Propane nitration

Nitrating propane produces a complex mixture of nitro compounds ranging from nitromethane to nitropropanes. The presence of lower nitroparaffins is attributed to carbon-carbon bond fission occurring at the temperature used. Temperatures and pressures are in the range of 390°-440°C and 100-125 psig, respectively. Increasing the mole ratio of propane to nitric acid increases the yield of nitropropanes. Typical product composition for 25 1 propane/acid ratio is ... 

NITROPROPANE PROPYL-NITRATE ISOPROPYL-NITRATE PROPANE ISOPROPANOL METHYL ETHYL ETHER n-PROPANOL... 

Processes for Paraffin Nitrations. Propane is thought to be the only paraffin that is commercially nitrated by vapor-phase processes. Temperature control is a primary factor in designing the reactor, and several approaches have been investigated. A spray mtrator in which liquid nunc acid is spiayed into hoi propane is used industiially. Relatively small-diameter tubular reactors, fluidized-bed reactors, and molten salt reactors have all been successfully used in laboratory units. 

Vapor-phase nitration of paraffin hydrocarbons, particularly propane, can be brought about by uncatalyzed contact between a large excess of hydrocarbon and nitric acid vapor at around 400°C, followed by quenching. A multiplicity of nitrated and oxidized products results from nitrating propane nitromethane, nitroethane, nitropropanes, and carbon dioxide all appear, but yields of useful products are fair. Materials of construction must be very oxidation-resistant and are usually of ceramic-lined steel. The nitroparaffins have found limited use as fuels for race cars, submarines, and model airplanes. Their reduction products, the amines, and other hydroxyl compounds resulting from aldol condensations have made a great many new aliphatic syntheses possible because of their ready reactivity. 

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. 

Only 20—40% of the HNO is converted ia the reactor to nitroparaffins. The remaining HNO produces mainly nitrogen oxides (and mainly NO) and acts primarily as an oxidising agent. Conversions of HNO to nitroparaffins are up to about 20% when methane is nitrated. Conversions are, however, often ia the 36—40% range for nitrations of propane and / -butane. These differences ia HNO conversions are explained by the types of C—H bonds ia the paraffins. Only primary C—H bonds exist ia methane and ethane. In propane and / -butane, both primary and secondary C—H bonds exist. Secondary C—H bonds are considerably weaker than primary C—H bonds. The kinetics of reaction 6 (a desired reaction for production of nitroparaffins) are hence considerably higher for both propane and / -butane as compared to methane and ethane. Experimental results also iadicate for propane nitration that more 2-nitropropane [79-46-9] is produced than 1-nitropropane [108-03-2]. Obviously the hydroxyl radical attacks the secondary bonds preferentially even though there are more primary bonds than secondary bonds. 

Conversions per pass of NO2 to nitroparaffins tend to be significantly less than when HNO is used. When propane is nitrated with NO2, conversions are as high as 27%, but they are much less for nitrations of methane and ethane. The remaining NO2 reacts mainly to produce NO, and a considerable number of oxidation steps occur. The theoretically maximum conversion of NO2 to nitroparaffins is 66.7%. 

In a commercial unit, a spray nitrator (39) is operated adiabaticaHy. The Hquid HNO feed is sprayed direcdy into the hot and preheated propane feed. The heat of nitration provides the heat to vaporize the HNO and to preheat it to the desired temperature for nitration. At one time, several spray nitrators were operated in series, with additional HNO being sprayed into each nitrator (32). In such an arrangement, the optimum propane HN02 ratios did not occur, and considerable amounts of nitroparaffins degraded. 

Eor vapor-phase processes, the product stream from the nitrator must be separated. The nitroparaffins, excess propane, and NO plus NO2 (which are converted back to HNO ), are recovered. The oxygenated products are removed, but there are generally insufficient amounts for economic recovery. 

The vapor-phase process of SocifitH Chemique de la Grande Paroisse for production of nitroparaffins employs propane, nitrogen dioxide, and air as feedstocks (34). The yields of nitroparaffins based on both propane and nitrogen dioxide are relatively high. Nitric oxide produced during nitration is oxidized to nitrogen dioxide, which is adsorbed in nitric acid. Next, the nitric dioxide is stripped from the acid and recirculated. 

The only method utilized commercially is vapor-phase nitration of propane, although methane (70), ethane, and butane also can be nitrated quite readily. The data in Table 5 show the typical distribution of nitroparaffins obtained from the nitration of propane with nitric acid at different temperatures (71). Nitrogen dioxide can be used for nitration, but its low boiling point (21°C) limits its effectiveness, except at increased pressure. Nitrogen pentoxide is a powerful nitrating agent for alkanes however, it is expensive and often gives polynitrated products. 

Table 5. Effect of Temperature on the Nitration of Propane with Nitric Acid...

The preparation of polynitroparaftins has been reviewed (75). 2,2-Dinitropropane has been produced ia pilot-plant quantities by Hquid-phase nitration starting from either propane or 2-nitropropane (76,77) (see Nitration). 

Gas-phase oxidation of propylene using oxygen in the presence of a molten nitrate salt such as sodium nitrate, potassium nitrate, or lithium nitrate and a co-catalyst such as sodium hydroxide results in propylene oxide selectivities greater than 50%. The principal by-products are acetaldehyde, carbon monoxide, carbon dioxide, and acrolein (206—207). This same catalyst system oxidizes propane to propylene oxide and a host of other by-products (208). 

Polar organic solvents readily precipitate exopolysaccharides from solution. The solvents commonly used are acetone, methanol, ethanol and propan-2-ol. Cation concentration of the fermentation liquor influences the amount of solvent required for efficient product recovery. In the case of propan-2-ol, increasing the cation concentration can lead to a four-fold reduction in die volume of solvent required to precipitate xanthan gum. Salts such as calcium nitrate and potassium chloride are added to fermentation broths for this purpose. 

Nitromethane. The industrial method of producing NM is based on a vapor phase reaction of propane and 70% nitric acid. The reaction is carried out at around 410° and 115—175psi press. In essence the production of NM involves five stepst 1) nitration 2) product recovery ... 

Nitroparaffins, Explosives Derived From. Although mononitroparaffms are generally not expl, they can be used for the prepn of expls Aaronson (Ref 1) nitrated nitroisobutyl-glycerin to Nitroisobutylgjycerintrinitrate, 2-nitro-2-methyl-l,3-propane diol to 2-Nitro-2-methyl-l, 3-propanedioIdinitrate, and 2-nitro-2-methyl-l-propanol to 2-Nitro-2-methyl-l-pro-panolnitrate. Their prepn and characterization follow ... 

Nitro-2-(3-nitrophenyl)-propanediol-1,3-dinitrate (2-Nitro-2-(m-nitrophenyl)-propane-l, 3-diol-dinitrate). (02N)C6H4. C(N02) (CH20N02)2, mw 332, N 16 %, OB to C02 -57.8%, pale yel acicular prisms, mp 71—73.6°. Can be prepd by nitrating 2-nitro-2-(3 r-nitrophenyl)-propanediol-1, 3 with mixed nitric-sulfuric acid, as described in Ref 2, p 23. Sol in most common organic solvents... 

By far the best efforts to measure product compns were made by Orncllas co-workers (Refs 3, 4 6) who made accurate calorimetry and compn measurements on highly confined and unconfined expl samples. The expls he studied were PETN, HMX, NM, TNT, Bis(2,2-dinitro-2-fluoroethyl)formal (FEFO), l,2-Bis(difluoro-amino) propane (1,2 DP), Benzotrifuroxan (BTF), LX-11-0 (80.1/19.9 HMX/Viton), XTX-8003 (80/20 PETN/Sylgard 182), and three Hydrazine Nitrate (HN) mixts. Of course, most of these measured compns are not CJ products, but reequilibrated mixts of CJ products at some frozen equilibrium temp Tfr < TCJ... 

Propane is highly flammable and is considered a dangerous fire and expin risk. FI pt —104.4° ignition temp 468° flammable limits 2.4—9.5% crit temp 96.8°. It forms expl nitrocompds and nitrates... 

F. SI sol in w (1.4ml/100ml) 0.5ml w dissolves in 100ml of 1-Nitropropane misc with many org solvents. Prepd by the vapor-phase nitration of propane (Refs 1 a 3)... 

Urbanski and Sion (Ref 3) later prepd it in small quantities, together with 1-nitropropane, on treating n-propane vapor with gaseous nitrogen. More recently, Kisp ersky et al (Ref 5) prepd a product from 1,3-diiodopropane and Ag nitrate which was stable for at least 9 months Its Na compd, C3Hs(N02)2Na, was prepd by Keppler Meyer (Ref 2), and was reported to be a violent expl ( heftig explodierendes pulver in Ger)... 

Propanediol (1,2-Propylene glycol, 1,2-Dihydroxy propane, Methyl glycol). CH3.CHOH.CH2OH mw 76.09 colorl, viscous, stable, hygr liq bp 187.3°, d 1.0381g/cc at 20/20° RI 1.4293 at 27° fl pt (open cup) 210°F autoignition temp 780°F. Misc with w, ales, and many org solvents in all proportions. Can be prepd by hydration of propylene oxide. On nitration it yields the exp] 1,2-Propanediol Dinitrate (see below)... 

A metal polishing fluid of a similar composition that contained propane-1,2-diol, nitric acid, hydrogen fluoride and silver nitrate detonated thirty minutes after being used. 

Propyl nitrate is very sensitive to impact. However, this sensitivity is lowered when adding 1 to 2% of propane, butane, chloroform, dimethyl ether or diethyl ether. 

Selection of appropriate conditions to modify polymers is facilitated by preliminary studies with well designed model compounds. The work with model systems is critical when studying condensation polymers because the main chain linkages have proved to be remarkably labile under certain conditions. Condensation of 4-chlorophenyl phenyl sulfone with the disodium salt of blsphenol-A yields 2,2-bis[4 -(4"-phenylsulfonylphenoxyl)phenyl] propane, T, an excellent model for the poly(arylene ether sulfone) substrate. Conditions for quantitative bromination, nitration, chloro-methylation, and aminomethylation of the model compound were established. Comparable conditions were employed to modify the corresponding polymers. 

Propane, 2,2-bis[4 -(4"-phenylsulfonyl-phenoxyl)phenyl] bromination, 9 13C NMR, 9 chloromethylation, 10 nitration, 9 preparation, 9 reduction, 10... 

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