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1

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Effect of chain length on the glyme-separated ion-pair formation in bolaform salts of α,ω-(9-fluorenyl)polymethylenes (1978)

Collins, George L. ; Hogen Esch, Thieo E. ; Smid, Johannes

Springer

Journal of solution chemistry 7 (1978), S. 9-18

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ISSN: 1572-8927

Keywords: Optical spectroscopy ; bolaform electrolytes ; ion pairs ; ion-pair aggregation ; glyme-separated ion pairs ; α,ω-(9-fluorenylsodium)-polymethylenes ; fluorenylsodium ; tetraglyme ; tetrahydrofuran ; tetrahydropyran

Source: Springer Online Journal Archives 1860-2000

Topics: Chemistry and Pharmacology

Notes: Abstract Formation constants of tetraglyme (glyme 5) separated ion pairs of bolaform electrolytes of the type Na+,−Fl(CH2) n Fl−, Na+ (Fl− denoting a fluorenyl carbanion) were measured spectrophotometrically in tetrahydrofuran (THF) and tetrahydropyran (THP) at 25°C as a function of the chain lengthn, withn=2, 3, 4, or 6. The ratiosK 1/K 2 of the first and second glyme ion-pair separation steps were found to be equal to the statistical factor 4 in all cases except in THP for the compoundn=2, where the ratio is 15. Values ofK 1 as well as K 2 increase considerably with chain length, the former by a factor 19 asn increases from 2 to 6. The ion-pair separation with glyme 5 is easier in THP than in THF. The results are discussed in terms of differences in external cation solvation and the possible involvement of cyclized structures or curled conformations as a result of interactions between the terminal ion pairs.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00654214

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2

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Stereochemistry of anionic oligomerization, 22Part 21: cf.. Effects of chain length and stereochemistry on the kinetics of addition of 1,1-diphenylethylene to oligomeric models of living poly(2-vinylpyridine)lithiumDedicated to Dr. Paul Rempp on the occasion of his 60th birthday (1989)

Helary, Gerard ; Fontanille, Michel ; Khan, Ishrat M. ; [et al.]

New York : Wiley-Blackwell

Die Makromolekulare Chemie 190 (1989), S. 341-348

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ISSN: 0025-116X

Keywords: Chemistry ; Polymer and Materials Science

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology , Physics

Notes: Rate constants and equilibrium constants were determined for the addition of 1,1-diphenylethylene to living trimers of 2-vinylpyridine in THF having either a meso or a racemic diad adjacent to the carbanion center. The racemic isomer was shown to be slightly more reactive (≈40%) compared with the meso isomer and slightly less than the corresponding dimer. The living dimer of 2-vinylpyridine in turn is slightly more reactive than the meso trimer, but is five times less reactive compared to the lithio salt of 2-ethylpyridine. The changes in equilibrium constant were quite dramatic, the constant for lithio-2-ethylpyridine being about 100-200 times larger than for the living oligomers and about 2 600 times larger than that of the living polymer.

Additional Material: 3 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/macp.1989.021900212

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3

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Relative affinities of mono and difunctional sulfoxides for lithium picrate in toluene. Effects of structure and stereochemistry (1987)

Buese, Mark A. ; Hogen-Esch, Thieo E. ; Xu, Wen-Ying ; [et al.]

New York : Wiley-Blackwell

Die Makromolekulare Chemie 188 (1987), S. 1631-1634

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ISSN: 0025-116X

Keywords: Chemistry ; Polymer and Materials Science

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology , Physics

Notes: The relative affinity of various mono and difunctional sulfoxides for lithium picrate in toluene was investigated by a competition method utilizing immobilized linear polyethers (glymes). In general, the difunctional sulfoxides were found to bind more strongly than the monofunctional sulfoxides. However, difunctional ligands which would result in eight-membered ring chelated structures bound lithium ion more strongly than those which would result in six-membered ring chelated structures.

Additional Material: 1 Tab.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/macp.1987.021880709

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4

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Synthesis of a stereoblock poly(methyl methacrylate) (1986)

Doherty, Martin A. ; Hogen-Esch, Thieo E.

New York : Wiley-Blackwell

Die Makromolekulare Chemie 187 (1986), S. 61-69

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ISSN: 0025-116X

Keywords: Chemistry ; Polymer and Materials Science

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology , Physics

Notes: The sequential block copolymerization of diphenylmethyl methacrylate (DMA) and trityl methacrylate (TrMA), initiated by diphenyl methyl lithium in THF at -78°C followed by hydrolysis and methylation with diazomethane, leads to the formation of an isotacticsyndiotactic stereoblock poly(methylmethacrylate) (PMMA) of narrow molecular weight and block length distribution. Complete conversion of DMA is shown to be essential, since the presence of small quantities of this monomer during the polymerization of TrMA significantly lowers the isotactic content of this block. Polymerization times of at least 12 h were found to be necessary for complete polymerization of the TrMA.

Additional Material: 4 Tab.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/macp.1986.021870106

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5

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Oligomerization of vinyl monomers. XXI. Characterization of model carbanions of living poly(2-vinylpyridine) in THF by 7Li-NMR and conductance: Evidence for the occurrence and nature of triple ion formation (1988)

Khan, Ishrat M. ; Hogen-Esch, Thieo E.

Bognor Regis [u.a.] : Wiley-Blackwell

Journal of Polymer Science Part A: Polymer Chemistry 26 (1988), S. 2553-2559

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ISSN: 0887-624X

Keywords: Chemistry ; Polymer and Materials Science

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: The formation of triple anions is demonstrated by 7Li-NMR in THF solutions of 1-lithio-1-(2-pyridyl)ethane, 1-lithio-1(3-methyl-2-pyridyl)ethane, and 1-lithio-1,3-di(2-pyridyl) butane. Good agreement with conductance data was demonstrated in the case of 1. Triple anion formation in the case of 2 was found to be about twice as high as in 1 possibly as a result of the greater charge density on the carbanion in the case of 2.

Additional Material: 3 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/pola.1988.080260924

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6

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Synthesis and characterization of poly (2-vinylpridine)-b-poly (t-butyl methacrylate) (1994)

Yin, Rui ; Hogen-Esch, Thieo E.

Bognor Regis [u.a.] : Wiley-Blackwell

Journal of Polymer Science Part A: Polymer Chemistry 32 (1994), S. 363-368

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ISSN: 0887-624X

Keywords: 2-vinylpyridine ; t-butyl methacrylate ; anionic polymerization ; Chemistry ; Polymer and Materials Science

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: The synthesis of well defined and monodisperse (Mw/Mn ≤ 1.2) narrow molecular weight distribution poly (2-vinylpyridine)-poly (t-butyl methacrylate) (P2VP-PTBMA) AB block copolymers is carried out by initiation of 2-vinylpyridine polymerization by 1,1-diphenylhexyllithium in THF at-78°C, followed by addition of TBMA and termination at -78°C using MeOH. The formation of the BAB block copolymer is carried out in a similar fashion except that 1,4-dilithio-1,1,4,4-tetraphenylbutane is used as initiator. The corresponding synthesis of P2VP-PMMA block copolymers is carried in a similar manner, except that 1-2 equivalents of TBMA is used to end-functionalize the living P2VP before the addition of MMA. Without the addition of TBMA, trimodal molecular weight distributions in P2VP-b-PMMA are obtained. All the block copolymers are characterized by Size Exclusion Chromatography (SEC), Nuclear Magnetic Resonance (NMR), and Differential Scanning Calorimetry (DSC). © 1994 John Wiley & Sons, Inc.

Additional Material: 3 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/pola.1994.080320218

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7

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Formation of macrocyclic polymers by intramolecular coupling of α,ω-difunctional precursors. Numerical evaluations (1996)

Dong, Dahai ; Hogen-Esch, Thieo E. ; Shaffer, J. Scott

Weinheim : Wiley-Blackwell

Macromolecular Chemistry and Physics 197 (1996), S. 3397-3406

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ISSN: 1022-1352

Keywords: Chemistry ; Polymer and Materials Science

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology , Physics

Notes: The end-to-end cyclization reaction of living monodisperse α,ω-dianion precursors with difunctional electrophiles (EX2) in the presence of partial anion termination is described. A computer simulation was developed to establish the relationship among the initial concentration, the molecular weight of the dianion precursor, the extent of anion termination, and the yield distribution for all of the cyclic and linear polymer species. A master curve is calculated allowing the determination of the macrocycle yield as a function of MW and concentration of the dianion precursor, and degree of anion termination.

Additional Material: 4 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/macp.1996.021971026

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8

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Anionic polymerization of 2-vinylpyridine: a computational study of solvent effects on polymerization stereochemistry.Dedicated to Professor Adi Eisenberg on the occasion of his 60th birthday (1996)

Pratt, Lawrence M. ; Khan, Ishrat M. ; Hogen-Esch, Thieo E.

Weinheim : Wiley-Blackwell

Macromolecular Chemistry and Physics 197 (1996), S. 3555-3566

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ISSN: 1022-1352

Keywords: Chemistry ; Polymer and Materials Science

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology , Physics

Notes: Anionic polymerization of 2-vinylpyridine shows significant solvent effects on the polymer stereochemistry. Polymerization with butyllithium in tetrahydrofuran (THF) yields a largely isotactic polymer, while polymerization with butyllithium in tetramethyl-ethylenediamine (TMEDA) results in a material with nearly the same stereochemistry as radical polymerization. Semiempirical molecular orbital calculations were used to explain these solvent effects.

Additional Material: 4 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/macp.1996.021971106

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9

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Oligomerization of vinyl monomers 18. Stereochemistry of anionic oligomerization of 4-vinylpyridine (1985)

Meverden, Craig C. ; Hogen-Esch, Thieo E.

New York : Wiley-Blackwell

Journal of Polymer Science: Polymer Chemistry Edition 23 (1985), S. 159-168

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ISSN: 0360-6376

Keywords: Physics ; Polymer and Materials Science

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Oligomers of 4-vinylpyridine were prepared by reaction in vacuo of 4-vinylpyridine with lithio-4-ethylpyridine at -78°C, followed by reaction with CH3I(13CH3I) or CH3OH. The stereochemistry was studied by NMR and GC. Methylation and the addition of 4-vinylpyridine occurred in a stereochemically nonselective manner. The data also indicated that in contrast to the oligomerization of 2-vinylpyridine the stereoisomeric meso and racemic 4-pyridyl carbanions propagated with equal reaction rates. The stereochemistry was readily explained by an absence of coordination of the Li ion by the nitrogen of the penultimate pyridine ring observed in the corresponding oligomerization of 2-vinylpyridine.

Additional Material: 5 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/pol.1985.170230116

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10

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Oligomerization stereochemistry of vinyl monomers III. Ion-pair effects on the stereoselective anionic oligomerization of 2-vinyl pyridine (1978)

Tien, C. F. ; Hogen-Esch, Thieo E.

New York : Wiley-Blackwell

Journal of Polymer Science: Polymer Letters Edition 16 (1978), S. 297-302

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ISSN: 0360-6384

Keywords: Chemistry ; Polymer and Materials Science

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Additional Material: 4 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/pol.1978.130160609

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