Nitrogen compounds spectrometry

The nitrogen compounds in the heavy oil were shown to be 40% weak base, 14% very weak base, and 46% neutral compounds. Mass spectrometry was used to classify the weak bases as 72% pyridines (one aromatic ring), 24% quinolines (two aromatic rings), and 4% acridines (three aromatic rings). Mass spectrometry combined with infrared analysis and pyrrolic-nitrogen determination were used to classify the very weak base and neutral nitrogen compounds as 7% pyrroles or indoles with either or both of the a and ft positions open and not N-substituted, 22% pyrroles or indoles with substitution on both a and p positions but no N-substitutions, 34% carbazoles with no N-substitutions, and 37% N-substituted carbazoles. 

Even though theoretical studies have identified a number of potentially metastable structures [1, 2], the experimentally observed nitrogen compounds are still few. The azide anion, N3, wai. first synthesized in 1890 by Curtius [3]. Christie and coworkers have since 1999 reported the preparation and isolation of Ns"1" together with several different counter ions [4, 5]. A few other species, such as N3, Ns+, N4+, and N6, have been observed only as gaseous or matrix-isolated ions or radicals [6-12], We recently reported the detection of cyclic N5 in a mass spectrometry experiment [13], This observation has later been verified by Christie et. al. in a more elaborate study [14], The experimental preparation and detection of an open-chain N4 molecule was reported in 2002 by Cacace et al [15]. This species is expected to be unstable towards bimolecular decomposition and also too low in energy to be of any greater interest as a HEDM. 

Derivatives of 6,7-dihydro-5//-1 -pyrindine (10) comprise the largest group of 1-pyrindines. Studies of the basic nitrogen compounds in the 120°-375° petroleum distillate fractions via chemical reactivity and infrared, mass, ultraviolet, and proton magnetic resonance spectrometry have led to the separation and identification of many derivatives of 10 2> 3> 5 8,56-66... 

In the structure sections, labelled compounds have often been used to solve a spectroscopic problem involved in microwave (Section 4.04.1.3.2), nitrogen NMR (Section 4.04.1.3.5), IR (Section 4.04.1.3.7(i)) or mass spectrometry (Section 4.04.1.3.8). The synthesis usually involves non-radioactive compounds ( H, N) by classical methods that must be repeated several times in order to obtain good yields. 

The nitrogen rule of mass spectrometry says that a compound containing an odd number of nitrogens has an odd-numbered molecular ion. Conversely, a compound containing an even number of nitrogens has an even-numbered M+ peak. Explain. 

The structures of compounds 55a,c and 56a,c were established by means of NMR spectroscopy and mass spectrometry. Due to the different polarity of the C=N and C=P triple bonds, the silicon ring atom in 55a,c is bound to the nitrogen atom, and in 56a,c to the carbon atom of the C=P moiety. The molecular structure of 55a was further determined by single-crystal X-ray diffraction analysis (Fig. 16).14 The four-membered SiNAsC framework is slightly puckered (folding angle N—Si—C/Si—C—As 7°), and... 

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