Peroxides industrial process

Figure 4-13 shows an example from a three-dimensional model simulation of the global atmospheric sulfur balance (Feichter et al, 1996). The model had a grid resolution of about 500 km in the horizontal and on average 1 km in the vertical. The chemical scheme of the model included emissions of dimethyl sulfide (DMS) from the oceans and SO2 from industrial processes and volcanoes. Atmospheric DMS is oxidized by the hydroxyl radical to form SO2, which, in turn, is further oxidized to sulfuric acid and sulfates by reaction with either hydroxyl radical in the gas phase or with hydrogen peroxide or ozone in cloud droplets. Both SO2 and aerosol sulfate are removed from the atmosphere by dry and wet deposition processes. The reasonable agreement between the simulated and observed wet deposition of sulfate indicates that the most important processes affecting the atmospheric sulfur balance have been adequately treated in the model. 

Indeed, several interesting procedures based on three families of active catalysts organometallic complexes, phase-transfer compounds and titanium silicalite (TS-1), and peroxides have been settled and used also in industrial processes in the last decades of the 20th century. The most impressive breakthrough in this field was achieved by Katsuki and Sharpless, who obtained the enantioselective oxidation of prochiral allylic alcohols with alkyl hydroperoxides catalyzed by titanium tetra-alkoxides in the presence of chiral nonracemic tartrates. In fact Sharpless was awarded the Nobel Prize in 2001. 

Hydrosilylation, the addition of a silicon-hydrogen bond to multiple bonds, is a valuable laboratory and industrial process in the synthesis of organosilicon compounds. The addition to carbon-carbon multiple bonds can be accomplished as a radical process initiated by ultraviolet (UV) light, y irradiation, or peroxides. Since the discovery in the 1950s that chloroplatinic acid is a good catalyst to promote the addition, metal-catalyzed transformations have become the commonly used hydrosi-... 

Fluorinated diaeyl peroxides have acquired an important role in organo-fluorine chemistry and have become the subject of intensive research.202-204 Bis(per)fluoroaIkanoyI or -aroyl peroxides are generally synthesized in excellent to moderate yields in the same manner as for nonfluorinated peroxides, that is by reaction of acid chlorides or anhydrides with sodium peroxide or hydrogen peroxide.205-206 Similarly, perfluoroalkanoyl chlorides and fluorides, many of which are accessible by industrial processes, react with hydrogen peroxide in the presence of hydroxide to give the diacyl peroxides l.206-207... 

Over 90% of industrial processes use catalysts. A catalyst is a substance which can alter the rate of a reaction without being chemically changed itself. In the laboratory, the effect of a catalyst can be observed using the decomposition of hydrogen peroxide as an example. 

The first observation indicates that energy is needed to transfer an electron from the solid to the 02 molecule to build the peroxide precursor state. At the defects however some pathways, leading to dissociation, must have a vanishing (or very small) activation barrier. Such pathways might be dominant for real catalytic conditions in industrial processes. 

This book gathers and analyzes information of both basic and applied aspects of heme peroxidases. Peroxidases are oxidoreductases that catalyze the oxidation of a wide range of molecules, using peroxide as electron acceptor. Although they have been proposed for applications in several fields (see for example [8, 9]) there are few industrial processes that utilize peroxidases. The commercial applications of these enzymes are reduced to diagnosis and research [10]. Unfortunately, the... 

The industrial manufacture of hydrogen peroxide can be traced back to its isolation in 1818 by L. J. Thenard.1 Thenard reacted barium peroxide with nitric acid to produce a low concentration of aqueous hydrogen peroxide the process can, however, be significantly improved by the use of hydrochloric acid. The hydrogen peroxide is formed in conjunction with barium chloride, both of which are soluble in water. The barium chloride is subsequently removed by precipitation with sulfuric acid (Figure 1.1). 

Before we leave the discussion of industrial processes, it is worth mentioning one other autoxidation process, based on the oxidation of propan-2-ol, developed by Shell Chemicals. The process was employed by Shell in its 15 000 metric tonnes per annum facility at Norco between 1957 and 1980. The process was discovered in 1954 by Harris,25 who showed that the oxidation of primary and secondary alcohols formed hydrogen peroxide, and the corresponding aldehyde or ketone (Figure 1.11). 

An important current industrial process based on N-C cleavage using hydrogen peroxide is the manufacture of iV-phosphonomethylglycine (systemic herbicide, glyphosate) from AT-phosphonomethyl imido diacetic acid via the N-oxide (Figure 3.88).347 //-Oxidation is catalysed by molybdate or tungstate and the intermediate formed can be decomposed with a second catalyst such as iron(II) to form the product.348... 

The industrial process for propene oxide manufacture is commonly referred to as the HPPO (hydrogen peroxide propene oxide) process. EniChem set up a prototype plant in 2002 [150]. BASF/Dow Chemicals and Degussa, in turn, have the construction of commercial plants already in progress or at the planning stage [151]. 

Unsaturated fatty compounds are the preferred educts in industrial epoxidation. Numerous methods are available to transform then to the corresponding epoxides. Epoxidation with molecular oxygen [3], dioxiranes [4], hydrogen peroxide with methyltrioxorhenium as catalyst [5, 6], the Halcon process [7], or enzymatic reactions [8] are the most important industrial processes (cf. Section 2.4.3). 

Peroxide complexes are intermediates in industrially important epoxidation reactions and research in this area is focused on mechanism and the development of regioselective, stereoselective, and environmentally benign industrial processes. Oxodiperoxo and oxoperoxo complexes will be discussed in that order. Reviews by Dickman and Pope454 and Caradonna455 provide full accounts of peroxo complexes and their use as oxidants in the period prior to 1994. 

P. T. Witte, P. L. Alsters, W. Jary, R. Milliner, P. Pochlauer, D. Sloboda-Rozner, R. Neumann, Self-assembled Nai2[WZn3(Zn Wg034)2] as an industrially attractive multi-purpose catalyst for oxidations with aqueous hydrogen peroxide, Org. Process Res. Dev. 8 (2004) 524. 

The heterogeneous epoxidation of compounds which contain carbon-carbon double bonds is an important industrial process in both the manufacture of fine chemicals and in the synthesis of natural products. A number of studies have demonstrated that alkenes can be readily epoxidised by hydrogen peroxide using the titanium silicalite TS-1 11 -3. However, it has been found that substitution of the alkene by electron withdrawing groups significantly decreases the reactivity of the carbon-carbon double bond since the decrease of the electron... 

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