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  • 1995-1999  (4)
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  • 1
    Electronic Resource
    Electronic Resource
    Transition structure for the retroene-type elimination reaction of propene from allylamines (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Heteroatom Chemistry 8 (1997), S. 85-89 
    Details
    ISSN: 1042-7163
    Keywords: Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The transition-state geometries of retroene elimination reactions of propene from allylamines have been calculated by using the semiempirical AM1 method. The most favored geometry resembles a half chair or a flattened boat. It is also found that the transition states are of polar character and that the negative charge on the N atom decreases in the transition state; thus, the reaction is favored by electron donor substituents on the nitrogen atom, as observed experimentally. © 1997 John Wiley & Sons, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 2
    Electronic Resource
    Electronic Resource
    On the transition state of the thermal propene elimination from allylphosphines (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Heteroatom Chemistry 8 (1997), S. 97-102 
    Details
    ISSN: 1042-7163
    Keywords: Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Diallyltetramethylpiperidinophosphine 1, diallyldiisopropylaminophosphine 2, and diallylmesitylphosphine 3 were pyrolyzed in a stirred flow reactor over the temperature range 400-450°C, using toluene as carrier gas, producing, in all cases, mixtures of phosphorus-containing products. The pyrolysis of 1 produced 1-tetramethylpiperidino-1-phosphabutadiene, in addition to a mixture of phosphines and polyphosphines. Compound 2 produced the azadiphosphole 4, the phosphinine 5, allylphosphine, and diisopropylaminophosphine as major phosphorated products. The pyrolysis of 3 produced a mixture of phosphines and polyphosphines. The complex mixture generated by the three diallylphosphines indicates the formation of free radicals during their pyrolyses. AM1 calculations on the transition state of an expected retroenetype propene elimination reaction showed that, due to the phosphaalkene character of the transition state, the structure of the latter is very rigid and sensitive to steric effects. Steric hindrance of the substituents on the phosphorus atom compels the molecule to distort the half-chair transition structure, causing a rise in the activation energy to values in the range of a homolytic P(SINGLE BOND)C bond dissociation energy. © 1997 John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 3
    Electronic Resource
    Electronic Resource
    Gas-phase thermolysis of diallyl(4-fluorophenyl) and allyl(t-butylamino)phenyl phosphines (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Heteroatom Chemistry 8 (1997), S. 91-96 
    Details
    ISSN: 1042-7163
    Keywords: Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Dially(4-fluorophenyl)phosphine and allyl(t-butylamino)phenylphosphine were pyrolyzed in a stirred-flow reactor at 340-420°C/9-19 Torr, using toluene as carrier gas. The primary reaction products were propene, 1-(4-fluorophenyl)-1-phosphabutadiene, and 1-phenyl-2-t-butyliminophosphine. The phosphorus-containing products gave rise to [4 + 2] and [2 + 2] cycloaddition products, respectively. The consumption of these phosphines showed first-order kinetics, with the rate coefficients following the Arrhenius equations: Dially(4-fluorophenyl)phosphine: k(s-1) = 109.00±0.32 exp (- 122 ± 4 kJ/mol RT) Allyl(t-butylamino)phenylphosphine: k(s-1) = 109.04±0.25 exp (-113 ± 3 kJ/mol RT) The results support a six-center cyclic transition-state unimolecular elimination reaction mechanism for both reactants. © 1997 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 4
    Electronic Resource
    Electronic Resource
    Reactivity of allylphosphines with iridium complexes: Diallylphosphines as new bidentate ligands (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Heteroatom Chemistry 9 (1998), S. 253-259 
    Details
    ISSN: 1042-7163
    Keywords: Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Addition of four equivalents of t-butyldiallylphosphine 1a to a solution of one equivalent of [(COE)2IrCl]2 in CHCl3 at low temperature produced two isomers of thecomplex [t-Bu(C3H5)PCH2CH=CH)]IrHCl(COE)-[PtBu(C3H5)2] (2a), which evolve at 40°C to [t-Bu(C3H5)PCH2CH=CH)]IrCl(C8H15)[PtBu(C3H5)2] (3a), by a hydride transfer from iridium to the cyclooctene (COE) ligand. It is reasonable that the unsaturation at the iridium center is fulfilled by interactions with the allyl moieties of the phosphine that are not metalated. This has been demonstrated by bubbling CO into a solution of 3a in CHCl3 at room temperature to obtain the carbonyl complex [t-Bu(C3H5)-PCH2CH=CH)]Ir(CO)Cl(C8H15)[PtBu(C3H5)2] (4a). Under the same conditions, the reaction of diisopropylamindiallylphosphine 1b and anisyldiallylphosphine 1c afforded a mixture of isomers 3b and 3c, respectively. These results show that diallylphosphines can be considered to be a new family of bidentate ligands. Finally, the reaction of these phosphines with [(COD)IrCl]2 (COD = 1,5 cyclooctadiene) shows the formation of tetracoordinated iridium (I) complexes IrCl(COD)(PR3), which are thermally stable. © 1998 John Wiley & Sons, Inc. Heteroatom Chem 9:253-259, 1998
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
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