Spiro-orthocarbonate

Sulfur-containing spiro orthocarbonates, cationic polymerization of, 23 729 Sulfur-cured EPDM, 21 8041. See also Ethylene- propylene-diene monomer (EPDM) rubber Sulfur deposits... 

This reaction is thermodynamically controlled, because the polymer containing 1,3-dioxolane rings converts itself to a polyether when allowed to stand at room temperature for several days or heated at 80 °C for a few hours in the presence of an acid catalyst. Similar double ring-opening polymerizations were observed for 2,6,7-trioxabicyclo[2.2.2]octane and its derivatives [86, 87] and for spiro orthoesters and spiro orthocarbonates as well (see Sects. 6 and 7). 

Takata et al. [99] found for two spiro orthocarbonates (119 and 121) having l,4,6,9-tetraoxaspiro[6.6]tridecane skeletons different cationic ring-opening polymerization behavior Irrespective of solvent, initiator, and temperature (from room temperature to 150°C), 119 gave polycarbonate (120), whereas 121 gave poly (ether-carbonate) (122). 

For some seven-membered spiro orthocarbonates (115 and 119), the attack along path b predominates over that along path c, whereas for 114, its derivatives,... 

Cationic polymerization of spiro orthocarbonates leading to a poly (ether-carbonate) alternating copolymer proceeds via the trialkoxycarbenium ion as a possible propagating species. Since this type of carbenium ion was found to be quite stable, [100] the growing chain end is expected to remain living after the completion of the polymerization. [101]... 

Cationic polymerization of norbomene spiro orthocarbonate (125) differs from that of other spiro orthocarbonates in that it gives a structurally complicated polymer. [102] When polymerized with boron trifluoride etherate at 100 °C in chlorobenzene for 24 h, the 1H NMR of a polymer of 125 showed very reduced olefinic proton signals (22% of the original monomer). The monomer was... 

Scheme 20 [103] shows that the polymerization of 131 proceeds via a stable tris(alkylthio)carbenium ion 135. This species can be attacked in three different ways by the second monomer, producing 134, 133, and 132 via paths a, a, and b, respectively. Kinetically, path a should dominate over the others. Path a is one of the possible pathways, but presumably it is of minor importance. Although the conversion of 134 to 132 cannot be ruled out, 132 is more likely to be formed via path b, as is the case with six-membered spiro orthocarbonates. At high... 

In contrast, radical polymerization of 2,3-benzo-7-methylene-l,4,6,9-tetraoxa-spiro[4.4]nona-2-ene (138) gave only a vinyl polymer (139) with no occurrence of ring-opening isomerization, even in the solution polymerization at 165 °C. [105] It appears that the propagating radical having a spiro orthocarbonate structure is too stable to liberate the corresponding carbonyl compound, phenylene carbonate. 

Patent Synthesis of Spiro Orthoesters, Spiro Orthocarbonates, and... 

In a similar combination of insertions of C=S into Sn—O bonds, and elimination of (Bu3Sn)2S, bis(tributyltin) derivatives of 1,2-diols react with CS2 to give first the corresponding cyclic ethylene thionocarbonate, and then the spiro-orthocarbonate . 

A combination of 1,2-addition and 1,5-elimination reactions between an organotin glycolate and carbon disulfide gives ethylene thionocarbonate, which by a similar sequence reacts with more glycolate to give a spiro-orthocarbonate.60... 

Figure 15. Radical ring-opening polymerization of spiro orthocarbonate derivatives bearing an exo-methylene group at a- (a) and P-position (b) of the...

Ring-Opening Pofymerization of a 2-Methylene Spiro Orthocarbonate Bearing a Pendant Methacrylate Group... 

Figure 2. Structures of an alternate spiro orthoester methacrylate (2) and the Spiro orthocarbonate methacrylate (SOCM, 3) monomer.

The IR spectra in Figure 4 trace the synthetic pathway to the SOCM monomer 3. The entire series is dominated by the strong IR bands characteristic of the spiro orthocarbonate group. IR absorptions associated with the shortened CO4 centr ether bonds occur near 1200 cm while the external ether bands are found near 1050 cm. Intermediates 6 and 7 produce a strong OH band around 3400 cm and 7 also yields peaks due to the oxaspiro-based double bond at 1698 and 880 cm". Addition of the methacrylate group in monomer 3 eliminates the OH band and gives rise to the carbonyl and methacrylate vinyl absorptions at 1720 and 1637 cm", respectively. 

Norbornene-spiro-orthocarbonate A compound that, when added in small concentrations to matrix resin of carbon composites, apparently strengthens the fiber-matrix interfacial bond, as evidenced by improved strength properties and lower water absorption of the composites. 

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