Anionic polymerization of stereoisomers of tetramethyltetraphenylcyclotetrasiloxanes

Vardosanidze, Ts. N.; Андрианов, К. А.; Nogaideli, A. I.; Yakushkina, S.Ye.; Rukhadze, N.P.

doi:10.1016/0032-3950(69)90043-4

Cited by 3 publications

(2 citation statements)

References 4 publications

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“…The first synthesis of this compound was reported in 1948 by Lewis, followed by the report in which partial separation and IR measurement were performed . Eighteen years later, isolation of a cis − trans-cis isomer was effected by distillation and fractional crystallization over a period of 2 months . Since then, structure elucidation by 1 H NMR and X-ray crystallographic analysis of a cis - trans-cis isomer have been accomplished .…”

Section: Resultsmentioning

confidence: 99%

Stereoisomers of 1,3,5,7-Tetrahydroxy-1,3,5,7-tetraisopropylcyclotetrasiloxane: Synthesis and Structures in the Crystal

et al. 2005

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The first synthesis of all four stereoisomers of 1,3,5,7-tetrahydroxy-1,3,5,7-tetraisopropylcyclotetrasiloxane, [i-PrSiO(OH)]4 (all-trans-, cis-cis-trans-, cis-trans-cis-, and all-cis-1), is presented. The starting compounds, all-trans-, cis-cis-trans-, cis-trans-cis-, and all-cis-1,3,5,7-tetraaryl-1,3,5,7-tetraisopropylcyclotetrasiloxanes, were prepared by the hydrolysis of the corresponding arylisopropyldichlorosilanes, i-PrArSiCl2 (Ar = Ph, p-tolyl), and subsequent separation of isomers. A combination of dephenylchlorination of tetraarylcyclotetrasiloxanes and the following hydrolysis proved to be an efficient method for the stereospecific transformation of aryl-substituted cyclotetrasiloxanes into (i-PrSiO(OH))4. For example, treatment of cis-trans-cis-1,3,5,7-tetraphenyl-1,3,5,7-tetraisopropylcyclotetrasilane with HCl and AlCl3, followed by hydrolysis in the presence of pyridine, resulted in the exclusive formation of cis-trans-cis-1 in 92% yield. The structures of cis-cis-trans-1, cis-trans-cis-1, and all-cis-1 were determined by X-ray crystallography. All isomers were found to construct unique packing structures by intermolecular hydrogen bonding; cis-trans-cis-1 composed an infinite antiladder structure, and cis-cis-trans-1 formed a sheetlike structure.

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Section: Resultsmentioning

confidence: 99%

Stereoisomers of 1,3,5,7-Tetrahydroxy-1,3,5,7-tetraisopropylcyclotetrasiloxane: Synthesis and Structures in the Crystal

et al. 2005

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“…Very often, these characteristics can be improved by the substitution of dimethylsiloxane units with those of phenylmethylsiloxane in the PDMS chain (Scheme 1b) [16,17]. The production of polyphenylmethylsiloxanes is usually carried out by anionic or cationic ring opening polymerization of triphenyltrimethylcyclotrisiloxane (Scheme 1c) [18][19][20][21]. They were obtained previously in the presence of strong bases as phosphazene bases [22][23][24][25], strong acids as dodecylbenzenesulfonic acid [26], triflic acid [27], tris(pentafluorophenyl)borane [28] and trifluoromethanesulfonic acid [29], etc.…”

Section: Introductionmentioning

confidence: 99%

Catalytic Activity of Maghnite-H+ in the Synthesis of Polyphenylmethylsiloxane under Mild and Solvent-free Conditions

Kherroub

Belbachir

Lamouri

et al. 2017

Period. Polytech. Chem. Eng.

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A new approach for the polymerization of tetraphenyltetramethylcyclotetrasiloxane by an environmentally friendly catalyst called Maghnite-H+

Kherroub

Belbachir

Lamouri

2018

Green Processing and Synthesis

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This work is devoted to the study of the cationic ring opening polymerization of tetraphenyltetramethylcyclotetrasiloxane (D4Ph,Me), using a solid green catalyst prepared by the activation of a natural clay by sulfuric acid (Maghnite-H+). This treatment leads to the spacing of the montmorillonite sheets due to the substitution of the existing interlayer cations by the protons of the acid. This consequence is clearly shown on the X-ray diffraction (XRD) spectrum. The polymerization reaction proceeded in bulk and under mild conditions. Various tests were carried out by changing the temperature, the time and the catalyst mass content in order to increase, at the same time, the yield of the reaction and the average molecular mass of the polyphenylmethylsiloxane (PPMS) obtained. The structure of the PPMS obtained was identified by infrared (IR), 1H nuclear magnetic resonance (NMR) and 13C NMR analyses over different periods of time. The thermal behavior was investigated by differential scanning calorimetry (DSC) analysis. At the end, in order to show the role played by the Maghnite-H+ during the various reaction stages, a reaction mechanism was proposed.

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Anionic polymerization of stereoisomers of tetramethyltetraphenylcyclotetrasiloxanes

Cited by 3 publications

References 4 publications

Stereoisomers of 1,3,5,7-Tetrahydroxy-1,3,5,7-tetraisopropylcyclotetrasiloxane: Synthesis and Structures in the Crystal

Stereoisomers of 1,3,5,7-Tetrahydroxy-1,3,5,7-tetraisopropylcyclotetrasiloxane: Synthesis and Structures in the Crystal

Catalytic Activity of Maghnite-H+ in the Synthesis of Polyphenylmethylsiloxane under Mild and Solvent-free Conditions

A new approach for the polymerization of tetraphenyltetramethylcyclotetrasiloxane by an environmentally friendly catalyst called Maghnite-H+

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