structural:reformatting, information:classification
Organic nitrogen compounds

Nitrogen is one of the most important elements in organic chemistry. Many organic functional groups involve a carbon–nitrogen bond, such as amides (RCONR), amines (R N), imines (RC(=NR)R), imides (RCO) NR, azides (RN), azo compounds (RN R), cyanates (ROCN), isocyanates (RNCO), nitrates (RONO), nitriles (RCN), isonitriles (RNC), nitrites (RONO), nitro compounds (RNO), nitroso compounds (RNO), oximes (RC(=NOH)R), and pyridine derivatives. C–N bonds are strongly polarised towards nitrogen. In these compounds, nitrogen is usually trivalent (though it can be tetravalent in quaternary ammonium salts, R N), with a lone pair that can confer basicity on the compound by being coordinated to a proton. This may be offset by other factors: for example, amides are not basic because the lone pair is delocalised into a double bond (though they may act as bases at very low pH, being protonated at the oxygen), and pyrrole is not basic because the lone pair is delocalised as part of an aromatic ring. The amount of nitrogen in a chemical substance can be determined by the Kjeldahl method. In particular, nitrogen is an essential component of nucleic acids, amino acids and thus proteins, and the energy-carrying molecule adenosine triphosphate and is thus vital to all life on Earth.