Fragmentation nitrogen

Amines have odd numbered molecular weights which helps identify them by mass spectrometry Fragmentation tends to be controlled by the formation of a nitrogen stabilized cation... 

The occurrence of the elements carbon, nitrogen, and oxygen manifests itself in the isotope patterns occurring for all molecular or fragment ions. For small numbers of carbon atoms, the... 

This is the branch-poiat differentiatiag phenylalanine (25, R = H) from tyrosiae (25, R = OH). Both phenylalanine and tyrosiae contain an aryl ring, a three-carbon side chain (a Cg—Cg fragment), and a nitrogen. Decarboxylation yields a two-carbon side chain (a Cg—Cg fragment), eg, 2-phenethylamine (59, R = H) from phenylalanine and tyramine (59, R = OH) from tyrosiae, although it is not certain that ia all cases decarboxylation must precede use ia alkaloid constmction. 

Introduction of Nitrogen into a Terpenoid Skeleton. The acetate-derived fragments (35) mevalonic acid (30), which yields isopentenyl pyrophosphate (31) and its isomer, 3,3-dimethyl ally pyrophosphate (32) a dimeric C -fragment, geranyl pyrophosphate (33), which gives rise to the iridoid loganin (34) and the trimer famesyl pyrophosphate (35), which is also considered the precursor to C q steroids, have already been mentioned (see Table 3... 

The characteristic times for waste destmction to an efficiency of 99.99%, for water in a nitrogen atmosphere, where the residue is a typical hydrocarbon breaking into two large fragments, eg, / -butane decomposing into two ethyl radicals would be droplet heatup, 0.073 s droplet evaporation,... 

Physical Chemical Characterization. Thiamine, its derivatives, and its degradation products have been fully characterized by spectroscopic methods (9,10). The ultraviolet spectmm of thiamine shows pH-dependent maxima (11). H, and nuclear magnetic resonance spectra show protonation occurs at the 1-nitrogen, and not the 4-amino position (12—14). The H spectmm in D2O shows no resonance for the thiazole 2-hydrogen, as this is acidic and readily exchanged via formation of the thiazole yUd (13) an important intermediate in the biochemical functions of thiamine. Recent work has revised the piC values for the two ionization reactions to 4.8 and 18 respectively (9,10,15). The mass spectmm of thiamine hydrochloride shows no molecular ion under standard electron impact ionization conditions, but fast atom bombardment and chemical ionization allow observation of both an intense peak for the patent cation and its major fragmentation ion, the pyrimidinylmethyl cation (16). 

The electron impact mass spectrometric fragmentations of (E)-3- and ( )-4-styryl-pyridazines show that the intensity ratio of the M and (M -1)" ions, the general degree of fragmentation and the elimination pathways of nitrogen are the most characteristic features distinguishing between the two isomeric compounds (81JHC255). 

Thiatriazoles readily decompose thermally into nitrogen, sulfur and an organic fragment, usually a cyanide, e.g. (27) Bu OCN + + S (76AHC(20)145). 

The distinction between these two classes of reactions is semantic for the five-membered rings Diels-Alder reaction at the F/B positions in (269) (four atom fragment) is equivalent to 1,3-dipolar cycloaddition in (270) across the three-atom fragment, both providing the 47t-electron component of the cycloaddition. Oxazoles and isoxazoles and their polyaza analogues show reduced aromatic character and will undergo many cycloadditions, whereas fully nitrogenous azoles such as pyrazoles and imidazoles do not, except in certain isolated cases. 

The most important chemistry of azidoazoles is the fragmentation of derived nitrenes of which the prototypes are (453) (454) and (455) (456). Thus 5-azido-l,4-diphenyltriazole (457) evolves nitrogen at 50 °C (70JOC2215). 4-Azido-pyrazoles and -1,2,3-triazoles (458) undergo fragmentation with formation of unsaturated nitriles (8lAHC(28)23l). 

---