Podcasts about 31g

One fine afternoon in San Diego, I found myself sitting in Justin Pearson's living room discussing the process of writing books, provoking reactions and the life of a gypsy. Justin has been the front man for many bands including Struggle, Swing Kids, The Locust and All Leather. His current band is called Retox and he also runs the independent record label called 31G. It's an incredible chat and I am excited to share with you. Please donate to the show! Learn more about your ad-choices at https://news.iheart.com/podcast-advertisers

Computational methods in quantum mechanics (QM), density functional theory (DFT) and molecular mechanics (MM), and the fast increase in computer power have opened up a new avenue for solving various vital chemical problems besides conventionally experimental measures. This thesis aims at deeper understanding of the mechanism in organocatalytic transformation and studying factors influencing the activity and selectivity of nucleophilic organocatalysts by theoretical methods. First, the concept of methyl cation affinity (MCA) is introduced and the methodology is discussed about how to calculate the MCA values accurately. The identified theoretical procedure MP2(FC)/6-31+G(2d,p)//B98/6-31G(d) is shown to provide accurate MCA values even for large molecular system. Then, it is used to calculate the MCA values of a set of commonly used N- and P-based organocatalysts. The currently known catalytic activities of nitrogen and phosphorus bases are much more readily correlated with MCA values than with proton affinity (PA) or pKa values. Thus, the MCA can be used as a guideline for the optimization of organocatalytic transformations. Later on, we extend these studies to include affinity values towards a prochiral cation. The so-called "Mosher’s Cation" (MOSC) is used to develop a new chiral descriptor for stereoselective organocatalytic transformations. By taking the example of cinchona alkaloids the energy difference between the adducts formed by re and si face attack to Mosher’s cation (MOSCAre-si) is taken as a measure of stereoinductive potential. Other properties such as continuous symmetry measures and dipole moment are also estimated and correlated with MOSCAre-si values. In many organocatalytic transformations neutral electrophiles react with neutral nucleophiles to give zwitterionic adducts at some stage of the catalytic cycle such as in the Morita-Baylis-Hillman (MBH) reaction. A series of theoretical methods have been studied systematically in order to identify theoretical methods appropriate for the reliable description of the formation of zwitterionic adducts. Geometry optimizations at the mPW1K/6-31+G(d) level provide a reliable basis for the development of compound energy schemes for the accurate description of the formation of zwitterionic adducts between neutral nucleophiles and electrophiles. Accurate energetics can be obtained using modified G3 schemes as well as double-hybrid DFT methods such as B2K-PLYP or B2-PLYP-M2. The issues concerning the reactivities and selectivities of organocatalysts in acylation reactions are further explored. The conformational properties and the stability of acylpyridinium intermediates formed in pyridine-catalyzed acylation reactions have been studied at the SCS-MP2(FC)/6-311+G(d,p)//MP2(FC)/6-31G(d) level of theory. It has been shown that stacking interactions can play a decisive role in the stability as well as the conformational preferences of these transient intermediates. The kinetic resolution of racemic 1-(1-naphthyl)ethanol catalyzed by atropisomeric derivatives of 4-dialkylaminopyridines is used as a model system for deeper understanding the mechanism of organocatalytic transformations and the factors controlling the selectivities of catalysts. Similar to other acylation reactions, the commonly accepted nucleophilic mechanism is more favorable than the general base mechanism for reactions with isobutyric anhydride. The conformational properties of the Transition State (TS) determining the selectivities are analyzed carefully. The key TS models are identified and studied to be used for rationalization of the selectivities of catalysts, and help new catalyst design. A new highly selective catalyst is suggested. From the perspective of catalysis research, 3-amino-1-(2-aminoimidazol-4-yl)-prop-1-ene, which is often used in natural product synthesis, may be used as an ideal starting point for the development of new organocatalysts due to the existence of its potentially four different active sites, based on the assumption of the comparable stability of its various tautomeric forms. Our results show that this assumption is not justified because some of the proposed tautomers are of rather low thermodynamic stability. The protonated form of the 2-aminoimidazole moiety, which is present in many synthetically used derivatives of 3-amino-1-(2-aminoimidazol-4-yl)-prop-1-ene, may act as electrophiles much more comfortably and with much less thermodynamic effort.

One of the important transformations of alcohols to esters is the reaction with acetic anhydride catalysed by 4-(dimethylamino)pyridine (DMAP) in the presence of an auxiliary base like triethyl amine. Although this is a widely used reaction, several questions left unaddressed until now: the reaction mechanism of the latter transformation was not completely conceived. Since Steglich and Litvenencko found DMAP in 1969 independently as nucleophilic catalyst, there was hardly any effort to search for new nucleophilic catalysts of higher catalytic efficiency than DMAP or 4-(pyrrolidinyl)pyridine (PPY). All chiral nucleophilic catalysts are based on these structural motifs and due to their lack of catalytic efficiency, there are hitherto no examples for kinetic resolution experiments of tertiary alcohols described. In this dissertation, the following goals were achieved: With computational methods, the reaction pathway of tert-butanol with acetic anhydride in the presence of DMAP was explored. Based on these results a fast computational tool was developed to screen for more efficient nucleophilic catalysts. The best candidates were synthesised, the catalytic efficiency quantified and the best catalysts applied in the synthesis of esters. The reaction mechanism of the acetylation of tert-alcohols was explored by calculating the nucleophilic and base catalysed reaction pathway of tert-butanol with acetic anhydride in the presence of DMAP at B3LYP/6-311+G(d,p)//B3LYP/6-31G(d) level of theory. In the course of this study, a nucleophilic and base catalysed reaction pathway with DMAP as catalyst was found. The energetically lowest transition state of the base catalysed reaction pathway is 37.9 kJ mol-1 higher in energy then the energetically lowest transition state in the rate-determining step of the nucleophilic reaction path. The combination of kinetic measurements with the calculation of the nucleophilic reaction path reveals that no triethyl amine is involved in the rate-determining step of nucleophilic reaction pathway. This shows clearly that nucleophilic catalysis is the preferred and that the acetate anion is deprotonating the alcohol in the rate-determining step. Furthermore, the results of the recalculation of the nucleophilic reaction path with a different catalyst show that a higher stabilisation of the transient acylpyridinium cation has a pivotal influence on the overall reaction rate of the ester formation. Therefore, relative acetylation enthalpies (ΔH298) were calculated at B3LYP/6-311+G(d,p)//B3LYP/6-31G(d) level of theory by using an isodesmic reaction approach. In this way a large number of new nucleophilic catalysts were screened and numerous promising candidates were synthesised which have a larger negative ΔH298 value then DMAP (-82.1 kJ mol 1). The catalytic effiency of the new nucleophilic catalysts was quantified by a test reaction using 1 equiv. of 1-ethynylcyclohexanol, 2 equiv. of acetic or isobutyric anhydride and 3 equiv. triethyl amine. The conversion of 1-ethynylcyclohexyl acetate or -isobutyrate was monitored by 1H NMR spectroscopy. Pyrido[3,4-b]pyrazine- and pyrido[3,4 b]quinoxaline-derivatives show the best catalytic effiency. Especially (rac) 5,10-diethyl-5,5a,6,7,8,9a,10-octahydropyrido[3,4 b]-quinoxaline (DOPQ) shows equal to better catalytic efficiency then 6,6-tricyloaminopyridine (TCAP), which was hitherto the best nucleophilic catalyst. DOPQ can be synthesised very efficiently in a four step protocol starting from commercially available 3,4-diaminopyridine and cyclohexane-1,2-dione with an overall yield of 45 % while TCAP is only available in a five step synthesis with an overall yield of 8-13 %. The synthesis of DOPQ starts with the Schiff-base formation of 3,4-diaminopyridine and cyclohexane-1,2-dione. Reduction with LiAlH4 yields the cis-configured octahydro[3,4-b]quinoxaline, which can be alkylated without the use of any protecting group in the presence of acetic anhydride in pyridine and subsequent reduction with LiAlH4/AlCl3 to yield DOPQ. The structure of the latter compound was confirmed by X ray single crystal structure. The new catalysts were applied to an enhanced Gooßen esterification to transform sterically hindered acids to their tert-butyl esters. The reaction mechanism was explored by monitoring the substrate, intermediate and product conversions with 1H NMR spectroscopy. With this enhanced reaction protocol, it was possible to transform 1-phenylcyclohexane carboxylic acid into the tert-butyl ester under high concentration conditions at room temperature in the presence of 5 mol% DOPQ within 270 min while with the standard DCC/DMAP protocol only the anhydride of the carboxylic acid is formed. With this very mild method, it was possible to convert a variety of substrates into their tert-butyl- and benzyl esters, which are not accessible with any other method starting from the free carboxylic acid. In the case of chiral substrates no lose of stereochemical information was detected. Combination of high concentration conditions and new catalysts provide attractive reaction times of a few minutes instead of several hours with the Gooßen protocol.

This thesis focuses on the experimental and theoretical investigation of small molecules containing phosphorus, nitrogen and sulfur. The first part of this work presents synthesis and characterisation of molecules bearing a P-N-N-group: N,N´,N´-[tris(trimethylsilyl)]-hydrazino-diphenylphosphane, (TMS)2N-(TMS)N-PPh2, and N,N´,N´-[tris(trimethylsilyl)]-hydrazino-phenyl(chloro)phosphane, (TMS)2N-(TMS)N-P(Cl)Ph, were obtained in the reaction of bis-[lithiumtris(trimethylsilyl)hydrazide] with PhnPCl3 - n (n = 1, 2). The structure and bonding of both species are discussed on the basis of experimentally observed (X-ray, Raman, NMR, and MS) and theoretically obtained data (B3LYP/6-31G(d,p), NBO analysis). Oxidation with sulfur and selenium results in the formation of (TMS)2N-(TMS)N-P(S)-Ph2, (TMS)2N-(TMS)N-P(Se)Ph2, (TMS)2N-(TMS)N-P(S)Ph(Cl) and (TMS)2N-(TMS)N-P(Se)Ph(Cl). Moreover, the thermal decomposition of N,N´,N´-[tris(trimethylsilyl)]hydrazine-dichlorophosphane, (TMS)2N-(TMS)N-PCl2 and the reaction with magnesium have been investigated. The formation and molecular structure of the novel MgCl2(THF)2* 2Mg[(TMS)NP(O)2N(TMS)2](THF) salt containing the hitherto unknown (TMS)NP-(O)2N(TMS)22- anion are discussed. DFT calculations (B3LYP/6-311+G(3df,2p)//B3LYP/6-31G(d,p)) are used to evaluate the bonding, ground-state structures, and energy landscape for the different isomers of (TMS)2N-(TMS)N-PCl2: the thermodynamics and kinetics of the successive elimination of chlorotrimethylsilane (TMS-Cl) resulting in the formation of covalent azide analogues such as TMS-PNN or TMS-NNP are discussed. While investigating the reaction of (TMS)2N-(TMS)N-PCl2 with Lewis acides a galliumtrichloride-adduct of 4-bis[trimethylsilylamino]-1,2,4,3,5-triazadiphosphole was discovered. This hitherto unknown triazadiphosphole represents one of the few examples of a five-membered ring-molecule containing only phosphorus and nitrogen. This ring system was unequivocally characterized by X-Ray, Raman, NMR and MS analysis. Furthermore the Staudinger-type reaction of N,N´,N´-[tris(trimethylsilyl)]-hydrazino-diphenylphosphane with SP(N3)3 and and C3N12 in different stoichiometries were investigated. It is possible to substitute only one azide group in SP(N3)3 and up to two azide groups in C3N12 with (TMS)2N-(TMS)N-PPh2, resulting in the expected products. Upon heating of a solution of (TMS)2N-(TMS)N-PPh2 and SP(N3)3 a new eight-membered ring containing phosphorus and nitrogen in alternating order was obtained. The molecule contains a long pnicogene-chain (eleven atoms in total, three phosphorus- and eight nitrogen-atoms). The reactions of (NSCl)3 and NSCl2- with AgX salts (X = CN, SCN, OCN), as well as the reaction of (NSCl)3 with [PPh4]X (X = CN, SCN, OCN) and HgX (X = CN, SCN) have been investigated in a combined experimental and theoretical study. Additionally, the reaction of NSCl2- salts with hydride-transferring-agents like NaBH4 or NaBH3CN was studied. The thermodynamics as well as structure and bonding of the formation of NSX, NSX2- and NSXY- (X, Y = Cl, H, CN, SCN, OCN) have been studied. Unfortunately the preparation of these species did not suceed. The substitution of sulfur by selenium with SeO2, as reported by Rawson, was investigated on the salts of NSCl2- and S2N3+. These reactions resulted polymeric products and selenium; the formation of a nitrogen-selenium-species could not be confirmed.

Quantenchemische Berechnungen von Carbokationen-Stabilitäten und Elektrophilieparametern E Die Strukturen von zwölf Benzhydrylkationen (XC6H4)2CH+ und ihrer Additionsprodukte mit dem Methylanion (XC6H4)2CH-CH3 wurden auf B3LYP/6-31G(d,p)-Niveau optimiert. Struktur und Reaktivität wurden diskutiert. ClClMeMeMeMeOOOOONMe2Me2NNNNNtol(Ph)CH+(tol)2CH+(ani)2CH+(pcp)2CH+ani(Ph)CH+ani(tol)CH+(fur)2CH+(mfa)2CH+(dma)2CH+(jul)2CH+(lil)2CH+Ph2CH+NNCF3MeMeF3COH3CH3CCH3H3C Abbildung 0-1: Zwölf Benzhydrylkationen; dargestellt ist jeweils das optimierte Konformere.Der Einfluss des Basissatzes wurde bis zum B3LYP/6-311++G(3df,2pd)//B3LYP/6-31g(d,p)-Niveau untersucht. Eine ausgezeichnete lineare Korrelation wurde zwischen dem experimentellen Elektrophilieparameter E (aus der Beziehung lg k = s (N + E)[1]) und den berechneten Methylanion-Affinitäten bereits auf B3LYP/6-31g(d,p)-Niveau gefunden.Abbildung 0-2: Korrelation zwischen den Elektrophilieparametern E verschiedener Benzhydrylkationen mit berechneten Methylanion Affinitäten [∆E0 = E0(Ar2CH–CH3) – E0(Ar2CH+) – E0(CH3–)] auf B3LYP/6-31G(d,p) Niveau (r = 0.9976). Hydrid- und Hydroxidanionaffinitäten von fünf Benzhydrylkationen wurden auf B3LYP/6-31G(d,p)-Niveau berechnet. Diese korrelieren mit den berechneten Methylanion-Affinitäten mit einer Steigung von 1.00; dies zeigt an, dass die relativen Anion-Affinitäten von Benzhydrylkationen von der Lewis-Base unabhängig sind. Um Solvatationseffekte zu berücksichtigen, wurden Hydroxidanionaffinitäten in der Gasphase mit entsprechenden experimentellen Affinitäten in Lösung (d.h. pKR+) verglichen. Dabei ergab sich, dass sich die Stabilitätsunterschiede derCarbokationen in Lösung verkleinern. Zum gleichen Ergebnis gelangt man durch Korrelation von experimentellen Chloridanion-Affinitäten in Lösung mit den berechneten Methylanion-Affinitäten in der Gasphase. Mit Hilfe der Marcus-Gleichung konnte gezeigt werden, dass die intrinsische Barriere konstant bleibt, wenn ein Nucleophil mit dem Steigungsparameter s = 0.67 mit einer Serie von Benzhydrylkationen umgesetzt wird. Größere bzw. kleinere Werte von s als 0.67 zeigen ein Absinken bzw. Ansteigen der intrinsischen Barriere mit zunehmender thermodynamischen Triebkraft der Reaktion an. Diels-Alder-Reaktionen von 1,3-Diarylallylkationen Die Allylkationen 41 und 42 wurden als Tetrafluoroborat-Salze synthetisiert. BF4NMe2Me2NBF4OMeMeO4142 Abbildung 0-3: Allylkationen 41 und 42. Bei den Umsetzungen von 41 und 42 mit one-bond-Nucleophilen (Allylsilane, Allylstannane, Silylenolether, Heteroarene und Hydriddonoren) wurden die erwarteten Produkte erhalten (Schema 0-1).BF4XXXXNuNuX = OMe, NMe241 / 42 Schema 0-1: Umsetzung von 41 und 42 mit one-bond Nucleophilen. 41 reagierte mit den Dienen 61-63 zu Sechsringen (Schema 0-2). Entsprechende Reaktionen mit 42 konnten auch mit elektronenreicheren Dienen nicht beobachtet werden. MeOMeOMeR1R2ZnCl2OMeMeMeOMeOMeOR1R261 62 6364 65 6641MeMeOMeOR1R2ZnCl2OMe68 Me HH HR1 R2H Me61, 6462, 6563, 66 Schema 0-2: Bildung von Cycloaddukten ausgehend von 41. Die Kinetik der Reaktionen von 41 und 42 mit one-bond Nucleophilen wurde UV-spektroskopisch untersucht. Dadurch konnten die Elektrophilieparameter der beiden Allylkationen 41 und 42 bestimmt werden.Aus diesen E-Parametern und bereits bekannten s- und N-Parametern der Diene konnten Geschwindigkeitskonstanten für die Reaktion von 41 und 42 mit Dienen für den Fall vorhergesagt werden, dass nur eine neue Bindung im geschwindigkeitsbestimmenden Schritt geknüpft wird. Entsprechend berechnete Werte stimmen mit den gemessenen Geschwindigkeitskonstanten überein. Übergangszustände mit hohem Grad an Konzertiertheit können daher ausgeschlossen werden. Quantenchemische Untersuchung der Reaktionspfade der Reaktion von Methyl-substituierten Allylkationen mit 1,3-Dienen Die Reaktion des 1,1-Dimethylallykations mit s-cis-1,3-Butadien[2] wurde auf B3LYP/6-311++G(3df,2pd)//B3LYP/6-311G(d,p)-Niveau studiert. Da die Reaktion keine Barriere bezüglich Etot besitzt, wurden drei Reaktionspfade (lineare-, exo- und endo-Annäherung) vorgegeben und an Strukturen entlang dieser Pfade Frequenzrechnungen durchgeführt. linexoendoHHHHHHHHH Abbildung 0-4: Untersuchte Reaktionspfade der Reaktions des 1,1-Dimethylallykations mit s-cis-1,3-Butadien. Auf diese Weise wurden Barrieren der freien Enthalpie (∆G ‡) zwischen 2 und 3 kcal mol-1 erhalten. Die Reaktion des 1,1,3-Trimethylallylkations mit 1,3-Butadien wurde auf B3LYP/6-311++G(3df,2pd)//B3LYP/6-311G(d,p)-Niveau untersucht. Die Strukturen der Edukte, von vier π-Komplexen, von fünf Übergangszuständen und von vier möglichen Produkten wurden auf B3LYP/6-311G(d,p)-Niveau durch Geometrieoptimierung ermittelt. Die Übergangsstrukturen zeigen ein hohes Maß an Unsymmetrie. Die durchgeführten IRC-Rechnungen (intrinsic reaction coordinate) belegen eine große Asynchronizität der [2++4]-Cycloadditionen. Berechnung der Übergangsstrukturen der Diels-Alder-Reaktion des Kations 41 mit 2,3-Dimethyl-1,3-butadien und Isopren zeigen in Übereinstimmung mit den experimentellen Ergebnissen keine Mehrzentrenbeteiligung. Experimentelle und theoretische Untersuchungen der Reaktion des N-Methyl-4-vinylpyridinium-Ions mit Cyclopentadien und Diazoessigester N-Methyl-4-vinylpyridiniumtriflat (103) wurde nach Literaturvorschrift synthetisiert. NOTf103 Abbildung 0-5: N-Methyl-4-vinylpyridiniumtriflat (103). Die Reaktionen von 103 mit Morpholinocyclohexen (72), Diazoessigester (89) sowie Cyclopentadien (86) lieferten die Cycloaddukte 105, 109 und 106.OTfNNHNCO2EtNOTfOTfNNO109106105 Abbildung 0-6: Cycloaddukte105, 109 und 106. Die Elektrophilie von 103 wurde aufgrund eigener kinetischer Untersuchungen und literaturbekannter Geschwindigkeitskonstanten ermittelt. Mit Hilfe der Gleichung lg k = s (N + E) wurden Geschwindigkeitskonstanten für die Reaktionen von 103 mit Nucleophilen berechnet, die Mehrzentrenreaktionen eingehen können. Der Vergleich dieser berechneten Geschwindigkeitskonstanten mit experimentellen Werten ergab große Abweichungen für die Reaktionen von 103 mit Cyclopentadien und Diazoessigester. Dies ermöglichte die Berechnung der „free enthalpy of concert“, den Energiebetrag um den die konzertierte (und real ablaufende) Reaktion gegenüber der (hypothetischen) stufenweisen Reaktion bevorzugt ist. Während man für die Diels-Alder-Reaktion des N-Methyl-4-vinylpyridinium-Ions 103 mit Cyclopentadien eine free enthalpy of concert von ca. 11 kcal mol-1 ermittelt, ergibt sich für die 1,3-dipolare Cycloaddition von 103 mit Diazoessigester ein Konzertiertheitsgrad von ca. 4 kcal mol-1. Berechnungen der Reaktion von 103 mit Cyclopentadien auf B3LYP/6-311++G(3df,2pd)//B3LYP/6-31G(d,p) wurden durchgeführt Die endo-Übergangsstruktur ist um 2.9 kcal mol-1 (∆G) gegenüber der Übergangsstruktur des linearen Angriffs von Cyclopentadien bevorzugt.

2,4,6-tribromophenyl azide was synthesised as previously described and fully characterised using Infrared and Raman spectroscopy, elemental analysis, NMR spectroscopy (1H, 13C, 14N) and X-ray structural analysis. 2,4,6-tribromophenyl azide was recrystallised from ethanol to give pink needles which are monoclinic, with space group P21/n. The crystal packing diagram of 2,4,6-tribromophenyl azide shows that every terminal N(3) atom of the azide group has two intermolecular contacts with two bromine atoms of symetrically related molecules within the unit cell. The intermolecular distances are N(3) to Br(2)* (x – 0.5, -y-0.5, z-0.5) 3.605 Å and N(3) to Br(1)* (x + 1, y, z) 3.881 Å. These distances are both below the sum of the van der Waals radii of both atoms. The crystal packing diagram of 2,4,6-tribromophenyl azide is shown in the figure below. 2,6-diiodo-4-nitrophenyl azide was synthesised as previously described and fully characterised using Infrared and Raman spectroscopy, elemental analysis, NMR. spectroscopy (1H, 13C, 14N) and X-ray structural analysis. 2,6-diiodo-4-nitrophenyl azide was recrystallised from ethanol to give green needles which are monoclinic, with space group P21/c. There are two independent molecules in the asymmetric unit, one molecule has an ordered azide group and the other molecule has a disordered azide group. There is a most unusual intermolecular contact of 3.041 Å between O(11) and I(22) and between O(21) and I(12). This distance is well below the sum of the van der Waals radii of both atoms. The crystal packing is a chain with alternate ordered ands disordered molecules linked by this oxygen –iodine intermolecular contact (see figure below) The ab initio calculations of the vibrational frequencies for all of the halogen phenyl azides derivates were carried out at the self consistent HF level of theory using a 6-31G(d) basis set. Generally the agreement between calculated and experimentally observed (IR, Raman) frequencies is very good at HF/6-31G(d) level of theory for all derivatives prepared so that no scaling of the computed frequencies was necessary. The fact that the asymmetric azide vibration is calculated too high for 2,4,6-tribromophenyl azide, 2,4,6-trichlorophenyl azide 199 and 2,6-diiodo-4-nitrophenyl azide may or may not be explained by strong intermolecular interactions via the N3 group in these compounds as revealed by X-ray diffraction which due to the increased formal) charges on Nβ and Nγ weaken the terminal nitrogen-nitrogen triple bond. The thermal decomposition of three nitrophenyl azides, 1,3,5-(NO2)3-2,4,6-(N3)3-C6 (TNTA), 1,3-(NO2)2-2,4,6-(N3)3-C6H (DNTA) and 1,3,5-(NO2)3-2-(N3)-C6H2 (TNMA) was studied experimentally using gas-phase IR spectroscopy 1,3,5-(NO2)3-2,4,6-(N3)3-C6 →  6 CO + 6 N2 (1) 1,3-(NO2)2-2,4,6-(N3)3-C6H →  HCN + 4 CO + 5 N2 + C (2) 1,3,5-(NO2)3-2-(N3)-C6H2 →  2 HCN + 2 CO2 + NO2 + 3/2 N2 + 2 C (3) The combustion of 1,3.5-(NO2)3-2,4,6-(N3)3-C6 (TNTA) in an O2 atmosphere (two fold excess) yielded CO2, N2, very small amounts of NO2 and traces of N2O (eq. 4). 1,3,5-(NO2)3-2,4,6-(N3)3-C6 + 3 O2 →  6 CO2 + 6 N2 (4) In a further experiment exploring the potential of TATA as a solid fuel we mixed the material with the stoichiometric amount (cf. eq. (5)) of NH4NO3 1,3,5-(NO2)3-2,4,6-(N3)3-C6 + 6 NH4NO3 →  6 CO2 + 12 N2 12 H2O (5) The calculated enthalpy value of –908.9 kcal mol-1 makes the 1:6 molar mixture of 1,3-5- (NO2)3-2,4,6-(N3)3-C6 and NH4NO3 a very promising high energy density material (HEDM) the potential of which we are going to explore in more detail in future studies. In the drophammer testing of TNMA, DNTA and TNTA the order of the acoustic level is TNMA < DNTA < TNTA, but the values for DNTA and TNTA are very similar. Even the weakest of the investigated organic explosives (TNMA) is more powerful than AgN3 or Pb(N3)2, if the acoustic level is interpret as somewhat proportional to the detonation power. The calculated factor (F) and detonation velocities ( D) for TNMA, DNTA and TNTA were calculated using the Rothstein equation that calculates the detonation velocities of a variety of explosives on the basis of their molecular formulae. The calculated detonation velocities (D) are in agreement with the drophammer tests for these compounds i.e the values for detonation velocities (D) show TNMA < DNTA < TNTA, but the values for DNTA (9.185 mm µs-1) and TNTA (9.441 mm µs-1) are very similar. TNMA, DNTA and TNTA have higher calculated F factors and detonation velocities than several commercial explosives. In order to measure the 14N NMR spectrum of a pentazole, the pentazole was prepared in the NMR tube already in the probe. This was done by dissolving the diazonium salt in dichloromethane and placing this solution in the NMR tube and freezing it solid with liquid nitrogen and then the azide solution was added on top and also frozen solid, the NMR tube was then placed in the probe at –50°C. The two layers were allowed mix in the NMR tube as it obtained equilibrium at –50°C. The 14N NMR spectrum was recorded from the moment the tube was placed in the probe. In most of the spectra recorded using this method it was possible to see very small signals in the predicted region for the nitrogen atoms of the pentazole for about 30 minutes but again the strongest signals belong to the corresponding azide. The signals in the predicted pentazole region were not much more than the noise signal so we were not able to assign these with any confidence. However in the experiment using the above method for 2,4-dichlorophenylpentazole we were able to see three clearly distinctive signals in the expect range for the nitrogen atoms in a pentazole . This experiment was carried out several times and each time we observed the same spectra. As well as the three signals of the pentazole the are two signal of the 2,4-diclorophenyl azide present. The spectrum of this experiment can be seen in figure below. When the sample was allowed to warm up to room temperature the three signals for the pentazole disappear but the two signals of the azide remain. We can tentatively assign the signals in the spectrum of 2,4-dichlorophenylpentazole and 2,4 diclorophenyl azide as N1 ( δ = -176.0 ) ppm, N2 N5 ( δ = -72.0 ) ppm, N3 N4 ( δ = -24.0 ) ppm for the pentazole and Nβ ( δ = -135.0 ) ppm and Nγ ( δ = -141.0 ) ppm for the azide. Although the values we obtained for the 14N spectrum of the 2,4-dichloropenyl pentazole are shifted from the values previously reported, we are certain that the signals have been assigned correctly due to the fact that no other nitrogen containing substance could be present at –50°C and that the signals disappear as the temperature is raised which is in accordance with the pentazole decomposing to the azide. This is the first reported 14N NMR spectrum of a pentazole.