Stable organic cation salts: Ion pair equilibria and use in cationic polymerisation

Ledwith, A.; Sherrington, David C.

doi:10.1007/3-540-07460-0_1

Cited by 29 publications

(3 citation statements)

References 121 publications

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“…Ring-opening of THF occurs upon interaction of a strong Brønsted or Lewis acid with the oxygen to form a cationic tertiary oxonium ion, which is activated to nucleophilic attack at the α-carbon . The THF ring-opening initiator can be a simple acid, an electrophilic phosphine (PBr 3 ), a Lewis acidic transition metal 33 or a lanthanide 34 complex.…”

Section: Resultssupporting

confidence: 81%

Synthesis of the Bifunctional Phosphinidene Cluster, Fe₃(CO)₉(μ₃-PH)₂, and a Systematic Study of the Reactivity of the Cluster-Bound P−H Functional Group

et al. 2000

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The synthesis and systematic study of the reaction chemistry of a bifunctional phosphinidene cluster, Fe3(CO)9(μ3-PH)2 (3) is reported. Reaction chemistry at one P−H functional site is effectively communicated through the Fe3(CO)9 core, and impacts on the reactivity of the second P−H site. Deprotonation of the acidic protons in 3 allows access to a lone electron pair on phosphorus. The first proton is readily removed with NEt3/[PPN]Cl ([PPN]+ = (Ph3P)2N+) to produce the [PPN]+ salt of [Fe3(CO)9(μ3-PH)(μ3-P)]- ([4]-). Removal of both phosphorus-bound hydrogen atoms in 3 requires the use of 2 equiv of n-BuLi, to produce Li2[Fe3(CO)9(μ3-P)2] (Li2[5]). Quenching of Li2[5] with MeOH-d 4 generates [Fe3(CO)9(μ3-PD)(μ3-P)]-. The lone electron pairs on the cluster-bound phosphorus atoms undergo analogous reaction chemistry to organophosphines. Alkylation at the phosphorus site is carried out by reaction of [Et3NH][4] with MeOSO2CF3 generating the monosubstituted cluster, Fe3(CO)9(μ3-PMe)(μ3-PH) (6) as the primary product. The cluster anions [4]- and [8]-, containing a phosphorus lone pair, are oxidized by elemental sulfur to produce the phosphine sulfide complexes, [Et3NH][Fe3(CO)9(μ3-PH)(μ3-PS)] ([Et3NH][10]) and [Et3NH][Fe3(CO)9 (μ3-PMe)(μ3-PS)] ([Et3NH][11]). Treatment of [10]- with an additional equivalent of NEt3 and S8 yields the dianionic cluster, [Et3NH]2[Fe3(CO)9(μ3-PS)2] ([Et3NH]2[12]). Without added base, reaction of the neutral clusters, 3 and 6, with S8 in THF solution yield the clusters Fe3(CO)9(μ3-PH)(μ3-PSCH2CH2CH2CH2OH) (13), Fe3(CO)9(μ3-PSCH2CH2CH2CH2OH)2 (14), and Fe3(CO)9(μ3-PMe)(μ3-PSCH2CH2CH2CH2OH) (15), with a ring-opened THF molecule appended to sulfur. Reaction of 3 with S8 in THF solution in the presence of ClAuPPh3 produces the gold derivative, Fe3(CO)9(μ3-PSAuPPh3)2 (17). Like PH groups in phosphines, the μ3-PH moieties in 3 react with activated alkenes to yield single- and double-insertion products, Fe3(CO)9(μ3-PH)(μ3-PCH2CH2R) (R = CN (18a), CO2Me (19a)) and Fe3(CO)9(μ3-PCH2CH2R)2 (R = CN (18b), CO2Me (19b)). The solid-state structures of 3, 17, and 18b were determined by single-crystal X-ray diffraction.

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Section: Resultssupporting

confidence: 81%

Synthesis of the Bifunctional Phosphinidene Cluster, Fe₃(CO)₉(μ₃-PH)₂, and a Systematic Study of the Reactivity of the Cluster-Bound P−H Functional Group

et al. 2000

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“…Very often these initiators eliminate the drawbacks presented by the more common protic and Lewis acid catalysts in that they are chemically well defined and allow a quantitative initiation reaction to proceed without complicated side reactions or the need for cocatalysts and promoters. Stable organic cations have provided a range of initiator systems for a wide variety of cationic polymerizations of olefinic and heterocyclic monomers .…”

Section: Resultsmentioning

confidence: 99%

Preparation of a versatile precursor of novel functionalized polymers: the influence of polymerization conditions on the structure of poly [1-(2-hydroxyethyl)aziridine]

2013

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The cationic polymerization of 1‐(2‐hydroxyethyl)aziridine was approached by means of several catalytic systems under various conditions in order to obtain a versatile hydroxylated starting material for chemical modification reactions. Largely regular polymers were obtained using BF3·EtNH2 and the selected conditions. The expected head and end groups, a secondary amine and a cyclic or branched quaternary ammonium, respectively, were identified with the aid of NMR. However, in all cases we observed the participation of the primary hydroxyl group in chain transfer reactions, leading to morpholine end groups. Kinetic studies performed during the first 120 min of the reactions showed that the more active the catalytic system, the more irregular the polymer structure. The best results were obtained when polymerization was performed with 1 mol% BF3·EtNH2 in the absence of solvent at 45°C, which yielded a polymerization degree of about 44 monomeric units. POLYM. ENG. SCI., 54:579–591, 2014. © 2013 Society of Plastics Engineers

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“…Independently we have shown that such stable carbocation salts are effectively separated from their counterions in CH2C12 at concentrations less than ^--5 M and that under such conditions polymerization of alkyl vinyl ethers occurs by propagation of free cations. 20 This technique affords the possibility to investigate homogeneous cationic polymerization of optically active vinyl ethers with propagation by freely dissociated cationic species. The optical activity of polymers produced under these conditions facilitates qualitative conclusions as to the stereoregulating influence of a chiral center, with a prevailing configuration, present in the monomer, on such freely propagating species.…”

mentioning

confidence: 99%

Stereoregulation in the Free-Ion Propagation of Optically Active Alkyl Vinyl Ethers

Ledwith¹,

Chiellini²,

Solaro³

1979

Macromolecules

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Stable organic cation salts: Ion pair equilibria and use in cationic polymerisation

Cited by 29 publications

References 121 publications

Synthesis of the Bifunctional Phosphinidene Cluster, Fe₃(CO)₉(μ₃-PH)₂, and a Systematic Study of the Reactivity of the Cluster-Bound P−H Functional Group

Synthesis of the Bifunctional Phosphinidene Cluster, Fe₃(CO)₉(μ₃-PH)₂, and a Systematic Study of the Reactivity of the Cluster-Bound P−H Functional Group

Preparation of a versatile precursor of novel functionalized polymers: the influence of polymerization conditions on the structure of poly [1-(2-hydroxyethyl)aziridine]

Stereoregulation in the Free-Ion Propagation of Optically Active Alkyl Vinyl Ethers

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Stable organic cation salts: Ion pair equilibria and use in cationic polymerisation

Cited by 29 publications

References 121 publications

Synthesis of the Bifunctional Phosphinidene Cluster, Fe3(CO)9(μ3-PH)2, and a Systematic Study of the Reactivity of the Cluster-Bound P−H Functional Group

Synthesis of the Bifunctional Phosphinidene Cluster, Fe3(CO)9(μ3-PH)2, and a Systematic Study of the Reactivity of the Cluster-Bound P−H Functional Group

Preparation of a versatile precursor of novel functionalized polymers: the influence of polymerization conditions on the structure of poly [1-(2-hydroxyethyl)aziridine]

Stereoregulation in the Free-Ion Propagation of Optically Active Alkyl Vinyl Ethers

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Synthesis of the Bifunctional Phosphinidene Cluster, Fe₃(CO)₉(μ₃-PH)₂, and a Systematic Study of the Reactivity of the Cluster-Bound P−H Functional Group

Synthesis of the Bifunctional Phosphinidene Cluster, Fe₃(CO)₉(μ₃-PH)₂, and a Systematic Study of the Reactivity of the Cluster-Bound P−H Functional Group