Reaction with solubilizers

The cyciomaitodextrins (a-CD, -CD, and y-CD) can be selectively obtained from a fermentation culture or an enzyme digest of cyclomaltodextrin glucanotransferase reaction with solubilized starch. The majority of the cyclomaltohexaose (a-CD) can be separated from cycloma-Itoheptaose (/3-CD) and y-CD by their selective precipitation with p-cymene from the culture supernatant or from an enzyme digest [168]. The a-CD can then be precipitated from the supernatant with cyclohexene, which is extracted with acetone to remove the cyclohexene and the a-CD can be crystallized from water or a propanol-1/water solution [169]. The p-cymene precipitates of /3-CD and y-CD are put into a water solution and /3-CD selectively precipitated from y-CD with fluorobenzene. The y-CD is then precipitated with anthracene saturated in diethyl ether. After the removal of the fluorobenzene from /3-CD with acetone or ethanol extraction, /3-CD can be crystallized from water, and after the removal of anthracene with acetone or ethanol extraction from y-CD, it can also be crystallized from water [170,171]. The selective precipitations of the cyciomaitodextrins with various organic molecules is based on the selective formation of complexes of the organic molecules with the specific sizes of the cyciomaitodextrins and the relatively hydrophobic interior cavities of the cyciomaitodextrins [166,167,168]. 

In the first method a secondary acetylenic bromide is warmed in THF with an equivalent amount of copper(I) cyanide. We found that a small amount of anhydrous lithium bromide is necessary to effect solubilization of the copper cyanide. Primary acetylenic bromides, RCECCH Br, under these conditions afford mainly the acetylenic nitriles, RCsCCHjCsN (see Chapter VIII). The aqueous procedure for the allenic nitriles is more attractive, in our opinion, because only a catalytic amount of copper cyanide is required the reaction of the acetylenic bromide with the KClV.CuCN complex is faster than the reaction with KCN. Excellent yields of allenic nitriles can be obtained if the potassium cyanide is added at a moderate rate during the reaction. Excess of KCN has to be avoided, as it causes resinifi-cation of the allenic nitrile. In the case of propargyl bromide 1,1-substitution may also occur, but the propargyl cyanide immediately isomerizes under the influence of the potassium cyanide. 

The strategy of Kaeriyama represents a so-called precursor route and was developed to overcome the characteristic shortcomings (insolubility, lack of process-ability) of previous PPP syntheses. The condensation reaction is carried out with solubilized monomers, leading to a soluble polymeric intermediate. In the final reaction step this intermediate is then converted, preferentially in the solid state allowing the formation of homogeneous PPP films or layers, into PPP (or other poly(arylene)s). 

The diphenylamino-substituted PPV107, with solubilizing alkoxy groups, was synthesized by Shi and Zheng [150] via Wittig-Horner reaction (Chart 2.23). Its PL (555 nm) is very similar to that of diamino-PPV 64 and dialkoxy-PPV 14 homopolymers. The PLQY is rather high in solution (80%), but it drops to only 8% in films. Consequently, only a moderate EL efficiency of 0.6cd/A was obtained with this material (device ITO/PEDOT/107/Mg/Al) [150]. Almost simultaneously, Kido and coworkers [151] reported a similar diphenylamino-substituted PPV copolymer 108, which affords very efficient PLEDs. The device ITO/PEDOT/108/Ca/Al... 

Interestingly, the Fe2+ ion in the core can be easily removed by base, the complex dissociates and the individual polymer dimers can be analyzed. Block copolymers of 2-ethyl-2-oxazoline with other substituted oxazolines have also been made [121]. Ru2+(4,4 dichloromethyl-2,2 bipyridine)3 has also been used as the multifunctional initiator for the ATRP of styrene at 110°C [122], It is interesting to note that the Cu+ ions necessary for the polymerization reaction are solubilized via complexation with other bipyridine species. 

Nucleophilic substitution reactions of halide anions in aprotic solvents are often accompanied by elimination reactions. For instance, reactions of secondary alkyl halides with potassium fluoride solubilized in acetonitrile with the aid of 18-crown-6 [3] give olefins as the main reaction product (Liotta and Harris, 1974). Similarly, the dicyclohexyl-18-crown-6 complex of potassium iodide acted exclusively as a base in its reaction with 2-bromo-octane in DMF (Sam and Simmons, 1974). The strongly basic character of weakly solvated fluoride has been exploited in peptide synthesis (Klausner and Chorev, 1977 Chorev and Klausner, 1976). It was shown that potassium fluoride solubilized... 

Humus/SOM enter into a wide variety of physical and chemical interactions, including sorption, ion exchange, free radical reactions, and solubilization. The water holding capacity and buffering capacity of solid surfaces and the availability of nutrients to plants are controlled to a large extent by the amount of humus in the solids. Humus also interacts with solid minerals to aid in the weathering and decomposition of silicate and aluminosilicate minerals. It is also adsorbed by some minerals. 

Other aspects of solvation have included the use of surfactants (SDS, CTAB, Triton X-100), sometimes in pyridine-containing solution, to solubilize and de-aggregate hemes, i.e., to dissolve them in water (see porphyrin complexes, Section 5.4.3.7.2). An example is provided by the solubilization of an iron-copper diporphyrin to permit a study of its reactions with dioxygen and with carbon monoxide in an aqueous environment. Iron complexes have provided the lipophilic and hydrophilic components in the bifunctional phase transfer catalysts [Fe(diimine)2Cl2]Cl and [EtsBzNJpeCU], respectively. 

Elemental composition Ni 53.00%, C 21.69%, N 25.30%. The compound may be identified by x-ray and selective chemical reactions with cyanide ions. Nickel may be analyzed in an acidified aqueous solution after it is solubilized with concentrated nitric acid or aqua regia (See Nickel). 

Elemental composition (Rh203) Rh 81.09%, 0 18.91%. The oxide may be solubilized by treatment with alkali to form hydrated oxide, which may be dissolved in acid and diluted for analysis of rhodium metal by AA or ICP. The oxide may be characterized by x-ray diffraction, physical properties, and reaction with strong alkali to form yellow precipitate of pentahydrate, and in excess alkali a black precipitate of the trihydrate. 

Reaction in the liquid phase (Trxn). Now consider the case where an irreversible, first-order reaction with rate constant k (s-1) takes place, in addition to diffusion and solubilization. Equation (CCC) becomes... 

The products of the reactions between silver(I) carboxylates and triphenylphosphine were colourless, diamagnetic solids, stable at room temperature to oxygen and not significantly light sensitive. Reaction with triphenylphosphine was also found useful as a method of solubilizing silver carboxylates. 

Bacterial cytochrome oxidases offer an interesting area of study that complements well that of mitochondrial cytochrome oxidase. In some cases they are readily solubilized from the membrane they tend to have fewer subunits than the mitochondrial oxidase and they form stable intermediates during the reaction with dioxygen. They often do not have a role in energy transduction, a fact reflected in their simpler structures. 

---