Oxidative improvers

Long ago it was noticed that the baking quality of white flour improved with storage for 1-2 months. This effect occurred more rapidly if the flour was exposed to the air. During storage, initially the level of free fatty acids increases, presumably owing to lipolytic activity. Lipoxygenase activity then produces oxidised fatty acids as the proportion of linoleic and linolenic acids falls while the number of -S-S- bonds decreases. 

Ascorbic acid gives less increase in loaf volume than the same weight of potassium bromate and is more expensive. However, potassium bromate is now banned throughout the EU. Ascorbic acid is now permitted almost everywhere, with some countries such as Australia, Greece, Portugal and Germany not even bothering to limit the maximum level. Ascorbic acid appears to be entirely safe. 

The action of ascorbic acid in the dough is to strengthen the gluten, which improves gas retention and hence the volume of loaves is improved. Ascorbic acid is faster acting than potassium bromate, which why ascorbic acid has always been associated with rapid processes. 

2 Azodicarbonamide (1,1 -azobisformamide NH2CONNCONH2 ADA). This oxidising treatment is normally supplied dispersed on calcium sulfate or magnesium carbonate to avoid the risk of explosions. The trade names Maturox and Genitron are used. 

Azodicarbonamide is legal in the UK, Canada, New Zealand, and the USA but not Australia or the EU (except the UK). As always the legal position should be checked. At the time of writing, azodicarbonamide appears to have escaped any health worries. The residue produced by its action is biurea, which does not appear to be a problem. 

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Excellent yields of the former product are also obtained with quinoline N-oxide. Improved yields of Reissert compounds are found under phase-transfer conditions (29). The regiochemistry of the method changes dramatically with /V-alkyl quin olinium salts, eg, /V-methy1quino1inium iodide [3947-76-0] (12), which form 4-cyanoquinoline [23395-72-4] (13) (30), through the intermediary in this example of A[-methyl-4-cyano-l,4-dihydroquinoline... 

Dehydrogenation, Ammoxidation, and Other Heterogeneous Catalysts. Cerium has minor uses in other commercial catalysts (41) where the element s role is probably related to Ce(III)/Ce(IV) chemistry. Styrene is made from ethylbenzene by an alkah-promoted iron oxide-based catalyst. The addition of a few percent of cerium oxide improves this catalyst s activity for styrene formation presumably because of a beneficial interaction between the Fe(II)/Fe(III) and Ce(III)/Ce(IV) redox couples. The ammoxidation of propjiene to produce acrylonitrile is carried out over catalyticaHy active complex molybdates. Cerium, a component of several patented compositions (42), functions as an oxygen and electron transfer through its redox couple. 

Interesting hydrocarbon oxidations have been observed using Fe(II) catalysts with oxygen or hydrogen peroxide as the oxidant. These catalytic systems have become known as Gif chemistry after the location of their discovery in France.287 An Oxidations improved system involving Fe(III), picolinic acid, and H202 has been developed. The... 

Films of polyolefins, polyamides and poly(vinylidene dichloride) are made using this technique. As most of the films are used for flexible packaging, further down-stream surface treatments are usually applied to improve performance. For example, aqueous polymer emulsions, e.g., poly(vinylidene dichloride), or delaminated clay particles improve the barrier properties as will metallising with aluminium vapour. Corona discharge, causing slight surface oxidation, improves printability. 

Both compounds were tested for their catalytic activity in asymmetric aziridination using p-toluenesullbnic anhydride (TS2O) to activate the nitridomanganese complex. As shown in Scheme 4-60, the aziridination generally gave poor results, while addition of pyridine A-oxide improved both the yield and the enantiomeric excess of the products. 

The influence of ZnCFO concentration (3,0 5,0 7,0 phr) on formation of properties complex of the unfilled rubber mixes and their vulcanizates on the basis of isoprene rubber of the following recipe, phr isoprene rubber - 100,0 sulfur - 1,0 di - (2-benzothiazolyl) -disulfide - 0,6 N, N -diphenylguanidine - 3,0 stearic acid - 1,0, was carried out in comparison with the known activator - zinc oxide (5,0 phr). The analysis of Rheometer data of sulfur vulcanization process of elastomeric compositions at 155°C (fig. 5) shows, that on crosslink density and cure rate, about what the constants of speed in the main period (k2) testify, they surpass the control composition with 5,0 phr of zinc oxide. Improvement of the complex of elastic - strong parameters of rubbers with ZnCFO as at normal test conditions, and after thermal air aging (tab. 1), probably, is caused by influence of the new activator on vulcanization network character. So, the percent part of polysulfide bonds (C-Sx-C) and amount of sulfur atoms appropriating to one crosslink (S atoms/crosslink) in vulcanizates with ZnCFO are decreased, the percent part of disulfide bonds (C-S2-C) is increased (fig. 62). 

Several reports have appeared on the effect of additives on the Pauson-Khand reaction employing an alkyne-Co2(CO)6 complex. For example, addition of phosphine oxide improves the yields of cyclopentenones 119], while addition of dimethyl sulfoxide accelerates the reaction considerably [20]. Furthermore, it has been reported that the Pauson-Khand reaction proceeds even at room temperature when a tertiary amine M-oxide, such as trimethylamine M-oxide or N-methylmorpholine M-oxide, is added to the alkyne-Co2(CO)6 complex in the presence of alkenes [21]. These results suggest that in the Pauson-Khand reaction generation of coordinatively unsaturated cobalt species by the attack of oxides on the carbonyl ligand of the alkyne-Co2(CO)6 complex [22] is the key step. With this knowledge in mind, we examined further the effect of various other additives on the reaction to obtain information on the mechanism of this rearrangement. 

Lissens, G. Thomsen, A. B. De Baere, L. Verstraete, W. Ahring, B. K. Thermal Wet Oxidation Improves Anaerobic Biodegradability of Raw and Digested Biowaste. Fnviron. Sci. Technol. 2004, 38, 3418-3424. 

Priming is the process of applying a dilute solution of the adhesive mixed with an organic solvent on the adherend to a dried film thickness between 0.0015 and 0.005 mm (0.00006 to 0.002 in). Priming protects the surface from oxidation, improves wetting, helps prevent adhesive peeling, and serves as a barrier layer to prevent undesirable reactions between the adhesive and the adherent. 

The Steffen process, which uses calcium oxide for precipitation of sucrose from molasses, has been applied to the recovery of lactose from cheese whey (Cerbulis 1973). By proper control of the reaction, over 90% of the lactose can be recovered as an insoluble calcium-lactose complex. The addition of ferric chloride in combination with calcium oxide improves lactose yields. Addition of equal volumes of acetone or methanol gives almost complete precipitation of lactose and protein from whey. 

In contrast, the aziridination of c/s-(J-methylstyrene was not observed at 0°C in spite of the presence of pyridine A-oxide. At room temperature, in the absence of the /V-oxide, the cis-aziridine was obtained in a poor yield and with a low ee value (Table 6.4). The addition of the JV-oxide improved the yield of the product, but did not cause a dramatic change in the ee value. 

Modifying activated carbon fibres (ACF) by ferric oxide improved the gold dispersion and their activity at room temperature, but they deactivated quickly.111... 

K).8"10 The promotion of SZ catalysts by the addition of noble metals and transition metal oxides improved their stability, activity and selectivity even further. However, SZ catalysts suffer from several problems that impede their practical application.11... 

The kraft process has had a serious problem with air pollution due to the production of hydrogen sulfide, mercaptans, and other vilesmelling sulfur compounds. The use of various techniques such as black-liquor oxidation, improved evaporators and furnaces, and control of emissions has greatly improved this situation. Older mills were forced to expend large amounts of money to bring their operations up to the environmental standards. 

Fora non-reactive and non wetting pure metal on an oxide, improved wetting can be achieved either by adsorption at metal/oxide interface of oxygen supplied by a gas with a controlled P02 or by introducing certain specific alloying elements... 

Wilson (1990) has provided some details of the microstructural evolution in this fiber. A fine-grained o-AljOj fiber is obtained by seeding the high temperature a-alumina with a very fine hydrous colloidal iron oxide. The fine iron oxide improves the nucleation rate of a-Al Oj, with the result that a high density, ultra-fine, homogeneous o-Al203 fiber is obtained. The rationale for seeding with iron oxide as follows. Basic salts of aluminiun decompose into transition aluminum oxide spinels such as above 400°C. These transition cubic spinels... 

Further incorporation of thermal processing into the manufacturing process leads to products with improved color properties. In the commercial paint sector, the use of inorganic stabilizers, for example calcium, aluminum or zinc phosphate or oxides like aluminum oxide, improves other pigment properties, e.g. photochromism, weathering and acid resistance. 

A 72-year-old woman, who underwent emergency resection of a giant left atrial myxoma, had pulmonary hypertension (pulmonary artery pressure 40 mmHg) and a low cardiac output (2.21/minute). Inhaled nitric oxide, 40 ppm, before cardiopulmonary bjrpass resulted in pulmonary vasodilatation and a fall in pulmonary artery pressure from 39 to 31 mmHg. This was accompanied by a fall in cardiac output from 2.4 to 1.5 1/minute and a fall in mixed venous oxygen saturation. After bypass, inhaled nitric oxide improved pulmonary and systemic hemodynamics and resulted in a rise in cardiac output from 3.0 to 3.5 l/minute. 

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