scholarly journals Thermal decomposition of multiply charged T-rich oligonucleotide anions in the gas phase. Influence of internal solvation on the arrhenius parameters for neutral base loss

2006 ◽  
Vol 17 (9) ◽  
pp. 1229-1238 ◽  
Author(s):  
Rambod Daneshfar ◽  
John S. Klassen
Keyword(s):  
Thermal Decomposition ◽  
Gas Phase ◽  
Base Loss ◽  
Arrhenius Parameters ◽  
Multiply Charged ◽  
Neutral Base

Gas Phase Reactions of Trimethylborate with the [M − H]− Ions of Nucleotides and Their Non-Covalent Homo- and Heterodimer Complexes

2003 ◽  
Vol 56 (5) ◽  
pp. 389 ◽  
Author(s):  
Ana K. Vrkic ◽  
Richard A. J. O'Hair
Keyword(s):  
Gas Phase ◽  
Mass Spectrometer ◽  
Ion Trap ◽  
Quadrupole Ion Trap ◽  
Methanol Molecule ◽  
Collision Induced Dissociation ◽  
Base Loss ◽  
Gas Phase Reactions ◽  
Ion Trap Mass Spectrometer ◽  
Neutral Base

Trimethylborate (TMB) reacts with deprotonated monomer, homo-, and heterodimer ions of nucleotides (2′-deoxyadenosine-5′-monophosphate [dAMP], 2′-deoxycytidine-5′-monophosphate [dCMP], 2′-deoxyguanosine-5′-monophosphate [dGMP], and 2′-deoxythymidine-5′-monophosphate [dTMP]) in a quadrupole ion trap mass spectrometer by addition with concomitant elimination of one or two methanol molecules (monomers), one or three methanol molecules (homodimers), and three methanol molecules (heterodimers). The mode of reaction appears to influence the observed rates, with the loss of only one methanol molecule corresponding to the fastest rate. There appears to be a structure–reactivity correlation for the monomers, with the [dGMP – H]– ions (which adopt a syn conformation of the guanine moiety) reacting fastest with TMB through the loss of only one methanol molecule. No such structure–reactivity trends are observed for the homo- and heterodimers. In addition, the collision-induced dissociation (CID) reactions of the [(dXMP)n − H]– (n = 1 or 2) as well as the [dXMP + dYMP – H + (CH3O)3B – 3(CH3OH)]– ions (where nucleotides X, Y = A, C, G, or T) were studied. The latter fragment to form [dXMP – H + BPO4]– and [dXMP – 3H + BPO3]– ions (where X = A, C, G, or T), while [dXMP – H]– ions fragment by neutral base loss. The homo- and heterodimers fragment to form [dXMP – H]– and [dXMP + HPO3]– ions, and the relative abundances of the [dXMP – H]– monomer ions from the heterodimers led to the following acidity order: dGMP ≈ dTMP > dCMP > dAMP.

The thermal decomposition of cyclobutane-1,2-dione

1985 ◽  
Vol 63 (11) ◽  
pp. 2945-2948 ◽  
Author(s):  
J.-R. Cao ◽  
R. A. Back
Keyword(s):  
Activation Energy ◽  
Thermal Decomposition ◽  
Vapor Pressure ◽  
Gas Phase ◽  
Rate Constant ◽  
Surface Reaction ◽  
Order Rate Constant ◽  
Reaction Vessel ◽  
Arrhenius Parameters ◽  
First Order

The thermal decomposition of cyclobutane-1,2-dione has been studied in the gas phase at temperatures from 120 to 250 °C and pressures from 0.2 to 1.5 Torr. Products were C2H4 + 2CO, apparently formed in a simple unimolecular process. The first-order rate constant was strongly pressure dependent, and values of k∞ were obtained by extrapolation of plots of 1/k vs. 1/p to1/p = 0. Experiments in a packed reaction vessel showed that the reaction was enhanced by surface at the lower temperatures. Arrhenius parameters for k∞, corrected for surface reaction, were log A (s−1) = 15.07(±0.3) and E = 39.3(±2) kcal/mol. This activation energy seems too low for a biradical mechanism, and it is suggested that the decomposition is probably a concerted process. The vapor pressure of solid cyclobutane-1,2-dione was measured at temperatures from 22 to 62 °C and a heat of sublimation of 13.1 kcal/mol was estimated.

Free-radical-catalyzed isomerization of isocyanides

1967 ◽  
Vol 45 (22) ◽  
pp. 2749-2754 ◽  
Author(s):  
D. H. Shaw ◽  
H. O. Pritchard
Keyword(s):  
Thermal Decomposition ◽  
Free Radical ◽  
Carbon Atom ◽  
Gas Phase ◽  
Methyl Radicals ◽  
Kcal Mole ◽  
Arrhenius Parameters ◽  
Reaction Proceeds ◽  
Methyl Isocyanide ◽  
Butyl Peroxide

The isomerization of methyl isocyanide and of ethyl isocyanide, catalyzed by methyl radicals produced in the thermal decomposition of di-tert-butyl peroxide, has been studied in the gas phase at temperatures near 100 °C. The Arrhenius parameters for the reaction CH3NC + CH3 → CH3 + CH3CN are E = 7.8 ± 0.3 kcal/mole and A = 1012.25 mole−1 cc s−1. It is proposed that the reaction proceeds by addition of the incoming radical to the divalent carbon atom of the isocyanide group, followed by expulsion of the radical originally attached to the N atom. The thermochemistry of addition to the divalent carbon atom is discussed in an Appendix.

scholarly journals Super-electrophiles of Tri- and Tetra-Anions Stabilized by Selected Terminal Groups and Their Role in Binding Noble Gas atoms

2021 ◽  
Author(s):  
MingMin Zhong ◽  
Hong Fang ◽  
Deepika Deepika ◽  
Purusottam Jena
Keyword(s):  
Gas Phase ◽  
Noble Gas ◽  
Atomic Clusters ◽  
Weakly Coordinating Anions ◽  
Multiply Charged ◽  
Potential Applications ◽  
Weakly Coordinating

Stabilization of multiply-charged atomic clusters in the gas phase has been a topic of great interest not only because of their potential applications as weakly-coordinating anions, but also for their...

Synthesis of Sic Fine Particles by Gas-Phase Reaction Under Short-Time Microgravity

1992 ◽  
Vol 286 ◽  
Author(s):  
Takeshi Okutani ◽  
Yoshinori Nakata ◽  
Masaakt Suzuki ◽  
Yves Maniette ◽  
Nobuyoshi Goto ◽  
...  
Keyword(s):  
Thermal Decomposition ◽  
Heat Source ◽  
Size Distribution ◽  
Gas Phase ◽  
Fine Particles ◽  
Rapid Heating ◽  
Exothermic Reaction ◽  
Phase Reaction ◽  
Gas Phase Reaction ◽  
Short Time

ABSTRACTSiC fine particles were synthesized by the gas-phase thermal decomposition of tetramethylsilane (Si(CH3)4) in hydrogen under microgravity of 10−4G for 10 sec. Rapid heating to the temperature over 800°C which is required for thermal decomposition of Si(CH3)4) under short-time microgravity was attained using a chemical oven where the heat of exothermic reaction of combustion synthesis of Ti-A1-4B composites was used as the heat source. Monodisperse and spherical SiC fine particles were synthesized under microgravity, whereas aggregates of SiC fine particles were synthesized under 1 G gravity. The SiC particles synthesized under microgravity (150-200 nm) were bigger in size and narrower in size distribution than those under 1 G gravity (100-150 nm).

Thermal decomposition of benzoyl azide and diazoacetone in the gas phase

1988 ◽  
Vol 37 (8) ◽  
pp. 1541-1544
Author(s):  
V. G. Prokudin ◽  
A. M. Sipyagin ◽  
V. G. Kartsev ◽  
S. A. Vozchikova
Keyword(s):  
Thermal Decomposition ◽  
Gas Phase
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