Nitroethylene Results

The structures and optimized geometrical parameters of all the species involved were obtained, as well as their corresponding absolute energies, and relative (to nitroethylene) energies. The reader is referred to our original publication [6] for extensive tabulation of these numerical results for 

C-N plane. Thus, this group could then rotate either way. 

We concluded that the HONO elimination reaction B and nitro-to-nitrite rearrangement D are the lowest energy decomposition channels for nitroethylene with the G2 calculated activation barriers of 57.3 and 57.9 kcal/mol, respectively. This is -15 kcal/mol lower than the amount of energy required for the C-N02 bond cleavage. 

Having obtained a satisfactory description of nitroethylene decomposition, and a calibration of how modest basis DFT calculations fared in comparison to higher level calculations, we set out to apply them to the unimolecular decomposition of DADNE, which we consider next. 

In a manner analogous to that described above for nitroethylene, again all quantum mechanical calculations for DADNE were performed with the Gaussian 98 program package [22]. Intrinsic reaction coordinate (IRC) analysis was carried out for each transition state to make sure that it is the transition structure connecting the desired reactants and products. For all structures with an even number of electrons, a restricted (doubly occupied 

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Nitroethylene, IT2C — CHNCH, is a sensitive compound that must be prepared with great care. Attempted purification of nitroethylene by distillation often results in low recovery of product and a white coating on the inner walls of the distillation apparatus. Explain. 

N 16.59% crysts (from petr eth + eth, below 10°, 7 times), mp 66° was obtd by adding dropwise an excess of nitroethylene (CH2. CHN02) in an inert solv to benzyl-amine at -20° for 30 mins, isolating by treating the yel oil in ether with HC1, converting the resulting hydrochloride to base with aq NaOAc and recrystallizing as above (Ref 2)... 

Table I shows the effect of visible light illumination before raising the temperature of the irradiated glasses. It appears that polymerization is not initiated at the polymerization temperature in the absence of anion radicals in the glasses. The small but not zero values of conversion for the illuminated glasses may result from incomplete bleaching of the anion radicals, the diameter of the polymerization vessels (20 mm) being much larger than that of the ESR sample tubes (4 mm). The effect of pre-illumination on the conversion indicates that the anion radicals are involved in the initiation process of the radiation-induced polymerization of nitroethylene.

Ionic processes of monomers, nitroethylene, n-butylvinylether and styrene, in organic glass matrices of 2-methyltetrahydrofuran, 3-methyl-pentane and n-butylchloride irradiated by y-rays at 77° K, are studied by observing the electron spin resonance spectra of trapped electrons and ion radicals formed from the solute monomers. The primary ionic intermediates are the trapped electrons and their counterpart, cation radicals of matrix molecules. However, in 2-methyltetrahydrofuran glass, the anionic processes of solute monomers resulting from the trapped electrons proceed selectively. On the contrary, only the cationic processes proceed selectively in n-butylchloride glass. Both processes are able to occur in 3-methylpentane glass. 

The large difference between the values for this barrier obtained from the two methods merits a comment. While investigating the decomposition of nitroethylene [6], we found that the results obtained from the use of B3P86 and B3LYP were similar in almost all of the steps, except the ones which result in HONO formation. Moreover, the B3LYP results come... 

Dinitroethane is a very powerful explosive, giving a lead block expansion of 140-150 (picric acid = 100). Its density is 1.46. It is less sensitive to impact than picric acid. Since it is highly reactive, and hence unstable, it has not found any use as explosive. It reacts most readily with bases. For example, when stored in a glass vessel it decomposes after a few weeks as the result of its contact with glass, which has basic properties. Levy suggests adding to the product an organic acid, as for example p- toluenesulphonic acid, as a stabilizer. Under the influence of bases dinitroethane may form nitroethylene, as well as other less defined products, which can readily polymerize to form resinous substances. 

Similarly, treatment of 2-nitroethylene-l,l-dithiolate with a-halocarbonyl compounds results in derivatives of 3-nitrothiophene-2-thiol.29 The products are isolated either by oxidation to the disulfides (33) or by S-methylation (34) (Scheme 7). 

Reduction of the vinylogous amide 428 with sodium borohydride gave an alcohol which could be dehydrated with anhydrous pyridine and phosphorus tribromide in 64% overall yield to give the desired diene, 451. Treatment with nitroethylene at room temperature overnight afforded 452 in 80% yield as the result of regio- and stereoselective addition. 

After this model study, an attempt to synthesize discorhabdin C was carried out with 528, which was synthesized in 15 steps (Scheme 63) (222). The intramolecular phenolate alkylation of 528 gave a similar result, producing aldehyde 529, which with nitromethane gave the nitroethylene 530, in which the alkene functionality was successfully reduced with sodium borohydride, giving 531. As the reduction of the nitro group to the amine... 

By application of ab initio, MP2, MP4, G2, and DFT methods, it has been shown that unimolecular decomposition of nitroethylene occurs preferentially by nitro-to-nitrite rearrangement and 1,2-elimination pathways, rather than by C-NO2 bond breaking or 1,1-elimination. The results have been used to calibrate those of a DFT study of explosive decomposition of 1,1-diaminoethylene which is also initiated by the rearrangement pathway (with calculated and theoretical energy barriers of 59.1 and 58kcalmor respectively). Every step leading to fragments NO, HONO, CO, NH2, and HNC has been characterized. 

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