Nitric acid dehydrate

Bomeol is oxidized to camphor with chromic or nitric acid dehydration with dilute acids yields camphene. Bomeol is readily esterified with acids, but on an industrial scale bornyl esters are prepared by other routes. For example, levorotatory bomeol is synthesized industrially from levorotatory pinenes by Wagner Meerwein rearrangement with dilute acid, followed by hydrolysis of the resulting esters [86]. 

Zirconia may fie separated iptantitativcly from silica hy fusion with Na9( f), extract the melt with water, filter, evaporate with nitric acid, dehydrate the silica,. mil rxpel it with IIP ami IijHO. ... 

Lebrun N, Mahe F, Lanuot J et al (2001) A new crystalline phase of nitric acid dehydrate. Acta Cryst C57 1129-1131... 

Although periodic acid is known (Section 6.6), I2O7 is not. The highest known normal oxide of iodine is diiodine pentoxide, I2O5, which can be made by the dehydration of the white crystals of iodic acid, HIO3, which is itself obtained by the oxidation of iodine with nitric acid. Dehydration is achieved by heating in a stream of dry air ... 

Addition of water gives the hydrated nitrate Cu(N03)2.3H2O, the product obtained when copper (or the +2 oxide or carbonate) is dissolved in nitric acid. Attempts to dehydrate the hydrated nitrate, for example by gently heating in vacuo, yield a basic nitrate, not the anhydrous salt. 

Selenium dioxide. The compound is conveniently prepared by the oxidation of selenium with nitric acid, followed by dehydration of the selenious acid thus formed by cautious heating ... 

The Raman spectrum of nitric acid shows two weak bands at 1050 and 1400 cm. By comparison with the spectra of isolated nitronium salts ( 2.3.1), these bonds were attributed to the nitrate and nitronium ion respectively. Solutions of dinitrogen pentoxide in nitric acid show these bands , but not those characteristic of the covalent anhydride , indicating that the self-dehydration of nitric acid does not lead to molecular dinitrogen pentoxide. Later work on the Raman spectrum indicates that at —15 °C the concentrations of nitrate and nitronium ion are 0-37 mol 1 and 0 34 mol 1 , respectively. The infra-red spectrum of nitric acid shows absorption bands characteristic of the nitronium ion. The equivalence of the concentrations of nitronium and nitrate ions argues against the importance of the following equilibrium ... 

Perchloric acid Acetic acid, acetic anhydride, alcohols, antimony compounds, azo pigments, bismuth and its alloys, methanol, carbonaceous materials, carbon tetrachloride, cellulose, dehydrating agents, diethyl ether, glycols and glycolethers, HCl, HI, hypophosphites, ketones, nitric acid, pyridine, steel, sulfoxides, sulfuric acid... 

N). This area of the process has received considerable attention in recent years as companies strive to improve efficiency and reduce waste. Patents have appeared describing addition of SO2 to improve ion-exchange recovery of vanadium (111), improved separation of glutaric and succinic acids by dehydration and distillation of anhydrides (112), formation of imides (113), improved nitric acid removal prior to dibasic acid recovery (114), and other claims (115). 

In the commonly used Welland process, calcium cyanamide, made from calcium carbonate, is converted to cyanamide by reaction with carbon dioxide and water. Dicyandiamide is fused with ammonium nitrate to form guanidine nitrate. Dehydration with 96% sulfuric acid gives nitroguanidine which is precipitated by dilution. In the aqueous fusion process, calcium cyanamide is fused with ammonium nitrate ia the presence of some water. The calcium nitrate produced is removed by precipitation with ammonium carbonate or carbon dioxide. The filtrate contains the guanidine nitrate that is recovered by vacuum evaporation and converted to nitroguanidine. Both operations can be mn on a continuous basis (see Cyanamides). In the Marquerol and Loriette process, nitroguanidine is obtained directly ia about 90% yield from dicyandiamide by reaction with sulfuric acid to form guanidine sulfate followed by direct nitration with nitric acid (169—172). 

Organic Reactions. Nitric acid is used extensively ia iadustry to nitrate aHphatic and aromatic compounds (21). In many iastances nitration requires the use of sulfuric acid as a dehydrating agent or catalyst the extent of nitration achieved depends on the concentration of nitric and sulfuric acids used. This is of iadustrial importance ia the manufacture of nitrobenzene and dinitrotoluene, which are iatermediates ia the manufacture of polyurethanes. Trinitrotoluene (TNT) is an explosive. Various isomers of mononitrotoluene are used to make optical brighteners, herbicides (qv), and iasecticides. Such nitrations are generally attributed to the presence of the nitronium ion, NO2, the concentration of which iacreases with acid strength (see Nitration). 

In TBP extraction, the yeUowcake is dissolved ia nitric acid and extracted with tributyl phosphate ia a kerosene or hexane diluent. The uranyl ion forms the mixed complex U02(N02)2(TBP)2 which is extracted iato the diluent. The purified uranium is then back-extracted iato nitric acid or water, and concentrated. The uranyl nitrate solution is evaporated to uranyl nitrate hexahydrate [13520-83-7], U02(N02)2 6H20. The uranyl nitrate hexahydrate is dehydrated and denitrated duting a pyrolysis step to form uranium trioxide [1344-58-7], UO, as shown ia equation 10. The pyrolysis is most often carried out ia either a batch reactor (Fig. 2) or a fluidized-bed denitrator (Fig. 3). The UO is reduced with hydrogen to uranium dioxide [1344-57-6], UO2 (eq. 11), and converted to uranium tetrafluoride [10049-14-6], UF, with HF at elevated temperatures (eq. 12). The UF can be either reduced to uranium metal or fluotinated to uranium hexafluoride [7783-81-5], UF, for isotope enrichment. The chemistry and operating conditions of the TBP refining process, and conversion to UO, UO2, and ultimately UF have been discussed ia detail (40). 

Cu(N03 )26H2 0, is produced by crystallization from solutions below the transition poiat of 26.4°C. A basic copper nitrate [12158-75-7] Cu2(N02)(0H)2, rather than the anhydrous product is produced on dehydration of the hydrated salts. The most common commercial forms for copper nitrate ate the ttihydtate and solutions containing about 14% copper. Copper nitrate can be prepared by dissolution of the carbonate, hydroxide, or oxides ia nitric acid. Nitric acid vigorously attacks copper metal to give the nitrate and evolution of nitrogen oxides. 

N2O5 is the anhydride of nitric acid and is obtained as a highly reactive deliquescent, light-sensitive, colourless, crystalline solid by carefully dehydrating the concentrated acid with P4O10 at low temperatures ... 

Selenous acid, 0=Se(0H)2, i.e. H2Se03, and tellurous acid, H2Te03, are white solids which can readily be dehydrated to the dioxide (e.g. in a stream of dry air). H2Se03 is best prepared by slow crystallization of an aqueous solution of Se02 or by oxidation of powdered Se with dilute nitric acid ... 

An example where reactant concentration is solely governed by corrosion considerations is in the production of concentrated nitric acid by dehydration of weak nitric acid with concentrated sulphuric acid. The ratio of HN0j H2S04 acid feeds is determined by the need to keep the waste sulphuric acid at > 70 Vo at which concentrations it can be transported in cast-iron pipes and stored after cooling in carbon-steel tanks. 

Impure nitric acid can produce N02 via reaction (12). Titov (Refs 65 39b) also suggests the dehydration reaction for anhydrous nitric acid ... 

In both the liq the vapor phase, nitric acid decomps as 2HNO s NO l O+ Oj with a second equil with N02 2N02 2N0+02- The rate determining step is the dehydration of HN03... 

Prepd by dehydrating coned nitric acid with phosphorus pentoxide (Refs 3 4). Explds if heated suddenly (Ref 4). Can also be prepd by the flash photolysis of 02-N20-He mixts (Ref 11), and by the radiolysis of N2O4—HN03 with 7 rays (Ref 1.2)... 

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