Volatile organic compounds from filamentous fungi: a chemotaxonomic tool of the Botryosphaeriaceae family.

201

Mechanisms of nucleophilic substitution reactions of methylated Hydroxylamines with bis(2,4-dinitrophenyl)phosphate. Mass spectrometric identification of key intermediates

Mono- and dimethylation of hydroxylamine on nitrogen does not significantly affect rates of initial attack of NHMeOH and NMe2OH on bis(2,4-dinitrophenyl)phosphate (BDNPP), which is largely by oxygen phosphorylation. O-Methylation, however, blocks this reaction and NH2OMe then slowly reacts with BDNPP via N-attack at phosphorus and at the aryl group. With NHMeOH, the initial product of O-attack at phosphorus reacts further, either by reaction with a second NHMeOH or by a spontaneous shift of NHMe to the aryl group via a transient cyclic intermediate. There is a minor N-attack of NHMeOH on BDNPP in an S(N)2(Ar) reaction. Reactions occurring via N-attack are blocked by N-dimethylation, and reaction of NMe2OH with BDNPP occurs via O-attack, generating a long-lived product. Reaction mechanisms have been probed, and intermediates identified, by using both NMR and MS spectroscopy, with the novel interception of key reaction intermediates in the course of reaction by electrospray ionization mass and tandem mass spectrometry.69186024603

Reaction of bis(2,4-dinitrophenyl) phosphate with hydrazine and hydrogen peroxide. Comparison of O- and N-phosphorylation

Nonionic hydrazine reacts with anionic bis(2,4-dinitrophenyl) phosphate (BDNPP), giving 2,4dinitrophenyl hydrazine and dianionic 2,4-dinitrophenyl phosphate by an S(N)2(Ar) reaction, and at the phosphoryl center, giving 2,4-dinitrophenoxide ion and a transient phosphorylated hydrazine that rearranges intramolecularly to N-(2,4-dinitrophenyl)-N-phosphonohydrazine. Approximately 58% of the reaction at pD = 10 occurs by N-phosphorylation, as shown by P-31 NMR spectroscopy. Reaction of HO2- is wholly at phosphorus, and the intermediate peroxophosphate reacts intramolecularly, displacing a second 2,4-dinitrophenoxide ion, or with H2O2, giving 2,4-dinitrophenyl phosphate and O-2. Rate constants of O- and N-phosphorylation in reactions at phosphorus of NH2NH2, HO2-, and NH2OH and its methyl derivatives follow Bronsted relationships with similar slopes, but plots differ for oxygen and nitrogen nucleophiles. The reaction with NH2NH2 has been probed by using both NMR spectroscopy and electrospray ionization mass and tandem mass spectrometry, with the novel interception of key reaction intermediates in the course of reaction.69237898790