Dilute cyclohexane solution

Linear permethylpolysilanes Me(Me2Si) Me with n = 4-8 also undergo photolysis when their cyclohexane solutions are irradiated with a low-pressure mercury lamp (32,33). Octamethyltrisilane is always produced as the major volatile product, in addition to 1-hydroheptamethyltrisilane and polymeric substances arising from polymerization of dimethylsilyl-ene. Octamethyltrisilane (Xmax 215.0 nm) is photochemically rather stable under the conditions used, but prolonged irradiation of its dilute cyclohexane solution causes skeletal contraction, giving hexamethyldisilane with extrusion of dimethylsilylene. 

Figure 4. Time-dependent anisotropy for anthracene-labeled polyisoprene in dilute cyclohexane solution. The smooth curve through the data is the best fit to the Bendler-Yaris model(Ti=210 ps, t2=2750 ps, and r(0)=0.243).

Fig. 6.5. The temperature dependence of the hydrodynamic radius of high molecular weight (2-7x10 ) polystyrene in a very dilute cyclohexane solution showing the coil-to-globule transition (after Swislow et al., 1980).

Accordingly, the photolysis of the dihalomaleic anhydrides was examined. In the solid state the dichloro compound 211 gave the same polymer 212 as was obtained from thermolysis,a result which permits-but does not require-an aryne interpretation. In dilute cyclohexane solution, however, a monosubstitution product (220) (and no polymer) was isolated, indicating a stepwise decomposition. Irradiation of the dibromo compound 209... 

Table I. Collective results for model molecules In dilute cyclohexane solutions with Drago constants for acids (19).

One of the most intensively studied examples of excimer-forming molecules is pyrene. In dilute cyclohexane solution (10 M), the emission spectrum contains a... 

The concentration of the complex is obtained from the visible band of diiodine as follows. A highly diluted cyclohexane solution (So) of diiodine at concentration C obeys Beer s law at any wavelength A. ... 

Burchard [65] was the pioneer for the preparation of functional starshaped pol)miers in nonpolar solvents by an anionic core-first method. To build the cores pure / -DVB was reacted with /i-butyllithium in dilute cyclohexane solution. Suspensions of small crosslinked poly(DVB) noduli were obtained that contained numerous lithium organic sites. In a second step, styrene (or isoprene) was added to the living cores and polymerized. The polymeric species obtained exhibit huge molar mass distribution and rather large polydispersity indices. Even if these star-shaped polymers could exhibit active sites at the outer end of the branches, the efficiency of initiation of a second generation of monomers or of hmctionalization was never given by the authors. 

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