Solubility synthetic method

C, mole fraction solubility, synthetic method, measured range 60-100°C, Kakinuma 1941)... 

Unsubstituted poly(/ -phenylene) PPP 1 as a parent system of a whole class of polymers is an insoluble and intractable material, available by a variety of synthetic methods [3, 4]. The lack of solubility and fusibility hinders both unequivocal characterization and the processing of PPP 1. Moreover, the intractability of unsubstituted PPP materials has thwarted any serious commercial development of the polymer. 

The first series of soluble oligo(/ ara-phenylene)s OPVs 24 were generated by Kern and Wirth [48] and shortly after by Heitz and Ulrich [49]. They introduced alkyl substituents (methyls) in each repeat unit and synthesized oligomers 24 up to the hexamer. Various synthetic methods, like the copper-catalyzed Ullmann coupling, the copper-catalyzed condensation of lithium aryls, and the twofold addition of organomelallic species to cyclohexane-1,4-dione, have been thereby investigated. 

West (p. 6), Miller (p. 43), Zeigler (10), and Sawan (p. 112) outline the synthesis of a wide variety of soluble, processable polydiorganosilanes, a class of polymers which not long ago was thought to be intractable. Matyjaszewski (p. 78) has found significant improvements in the synthetic method for polydiorganosilane synthesis as well as new synthetic routes to unusual substituted polydiorganosilanes. Seyferth (p. 21, 143) reports synthetic routes to a number of new polycarbosilanes and polysilazanes which may be used as precursors to ceramic materials. 

Two general methods are available for determining solubility these can be identified as the analytical method and the synthetic method. In the analytical method, the temperature of equilibration is fixed and the concentration of the solute in the saturated solution is determined at equilibrium by a suitable analytical procedure. In other words, a saturated solution in the presence of an excess of the undissolved solute is prepared at an accurately known temperature. This situation may be achieved by suitable contact between the undissolved solid and the solvent in a thermostat until equilibrium is reached. The analytical method... 

Gel electrophoresis is widely used in the routine analysis and separation of many well-known biopolymers such as proteins or nucleic acids. Little has been reported concerning the use of this methodology for the analysis of synthetic polymers, undoubtedly since in many cases these polymers are not soluble in aqueous solution - a medium normally used for electrophoresis. Even for those water-soluble synthetic polymers, the broad molecular weight dispersities usually associated with traditional polymers generally preclude the use of electrophoretic methods. Dendrimers, however, especially those constructed using semi-controlled or controlled structure synthesis (Chapters 8 and 9), possess narrow molecular weight distribution and those that are sufficiently water solubile, usually are ideal analytes for electrophoretic methods. More specifically, poly(amidoamine) (PAMAM) and related dendrimers have been proven amendable to gel electrophoresis, as will be discussed in this chapter. 

Another synthetic method for the introduction of the C2B10 cage onto the pyrimidine nucleus using palladium-catalyzed coupling of 5-iodonucleoside derivatives with alkynes was developed [30], A polyol unit increases water solubility, and this allows the synthesis of a water-soluble uracil bearing an o-C2Bio cage (Scheme 2.2-7) [31]. 

The first example of biphasic catalysis was actually described for an ionic liquid system. In 1972, one year before Manassen proposed aqueous-organic biphasic catalysis [1], Par shall reported that the hydrogenation and alkoxycarbonylation of alkenes could be catalysed by PtCh when dissolved in tetraalkylammonium chloride/tin dichloride at temperatures of less than 100 °C [2], It was even noted that the product could be separated by decantation or distillation. Since this nascent study, synthetic chemistry in ionic liquids has developed at an incredible rate. In this chapter, we explore the different types of ionic liquids available and assess the factors that give rise to their low melting points. This is followed by an evaluation of synthetic methods used to prepare ionic liquids and the problems associated with these methods. The physical properties of ionic liquids are then described and a summary of the properties of ionic liquids that are attractive to clean synthesis is then given. The techniques that have been developed to improve catalyst solubility in ionic liquids to prevent leaching into the organic phase are also covered. 

A frequent complication in the use of an insoluble polymeric support lies in the on-bead characterization of intermediates. Although techniques such as MAS NMR, gel-phase NMR, and single bead IR have had a tremendous effect on the rapid characterization of solid-phase intermediates [27-30], the inherent heterogeneity of solid-phase systems precludes the use of many traditional analytical methods. Liquid-phase synthesis does not suffer from this drawback and permits product characterization on soluble polymer supports by routine analytical methods including UV/visible, IR, and NMR spectroscopies as well as high resolution mass spectrometry. Even traditional synthetic methods such as TLC may be used to monitor reactions without requiring preliminary cleavage from the polymer support [10, 18, 19]. Moreover, aliquots taken for characterization may be returned to the reaction flask upon recovery from these nondestructive... 

In the following few sections we shall now review the most important water-soluble ligands and the synthetic methods of general importance. It should be noted, that in many cases only a few examples of the numerous products available through a certain synthetic procedure are shown in the tables and the reader is referred to the literature for further details. 

Cyclopropanation is an important synthetic method, and enantioselective catalytic reactions of olefins and diazoacetates provide access to valuable products with biological activity. In general, these reactions are conducted in anhydrous solvents and in several cases water was found to diminish the rate or selectivity (or both) of a given process. Therefore it came as a surprise, that the Cyclopropanation of styrene with (+)- or (-)-menthyl diazoacetates, catalyzed by a water-soluble Ru-complex with a chiral bis(hydroxymethyldihydrooxazolyl)pyridine (hm-pybox) ligand proceeded not only faster but with much Wgher enantioselectivity (up to 97 % e.e.) than the analogous reactions in neat THF or toluene(8-28 % e.e.) (Scheme 6.34) [72]. The fine yields and enantioselectivities may be the results of an accidental favourable match of the steric and electronic properties of hm-pybox and those of the menthyl-dizaoacetates, since the hydroxyethyl or isopropyl derivatives of the ligand proved to be inferior to the hydroxymethyl compound. Nevertheless, this is the first catalytic aqueous cyclopropanation which may open the way to other similar reactions in aqueous media. 

Pyridine and its derivatives are technically-important fine chemicals. Their isolation from coal tar is decreasing, whereas their manufacture by synthetic methods has increased rapidly. The classical pathways to pyridine have been discussed by Abramovitch (74HC14-1-4). Many of them rely on the reaction of aldehydes or ketones with ammonia in the vapor phase. However, the condensation processes used suffer from unsatisfactory selectivity. Using soluble organocobalt catalysts of the type [YCoL] allows pyridine and a wide range of 2-substituted derivatives to be prepared selectively and in one step from acetylene and the appropriate cyano compound [Eq.(l)]. 

The Stassfurt deposits have been the subject of elaborate investigations by J. H. van t Hoff and his school.16 In 1849, J. Usiglio 17 studied the deposition of salts when sea.water is cone, by evaporation, and examined the residues analytically. He found that calcium carbonate was first eliminated, then calcium sulphate, then sodium chloride, and the more soluble salts accumulated in the mother liquid. This method of investigation does not allow sufficient time for the various salts to attain a state of equilibrium, and it therefore follows that the natural evaporation of brines probably furnishes somewhat different results. Moreover, it is difficult, if not impossible, to identify the several substances which separate from the mother liquid formed during the later stages of the evaporation. J. H. van t Hoff followed the synthetic method in his study of this subject. He started from simple soln. like those of sodium and potassium chlorides, under definite conditions of temp., and gradually added the pertinent constituents until the subject became so complicated that the crystallization of the constituents from concentrating sea water was reduced to a special case of a far more comprehensive work. 

Carbonylchlorocopper(I) (A) is a valuable precursor for the synthesis of organometallic and coordination compounds of copper(I). Previous methods11 utilizing water, tetrahydrofuran, methanol, or benzene as solvent may yield lower-purity products because copper(I) chloride is not soluble in these solvents without excess halide ligand. The synthetic method described here also provides a convenient way of growing large crystals of X-ray quality of carbonylchlorocopper(I). 

Since successful commercialization of Kapton by Du Pont Company in the 1960s (10), numerous compositions of polyimide and various new methods of syntheses have been described in the literature (1—5). A successful result for each method depends on the nature of the chemical components involved in the system, including monomers, intermediates, solvents, and the polyimide products, as well as on physical conditions during the synthesis. Properties such as monomer reactivity and solubility, and the glass-transition temperature,T, crystallinity, Tm> and melt viscosity of the polyimide products ultimately determine the effectiveness of each process. Accordingly, proper selection of synthetic method is often critical for preparation of polyimides of a given chemical composition. 

The simplest and most generally useful synthetic method for metal diketonates is from the diketone and a metal such as a halide, hydroxide, oxide, sulfate, carbonate, carboxylate, etc. in a variety of solvents such as water, alcohol, carbon tetrachloride or neat diketone. Since many / -diketones are poorly soluble in water, use of an organic solvent or cosolvent may be helpful. Optionally, a base such as sodium carbonate, triethylamine or urea may be added. Addition of a base early in the reaction converts the diketone to its conjugate base, which usually has greater solubility in aqueous media.159 In some cases, metal halide complexes of the diketone form as intermediates, e.g. SnCl4(MeCOCH2COMe), which has been formulated as... 

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