Soluble-insoluble changes, periodic

The periodic changes of linear and un-cross-linked polymer chains can be easily observed as cyclic transparent and opaque changes for the polymer solution with color changes due to the redox oscillation of the catalyst [32]. Synchronized with the periodical changes between Ru(II) and Ru(III) states of the Ru(bpy)3 " site, the polymer becomes hydrophobic and hydrophilic, and exhibits cyclic soluble-insoluble changes (Figure 7.9). 

Base-free dialkylmagnesium is sensitive to oxygen and reacts violently with water. It melts at 200-205°, though it does not sublime until 180° in vacuum. It is insoluble in benzene and petroleum ether, although it is readily soluble in diethyl ether and tetrahydrofuran. The diethyl ether solutions are conveniently stored at 0-5°. The titer does not change over a period of 1 month. The compound can be further characterized as its Af. /V)jV,jV,-tetramethylethylene-diamine complex, [Mg(Me3Si)CH2]2 tmed, mp 93-95°. 

The presence of soluble impurities can also affect the induction period, (section 5.5), but it is virtually impossible to predict the effect. Ionic impurities, especially Fe + and Cr +, may increase the induction period in aqueous solutions of inorganic salts. Some substances, such as sodium carboxymethyl-cellulose or polyacrylamide, can also increase whereas others may have no effect at all. The effects of soluble impurities may be caused by changing the equilibrium solubility or the solution structure, by adsorption or chemisorption on nuclei or heteronuclei, by chemical reaction or complex formation in the solution, and so on. The effects of insoluble impurities are also unpredictable. 

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