Hydrocarbons, hydrocarbon nitric

Fig. 7.1. Nitration of polynuclear hydrocarbons by nitric acid in acetic anhydride, (i) Plot of login (KijK against N. ,g-AnthryI positions A,

In the chemical industry, titanium is used in heat-exchanger tubing for salt production, in the production of ethylene glycol, ethylene oxide, propylene oxide, and terephthaHc acid, and in industrial wastewater treatment. Titanium is used in environments of aqueous chloride salts, eg, ZnCl2, NH4CI, CaCl2, and MgCl2 chlorine gas chlorinated hydrocarbons and nitric acid. 

Similar chemical steps occur in the ambient air and in laboratory smog chamber simulations. Initially, hydrocarbons and nitric oxide are oxidized... 

In contrast to carbon monoxide, small hydrocarbon molecules and soot that result from incomplete conversion of the hydrocarbon fuels, nitric oxide and nitrogen dioxide, are noxious emissions that result from the oxidizer—air. However, fuel components that contain nitrogen may also contribute, in a lesser way, to the formation of the oxides of nitrogen. 

There is a synthesis, which is supposed to be safe and consists in using very small quantities of reagents and closely monitoring the temperature. However, the thermai control of the aromatic hydrocarbons/nitric acid reaction usually proves to be very difficult. Indeed, the temperature is either too high and the reaction is out of controi and can lead to detonation, or too low and the nitration or oxidation takes place too slowly causing the compounds to accumulate and the reaction to be delayed. The consequences are the same as before. 

Ravi, V., Mok, Y.S., Rajanikanth, B.S. et al. (2003) Temperature effect on hydrocarbon-enhanced nitric oxide conversion using a dielectric barrier discharge reactor, Fuel Processing Technology 81, 187-99. 

Kagawa and Toyama in Tokyo followed 20 normal 11-yr-old school children once a week from June to December 1972 with a battery of pulmonary-function tests. Environmental factors studied included oxidant, ozone, hydrocarbon, nitric oxide, nitrogen dioxide, sulfur dioxide, particles, temperature, and relative humidity. Temperature was found to be the most important environmental factor affecting respiratory tests. The observers noted that pulmonary-function tests of the upper airway were more susceptible to increased temperature than those of the lower airway. Although the effect of temperature was the most marked, ozone concentration was significantly associated with airway resistance and specific airway conductance. Increased ozone concentrations usually occur at the same time as increased temperature, so their relative contributions could not be determined. 

CA 70, 57139(1969) (Nitration of hydrocarbons with nitric acid—trifluoroacetic anhydride mixts)... 

Ozone is produced in substantial concentrations by industrial activity and, indirectly, from automobile exhausts. The most important sequence of reactions producing tropospheric ozone begins with hydrocarbon vapors, nitric oxide, and sunlight ... 

P. Glarborg, M.U. Alzueta, K. Dam-Johansen, and J.A. Miller. Kinetic Modeling of Hydrocarbon/Nitric Oxide Interactions in a Flow Reactor. Combust. Flame, 115 1— 27,1998. 

Nitro compounds can be prepared in a number of ways, including the direct substitution of hydrocarbons with nitric acid,... 

Fig. 7.1. Nitration of polynuclear hydrocarbons by nitric acid in acetic anhydride, (i) Plot of logio (KJKo) against N. , 9-Anthryl positions A,a-napthyl positions V, 4-phenanthryi positions O, other positions. (From Dewar et a/.286) (ii) and (iii) Relative electrophilic localization energies vs. logarithms of partial rate factors for nitration (a) Hiickel, (6) PPP with fixed p. (From Dewar Thompson.83 ) (iv) Plot of log K vs. AEiac- (From Dewar.23 )...

Nitration is the insertion of a nitro group (-N02) into an organic compound, usually through the agency of the reaction of a hydrocarbon with nitric acid. Concentrated sulfuric acid may be used as a catalyst. 

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 kinetics of nitration of aromatic hydrocarbons with nitric acid in the presence of acetic anhydride was first studied by Tronov, Kamay and Kovalenko [110], Their studies will be discussed later. 

This is the theoretical value of D.V.S. In practical work allowance should be made for the presence of the excess of HN03 used. The above calculations may be made with theoretical reference to either hydrocarbon or nitric acid. When 95% of the theoretical hydrocarbon is used, the hydrocarbon factor is calculated. ... 

Nitration in the vapour phase, hi methods of this kind (e.g. the Wilhelm method [13]) a continuous stream of vapours of the aromatic hydrocarbon and nitric acid or nitrogen dioxide is introduced into the reactor. Sulphuric acid is not used in this reaction. 

Partial pressures method. Othmer aid his co-workers [14-16] have suggested amethod in which a mixture of hydrocarbon aid nitric acid of about 61% concentration is boiled. The water liberated in the reaction is distilled off with pat of hydrocarbon, as an azeotrope. The two components ae sepaated in a receiver into two layers, the water being drained off aid the hydrocarbon recycled. As a result of the reaction mono- aid di-nitro derivatives cai be obtained. The method has been developed on the laboratory scale only. 

In addition to the foregoing, the following gases are usually present m variable but minute proportions—carbon monoxide, hydrocarbons, nitric acid, sulphur dioxide, sulphuric acid, hydrogen sulphide, mineral salts, organic matter. The amount of water-vapour in the air is extremely variable. 

By means of amperometric sensors a simultaneous determination of oxygen and hydrocarbons or nitric oxides is possible. For such sensors tube [vi,vii] or planar [viii] designs were described. The current measured is proportional to the oxygen concentration and the concentration of hydrocarbons and nitric oxides, respectively. 

Precautions Diborane is a highly toxic, flammable, and reactive gas. It is spontaneously combustible in moist air and may burn or explode upon contact with halogenated compounds. It explodes on contact with fluorine, chlorine, halogenated hydrocarbons, fuming nitric acid, and nitrogen trifluoride. It is a very dangerous gas and must be handled and used only in chemical laboratories by experienced and trained professional workers. ... 

ESCHENROEDER AND MARTINEZ Fhotochemicol Smog Models of the Hydrocarbon/Nitric Oxide Mechanism ... 

In the parametric study the same initial values of total hydrocarbon and nitric oxide as those in Figure 6 were used. The hydrocarbon, however, was partitioned into two hypothetical compounds, one having triple the (OH + HC) rate constant and the other having one-third the (OH + HC) rate constant as propylene. The compound with the tripled rate is called species B, and the one with the decreased rate is called species A. All other reactions in the scheme are the same in all respects as their counterparts in the (C3H6 + NO. ) system. 

Examination of Carbon Monoxide Effects. Recent work (44, 50, 51) of smog photochemistry has suggested that carbon monoxide may play a role in accelerating the photooxidation of hydrocarbon/nitric oxide mixtures. The mechanism suggested is... 

To examine parametrically the influence of inventory levels, we altered the rate of emission for ground level. Halving the nominal NO-fluxes is suggested by the departures of the CO/NOa,-ratios and the C2H2/NOa,-ratios obtained for high oxidant days (87). Subsequent halving of reactive hydrocarbon and nitric oxide fluxes results in the adjustment represented by f = 1/4 in Figures 30, 31, and 32 but preserves the HC/NOa -ratio. In both cases the full propylene oxidation rates were used. 

In the 1030 case, hydrocarbon and nitric oxide are low, but NO2 and ozone are high. Changes in the fluxes have marked effects on everything but the ozone. Comparing these end-point compositions with the initial values cited above, we note a strong dependence on initial conditions accuracy for this short time scale. However, the Azusa data are available as an aid in this respect. 

Tire molar ratio hydrocarbon nitric acid was of the order of 10 1 and if oxygen was added it was up to 4 moles in quantity. 

Typical concentrations of car exhaust gas constituents present in addition to CO2 and H2O are given in Table 5.1. The presence of CO, tire most toxic component of exhausts, is due to incomplete oxidation of hydrocarbons. Hydrogen is always present at approximately 1/3 the concentration of CO, and originates from the cracking of hydrocarbons. Nitric oxide (almost exclusively NO) is formed during combustion of fuel at high temperatures. 

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