Catalysis with Cation-Exchange Resins

Astle, Melvin J.; Zaslowsky, J. A.; Lafyatis, Paul G.

doi:10.1021/ie50532a049

Cited by 68 publications

(14 citation statements)

References 2 publications

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“…A possible explanation for the formation of the AB diads is the difference between the growing species of DOL and THF in these two initiator series. In the cationic polymerization of cyclic ethers initiated with superacids or their esters, the contributions of ester growing species have been confirmed by means of 1 H, 13 C, and 19 F NMR spectroscopy. 17 Moreover, in the cationic polymerization of DOL in chloroform with CH 3 0S0 2 F, the propagation through the ester species -OCH20S02 F has been deduced from kinetic data as well as NMR spectral data.'…”

Section: Discussionmentioning

confidence: 88%

“…1,3-Dioxolane (DOL) was prepared according to the procedure described by Astle eta!., 13 dried over metallic sodium, and fractionally distilled from calcium hydride. bp 75-76°C.…”

Section: Methodsmentioning

confidence: 99%

“…The validity of these assignments is confirmed by the calculation of AB diad fractions based on the assignments of the three signals a, {3, and y, as will be described below. 13 C NMR spectra of the hexane-soluble and -insoluble parts of the .copolymers prepared with Et30BF 4 show only one signal, assigned to the acetal carbon in the triad AAA (VI and VII in Figure 4); this indicates that very few AB diad, if any, are present in the copolymer chain.…”

Section: Babmentioning

confidence: 98%

“…3.6 (-OCH 2 -, 12H), and 4.74 (-OCH 2 0-, lution. The mixture was poured into a large amount 2H) ppm; 13 …”

Section: Fractionation Of Copolymermentioning

confidence: 99%

“…The signal y at 13 95.6 ppm corresponds to that of the acetal carbon in the DOL homopolymer, and is assigned to the acetal carbon in the triad AAA 6. From the chemical shifts of the acetal carbon in 4 and 5 (13 -OCH 2 CH 2 CH 2 CH 2 -0CH 2 CH20CH2-0CH2CH2CH2CHz-…”

Section: Fractionation Of Copolymersmentioning

confidence: 99%

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Cationic Copolymerization of 1,3-Dioxolane with Tetrahydrofuran Initiated with Methyl Fluorosulfate

Yokoyama

Okada

Sumitomo

1979

Polym J

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ABSTRACT:Cationic copolymerization of 1,3-dioxolane (DOL) with tetrahydrofuran (THF) was carried out in chloroform at ooc with methyl fluorosulfate (CH30S02 F) and triethyloxonium tetrafluoroborate (Et30BF4 ) as initiators. The gas chromatographic determination of the residual monomers during the copolymerization revealed that both DOL and THF were consumed concurrently from the initial stage of the polymerization with CH30S02 F. With Et30BF4 , on the other hand, only THF was consumed at first, followed by the rapid consumption of DOL after an induction period. The fractionation of the reaction products and the microstructural analysis by 1 H and 13 C NMR spectroscopy showed that the products obtained with CH30S02F were real copolymers containing an appreciable ammount of cross-over diads, while those with Et30BF4 were block copolymers and/or mixtures of homopolymers. The structures and reactivities of the growing species in these two copolymerization systems are discussed on the basis of these findings. In a previous paper, 1 we reported kinetic studies on the cationic polymerization of I ,3-dioxolane (DOL) initiated with methyl fluorosulfate (CH 3 0S02 F) in deuteriochloroform, and concluded that the polymerization proceeded through an ester growing species, although the coexistence of an undetectable amount of oxonium ionic growing species can not be ruled out. This conclusion was drawn on the basis of a large negative value of the activation entropy [8S:= -42calmol-1 deg-1 ( -176 J k -1 mol-1 )], which is characteristic of dipole-dipole SN2 reactions producing ionic species, e.g., the Menschutkin reaction, together with 1 Hand 13 C NMR scpectral data of the reaction system. This paper describes the cationic copolymerization of DOL with THF which was undertaken in chloroform using two different initiators, CH 3 0S0 2 F and Et30BF4 , in order to make clear the reactivity of the ester growing species in the polymerization of DOL.The cationic copolymerization of DOL with THF using stable oxonium salts as initiators has been attempted by two research groups. 2 • 3 Yamashita et a/. 2 confirmed by the gas chromatographic determination of the unreacted monomers during the copolymerization initiated with Et30BF4 that preferential polymerization of THF occurred in the initial stage of the copolymerization, and that once DOL began to polymerize after an induction period, the polymerization of THF slowed down gradually and eventually ceased. However, it was resumed, although very slowly, after the polymerization of DOL reached the equilibrium conversion. Lyudvig et a/. 3 studied the same copolymerization with Et 3 0SbCI 6 as an initiator and they concluded that the propagating species of DOL, which are supposedly solvated by THF monomers, grow only by the addition of DOL monomers, in agreement with the results of Yamashita et a/. 2 It seems strange at first glance that DOL cannot copolymerize with THF, because both DOL 4 · 5 and THF 6 • 7 copolymerize with 3,3-bischloromethyloxacyclobutane (BCMO), and both growing speci...

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Section: Discussionmentioning

confidence: 88%

“…1,3-Dioxolane (DOL) was prepared according to the procedure described by Astle eta!., 13 dried over metallic sodium, and fractionally distilled from calcium hydride. bp 75-76°C.…”

Section: Methodsmentioning

confidence: 99%

Section: Babmentioning

confidence: 98%

“…3.6 (-OCH 2 -, 12H), and 4.74 (-OCH 2 0-, lution. The mixture was poured into a large amount 2H) ppm; 13 …”

Section: Fractionation Of Copolymermentioning

confidence: 99%

Section: Fractionation Of Copolymersmentioning

confidence: 99%

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