Nitroalkanes nitropropane

Barton and co workers have explored the aryladon of various nucleophiles inclndmg nitroalkanes using bismuth reagents Reacdon of 2-nitropropane v/ith triphenylbismnth carbonate gives 2-nitro-2-phenylpropane in 80% yield Recently, this aryladon has been used for the synthesis of unusual amino acids Aryladon of ct-nitro esters v/ith triphenylbismnth dichloride followed by redncdon gives unique ct-amino acids fEq 5 68 ... 

Although this method is aot a geaeral procedure, bemg specific for ct-nitroketoues, k has several merits to avoid the use of toxic reageuts such as organodn compounds Functionalized ketones have been prepared by this denitration reaction, in which functionalized nitroalkanes are used as alkyl anion synthons For example, 3-nitropropanal ethylene acetal can be used as synthon of the 3-oxo-propyl anion and 1,4-dicarbonyl compounds are prepared, as shovm In Eq 7 88... 

Other compounds with reactive methylene and methyl groups are completely analogous to the nitroalkanes. Compounds with ketonic carbonyl groups are the most important. Their simplest representatives, formaldehyde and acetone, were considered for many decades to be unreactive with diazonium ions until Allan and Podstata (1960) demonstrated that acetone does react. Its reactivity is much lower, however, than that of 2-nitropropane, as seen from the extremely low enolization equilibrium constant of acetone ( E = 0.9 x 10-7, Guthrie and Cullimore, 1979 Guthrie, 1979) and its low CH acidity (pK = 19.1 0.5, Guthrie et al., 1982). ... 

The monoanions of primary nitroalkanes, phenylnitromethane, and a-nitro esters are all preferentially C-alkylated by cinnamyl acetate and 2-butenyl acetate in 50-89% yield in the presence of Pd catalyst (Eq. 5.51).75 The a-nitro ester gives the C-alkylate in 89% yield, but 2-nitropropane gives the C-alkylate in only 29% yield. The main product is cinnamaldehyde, which is derived from 0-alkylation.75a... 

Simple nitroalkanes such as nitroethane, 1-nitropropane, or 2-nitropropane are generally bad electrophiles for the SN2 reactions.14 In contrast, nitro groups at allylic positions are readily displaced by thiolate ions (Eq. 7.13)15 or lithium dialkylcuprates (Eq. 7.14).16... 

Nitromethane is a detonable explosive, nitroethane can be detonated if both hot and under strong confinement, other nitroalkanes are mild oxidants under ordinary conditions, but precautions should be taken when they are subjected to high temperatures and pressures, since violent reactions may occur [1], Explosives are described consisting of nitromethane stabilised for transport by admixture with nitroethane or nitropropane, then resensitised by addition of an amine [4], The polynitroalkanes, being more in oxygen balance than the mono-derivatives, tend to explode more easily [2], and caution is urged, particularly during distillation [3], See also POLYNITROALKYL COMPOUNDS... 

The reaction of a -halocarboxylic acids with sodium nitrite has been used to synthesize ni-tromethane, nitroethane and nitropropane, although the reaction fails for higher nitroalkanes. " A number of other reactions have been reported which use nitrite anion as a nucleophile, including (1) reaction of alkyl halides with potassium nitrite in the presence of 18-crown-6, (2) reaction of alkyl halides with nitrite anion bound to amberlite resins, (3) synthesis of 2-nitroethanol from the acid-catalyzed ring opening of ethylene oxide with sodium nitrite, and (4) reaction of primary alkyl chlorides with sodium nitrite in the presence of sodium iodide. ... 

The tautomeric nitronic acids of secondary nitroalkanes or their nitronate salts react with nitrous acid or alkali metal nitrites to yield pseudonitroles.These pseudonitroles are often isolated as their colourless dimers (78b) but are deep blue in monomeric form (78a). Primary nitroalkanes also form pseudonitroles (80b) but these rapidly isomerise to the nitrolic acid (80a).Reactions are commonly conducted by slowly acidifying a mixture containing the nitronate salt and the metal nitrite, during which, the nitronic acid reacts with the nitrite anion. These reactions, first discovered by Meyer, have been used to prepare 2-nitroso-2-nitropropane (78a) and acetonitrolic acid (80a) from 2-nitropropane (76) and nitroethane (22) respectively. ... 

A range of primary and secondary nitroalkanes and their derivatives have been converted to the corresponding gem-dinitroalkanes via oxidative nitration, including the conversion of nitroethane, 1-nitropropane, 2-nitropropane and 2-nitro-1,3-propanediol to 1,1-dinitroethane (78 %), 1,1-dinitropropane (86 %), 2,2-dinitropropane (93 %) and 2,2-dinitro-1,3-propanediol (77 %) respectively. The silver nitrate used in these reactions can be recovered quantitatively on a laboratory scale and this has led to a study where oxidative nitration has been considered for the large-scale production of 2,2-dinitropropanol (25) from the nitroethane (22). ... 

Oxidative dimerization gives reasonable yields of vtc-dinitroalkanes for some substrates 2,3-dimethyl-2,3-dinitrobutane (48, 53 %) and 3,4-dimethyl-3,4-dinitrohexane (37 %) are obtained from 2-nitropropane (76) and 2-nitrobutane respectively.However, oxidative dimerization fails to convert 1,1-dinitroethane and trinitromethane into 2,2,3,3-tetranitrobutane and hexanitroethane respectively. Additionally, oxidative dimerisation is not a feasible route for the synthesis of v/c-dinitroalkanes from primary nitroalkanes. Although oxidative dimerization is limited in scope, and yields are often poor, the starting materials are usually inexpensive. 

Bowman and co-workers synthesized 2-azido-2-nitropropane by treating the sodium salt of 2-nitropropane with a mixture of sodium azide and potassium ferricyanide. Olah and co-workers used the same methodology for the synthesis of alicyclic gem-azidonitroalkanes from secondary nitroalkanes. Isomeric azidonitronorbornanes (38) and (39) were synthesized from 2,5-dinitronorbornane (37). Some of the gem-azidonitroalkanes synthesized during this work have poor chemical and thermal stability. 

The nitronates derived from secondary nitroalkanes suffer from greatly decreased reactivity (Table 2.33). The reaction of the silyl nitronate of methyl nitromalonate with methyl acrylate proceeds in 96 h at room temperamre (entry 1), while the corresponding monosubstituted nitronate (85) proceeds in 1 h (entry 5, Table 2.32) (16). Nitronates with dialkyl substitution typically require elevated temperatures for complete reaction (101). For example, the silyl nitronate of 2-nitropropane and nitrocyclopentane both react in under 3 h at 50 °C in acetonitrile... 

Nitroalkanes are acidic compounds the dissociation of a proton from a nitroalkane produces the nitroalkane anion, or nitronate, whose chemical and physical properties differ from those of the parent nitroalkane. The nitronate form of 2-nitropropane is more mutagenic in S. typhimurium TAIOO and TA 102 than is the neutral parent compound (Fiala et al., 1987b Dayal et al., 1989 Kohl et al., 1994), suggesting that propane 2-nitronate may act as an intennediate in the mechanism by w hich 2-nitropropane exerts its genotoxic and carcinogenic effects. This hypothesis is supported by studies indicating that both bacterial mutagenicity and induction of unscheduled DNA synthesis in rat hepatocytes are decreased by conditions (low pH or deuteration of the secondary carbon atom) that limit formation of the nitronate tautomer, and that the tautomerization of 2-nitropropane can be influenced by hepatic enzymes (Kohl et al., 1994). 

Nitroalkanes. A process was developed and operated for a time for the manufacture of s-caprolactam based on the nitration of cyclohexane.197 Nitrocyclohexane thus prepared was transformed to e-caprolactam via cyclohexanone oxime. At present the only industrial process to produce nitroalkanes by direct nitration is the manufacture of nitromethane, nitroethane, 1-nitropropane, and 2-nitropropane. 

Yamaguchi et al. also showed that Rb-L-prolinate catalyzes enantioselective addition of nitroalkanes to several acyclic and cyclic enones [25, 26]. For acyclic enone acceptors the best result, i.e. 74% yield and 68% ee of the S product, was achieved in the addition of 2-nitropropane to -3-penten-2-one (40a, Scheme 4.13) [25]. Screening of several proline derivatives and cyclic amino acids of other ring size resulted in the identification of the O-TBDMS-derivative of 4-hydroxyproline as the best catalyst for addition of nitrocyclohexane to cycloheptenone. In this particular reaction 74% yield and 86% ee were achieved [26]. 

Hydrogen Sulfide. Ignition occurs on contact of the gas with the metal oxide.15 Metals. Potassium reacts explosively and magnesium violently.16 Nitroalkanes. Ignition temperature of nitromethane, nitroethane, and 1-nitropropane, and sensitivity of nitromethane to detonation lowered by contact with lead oxide.17... 

Few nitroalkanes have found use as explosives. Nitromethane (CH3NO2) is a notable exception, and there have been numerous studies of its decomposition pathway [42,43,44]. It has been reported that nitromethane is sensitized to detonation by acidic and basic media. This sensitizing effect is approximately linear with the pKa [45], The best explanation of the effect is that nitromethane undergoes autocatalytic decomposition by an ionic mechanism under acidic or basic conditions [46,47], Among other mononitroalkanes, nitroethane, the nitropropanes, and chloropicrin C13C(N02), have been the most extensively studied. The decomposition... 

Nitroalkane dianions. Seebach et al.1 have shown that reaction of nitroethane with BuLi (2 equiv.) and excess HMPT generates the a,a-dianion as shown by reaction with benzaldehyde to form 3 as the major product. If the sequence is reversed, addition of nitroethane to a solution of BuLi and HMPT, then the a,13-dianion is formed as shown by reaction with benzaldehyde to form 4.2 Thus the ratio of 3 4 is controlled by HMPT. In its absence, 3 is exclusive product (57%). Similar results obtain with 1-nitropropane. 

On the other hand, Russell and coworkers have proposed that the substitution and enolate dimerization products, formed in the reactions of 2-substituted-2-nitropropanes (XCMe2N02, X = Cl, N02, / -MePhS02) with nucleophiles that easily lose one electron, such as the mono enolate anions ArC(OLi)=CHR (R = Me, Et, z -Pr, zz-Bu) and t-BuC(OLi)=CH2, can be rationalized on the basis of a free radical chain mechanism involving bimolecular substitution or ET reactions between the enolate anion and the intermediate nitroalkane radical anion62. An S 2 -type mechanism has also been recently suggested for the reaction of pentafluoronitrobenzene with several nucleophiles in aqueous media65. 

The clearest example of the danger in using a as a measure of transition state structure is illustrated in the work of Bordwell et al. (1969, 1970, 1975). In the rate-equilibrium relationship for the deprotonation of a series of nitroalkanes the unprecedented Br nsted slopes of 1 61 for l-aryl-2-nitropropanes and 1-37 for 1-arylnitro-ethanes were obtained. The simple exposition of the mechanistic significance of a disallows values greater than 1. This, coupled with the fact that the transition state for the proton transfer is not product-like (as established by alternative criteria) indicates at best that, in at least some cases, a does not reflect the selectivity of a particular reaction. Several attempts to rationalize these anomalous results have been made. 

In the preparation of dynamic nitroaldol systems, different aldehydes and nitroalkanes were first evaluated for reversible nitroaldol reactions in the presence of base to avoid any side- or competitive reactions, and to investigate the rate of the reactions. 1H-NMR spectroscopy was used to follow the reactions by comparison of the ratios of aldehyde and the nitroalcohols. Among various bases, triethylamine was chosen as catalyst because its reactions provided the fastest exchange reaction and proved compatible with the enzymatic reactions. Then, five benzaldehydes 18A-E and 2-nitropropane 19 (Scheme 9) were chosen to study dynamic nitroaldol system (CDS-2) generation, because of their similar individual reactivity and product stabilities in the nitroaldol reaction. Ten nitroaldol adducts ( )-20A-E were generated under basic conditions under thermodynamic control, showing... 

SAFETY PROFILE Moderately toxic by intraperitoneal and subcutaneous routes. Questionable carcinogen. Violent reaction with hydrogen peroxide. The oxide increases the sensitivity of nitroalkanes (e.g., nitromethane, nitroethane, and 1-nitropropane) to heat or detonation. See also COBALT COMPOUNDS. 

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