Reactive solvents

Solvents may enter into the reaction sequence transiently or permanently. Well-known examples of the transient participation of solvent are the use of 

Solvents sometimes participate in the reduction unexpectedly. For example 

This ether formation arises from conversion of the phenol to a cyclohexanone, and ketal formation catalyzed by Pd-Hj and hydrogenolysis. With Ru-on-C, the alcohol is formed solely (84). 

There are several sources of potential danger in catalytic hydrogenations these are failure of equipment because of excessive pressures, solvent fires, explosions and fires from mixtures of hydrogen in air, and, with finely divided carbon supports, dust explosions. None of these should cause concern, for all may be avoided easily. 

Unlike reactions such as certain oxidations and polymerizations, hydroge nations will noi detonate unless the substrate or solvent itself is explosive or undergoes extensive decomposition. Excessive pressures can only come from overpressuring the reaction vessels and from pressures generated by large 

Negative deviations from Raoult s law imply that the interaction energy of two unlike molecules is greater than the mean of the two hke-like interactions. (We have seen that mere difference between the molecules leads to the opposite effect.) Specific interactions that could cause negative deviations include hydrogen bonding, Lewis 

Solvolysis, on the other hand, describes a reaction between the solute and the solvent, in which the identity of the solute is lost. In sulfuric acid, typical of strongly acidic solvents, most salts, if they are at all soluble, react to produce the conjugate acid of the anion and the sulfate of the cation (which may precipitate), 

Solvent Effects in Chemistry, Second Edition. Erwin Buncel and Robert A. Stairs. 2016 Jdin WQey Sons, Inc. Published 2016 by John Wiley Sons, Inc. 

In aqueous solution, many salts are to different extents solvolyzed (hydrolyzed), the solution becoming acidic if the cation is small or highly charged  

An example of solvolysis important in physical organic chemistry is the solvolysis of t-butyl chloride (2-chloro-2-methylpropane), the rate of which is the basis of the Grunwald and Winstein (1948) parameter F, described in Section 2.10. 

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Furfural can be classified as a reactive solvent. It resiniftes in the presence of strong acid the reaction is accelerated by heat. Furfural is an excellent solvent for many organic materials, especially resins and polymers. On catalyzation and curing of such a solution, a hard rigid matrix results, which does not soften on heating and is not affected by most solvents and corrosive chemicals. 

Uses. Furfuryl alcohol is widely used as a monomer in manufacturing furfuryl alcohol resins, and as a reactive solvent in a variety of synthetic resins and appHcations. Resins derived from furfuryl alcohol are the most important appHcation for furfuryl alcohol in both utihty and volume. The final cross-linked products display outstanding chemical, thermal, and mechanical properties. They are also heat-stable and remarkably resistant to acids, alkaUes, and solvents. Many commercial resins of various compositions and properties have been prepared by polymerization of furfuryl alcohol and other co-reactants such as furfural, formaldehyde, glyoxal, resorcinol, phenoHc compounds and urea. In 1992, domestic furfuryl alcohol consumption was estimated at 47 million pounds (38). 

High Carbon Yield. Furfuryl alcohol and furfural are reactive solvents (monomers) and are effective in producing high carbon yield (heat induced carbonization in a reducing atmosphere). They function as binders for refractory materials or carbon bodies. Furfuryl alcohol usually requires acidic catalysis and furfural basic catalysis. Mixtures of furfuryl alcohol and furfural are generally catalyzed with acid although some systems may be catalyzed with base. 

Extraction of C-8 Aromatics. The Japan Gas Chemical Co. developed an extraction process for the separation of -xylene [106-42-3] from its isomers using HF—BF as an extraction solvent and isomerization catalyst (235). The highly reactive solvent imposes its own restrictions but this approach is claimed to be economically superior to mote conventional separation processes (see Xylenes and ethylbenzene). 

VOC Emissions Reduction Approach. The Rule 66-type approach focuses on solvent composition further developments have led to regulatory approaches that emphasize overall VOC emission reduction. Even though the more reactive solvents react near their emission point, all VOC compounds eventually react to form ozone pollution. This may occur some distance downwind, increasing ozone levels in areas which have low artificial emissions. 

Many chlorinated hydrocarbons react readily with aluminum in the so-caHed bleeding reaction. A red aluminum chloride—chlorinated hydrocarbon complex is formed. Storage of uninhibited chlorinated solvents in aluminum vessels results in corrosion in a short period of time. Proprietary organic inhibitors permit commercial use of reactive solvents such as 1,1,1-trichloroethane and trichloroethylene for cleaning of aluminum. 

In 1966, the Los Angeles Air Pollution Control Board designated trichloroethylene as a photochemically reactive solvent that decomposes in the lower atmosphere, contributing to air pollution. In 1970 all states were requited to submit pollution control plans to EPA to meet national air quaUty standards. These plans, known as State Implementation Plans (SIPS), controlled trichloroethylene as a volatile organic compound (VOC). They were designed to have each state achieve the National Ambient Air QuaUty Standard (NAAQS) for ozone. The regulations were estabUshed to control the emission of precursors for ozone, of which trichloroethylene is one. 

With a reactive solvent, the mass-transfer coefficient may be enhanced by a factor E so that, for instance. Kg is replaced by EKg. Like specific rates of ordinary chemical reactions, such enhancements must be found experimentally. There are no generalized correlations. Some calculations have been made for idealized situations, such as complete reaction in the liquid film. Tables 23-6 and 23-7 show a few spot data. On that basis, a tower for absorption of SO9 with NaOH is smaller than that with pure water by a factor of roughly 0.317/7.0 = 0.045. Table 23-8 lists the main factors that are needed for mathematical representation of KgO in a typical case of the absorption of CO9 by aqueous mouethauolamiue. Figure 23-27 shows some of the complex behaviors of equilibria and mass-transfer coefficients for the absorption of CO9 in solutions of potassium carbonate. Other than Henry s law, p = HC, which holds for some fairly dilute solutions, there is no general form of equilibrium relation. A typically complex equation is that for CO9 in contact with sodium carbonate solutions (Harte, Baker, and Purcell, Ind. Eng. Chem., 25, 528 [1933]), which is... 

Solvent-home adhesives are of two different types reactive and non-reactive. The reactive solvent-home adhesives are usually high molecular weight oligomers with isocyanate functionality. When applied, these adhesives can react further, increasing physical properties. The non-reactive solvent-home adhesives will not react further after application. 

Six potential MSAs should be simultaneously screened. Riese include absoiption in water. Si. adsorption onto activated carbon, Sj, absorption in chilled methanol, S3, and the use of the following reactive solvents diethanolamine (DEA), S4, hot potassium carbonate, Sj, and diisc ir ranolamine (DIPA), S. ... 

During the past 20 y numerous other highly coloured halogen cations have been characterized by Raman spectroscopy. X-ray crystallography, and other techniques, as summarized in Table 17.18. Typical preparative routes involve direct oxidation of the halogen (a) in the absence of solvent, (b) in a solvent which is itself the oxidant (e.g. AsFs) or (c) in a non-reactive solvent (e.g. SO2). Some examples are listed below ... 

A great variety of solvents has been used with success. Reactive solvents, such as acetic anhydride, will react with the amine as formed. Basic solvents cause the formation of azo, azoxy. and hydrazo compounds, paralleling chemical reductions (39,73). 

An alternative explanation suggested by the authors for the non-linearity of R° with dose is the formation of reactive solvent species capable of intercepting the scission reaction, with a yield which becomes greater the higher the absorbed dose per pulse. However, this mechanism does not explain the effect of oxygen. 

Anionic polymerization Narrow molecular weight distribution Limited chain transfer reactions Predictable molecular weight average Possibility of forming living polymers End groups can be tailored for further reactivity Solvent-sensitive due to the possibility of chain transfer to the solvent Can be slow Sensitive to trace impurities Narrow molecular weight distribution... 

Solvent additives to the melt (Table 3) fall into two categories extractive and reactive. The extractive solvents (decane, perchloroethane, o-dichlorobenzene, and pyrrolidine) had negligible effect on solubility, possibly due to the preferential wetting of the coal by the solvent and exclusion of the ZnCl2 melt. Reactive solvents (anthracene oil, indoline, cyclohexanol, and tetralin) all incorporated strongly. Donor solvents, tetralin and indoline, increase the "corrected solubility, whereas anthracene oil and cyclohexanol have negligible effect. 

BrF5 reacts with water to produce HF and HBr03 if the water is diluted with a less reactive solvent such as acetonitrile. IF5 reacts with water to produce HF and HI03. 

As carriers for proteins and enzymes biocompatible reactive microgels must be synthesized which are soluble in the serum at 37 °C. Moreover they should be hydrophilic enough that no ionic monomers are needed but they should not be soluble in water. An inert comonomer should serve as a spacer as well as a reactive solvent that may dissolve solid comonomers. The coupling reaction should be possible under mild reaction conditions. 

Determine the sprinkler requirements for a chemical process area within a building with an area of 100 ft by 30 ft that handles reactive solvents. Determine the number of sprinkler spray nozzles and pump specifications. Assume 0.5-in orifice sprinklers with 35 psig at each nozzle, giving 34 gpm each, a 10-psig frictional loss within the system, and a 15-ft elevation of the sprinkler system above the pump. 

Determine the water requirement (gpm) and number of nozzles for a deluge system required to protect a 10,000-gal storage tank that has a diameter of 15 ft. Use 0.5-in nozzles with a nozzle pressure of 35 psig, and assume that the vessel contains a reactive solvent. 

Water is a highly polar - and hence protic - solvent, the presence of which may strongly influence the chemistry of two-phase aqueous processes. Of course, all components of the reaction mixture should be stable to water, and to this end care must be taken with the choice of catalyst. Today, aqueous organo-metallic catalysis has become a mature field of chemistry, and a very wide choice of water-soluble and water-stable hydrogenation catalysts is available. It should also be borne in mind that water is a reactive solvent and may take part... 

With a reactive solvent, the mass transfer coefficient may be enhanced by a factor E so that, for instance Kg is replaced by EKg. Like specific rates of ordinary chemical reactions, such enhancements must be found experimentally, although some theoretical relations for idealized situations have been found. Tables 8.1 and 8.2 show a few spot data. A particular... 

Acid Basic Direct Disperse Mordant Pigment Reactive Solvent Vat... 

Anion solvation in alcohol clusters has been studied extensively (see Refs. 135 and 136 and references cited therein). Among the anions that can be solvated by alcohols, the free electron is certainly the most exotic one. It can be attached to neutral alcohol clusters [137], or a sodium atom picked up by the cluster may dissociate into a sodium cation and a more or less solvated electron [48]. Solvation of the electron by alcohols may help in understanding the classical solvent ammonia and the more related and reactive solvent water [138], By studying molecules with amine and alcohol functionalities [139] one may hope to unravel the essential differences between O- and N-solvents. One should note that dissociative electron attachment processes become more facile with an increasing number of O—H groups in the molecule [140],... 

A number of reactions between metals (or metals and semi-metals) may be carried out by dissolving the elements in a suitable solvent , technically also termed a flux . The solvent may also act as a reactant and be involved in the formation of the compound (reactive solvent, reactive flux). Several fluxes, ranging from simple metallic elements up to complex substances have been used. 

Synthesis in liquidAl Al as a reactive solvent Several intermetallic alu-minides have been prepared from liquid aluminium very often the separation of the compounds may be achieved through the dissolution of Al which dissolves readily in several non-oxidizing acids (for instance HC1). For a review on the reactions carried out in liquid aluminium and on several compounds prepared, see Kanatzidis et al. (2005) binary compounds are listed (Re-Al, Co-Al, Ir-Al) as well as ternary phases (lanthanide and actinide-transition metal aluminides). Examples of quaternary compounds (alumino-silicides, alumino-germanides of lanthanides and transition metals) have also been described. As an example, a few preparative details of specific compounds are reported in the following. 

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