Kinetics of the chelate effect. Ring closing and ring opening in cis-dichloro(dimethyl sulfoxide)(3-aminopropyl)ammonium)- and -((4-aminobutyl)ammonium)platinum(II) chloride. Effect of ring size

1978 ◽  
Vol 17 (9) ◽  
pp. 2436-2441 ◽  
Author(s):  
Raffaello Romeo ◽  
Santo Lanza ◽  
Domenico Minniti ◽  
Martin L. Tobe
Keyword(s):  
Dimethyl Sulfoxide ◽  
Ring Opening ◽  
Ring Size ◽  
Chelate Effect ◽  
Chloride Effect ◽  
In Cis ◽  
Kinetics Of ◽  
Effect Ring

Kinetics of sulfoxide displacement by 2,2′-bipyridine in cis-diphenyl-, dimethyl- and dichloro-bis(dimethyl sulfoxide)platinum(II) in acetonitrile

1992 ◽  
Vol 201 (2) ◽  
pp. 137-142 ◽  
Author(s):  
Santo Lanza ◽  
Giuseppe Alibrandi ◽  
Luigi Monsù Scolaro ◽  
Sergio Sergi
Keyword(s):  
Dimethyl Sulfoxide ◽  
In Cis ◽  
Kinetics Of

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

2006 ◽  
Vol 71 (4) ◽  
pp. 567-578 ◽  
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.

Determination of the kinetics of permeation of dimethyl sulfoxide in isolated corneas

1995 ◽  
Vol 26 (2) ◽  
pp. 79-102 ◽  
Author(s):  
D. B. Walcerz ◽  
M. J. Taylor ◽  
A. L. Busza
Keyword(s):  
Dimethyl Sulfoxide ◽  
Kinetics Of

Derivatives of isatin in aqueous solution. I. Kinetics of ring opening of Isatin-5-sulfonate

1981 ◽  
Vol 34 (2) ◽  
pp. 365 ◽  
Author(s):  
H Stunzi
Keyword(s):  
Ring Opening ◽  
Rate Of Change ◽  
Spectroscopic Methods ◽  
Ph Values ◽  
Buffer Region ◽  
Pka Value ◽  
Back Titration ◽  
Kinetics Of ◽  
Derivatives Of ◽  
Sulfonate Anion

The reactions of isatin-5-sulfonate anion (si-) which cause a hysteresis in pH titrations were studied by pH-metric and n.m.r, spectroscopic methods. Rapid alkalimetric titrations [I 0.15 M (KNO3),37�] gave the pKa value corresponding to the addition of OH- to si- [pKa(ring) 9.55]. The slow ring opening to the sulfonatoisatate dianion (sia2-) led to a drift of the pH values towards an equilibrium buffer region. Its pKa, value [pKa(eq) 3.44] corresponds to the reaction si-+H2O ↔ sia 2-+H+ Rapid back-titration gave the pKa value of the ring-opened species Hsia- [pKa(open) c. 1.3]. The rate law for the ring opening d[sia]/dt=k2 [siOH](OH)+k1*[si] was obtained from the rate of change of pH. N-Methylisatin-5-sulfonate behaves analogously.

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