Mixed Acid Ratio After Nitration

Change in the mixed acid ratio after nitration... 

Environmental aspects, as well as the requirement of efficient mixing in the mixed acid process, have led to the development of single-phase nitrations. These can be divided into Hquid- and vapor-phase nitrations. One Hquid-phase technique involves the use of > 98% by weight nitric acid, with temperatures of 20—60°C and atmospheric pressure (21). The molar ratios of nitric acid benzene are 2 1 to 4 1. After the reaction is complete, excess nitric acid is vacuum distilled and recycled. An analogous process is used to simultaneously produce a nitrobenzene and dinitrotoluene mixture (22). A conversion of 100% is obtained without the formation of nitrophenols or nitrocresols. The nitrobenzene and dinitrotoluene are separated by distillation. 

Details on commercial production of NS are scarce. Davis (Ref 17) describes a mixed acid consisting of 38% HN03 and 62% H2S04, with a 4 to 1 acid-to-starch ratio, and a nitration temp of 38—40°. He states that after nitration the contents are drowned in water and the NS is separated by filtration... 

RH, 4.1%. It was prepd at picArsn Lab by Warren on adding in small portions and with agitation 25g of pulverized dimethylol butanol to cooled to 0° mixed acid consist-of nitric acid 25.3, sulfuric acid 59.6 water 15.1% in the ratio of 1.5 parts of nitric acid to 1 part of dimethylbutanol time of nitration after addn of butanol was ca 1.5 hrs. 

N 12.61% (theory) (12.4% found in oily product of Warren) OB to COj minus 72.0%. The oily product puffed off at 187 after heating for 5 secs it did not explode by impact of 2kg wt at lOOcm hygroscopicity at 30 90% RH 0.40% volatility at 27° in 48 hrg 0.34% thermal stability at 82.2° KI test 1 min. Warren prepd it at PicArsn Lab hy adding in small portions and with agitation, pulverized di-methylolbucanone to cooled to ca 5 mixed acid consisting of nitric acid 25.3, sulfuric acid 59.6 water 15.1% in the ratio of 1.5 parts nitric acid per 1 part of butanone time of nitration 1 hour. Separation of crude product from acid and further purification was the same as described under 3,3"Dimethylol-2-hutanol Trinitrate... 

The y and 8 forms form together by precipitation from an unstirred diluted aqueous solution of sodium azide and lead nitrate in presence of nitric acid (in molar ratio 2 2 1) at room temperature. The reaction mixture is admixed and swirled once after mixing of the nitric acid and lead nitrate with solution of sodium azide. Both forms appear after 3 days in an unstirred mixture the crystals need to be collected and separated by hand [15]. 

Fluorhydroxyapatite solid solutions can be prepared by the sol-gel method [134,135]. Cheng et al. reported the control of fluoride content in fluorhydroxyapatite solid solutions by the amounts of triethanolamine (N(CH2CH20H)3) and trifluoroacetic acid (CF3COOH) in the mixed ethanol solutions of Ca(N03)2 and P0(CH2CH20H)x(0H)3 x with a Ca/P ratio of 1.67 [134]. After evaporation of the mixed ethanol solution at 150°C on a hot plate, the powder obtained, comprising a homogeneous mixture of calcium nitrate crystallites and amorphous calcium phosphates, is then heated at 500 or 900°C for 1 h to be transformed into the pure apatitic phase. 

To prepare the solution we used zirconium nitrate containing 1.5 to 2.1% of hafnium in a ratio to the sum of zirconium and hafnium oxides (2 Zr(Hf)02). Initial solutions of zirconium nitrate with different concentrations of salts and nitric acid have been prepared by dissolving a concentrated water solution of zirconium nitrate salts. TBF, dissolved by o-xylol has been used as extraction media. Trials have been done in batches. The extraction media, previously saturated by nitric acid, is mixed with water solution (20 ml at a time) for 15 minutes on a vibration apparatus. Re-extraction has been done by two-step vibration of the organic phase with equal volumes of distilled water. The water phase was, after extraction and reextraction, analyzed gravimetrically to find out the contents of the sum of zirconium and hafnium oxides. Hafnium contents were determined by spectral analysis. Nitric acid concentration has been determined by titration. 

Once the importance of DMS to the global sulfur cycle was established, numerous measurements of DMS concentrations in the marine atmosphere have been conducted. The average DMS mixing ratio in the marine boundary layer (MBL) is in the range of 80-1 lOppt but can reach values as high as 1 ppb over entrophic (e.g., coastal, upwelling) waters. DMS mixing ratios fall rapidly with altitude to a few parts per trillion in the free troposphere. After transfer across the air-sea interface into the atmosphere, DMS reacts predominantly with the hydroxyl radical and also with the nitrate (N03) radical. Oxidation of DMS is the exclusive source of methane sulfonic acid (MSA) in the atmosphere, and the dominant source of S02 in the marine atmosphere. We will return to the atmospheric chemistry of DMS in Chapter 6. 

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