Nitration grade

Table 14. United States Toluene, Nitration-Grade DCI Historical Prices...

Table 16. Specifications for Nitration-Grade Toluene, ASTM D841-80 ...

Commercial grades Available in three grades refined-535, refined-485 (nitration grade), and industrial. The numbers following the grade refer to the freezing point specification times 100. It is shipped in steel drums, tank trucks, and tank cars under heavily regulated conditions. 

Production of p-xylene via p-xylene removal, i.e., by crystallization or adsorption, and re-equilibration of the para-depleted stream requires recycle operation. Ethylbenzene in the feed must therefore be converted to lower or higher boiling products during the xylene isomerization step, otherwise it would build up in the recycle stream. With dual-functional catalysts, ethylbenzene is converted partly to xylenes and is partly hydrocracked. With mono-functional acid ZSM-5, ethylbenzene is converted at low temperature via transalkylation, and at higher temperature via transalkylation and dealkylation. In both cases, benzene of nitration grade purity is produced as a valuable by-product. 

Mixed xylenes are commercially available in nitration grades that have tolerances of 3 and 10°F, depending on the specified amount of the hydrocarbon present. Purities of the ortho-, meta-, and para-xylenes are more often than not a matter of negotiation between buyer and seller. 

The historical development of aromatics production from petroleum is outlined, and the methods employed during World War II for the production of nitration grade toluene are described. Included is a discussion of methods of synthesizing and purifying benzene, xylenes, and aromatics of higher molecular weight both as mixtures and as pure compounds. Data are presented on the composition of the aromatic hydrocarbons available from typical hydroformates. Aromatics and mixtures thereof currently available from petroleum are listed. Some of the problems facing the industry in the field of aromatics production are discussed and the probable trend of future research is indicated. 

C Nitration-grade, ASTM D835-85. d ASTM D836-84. 

Pentaerythritol destined for the preparation of PETN must be exceptionally pure. In Germany, nitrating grade pentaerythritol ( grade M ) had to conform to the following technical specification ... 

Recently interest was evinced in nitrocelluloses of very low nitration grade, e.g. 0.5-2.0% [4], They were obtained by nitrating cellulose with mixtures containing 32% HN03, 31-38% H2S04 and 32-37% H20 at 8-30°C. 

In one process, the chargestuck is nitration-grade toluene, air. hydrogen, anhydrous NHj. and H,S04. The toluene is oxidized to yield u 301 solution of benzoic acid, plus intermediates and byproducts. Pure benzoic acid, after fractionation, is hydrogenated with a palladium catalyst in stirred reactors operated at about 17o"C under a pressure of ID atmospheres. The resultant product, cyclohexanccarboxylic acid, is mixed with H,S04... 

A lab scale prepn (from Ref 7) follows Twenty grams (0.054 mole) of nitration grade tripentaerythritol (TPE), 99% min purity, were... 

The charge to the unit is treated refinery propane-propylene along with recycle benzene from the recycle column overhead. Make-up benzene is added to the recycle. Nitration-grade benzene is usually used so that a drag stream of benzene is not required to remove contaminants from the unit. Table IX shows the component analysis of the various streams in the cumene process. 

The process of starch O-nitration by the Hackel and Urbanski s method (see Vol. II, Fig. 164) shows how homogeneity of the system affects the O-nitration grade. 

The U.S.S.R. specification (OST 464) for nitration grade toluene requires the following properties (Table 81) ... 

In spite of its drawbacks, during World War I France, Russia, and the United States used commercial trinitroxylene as an explosive, mostly in mixtures with other nitro compounds, or with ammonium nitrate, when these countries were short of nitration grade toluene. In the period between the two World Wars trinitroxylene was manufactured in the U.S.S.R and France and on a small scale in Poland. 

Due to a relatively high content of the m- isomer xylene derived from coal or xylene from Borneo oil is the most convenient starting material for the preparation of nitration grade xylene. 

Recent German specifications for nitration grade xylene require determination of the freezing point of m- xylene, which should not be lower than -52°C. 100% of the xylene should distil within 1-2°C. 

Nitration grade naphthalene should be almost chemically pure, purified by sublimation or crystallization (pressed naphthalene). Sublimated naphthalene should not melt below 79.6°C, while the melting point of the pressed product (in lumps, 2-4 cm) should not be lower than 79.0°C. 

Nitration grade phenol should be completely soluble in water, giving a clear solution. Not more than 0.1% of non-volatile residue left after the evaporation of phenol, when heated on a steam bath, is permissible. 

Information regarding the physical and chemical properties of benzene is shown in Table 3-2. The major impurities found in commercial products are toluene, xylene, phenol, thiophene, carbon disulfide, acetylnitrile and pyridine (NIOSH 1974). Commercial refined benzene-535 is free of hydrogen sulfide and sulfur dioxide, but contains a maximum of 1 ppm thiophene and a maximum of 0.15% nonaromatics. Refined nitration-grade benzene is free of hydrogen sulfide and sulfur dioxide. Benzene is also commercially available as thiophene-free, 99 mole%, 99.94 mole% and nanograde quality (HSDB 1996). 

Application A process to manufacture caprolactam from nitration-grade toluene. Fiber-grade flaked or molten caprolactam and white ammonium sulfate crystals are produced. 

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