Nitromethane, deuterated

When l,3r5-triazine is allowed to react with dinitrogen pentoxide and quenched with methanol the cis and trans isomers of 13 3-trinitro-2,4,6-trimethoxy-hexahy drotriazine are obtained. Nitration of the triazine in deuterated nitromethane at -10 °C affords the mixture of cis and trans 2,4,6-trinitrato-l,3,5-trinitro-hexahydro-13,5-triazines which are decomposed at room temperature . Hexahydro-13,5-triaryl-133-triazines cyclorevert upon exposure to HC1 gas to give solid arylmethylene iminium chlorides as new versatile reagents... 

Even for barriers as high as 3.5kcal/mol, when 0 — 200 cm"1, (2) — 0.2 rad, so that zero-point linear displacements of H atoms are 0.20-0.22 A. Thus, the torsion vibrations, unlike stretching modes, are really motions with wide amplitudes in the full sense of these words. The temperature dependence of can be found in the harmonic approximation using (2.82) experimentally, it can be extracted from the temperature dependence of the width of INS peaks assigned to torsion vibrations. As a typical example of this dependence, the results of Trevino et al. [1980] for deuterated nitromethane crystal are represented in Figure 7.8. 

The continuous line has been calculated with = 10 ms and Tit = 95 ms , (b) Time dependence of the transverse magnetization at 46 MHz for deuterated nitromethane adsorbed on organic polymeric resin crosslinked by paramagnetic VO and diamagnetic Cd ions. The continuous line has been calculated with Tj, = 0.9 ms and Tjb =11 ms . 

Nitromethane decomposes under pressure when heated to temperatures above 440K at pressures greater than 1.6 GPa. Both pressure and temperature accelerate the rate of decomposition. The condensed product residues are mainly ammonium formate and water in addition to nonretrievable volatile gases. More than one reaction mechanism appears to be present as indicated by the complex kinetic results. A proposed bimolecular decomposition mechanism is presented that can account for the observed positive pressure dependence of the reaction rate and the experimentally detected reaction products. Nitromethane undergoes a catastrophic reaction under certain dynamic stress conditions in the DAG at room temperature. The sensitivity level to the initiation of this reaction appears to be crystal orientation dependent with respect to the applied stress in the DAC. The resulting opaque solid residue is amorphous and carbonaceous and stable to temperatures in excess of 573 K. Deuterated nitromethane was not observed to undergo this catastrophic reaction. 

A kinetic isotope effect, kH/kD = 1.4, has been observed in the bromination of 3-bromo-l,2,4,5-tetramethylbenzene and its 6-deuterated isomer by bromine in nitromethane at 30 °C, and this has been attributed to steric hindrance to the electrophile causing kLx to become significant relative to k 2 (see p. 8)268. A more extensive subsequent investigation304 of the isotope effects obtained for reaction in acetic acid and in nitromethane (in parentheses) revealed the following values mesitylene, 1.1 pentamethylbenzene 1.2 3-methoxy-1,2,4,5-tetramethyl-benzene 1.5 5-t-butyl-1,2,3-trimethylbenzene 1.6 (2.7) 3-bromo-1,2,4,5-tetra-methylbenzene 1.4 and for 1,3,5-tri-f-butylbenzene in acetic acid-dioxan, with silver ion catalyst, kH/kD = 3.6. All of these isotope effects are obtained with hindered compounds, and the larger the steric hindrance, the greater the isotope... 

I he kinetics of pyridine (py) exchange on the cations tra r-[Tc 02(py)4] and tranx-[Rc 02(py)4] were followed by H NMR in deutcrated nitromethane using deuterated pyridine as the reacting ligand (Table 6.6.A). 

The mechanism of hydroformylation by Pt/Sn systems has been investigated with the help of model complexes (Scheme 42). Only platinum SnCla complexes react with H2 to give EtCHO and close the cycle. 4-Pentenal is cyclized to cyclopentanone by cationic rhodium catalyst such as [Rh(dppe)2] in nitromethane or dichloromethane at 20 °C. The initiating step of the process is the oxidative addition of aldehyde-CH to the Rh(I) centre, a reversal of the final step in an olefin hydroformylation sequence. The mechanism was probed by deuteration studies direct evidence for the catalytic intermediates by NMR was unobtainable. The intermediates are involved in the reversible formation of side products, although selectivity to cyclopentanone can be as high as 98%. The essential features of the reaction are outlined in Scheme 43. ... 

The fact that Udenfriend s system does not bring about the NIH-shift [45] points to a mechanism different from that operative in enzymic hydroxylations. However, deuterated arenes with Fenton s reagent produce an NIH-shift in non-protic solvents (acetonitrile, nitromethane) [46] to an extent related to the amount of water in the system. Taking into account Groves results, supporting the formation of oxoiron intermediates from Fenton s reagent [47-50] ... 

Pressure tends to increase the chemical reactivity of nitromethane as well as the rate of thermal decomposition. It was observed, quite accidentally, that a pressure-induced spontaneous explosion of single crystals of nitromethane at room temperature can occur. Further study revealed that single crystals grown from the liquid with the (111) and either the (001) or the (100) crystal faces perpendicular to the applied load direction in the DAG, if pressed rapidly to over 3 GPa, explode instantaneously accompanied by an audible snapping sound. The normally transparent sample becomes opaque instantly. Visual examination of the residue revealed a dark brown solid which was stable when heated to over 300 C. Subsequent x-ray analysis showed the material to be amorphous. Mass spectral analysis of the residue was inconclusive because no well defined spectra were observed. Because most of the sample is recovered as solid residue after the explosion and is stable to over 300°C, the material may be amorphous carbon. This stress-induced explosion occurs only in protonated nitromethane because similar attempts on the deuterated form did not result in explosion. Shock experiments on oriented pentaerythritol (PETN) crystals have shown similar type behavior [25]. In this case it was suggested that the sensitivity of shock pressures to crystal orientation is the result of the availability of slip planes or system of planes in the crystal to absorb the shock, thereby increasing the threshold to explosion. A similar explanation may be applicable to the nitromethane crystals as well. The deuteration effect must play a role in the initiation chemistry. An isotope effect has been observed previously in the sensitivity of HMX and RDX to shock and thermal conditions [23]. 

S. Shigeto, Y. Pang, Y. Fang, and D. D. Dlott,/. Phys. Chem. B, 112,232 (2008). Vibrational Relaxation of Normal and Deuterated Liquid Nitromethane. 

The present writer (136) attempted to explain this discrepancy in terms of a balance between hyperconjugative retardation and inductive acceleration by the heavier isotope. Only the inductive effect should manifest itself in the meba position, and strong support for the inductive interpretation was provided by Suhr and Zollinger (174), who found, by painstaking chromatographic analysis of the products of nitration of toluene and toluene-ads in nitromethane at 20°C., that methyl deuteration activates the meta position to an extent of kn/kj) = 0.94. The total rate was the same, within experimental error, and and there were no significant effects on nitration in the ortho and para positions. The latter point was recently confirmed with toluene-af by Eastham et al. (175). 

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