Cyclotetrasiloxane equation

When (Me2SiO)3 (D3) was present, the diarylsilanone (83) was intercepted as the cyclotetrasiloxane (equation 130) this is a known reaction for silanone capture. 

Barton and Hussmann suggested that a silylsilanone-to-siloxysilylene rearrangement occurred during the copyrolysis of cyclotetrasiloxane 58 with butadiene to afford the corresponding silacyclopentene (equation 47)123. 

Figure 16 4. Experimentally obtained equilibrium constants Kcof cyclization as a function of the number N of ring atoms for bulk polyreactions of cyclooctene (PCO) at 25° C, terephthalic acid and ethylene glycol (PET) at 270 C, and octamethyl cyclotetrasiloxane (PDMS) at 110° C. The dotted lines give the theoretically calculated dependence according to Equation (16-49), with the slope —5/2.

Linear polysiloxane can be synthesized by both anionic and cationic polymerizations of cyclic siloxanes such as hexamethylcyclotrisiloxane (n = 3) and octamethyl cyclotetrasiloxane (n = 4). Anionic polymerization is initiated by hydroxide, alkoxides, phenolates, silanolates and siloxoano-lates. The active species in the polymerization is the silanolate anion. Cationic polymerization is initiated by strong protonic acids such as sulfuric acid, trifluoromethane sulfonic acid and trifluoro-acetic acid (equation 53). Both the anionic and the cationic species undergo backbiting reactions during polymerization, such that an equilibrium exists between linear chains and rings. ... 

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