Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Chemistry  (13)
  • Organic Chemistry  (1)
  • bolaform electrolytes  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Effect of chain length on the glyme-separated ion-pair formation in bolaform salts of α,ω-(9-fluorenyl)polymethylenes (1978)
    Springer
    Journal of solution chemistry 7 (1978), S. 9-18 
    Details
    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
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    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)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 190 (1989), S. 341-348 
    Details
    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
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Relative affinities of mono and difunctional sulfoxides for lithium picrate in toluene. Effects of structure and stereochemistry (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 1631-1634 
    Details
    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
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Synthesis of a stereoblock poly(methyl methacrylate) (1986)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 187 (1986), S. 61-69 
    Details
    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
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    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)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 26 (1988), S. 2553-2559 
    Details
    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
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Synthesis and characterization of poly (2-vinylpridine)-b-poly (t-butyl methacrylate) (1994)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 32 (1994), S. 363-368 
    Details
    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
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Formation of macrocyclic polymers by intramolecular coupling of α,ω-difunctional precursors. Numerical evaluations (1996)
    Weinheim : Wiley-Blackwell
    Macromolecular Chemistry and Physics 197 (1996), S. 3397-3406 
    Details
    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
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    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)
    Weinheim : Wiley-Blackwell
    Macromolecular Chemistry and Physics 197 (1996), S. 3555-3566 
    Details
    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
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Stereochemical control in anionic polymerization of 2-vinylpyridine and related vinyl monomers (1995)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 8 (1995), S. 222-230 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The alkylation, silylation and other electrophilic reactions of 1-lithio-1,3-bis(2-pyridyl)butane (2a) in THF at -78°C leads to meso-like products that may be accounted for by intramolecular coordination of Li ion with the penultimate 2-pyridyl group. This is also demonstrated by proton-transfer equilibria between 1-lithio-2-ethylpyridine and 2a, allowing the determination of the ΔH and ΔS of intramolecular chelation in 2a. The ΔS of chelation is nearly zero, probably as a result of chelation-induced desolvation of Li ion. Surprisingly, however, the corresponding addition of 2-vinylpyridine to 2a and higher P2VPLi homologs in THF is not stereoselective. In toluene at -78°C the t-BuLi-initiated polymerization of 2-VP is actually somewhat syndiotactic (rr = 0·44). The presence in this polymerization of at least one equivalent of t-BuOLi or other tertiary ROLi surprisingly leads to isotactic P2VP. SEC viscometric and other studies indicate that both the P2VPLi- and P2VPLi-ROLi complexes are monomeric in toluene. The stereochemistry is apparently due to a 1 : 1 P2VPLi-ROLi complex that discriminates between the two pro-chiral faces of the anion by preferntial coordination of the (ROLi2) moiety to the meso-prochiral face. Isotactic-like addition now occurs by electrophilic attack of 2-VP that is syn with respect to the (ROLi2) ‘counter ion.’
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610080405
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Oligomerization stereochemistry of vinyl monomers III. Ion-pair effects on the stereoselective anionic oligomerization of 2-vinyl pyridine (1978)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Letters Edition 16 (1978), S. 297-302 
    Details
    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
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...