Bases solvents for

The term encumbered has been used to describe carbocations having strong interactions with Lewis base solvents. For a discussion, see Keating, J. T. Skell, P. S. in Olah, G. A. Schleyer, P. v. R., Eds. Carbonium Ions. Volume II. Methods Formation and Major Types Wiley-Interscience New York, 1970 pp. 573-653 and references therein. 

A number of classes of solvents have been called neoteric (novel, newfangled). These include the room-temperature ionic liquids, fluorous solvents (perfluori-nated or with perfluorinated tails), and supercritical fluids, chiefly water and carbon dioxide, though other examples such as the lower alcohols have been used. Recent work has highlighted the potential of biologically based solvents for their special properties and green character (see, e.g., Gu and Jerome, 2013). These new solvents offer a range of properties that have raised hopes of better synthetic methods and major improvements in environmental and workplace safety. 

Until recently, the manufacture of high molecular weight acrylamide polymers or copolymers was accomplished by one of two methods. The polymers could be produced as water-in-oil emulsions (or "latex" polymers), consisting of a hydrocarbon-based solvent for the continuous phase and various surfactants to provide emulsion stability. Polymers prepared in this fashion are generally 20% to... 

A greater awareness of the origin of solvents, and why they are suitable for some reactions but not others, will be an essential quality of the future medicinal chemist. They will also need to embrace unconventional solvents in order to continue practicing the reactions familiar to medicinal chem-istiy. Computational tools such as COSMO-RS are available for solvent selection that can improve the understanding and uptake of bio-based solvents. For example, limonene and p-cymene are bio-based solvent substitutes for traditional hydrocarbon solvents. 

This technique is based on the selectivity of a solvent for different families or individual components in a mixture. Solvent extraction can be either analytical or preparatory in function. 

In summary, water is clearly an extremely bad solvent for coordination of a hard Lewis acid to a hard Lewis base. Hence, catalysis of Diels-Alder reactions in water is expected to be difficult due to the relative inefficiency of the interactions between the Diels-Alder reactants and the Lewis-acid catalyst in this medium. 

The Dk parameter is based on the solvent effect, on the reaction of tetracyanoethylene with diazodiphenylmethane with benzene as a reference solvent. For details see Osbima, T. Arikata, S. Nagai, T. J. Chem. Research (S), 1981, 204... 

Solventless Extrusion Process. The solvendess process for making double-base propellants has been used ia the United States primarily for the manufacture of rocket propellant grains having web thickness from ca 1.35 to 15 cm and for thin-sheet mortar (M8) propellant. The process offers such advantages as minimal dimensional changes after extmsion, the elimination of the drying process, and better long-term baUistic uniformity because there is no loss of volatile solvent. The composition and properties of typical double-base solvent extmded rocket and mortar propellant are Hsted ia Table... 

The first reported synthesis of acrylonitrile [107-13-1] (qv) and polyacrylonitrile [25014-41-9] (PAN) was in 1894. The polymer received Htde attention for a number of years, until shortly before World War II, because there were no known solvents and the polymer decomposes before reaching its melting point. The first breakthrough in developing solvents for PAN occurred at I. G. Farbenindustrie where fibers made from the polymer were dissolved in aqueous solutions of quaternary ammonium compounds, such as ben2ylpyridinium chloride, or of metal salts, such as lithium bromide, sodium thiocyanate, and aluminum perchlorate. Early interest in acrylonitrile polymers (qv), however, was based primarily on its use in synthetic mbber (see Elastomers, synthetic). 

Anhydrous hydrogen fluoride is an excellent solvent for ionic fluorides (Table 3). The soluble fluorides act as simple bases, becoming fully ionized and increasing the concentration of HF 2- Foi example,... 

Silver readily forms alloys with lead. Lead is often used as a base metal solvent for silver recovery processes. The lead—silver system is a simple eutectic having the eutectic point at 2.5 wt % silver and 304°C. The soHd solubihty of silver in lead is 0.10 wt % at 304°C, dropping to less than 0.02 wt % at 20°C. 

The bimodal profile observed at low catalyst concentration has been explained by a combination of two light generating reactive intermediates in equihbrium with a third dark reaction intermediate which serves as a way station or delay in the chemiexcitation processes. Possible candidates for the three intermediates include those shown as "pooled intermediates". At high catalyst concentration or in imidazole-buffered aqueous-based solvent, the series of intermediates rapidly attain equihbrium and behave kineticaHy as a single kinetic entity, ie, as pooled intermediates (71). Under these latter conditions, the time—intensity profile (Fig. 2) displays the single maximum as a biexponential rise and fall of the intensity which is readily modeled as a typical irreversible, consecutive, unimolecular process ... 

Other. 2-Nitro-1-butanol is an excellent solvent for many polyamide resins, cellulose acetate butyrate, and ethylceUulose. It can be utilized in paint removers for epoxy-based coatings. 2-Hydroxymethyl-2-nitro-l,3-propanediol is usebil for control of odors in chemical toilets. Its slow release of formaldehyde ensures prolonged action to control odor, and there is no reodorant problem which sometimes is associated with the use of free formaldehyde. 2-Hydroxymethyl-2-nitro-l,3-propanediol solutions are effective preservative and embalming fluids. The slow Uberation of formaldehyde permits thorough penetration of the tissues before hardening. 

Both regulatory limits on the amount of organic solvents allowed in paints and advancements in alkyd resin technology have resulted in the development of higher soHds alkyd resins that requke less solvent for dilution and viscosity reduction. In addition, developments of water-reducible alkyds and alkyd emulsions have resulted in alkyd-based paints that requke less organic solvent in thek formulations. 

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