Nitration process

Safety has been greatly increased by use of the continuous nitration processes. The quantity of nitroglycerin in process at any one time is greatly reduced, and emulsification of nitroglycerin with water decreases the likelihood of detonation. Process sensors (qv) and automatic controls minimize the likelihood of mnaway reactions. Detonation traps may be used to decrease the likelihood of propagation of an accidental initiation eg, a tank of water into which the nitrated product flows and settles on the bottom. 

Ma.nufa.cture. The batch nitration processes for nitrocellulose have included the pot process, the centrifugal process, the Thompson displacement process, and the mechanical dipper process. Semicontinuous nitration processes are also widely used for military and industrial grades. 

Cotton linters or wood pulp are nitrated using mixed acid followed by treatment with hot acidified water, pulping, neutralization, and washing. The finished product is blended for uniformity to a required nitrogen content. The controlling factors in the nitration process are the rates of diffusion of the acid into the fibers and of water out of the fibers, the composition of mixed acid, and the temperature (see Cellulose esters, inorganic esters). 

J. M. Goldman and E. H. Zeigler, Jr., "The Shock Nitration Process for Spherical Propellant Manufacture," in Symposium on Processing Propellants, Explosives, and Ingredients, ADPA, Washington, D.C., 1977, p. 23. 

Because of restrictions in equipment si2e, magnesium nitrate processes were initially limited to small plants. Improvements in the materials of constmction have led to increased capacities and a lower capital cost. Sulfuric acid processes are usually preferred when reconcentration of the sulfuric acid is not requited, ie, when the dilute sulfuric can be used to make another product. 

In the last few years several modifications to the traditional mixed acid nitration procedure have been reported. An adiabatic nitration process was developed for the production of nitrobenzene (9). This method eliminated the need to remove the heat of reaction by excessive cooling. The excess heat can be used in the sulfuric acid reconcentration step. An additional advantage of this method is the reduction in reaction times to 0.5—7.5 minutes. 

When the spent sulfuric acid must be reconcentrated, it has been found that reconcentration to 100% sulfuric acid is not necessary (13). An energy savings can be realized if the sulfuric acid is concentrated under a vacuum to only 75—92%. If the process is carried out at 130—195°C, these medium concentration ranges are sufficient to destroy trace organics, thus preventing any loss in the efficiency or capacity of the nitration process. This process is adaptable to existing manufacturing installations. 

Product CAS Registry Number Starting material Nitration process... 

In a typical process 12001b (545 kg) of the mixed acids are run into the reaction vessel and 301b (13.5 kg) of the dried cotton linters are added. The mixture is agitated by a pair of contra-rotating stirrers and nitration is allowed to proceed at about 35-40°C for 20 minutes. It is interesting to note that the cellulosic material retains its fibrous form throughout the nitration process. 

Let us first segregate the two sources forming the feed to the incinerator. As can be seen from the source-sink mapping diagram (Fig. 9.20), the gaseous emission from the ammonium nitrate process (R2) is within the acceptable zone for the incinerator. Therefore, it should not be mixed with R] then separated. Instead, the ammonia content of Ri should be reduced to 0.10 wt% then mixed with R2 to provide an acceptable feed to the incinerator as shown by Fig. 9.20. The task of removing ammonia from Rj to from 1.10 wt% to 0.10 wt% is identical to the case study solved in Section 9.3. Hence, the solution presented in Fig. 9.18 can be used. 

The nitration of nitrobenzene and of chlorobenzene are known to occur via the same mechanism the ring is initially attacked by NO2, yielding a cation intermediate for each isomer. When the nitration process is fully complete, the distribution of the various isomers of the final product varies greatly for the two compounds ... 

The appropriate mixed acid compns for the nitration processes that produce militarily and industrially important expls will be described in Sections V VI. Typical MA compns for aromatic nitrations contain 110 to 200% nitric acid over the stoichiometric requirement. For the nitration of toluene to MNT DNT, a typical MA compn in round figures is 30% HN03,60% H2S04, 10% H20. For the nitration of DNT to TNT the MA contains no water and is approx 20% HN03, 80% H2S04... 

A continuous fully automatic nitrating process for producing NC was developed by Hercules, Inc (Ref 55a Fig 14a)... 

Tetryl. In the manufacture of Tetryl, it is usual not to nitrate dime thy laniline directly, but to dissolve it first in coned sulfuric acid and then to nitrate the dimethylaniline sulfate so obtained. Direct nitration of dimethylaniline proceeds so violently that it can be carried out only under specialized conditions. Many years experience of Tetryl manufacture has shown that the ratio of sulfuric acid to dimethylaniline should not be lower than 3 1, since a smaller amount of sulfuric acid may be detrimental to the nitration process. However, the ratio of sulfuric acid to dimethylaniline must not be too high, otherwise Tetryl yield is decreased. Temp must be maintained between 20-45° to avoid sulfonation of the benzene ring. Care must be exercised not to leave any unreacted dimethylaniline prior to introduction of nitric acid, because of the potential violence of the dimethyl-aniline-nitric acid reaction. Consequently, continuous methods of prepn are to be preferred as they inherently minimize accumulation of unreacted dimethylaniline... 

A three-step nitration process of toluene is described. The advantages of the modified process are reduced waste, less hazardous operation, reduced oleum requirement, partial replacement of coned HN03 with dil HN03, and higher rate of toluene flow into the reactor (Ref 86) The continuous process of H.C. Prime (Ref 73) for preparing TNT was studied by thin-layer chromatography on silica gel with a starch binder and a fluorescent indicator. The nitration... 

Since the nitrations of interest to us are exothermic reactions that produce expl substances it is obvious that safety is an important consideration in any laboratory nitration and even more so in an industrial nitration process, in the... 

S. V. Egorov et al, Otkrytiya, Izobret, Prom Obraztsy, Tovarnye Znaki 46 (34), 199 (1969) CA 72, 91696 (1970) (Describes an automatic safety system for nitration processes based on the generation of warning signals by press inside the nit rator)... 

Class 2 ammonium picrate shall contain no reworked ammonium picrate made by way of any process other than the phenol nitration process Not applicable to ammonium picrate made from picric acid produced by the nitration of phenol... 

Its presence is advisable, as later it will facilitate the nitration process ... 

These three steps all produce significant amounts of waste. First, as discussed earlier, the nitration process results in the production of spent sulfuric acid. In the past the company had been able to sell much of this material to the coke and steel industries but declining demand meant that the acid now required disposing of, at additional cost. At the time green catalytic nitration technology was becoming available with clay, zeolite and lanthanide catalysts all providing possible alternatives to the use of sulfuric acid (see below). Improved selectivity to the desired para-isomer is an added benefit of some of these catalytic systems. However on the... 

Since many dyes contain aromatic amines one of the most important reactions carried out in the synthesis of dye intermediates is aromatic nitration, involving use of stoichiometric amounts of nitric and sulfuric acid as discussed previously. Many cleaner nitration processes have been proposed, but here discussion will be limited to the use of lanthanide... 

Keggin type H3PW)2O40 is a stable, recyclable and effective catalyst for H2S04-free liquid phase nitration of bezene, chlorobenzene and toluene with nitric acid as a nitration agent. Higher para-selectivity of nitrotoluene was obtained, and the result implies that HPA can effectively catalyze the liquid phase nitration of various aromatics as an environmentally friendly nitration process. 

Elimination or reduction of all potential nitrosating agents formed or added during the manufacturing process (e.g. nitrous acid resulting from nitration process during the process). 

Use of microreactors for nitration processes, in Proceedings of the 4th International Conference on Microreaction Technology, IMRET 4, pp. 194—200 (5-9 March 2000), AIChE Topical Conf Proc., Atlanta, USA. 

Type of nitration process Inlet rq Outlet rq H,SO, (mass-%) Con- version r/oj By- product (ppm) Time N Rate (min )... 

Hercules (1) An organic nitration process, similar to the Bofors process but using a tee-joint for mixing. Developed by the Hercules Powder Company, Wilmington, DE, from 1957. U.S. Patents 2,951,746 2,951,877. 

A reaction at the interface caused by a loss of mixing can eventually lead to a runaway itself. Examples include nitration processes and the well-known Seveso incident where agitation stopped in a reactor during the manufacture of trichlorophenol this led to higher than normal temperatures and increased production of the undesirable side product 2,3, 7,8-tetrachlorodibenzo-p-di-oxin (commonly referred to as "dioxin"), ultimately resulting in a vapor release to the atmosphere. 

This example involves a continuous adiabatic nitration process for the manufacture of mono-nitrobenzene (MNB) [215] by the reaction of benzene with nitric acid in a CSTR system. The process is designed to be inherently safe. No external cooling is used, but the reaction mass is heated by the reaction itself to a temperature level controlled by the amount of sulfuric add-water mixture circulating through the system. This acid actually acts as both a heat sink and as a nitration enhancer. If the sulfuric add pumps fail, the nitric add and benzene pumps are automatically shut off. 

YDC has been prepared by various methods, including solid-state reaction, coprecipitation, glycine-nitrate process and metal organic chemical vapor deposition (MOCVD). Table 1.4 shows that the properties depend on the preparation method [118,119,127,129,130], Zha et al. [129] have studied the influence of sintering... 

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