Nitrogen rule

Abstract: Preface to the Second Edition. Acknowledgments. Abbreviations and Notations Used in This Book. 1. Instrumentation. 1.1. Introduction. 1.1.1. Overview. 1.1.2. Sample Introduction. 1.2. Ionization Source. 1.2.1. Electron Ionization Source. 1.2.2. Chemical Ionization. 1.2.3. Other Ionization Methods. 1.2.3.1. Electrospray Ionization. 1.2.3.2. Desorption Ionization. 1.3. m/z Analysis. 1.3.1. Time-of-Flight (TOF). 1.3.2. Magnetic Sector. 1.3.3. Transmission Quadrupole. 1.3.3.1. Selected Ion Monitoring (SIM). 1.3.4. Quadrupole Ion Trap (QIT). 1.3.5. Other Types of Mass Analysis. 1.3.5.1. Mass Spectrometry/Mass Spectrometry(MS/MS). 1.3.5.2. Accurate m/z Analysis. 1.3.6. Spectral Skewing. 1.4. Ion Detection. 1.4.1. Electron Multiplier. 1.4.2. Photomultiplier Detector. 1.5. Data System. 1.5.1. Instrument Tuning and Calibration. 1.5.2. The Mass Spectrum. 1.5.2.1. Production of the Mass Spectrum. 1.5.2.2. Terminology: Ions vs. Peaks. 1.5.3. Library Searches. 1.5.4. Using the Data System to Analyze GC/MS Data. 1.6. Criteria for Good-Quality Spectra. Additional Problems. Mass Spectrometric Resources on the Internet. References and Suggested Reading. 2. Elemental Composition from Peak Intensities. 2.1. Natural Isotopic Abundances. 2.1.1. Atomic and Molecular Mass. 2.1.2. Calculated Exact Masses and Mass Defects. 2.2. Determining Elemental Composition from Isotope Peak Intensities. 2.2.1. One or More Atoms of a Single Element. 2.2.1.1. Chlorine and Bromine. 2.2.1.2. Ion Designation and Nomenclature. 2.2.1.3. Probability Considerations with Multiple Numbers of Atoms. 2.2.1.4. Isotope Peak Intensity Ratios for Carbon-Containing Ions-The X + 1 Peak. 2.2.1.5. A, A + 1, and A + 2 Elements. 2.2.1.6. Isotope Peak Intensity Ratios for Carbon-Containing Ions-The X + 2 Peak. 2.2.1.7. Overlapping Peak Clusters-Contributions from 13C Only. 2.2.1.8. Silicon. 2.2.2. Complex Isotope Clusters. 2.2.2.1. Sulfur Dioxide. 2.2.2.2. Diazepam. 2.3. Obtaining Elemental Compositions from Isotope Peak Intensities. Examples. Additional Problems. References. 3. Ionization, Fragmentation, and Electron Accounting. 3.1. A Brief Review of Orbitals and Bonding. 3.2. Even- and Odd-Electron Species. 3.3. Site of Initial Ionization. 3.4. Types of Fragmentation. 3.5. The Nitrogen Rule. 3.6. Energy Considerations in Fragmentation Processes. 3.6.1. Fragmentation Rates. 3.6.2. Metastable Ions. 3.6.3. Energy Diagrams. 3.6.4. Stevenson's Rule. Additional Examples. Problems. References. 4. Neutral Losses and Ion Series. 4.1. Neutral Losses. 4.1.1. Losses from the Molecular Ion. 4.1.2. Loss of Small Molecules from Aromatic Ions. 4.2. Low-Mass Ion Series. 4.2.1. n-Alkane Spectra. 4.2.2. Effect of Chain Branching on the Spectra of Aliphatic Hydrocarbons. 4.2.3. Ion Series for Nonaromatic Compounds. 4.2.4. Aromatic Ion Series. 4.2.5. Use of Ion Series: Mass Chromatograms. Additional Problems. References. 5. A Rational Approach to Mass Spectral Problem Solving. 5.1. Guidelines for Solving Mass Spectral Problems. Examples. Problems. Reference. 6. a-Cleavage and Related Fragmentations. 6.1. Introduction. 6.2. Benzylic Cleavage. 6.3. Cleavage Next to Aliphatic Nitrogen. 6.3.1. Structural Relationships: a-Cleavage in 1-Phenyl-2-aminopropanes. 6.3.2. Cleavage Next to Electron-Deficient Nitrogen. 6.3.3. a-Cleavage in Complex Nitrogenous Ring Systems. 6.4. Cleavages of Aliphatic Oxygenated Compounds. 6.4.1. a-Cleavage. 6.4.2. Bond Cleavage Away from the Ionization Site. 6.4.3. Cleavage at Carbonyl Groups. 6.5. Elimination Fragmentations in Oxygen and Nitrogen Compounds . 6.5.1. Secondary Elimination from Initial a-Cleavage Ions. 6.5.2. Hydride Shifts. 6.5.3. Elimination Fragmentations of Some Aromatic Compounds. 6.5.4. Water Elimination in Aliphatic Alcohols. Examples. Additional Problems. References. 7. Important Mass Spectral Rearrangements. 7.1. Introduction. 7.2. gamma-Hydrogen Rearrangement. 7.2.1. McLafferty-Type Rearrangement. 7.2.2. gamma-Hydrogen Rearrangement in Alkylbenzenes. 7.2.3. gamma-Hydrogen Rearrangement Initiated by a Remote Ionization Site. 7.3. Cyclohexanone-Type Rearrangement. 7.4. Retro Diels-Alder Fragmentation. 7.5. Double-Hydrogen (McLafferty t 1) Rearrangement. Additional Problems. References. 8. Rationalizing Mass Spectral Fragmentations. 8.1. General Guidelines. 8.2. Loss of Small Molecules. 8.2.1. Loss of Small Molecules from Aromatic Ions Revisited. 8.2.2. gamma-Butyrolactone. 8.3. Ephedrine. 8.4. Ortho Effect: The Hydroxybenzoic Acids. Additional Problems. References. 9. Structure Determination in Complex Molecules Using Mass Spectrometry. 9.1. Introduction. 9.2. "Designer Drugs" Related to MDA. 9.3. Cocaine and Its Metabolites. 9.3.1. Peak Correlations. 9.3.2. Proposed Fragmentations. 9.3.3. Application. 9.4. Phencyclidine and Its Analogs. 9.4.1. Fragmentations of Phencyclidine. 9.4.2. Phencyclidine Analogs. 9.5. A Practical Problem. References. 10. Answers to Problems. Index.

Abstract: Pulsed laser evaporation of boron and dissociation of nitrogen have provided B and N atoms for reaction in a condensing nitrogen stream. The major product NNBN and the minor products NBN and BNN were identified by mixed nitrogen and boron isotopic multiplets from the FTIR spectra in solid nitrogen. Nitrogen atoms partiapate in these reactions as verified by the observation of N 3 radical and an intense green glow on annealing.

Abstract: In the design of novel protein ligands one of the major challenges is the replacement of functional groups to modify and improve the binding characteristics. Often nitrogen- and oxygen-containing groups are exchanged, or both atoms occur in a competitive situation. We have investigated the hydrogen-bonding abilities of oxygen atoms covalently bound to two non-hydrogen atoms of which at least one is formally assigned to an sp2-type hybridization. In particular, examples in which such oxygen atoms compete with nitrogen atoms in the same molecular segment have been studied. Based on interaction energies obtained from ab initio calculations for complexes of these molecules with water, the oxygen atoms can be classified as rather weak hydrogen-bond acceptors; nitrogen atoms present in the same fragment exhibit much stronger interaction energies. The ab initio results are confirmed by the relative frequencies with which oxygen and nitrogen atoms are found to be involved in hydrogen bonding in the crystal structures of organic molecules containing the fragments of interest.

Abstract: This article wishes to demonstrate the nitrogen rule and the formula for calculating the number of rings plus double bonds of any common organic compound.