the functional groups which are present on the backbone of other polymers. Thus, miscibility in these type of systems is an example of a specific interaction that leads to a negative enthalpy of mixing, a requirement for forming miscible mixtures. 

The N-H functional group found in amines and amides has not been studied as extensively as hydroxyls, but it is important because it appears in many natural products, pharmaceuticals, and polymers. N-H participates in hydrogen bonding and therefore behaves differently in various solvents and matrices. The near-infrared region offers a special advantage in the measurement of the primary amine group NH2 due to a unique combination band. 

More recent studies, particularly with slower hafnium complexes, have provided more detailed mechanistic insight As a step polymerization, the reaction is "nonideal" in that inequivalent reactivities for different Si-H functional groups in the system are observed. For exaniple, disilanes tend to be more reactive than monosilanes. Beyond disilane formation, the preferred dehydrocoupling reaction appears to involve addition of one silicon at a time to the growing chain, via M-S1H2R intermediates (n = 1 above). The Si-Si bond-forming reactions are also reversible. 

Yokomatsu, T.. Hayakawa. Y.. Suemune, K., Kihara, T., Soeda, S., Shimeno, H., and Shibuya, S., Synthesis and biological evaluation of 1, l-difluoro-2-(tetrahydro-3-furanyl)ethylphosphonic acids possessing a N -purinylmethyl functional group at the ring. A new class of inhibitors for purine nucleoside phosphorylases. Bioorg. Med. Chem. Lett., 9, 2833, 1999. 

Intramolecular Reaction of Alkynes with N-H and O-H Functional Groups... 

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