Transformation small scale

Sodium selenate has been used on a small scale in commercial greenhouses, primarily for growing carnations and chrysanthemums. It is transformed by the plants into volatile selenides, which repel red spiders, mites, thrips, and aphids (see Insect control technology). Sodium selenite is not intended for crops which could ultimately be used as food for humans or domestic animals. 

For small-scale laboratory work, the exhaust surface is often made as a separate section added to the side of a table or put into a large hole in a table. These tables usually have a sheet metal surface that is resistant to the chemicals used and is easily cleaned. Many circular holes are cut into the metal surface to allow for airflow. This perforation makes the pressure difference over the table quite high and at the same time gives an even distribution of the airflow over the entire surface. These types of exhaust surfaces could be formed to suit different working conditions, e.g., the surface could be made to fit into a sink or to be placed below and around a balance. Using side walls that are not too high, on three or four sides, transforms the table to a partial enclosure, which increases... 

Clipperton and Orozco Transforms (10-12°N EPR) (Fig. 2D). These authors analyzed samples known to be derived from a heterogeneous source based on their Sr/ Sr signatures and found a strong relationship between ( Th)/( Th) and Th (and U) concentrations of their samples. This study was the first to suggest that small-scale mafic heterogeneities in the mantle source control much of the U-series systematics of MORE. 

Industrial interest in the application of enantioselective catalysts began in earnest during the mid-1960s when the first reports of successful enantioselective transformations with homogeneous metal complexes were published. Within a surprisingly short period, production processes for two small-scale products, L-dopa (hydrogenation) and cilostatin (cyclopropanation) were developed and implemented by... 

Synthesis of aldehydes from alcohols is an important transformation in several applications. In small scale oxidations still chromic acid is being used as a stoichiometric oxidant of alcohols, which leads to a large amount of toxic waste and it is also expensive. Catalytic routes have been reported using palladium catalyst [18], or TEMPO (see also Figure 15.13) as a radical catalyst for the oxidation of alcohols [19], or combinations of TEMPO and copper [20] related work is mentioned in the references of these articles. The mechanism of... 

For syntheses on a relatively small scale, lithium alkynylides are the most convenient starting compounds they can be used as such or transformed into other organametallic intermediates. 

The transition metal-catalyzed addition of the Si-H bond of a hydrosilane across a C=C or C=C bond is a transformation of considerable importance in both large-scale industrial processes and in small-scale organic synthesis.Perhaps the most common industrial application of catalytic hydrosilylation is the platinum-catalyzed cross-linking of vinylsilane polymers with hydrosilanes. The interest in catalytic hydrosilylation in organic synthesis... 

Sulfonation of Benzene and Alkylbenzenes. Since the main utilization of ben-zenesulfonic acid was its transformation to phenol, the importance of the sulfonation of benzene has diminished. The process, however, is still occasionally utilized since it is a simple and economical procedure even on a small scale. Excess sulfuric acid or oleum is used at 110-150°C to produce benzenesulfonic acid.97,102 Sulfonation of toluene under similar conditions yields a mixture of isomeric toluenesul-fonic acids rich in the para isomer. This mixture is transformed directly to cresols by alkali fusion. 

Measurements either from the ground or from satellites have been a major contribution to this effort, and satellite instruments such as LIMS (Limb Infrared Monitor of the Stratosphere) on the Nimbus 7 satellite (I) in 1979 and ATMOS (Atmospheric Trace Molecular Spectroscopy instrument), a Fourier transform infrared spectrometer aboard Spacelab 3 (2) in 1987, have produced valuable data sets that still challenge our models. But these remote techniques are not always adequate for resolving photochemistry on the small scale, particularly in the lower stratosphere. In some cases, the altitude resolution provided by remote techniques has been insufficient to provide unambiguous concentrations of trace gas species at specific altitudes. Insufficient altitude resolution is a handicap particularly for those trace species with large gradients in either altitude or latitude. Often only the most abundant species can be measured. Many of the reactive trace gases, the key species in most chemical transformations, have small abundances that are difficult to detect accurately from remote platforms. 

In situ measurements of stratospheric reactive trace gas abundances provide an opportunity to test the fundamental photochemical mechanisms (3). The advantage of such measurements is that they are local, so the simultaneous measurements of trace gases place a true constraint on the possible photochemical mechanisms. These measurements are also able to resolve small-scale spatial and temporal structure in the trace constituent fields. The disadvantage of in situ measurements is that they do not capture the global or perhaps even seasonal view of photochemical transformations because they are seldom done frequently enough or in enough places to provide that information. Another disadvantage of in situ measurements is that they must be made from platforms in the stratosphere, and these remote observational outposts have their liabilities. 

There are several approaches to the conversion of sunlight into electrical or chemical energy. The first method is the direct transformation into electricity by means of photovoltaic cells. These are based on a purely photophysical process, and they have been used successfully in many small-scale applications to provide electrical power for artificial satellites, for... 

The first microwave-assisted Wolff-Kishner reduction was described by Parquet and Lin in 199763. The transformation of isatin to oxindole was performed on a small scale in a domestic microwave oven in two steps with a total reaction time of 40 s, as compared to 3—4 h if classical heating was utilised (Scheme 4.36). The first step involved the transformation of the carbonyl group into the hydrazone with 55% hydrazine in ethylene glycol and medium power microwave irradiation for 30 s. In the subsequent reduction step, KOH in ethylene glycol was used to substitute the more hazardous sodium ethoxide. The reaction mixture was irradiated for 10 s and the product was obtained in a yield of 32%. 

Despite the current success and popularity of polymer reagents, the availability of functional resins has been a severe limitation in recent years. For many synthetically important transformations, reliable reagents were not available. Moreover, polymer-assisted synthesis was usually restricted to small scale apphcations, and also suffered from the inherent limitations of the standard support material (e.g., cross-linked polystyrene) such as solvent incompatibihty, adsorption of reagents,14 or the chemical reactivity of the resin backbone. 

One of the most important aspects of carbonate diagenesis is the net movement of carbonate minerals. This mass transfer can be accomplished on a small scale by diffusive transport or on a large scale by the flow of subsurface waters. It is the basic process by which secondary porosity is created and cementation occurs. In most cases, it involves carbonate mineral dissolution at one site and precipitation at another. While this can be simply accomplished where mineralogic transformations from a metastable phase to a more stable phase are involved, more complex mechanisms may be required within mineralogically homogeneous carbonate bodies. 

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