ChemInform Abstract: ANOMERIZATION OF FURANOSE SUGARS: KINETICS OF RING-OPENING REACTIONS BY PROTON AND CARBON-13 SATURATION-TRANSFER NMR SPECTROSCOPY

Open chain intermediates from the ring-opening reaction of aqueous sodium deuteroxide (2 mol) with 2-chloro-5-nitropyridine (1 mol) and 2-chloro-3-nitropyridine (1 mol) were isolated. These intermediates were purified, analyzed for elemental composition, and characterized by various spectrophotometric techniques. The intermediate formed from 2-chloro-5-nitropyridine and two equivalents of deuteroxide ion reacts with additional deuteroxide in D2O in various polar solvents to reclose the pyridine ring. The kinetics of the ring closure reaction are reported and are supplemented with observations of salt and solvent effects upon the rate of closure. In addition, a mechanism for the ring closure is presented. The intermediate formed from 2-chloro-3-nitropyridine did not undergo a similar ring closure when reacted with additional deuteroxide, but instead formed various decomposition products. A reason for the failure of this ring closure is suggested.

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Influence of ring-opening reactions on the kinetics of cottonseed oil epoxidation

International Journal of Chemical Kinetics ◽

10.1002/kin.21208 ◽

2018 ◽

Vol 50 (10) ◽

pp. 726-741 ◽

Cited By ~ 16

Author(s):

Xiaoshuang Cai ◽

Jun Liu Zheng ◽

Adriana Freites Aguilera ◽

Lamiae Vernières-Hassimi ◽

Pasi Tolvanen ◽

...

Keyword(s):

Ring Opening ◽

Cottonseed Oil ◽

Ring Opening Reactions ◽

Kinetics Of

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Soybean Oil Epoxidation: Kinetics of the Epoxide Ring Opening Reactions

Authorea ◽

10.22541/au.158698520.02740558 ◽

2020 ◽

Author(s):

Elio Santacesaria ◽

Rosa Turco ◽

Vincenzo Russo ◽

Riccardo TESSER ◽

Martino Di Serio

Keyword(s):

Soybean Oil ◽

Ring Opening ◽

Epoxide Ring ◽

Epoxide Ring Opening ◽

Ring Opening Reactions ◽

Kinetics Of

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Catalytic activity of rhodium(I) complexes containing (ω-trimethylsilylalkyl)diphenylphosphines

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19802219 ◽

1980 ◽

Vol 45 (8) ◽

pp. 2219-2223 ◽

Cited By ~ 6

Author(s):

Marie Jakoubková ◽

Martin Čapka

Keyword(s):

Catalytic Activity ◽

Nmr Spectroscopy ◽

Ir Spectroscopy ◽

Electron Density ◽

Phosphorus Atom ◽

Proton Acceptor ◽

Trimethylsilyl Group ◽

Kinetics Of

Kinetics of homogenous hydrogenation of 1-heptene catalysed by rhodium(I) complexes prepared in situ from μ,μ'-dichloro-bis(cyclooctenerhodium) and phosphines of the type RP(C6H5)2 (R = -CH3, -(CH2)nSi(CH3)3; n = 1-4) have been studied. The substitution of the ligands by the trimethylsilyl group was found to increase significantly the catalytic activity of the complexes. The results are discussed in relation to the electron density on the phosphorus atom determined by 31P NMR spectroscopy and to its proton acceptor ability determined by IR spectroscopy.

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Kinetics of the Imidazolium Ring-Opening of mRNA 5'-cap Analogs in Aqueous Alkali

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc20060567 ◽

2006 ◽

Vol 71 (4) ◽

pp. 567-578 ◽

Cited By ~ 2

Author(s):

Alicja Stachelska ◽

Zbigniew J. Wieczorek ◽

Janusz Stępiński ◽

Marzena Jankowska-Anyszka ◽

Harri Lönnberg ◽

...

Keyword(s):

Electrostatic Interaction ◽

Ring Opening ◽

Nucleophilic Attack ◽

Amino Groups ◽

Hydroxide Ion ◽

Methyl Group ◽

Structural Modifications ◽

Alkyl Groups ◽

Imidazolium Ring ◽

Kinetics Of

Second-order rate constants for the hydroxide-ion-catalyzed imidazolium ring-opening of several mono- and dinucleosidic analogs of mRNA 5'-cap have been determined. Intramolecular stacking of the two nucleobases in the dinucleosidic analogs, m7GpppN (m7G = 7-methylguanosine, N = 5'-linked nucleoside), and electrostatic interaction between the N-alkylated imidazolium ring and phosphate moiety have been shown to shield the m7G moiety against the nucleophilic attack of hydroxide ion. In addition, the effect of methylation of the nucleobase amino groups and replacement of the 7-methyl group with other alkyl groups have been studied. The influence of all the structural modifications studied turned out to be modest, the cleavage rates of the most and least reactive analogs (with the exception of non-phosphorylated nucleosides) differing only by a factor of 5.

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