Indirect removal

When reductive conditions are contraindicated, the indirect removal of chlorine by oxidation of a derived hydrazino derivative with silver oxide, may be used this is illustrated... 

It was not until 1966 that the synthesis of proto-quercitol (levo) was finally accomplished (30) by indirect removal of the position 2 hydroxyl group in (—) -inositol (14). 

Indirect removal of agonists wherein an enzyme liberates a product which reacts with a second chemical rendering the last less biologically active. 

Table 7.29 indicate that the results obtained by shortcut calculations are quite different with those predicted by heuristics (see Table 7.27). It can be seen the sequences can be classified in two groups higher energetic consumption (3, 8, 9) and lower energetic consumption (11,12). The best is the sequence 12 where the first split is indirect removing the most plentiful as bottoms. The second is the sequence 11 that has the same first split. Sequence 12 is only slightly better because 50/50 second split. Third is the sequence 9 based on 50/50 first split, but well behind the first two in term of total duty. The other two sequences gives very close results.

Eger, Hayes and Nair have demonstrated the stimulative effect of Pseudomonas putida. But why Pseudomonas putida stimulates primordia formation is a question yet unanswered. Some believe its effect is indirect, removing chelating compounds that inhibit mushroom initiation. Others (Fritsche, 1 981 Visscher, 1981) suspect its influence is more direct and biologically oriented. 

Pintar A., Batista J. and Levee J. 2001. Catalytic denitrification direct and indirect removal of nitrates from potable water, Catal. Today, 66, 503-510. 

Note that the direct removal of a sulfur atom from dibenzothiophene requires 2 molecules of hydrogen, while the indirect removal of sulfur from a hindered dibenzothiophene requires 5 molecules of hydrogen per sulfur atom. This is important when estimating hydrogen requirements for deep-... 

Other techniques to detennine the corrosion rate use instead of DC biasing, an AC approach (electrochemical impedance spectroscopy). From the impedance spectra, the polarization resistance (R ) of the system can be detennined. The polarization resistance is indirectly proportional to j. An advantage of an AC method is given by the fact that a small AC amplitude applied to a sample at the corrosion potential essentially does not remove the system from equilibrium. 

When the ascending solvent-front has reached a convenient height, the strip is removed, the position of the solvent-front marked, and the paper strip dried. The positions of the various solutes, if they are coloured compounds, now appear as clear separate spots. Frequently however, the solutes are colourless, and the position of their spots must be determined by indirect methods, such as their fluorescence in ultraviolet light, or their absorption in such light (when the spots appear almost black), or by spraying the paper with a dilute solution of a reagent which will give a coloured insoluble derivative with the solutes. 

Fresh reducing gas is generated by reforming natural gas with steam. The natural gas is heated in a recuperator, desulfurized to less than 1 ppm sulfur, mixed with superheated steam, further preheated to 620°C in another recuperator, then reformed in alloy tubes filled with nickel-based catalyst at a temperature of 830°C. The reformed gas is quenched to remove water vapor, mixed with clean recycled top gas from the shaft furnace, reheated to 925°C in an indirect fired heater, and injected into the shaft furnace. For high (above 92%) metallization a CO2 removal unit is added in the top gas recycle line in order to upgrade the quaUty of the recycled top gas and reducing gas. 

SL/RN Process. In the SL/RN process (Fig. 4), sized iron ore, coal, and dolomite are fed to the rotary kiln wherein the coal is gasified and the iron ore is reduced. The endothermic heat of reduction and the sensible energy that is required to heat the reactants is provided by combustion of volatiles and carbon monoxide leaving the bed with air introduced into the free space above the bed. The temperature profile in the kiln is controlled by radial air ports in the preheat zone and axial air ports in the reduction zone. Part of the coal is injected through the centerline of the kiln at the discharge end. The hot reduced iron and char is discharged into an indirect rotary dmm cooler. The cooled product is screened and magnetically separated to remove char and ash. 

Manufacture. Ketenes can be considered the internal anhydrides of the corresponding carboxyHc acids, and as such can be made by removing a molecule of water from these acids, either directly or indirectly. Numerous methods to convert a carboxyHc acid or derivative to the corresponding ketene have been described (1 4). 

Vacuum Treatment. Milk can be exposed to a vacuum to remove low boiling substances, eg, onions, garlic, and some silage, which may impart off-flavors to the milk, particularly the fat portion. A three-stage vacuum unit, known as a vacreator, produces pressures of 17, 51—68, and 88—95 kPa (127, 381—508, and 660—711 mm Hg). A continuous vacuum unit in the HTST system may consist of one or two chambers and be heated by Hve steam, with an equivalent release of water by evaporation, or flash steam to carry off the volatiles. If Hve steam is used, it must be cuUnary steam which is produced by heating potable water with an indirect heat exchanger. Dry saturated steam is desired for food processing operations. 

The common types of dryers are rotary, hearth, flash (spray), and fluidized beds (10). Hot gases are used invariably to remove moisture. The gas flow can be either cocurrent or countercurrent to the flow of soHds, the former tends to be more efficient. In the hearths, the gas flow is countercurrent as the soHds are raked down from one hearth to the next below. Flash dryers are very rapid because the soHds are exposed only briefly to the hot gases. Fluidized-bed dryers, which use hot gases to suspend the soHds, are rapid and efficient, but require elaborate dust coHection systems. These are preferred when fine soHds are involved, and are used commonly for drying fine coal. Indirect-fired dryers are used when the soHds are heat sensitive or combustible. 

Hydrogen Abstra.ction. These important reactions have been carried out using a variety of substrates. In general, the reactions involve the removal of hydrogen either direcdy as a hydrogen atom or indirectly by electron transfer followed by proton transfer. The products are derived from ground-state reactions. For example, chlorarul probably reacts with cycloheptatrienyl radicals to produce ether (50) (39). This chemistry contrasts with the ground-state reaction in which DDQ produces tropyhum quinolate in 91% yield (40). 

Bromine is used as an analytical reagent to determine the amount of unsaturation in organic compounds because carbon—carbon double bonds add bromine quantitatively, and for phenols which add bromine in the ortho and para positions. Standard bromine is added in excess and the amount unreacted is deterrnined by an indirect iodine titration. Bromine is also used to oxidize several elements, such as T1(I) to T1(III). Excess bromine is removed by adding phenol. Bromine plus an acid, such as nitric and/or hydrochloric, provides an oxidizing acid mixture usefiil in dissolving metal or mineral samples prior to analysis for sulfur. 

Butanol is produced commercially by the indirect hydration of / -butenes. However, current trends are towards the employment of inexpensive Raffinate 11 type feedstocks, ie, C-4 refinery streams containing predominandy / -butenes and saturated C-4s after removal of butadiene and isobutylene. In the traditional indirect hydration process, / -butenes are esterified with Hquid sulfuric acid and the intermediate butyl sulfate esters hydroly2ed. DEA Mineraloel (formerly Deutsche Texaco) currentiy operates a 2-butanol plant employing a direct hydration of / -butenes route (18) with their own proprietary catalyst. 

Thus the amount of heat that must be produced by burning coke ia the regenerator is set by the heat balance requirements and not directly set by the coke-making tendencies of the catalyst used ia the catalytic cracker or by the coking tendencies of the feed. Indirectly, these tendencies may cause the cracker operator to change some of the heat-balance elements, such as the amount of heat removed by a catalyst cooler or the amount put iato the system with the feed, which would then change the amount of heat needed from coke burning. 

The ring-chlorinated derivatives of toluene form a group of stable, industrially important compounds. Many chlorotoluene isomers can be prepared by direct chlorination. Other chlorotoluenes are prepared by indirect routes involving the replacement of amino, hydroxyl, chlorosulfonyl, and nitro groups by chlorine and the use of substituents, such as nitro, amino, and sulfonic acid, to orient substitution followed by their removal from the ring. 

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