And 2-nitropropane

The simpler nitrop>arafIins (nitromethane, nitroethane, 1- and 2-nitroproj)ane) are now cheap commercial products. They are obtained by the vapour phase nitration of the hydrocarbons a gaseous mixture of two mols of hydrocarbon and 1 mol of nitric acid vapour is passed through a narrow reaction tube at 420-476°. Thus with methane at 476° a 13 per cent, conversion into nitro methane is obtained ethane at 420° gives a 9 1 mixture of nitroethane (b.p. 114°) and nitromethane (b.p. 102°) propane at 420° afifords a 21 per cent, yield of a complex mixture of 1- (b.p. 130-6°) and 2-nitropropane (b.p. 120°), nitroethane and nitromethane, which are separated by fractional distillation. 

A solution of gramine (87,3 mg, 0,50 mmol) and 2-nitropropane (33.7 mg, 0.38 mmol) in CHjCN (3 ml) was treated with -Bu3P (18.6 mg, 0.l4mmol). The mixture was refluxed for 4 h. The solvent was removed in vacuo and the residue was acidified with 0.5N aq. HCl and extracted with 95 5 CHjClj-MeOH. The extract was washed with brine and dried (Na2S04). The solvent was removed in vacuo and the residue purified by TLC to yield 138.5 mg (99% yield) of the product. 

Nitromethane, nitroethane, 1-nitropropane, and 2-nitropropane are produced by a vapor-phase process developed ia the 1930s (2). 

High performance Hquid chromatography (hplc) may be used to determine nitroparaffins by utilizing a standard uv detector at 254 nm. This method is particularly appHcable to small amounts of nitroparaffins present, eg, in nitro alcohols (qv), which caimot be analyzed easily by gas chromatography. Suitable methods for monitoring and deterrnination of airborne nitromethane, nitroethane, and 2-nitropropane have been pubUshed by the National Institute of Occupational Safety and Health (NIOSH) (97). Ordinary sorbant tubes containing charcoal are unsatisfactory, because the nitroparaffins decompose on it unless the tubes are held in dry ice and analyzed as soon after collection as possible. 

Environmental Concerns. Few data on the environmental effects of the nitroparaffins are available. However, they are known to be of low toxicity to the fathead minnow (109). Based on their uv spectra, the nitroparaffins would be expected to undergo photolysis in the atmosphere. The estimated half-life of 2-nitropropane in the atmosphere is 3.36 h (110). Various values have been determined for the half-life of nitromethane, but it is similar to 2-nitropropane in persistence (111). Reviews of the available data on the environmental effects of nitromethane and 2-nitropropane have been pubhshed by the U.S. Environmental Protection Agency (112,113). 

The solubility parameters of PCL are 20.8 and 20.4 jl/2.cm"2 2 when calculated using the parameters of Fedors and Hoy, respectively (58). PCL is soluble in a number of solvents at room temperature, including THF, chloroform, methylene chloride, carbon tetrachlornie, benzene, toluene, cyclohexanone, dihydropyran, and 2-nitropropane. 

The enthalpy of absorption of 1- and 2-nitropropane on breathing mask cartridges made with carbon is such that the decomposition of the nitrated derivative can cause its ignition. This accident is aggravated when the cartridge also contains metal oxides such as copper (II) oxide or manganese dioxide. 

Adachi, S., Takemoto, K., Hirosuc, T. and Hosogai, Y. (1993). Spontaneous and 2-nitropropane induced levels of 8-hydroxy-2 -deoxyguanosine in liver DNA of rats fed iron-deficient or manganese- and copper-deficient diets. Carcinogenesis 14, 265-268. 

The effect of chain length on the ability of degraded amylose to form complexes was studied by Whistler and associates.63 When amylose is hydrolyzed to a degree of polymerization of 20 to 40, it no longer forms insoluble complexes with nitrobenzene, n-pentyl acetate and 2-heptanone, although it still does with 1-butanol and 2-nitropropane. 

In addition to the data already discussed on acids or Lewis acids as solvents, some data are available for solvents in which the interpretation in terms of molecular complexing is less obvious. For example, the ionization of trityl chloride has been compared spectroscopically in nitromethane, nitroethane, and 2-nitropropane.198 Unfortunately the absorption band broadens as the solvent is changed, rendering a quantitative interpretation difficult. In the author s laboratory two... 

Alkylation with Oxonium Salts Oxonium salts are the most efficient alkylating agents and can react with both activated and nonactivated AN, including nitromethane and 2-nitropropane (Scheme 3.4). 

FIGURE 17. Hel (left) and Hell (right) spectra of nitromethane, nitroethane, 1- and 2-nitropropane. Reproduced with permission from Reference 143... 

The mechanism of the thermal 5 rnI reaction, using 4-nitrocumyl chloride and 2-nitropropanate ion as a model has been investigated. The results provided unambiguous evidence that a decrease in driving force is able to change the mechanism of homogeneous reductive cleavage reactions from stepwise to concerted. ... 

The DCL was generated from equimolar amounts of five different aromatic aldehydes (24, 26, 27, 36, and 37) and 2-nitropropane (38) to provide 10 3-nitroalcohol substrates including all enantiomers (DCL-E, Scheme 6.9). 

Lewis TR, Ulrich CE, Busey WM Subchronic inhalation toxicity of nitromethane and 2-nitropropane. J Environ Pathol Toxicol 2 233-249, 1979... 

Determination of Cell Absorbance and Absorptiv ity of NG, EGDN, Benzene and 2 Nitropropane. By means of a 0.2mm cell filled with a soln of 1 % NG in benz, the peak of a 9.20-micron band was located by very slowly scanning from about 0.05/J below to about 0.05/J above 9.20fi. A 0.2mi cell filled with a soln of 5% EGDN in 2-nitropro-pane was similarly used to locate the peak of tht 9.60-micron band. This procedure was followed to insure measurement of the maximum absorbanc of die two bands... 

Lewis, T.R., Ulrich, C.E. Busey, W.M. (1979) Subchronic inhalation toxicity of nitro-methane and 2-nitropropane. J. environ. Pathol. Toxicol., 2, 233-249 Lide, D.R. Milne, G.W.A. (1996) Properties of Organic Compounds, Version 5.0 [CD-ROM], Boca Raton, FL, CRC Press... 

Haas-Jobelius, M., Coulston, F. Korte, F. (1992) Effects of short-term inhalation exposure to 1-nitropropane and 2-nitropropane on rat liver enzymes. Ecotoxicol. environ. Saf. 23,253-259... 

HMX is non-hygroscopic and insoluble in water. It behaves like RDX with respect to its chemical reactivity and solubility in organic solvents. However, HMX is more resistant to attack by sodium hydroxide and is more soluble in 55% nitric acid, and 2-nitropropane than RDX. In some instances, HMX needs to be separated from RDX and the reactions described above are employed for the separation. As an explosive, HMX is superior to RDX in that its ignition temperature is higher and its chemical stability is greater however, the explosive power of HMX is somewhat less than RDX. Some of the properties of HMX are presented in Table 2.16. 

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. 

All available evidence points to a radical mechanism for nitration, but many aspects of the reaction are not fully understood. Mixtures are obtained nitration of propane gives not only 1- and 2-nitropropanes but nitroethane and nitromethane ... 

In the case of simplest nitro compounds the absorption band produced by this group corresponds to the following values. For aliphatic nitro compounds, for example nitromethane, nitroethane, 1- and 2-nitropropanes, they are 260-270 mu at extinctions s = 40-120. (According to Ungnade said Smiley [1] the values for higher nitroparaffins are 274-278 mp, s = 24-41.) For aromatic nitro compounds, such as nitrobenzene the bands are 250-260 mp at extinctions s = 9000-10,000. When a primary or secondary nitro group takes an aci-form, the maximum disappears, as shown by earlier research work of Hantzsch and Voigt [2]. 

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