Nitrogen-Containing Solvents

The first systematic work on the extraction of coal using nitrogen-containing solvents (e.g., pyridine) resulted in the production of substantial amounts of 

TABLE 10.1 Extraction of Coal Using Aromatic-Hydroaromatic Solvents 

TABLE 10.2 Extraction of Coal Using Nitrogen-Containing Solvents 

Increasing with decreasing rank Pyridine Two coals of 90.4 and 88.5% C 

Exhibiting no correlation Pyridine South Wales coals, maximum extraction at 30% volatile matter 

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Nitrogen-containing solvents 409 Sulphur-containing solvents 411 Phosphorus-containing solvents 412... 

Unlike the case of phenylacetylene, Mo catalysts are more active than their W counterparts. fert-Butylacetylene is so reactive that it can polymerize even in various oxygen-or nitrogen-containing solvents (e.g., anisole, acetophenone, benzonitrile, nitrobenzene) 19). 

The kind of useful polymerization solvents depends on the reactivity of monomers. tert-Butylacetylene polymerizes not only in oxygen-containing solvents (1,4-dioxane, anisole, methyl benzoate, acetophenone, etc.) but also in nitrogen-containing solvents (benzonitrile, acetonitrile, nitrobenzene, nitroethane, etc.)19). Therefore, it can be said that tm-butylacetylene is one of the most reactive monomers in the polymeriza-... 

CoS, C02S3 PR, Addition of nitrogen-containing solvent 36 Ethanol/86.3 Acetaldehyde/2.1 Methyl acetate/3.2 Ethyl acetate/1 [32]... 

More recently, the mechanisms of solvent diffusion into coal have been shown to vary with the extent to which the diffusing solvent reacts with the coal (Hall et al., 1992). For basic (usually nitrogen-containing) solvents, this may be related to the number of hydrogen bonds that are disrupted by the diffusing solvent, which, in turn, is related to coal structure (Carlson, 1992 Nishioka, 1992). 

The first systematic work on the extraction of coal using nitrogen-containing solvents (e.g., pyridine) resulted in the production of substantial amounts of extract, which was then further fractionated to produce a series of fractions based on their solubility/insolubility in different solvents (Figure 11.3) (Burgess and Wheeler, 1911). 

Influence of Coal Rank on the Degree of Extraction by Nitrogen-Containing Solvents... 

Superficially the simplest way to do this is to drown-out the reaction mass into water in order to recover product as a separate phase. This generates a ternary mixture of water/inorganic salt(s)/dipolar aprotic solvent from which it is not easy to recover quantitatively dry solvent. In the case of dimethylformamide a recovery option involving extraction with dichloromethane is available, but this is only viable for relatively concentrated aqueous solutions. Disposal to drain may be precluded in the case of nitrogen-containing solvents due to limits imposed on nitrogen levels in effluent to prevent eutrophication. Where possible the preferred recovery method is to filter off inorganics directly from the reaction mass and then recover dry solvent by distillation. 

As follows from the above mentioned method of preparation of the incorporated complex, the interaction between APTES and cobalt complex precedes hydrolytic polycondensation. It is known from [15] that dioxygen complexes are formed by dissolving Cosalen in nitrogen-containing solvents... 

It should be noted that the EPR signals are not observed for Cosalen an Cosalophen in APTES solutions (Fig.Se). This may be due to the creation of diamagnetic binuclear complexes [CoSB(APTES)]202- Such a behavior is inherent to CoSB in nitrogen-containing solvents [19]. Probably either complete or partial destruction of such binuclear compounds occurs at the incorporation of the complexes in a SAP matrix. 

Table 10.1 lists the common chemical names for the nitrogen containing solvents, the CA index names (Chemical Abstract Index, American Chemical Society) and the CAS numbers (Chemical Abstract Service, American Chem-... 

The kinetics of the Menshutkin reaction of pyridine with benzyl bromide in methanol, acetone, and acetonitrile have been studied. " Second-order rate constants for the reactions of ethyl a-haloacetate and triethylamine have been determined in aprotic dipolar ketonic and halogenated solvents, nitrogen-containing solvents, and alcoholic solvents at 30 °C. Simple and multiple regression on various solvent parameters was applied to the results. The same group made a similar study of the reactions of ethyl a-haloacetate with triethylammonium carboxylates in a wide range of protic and aprotic solvents. The kinetics of alkylation of sodium acetate by butyl bromide have been investigated in dipolar non-hydroxylic solvents. Hexamethylphosphoramide is the best solvent for this reaction. 

Hahn, S., Miller, W.M., Lichtenthaler, R.N. and Prausnitz, J.M. (1985) Donor number estimation for oxygen- and nitrogen-containing solvents via proton NMR shift of chloroform. J. Solution Chem., 14, 129-137. 

Besides being the basis for this broad classification, solvation may show distinctive effects in special situations. For instance, the silver ion is known to form very stable ammines, and in keeping with this, silver salts tend to be soluble, and rather strong electrolytes, in nitrogen-containing solvents. 

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