EXCHANGE REACTIONS OF IODIDE ION WITH AROMATIC IODIDES

1951 ◽  
Vol 29 (2) ◽  
pp. 154-161 ◽  
Author(s):  
A. M. Kristjanson ◽  
C. A. Winkler
Keyword(s):  
Activation Energies ◽  
Second Order ◽  
Exchange Reactions ◽  
First Order ◽  
Temperature Range ◽  
Iodide Ion

The exchange reactions of iodide ion with o- and p-nitroiodobenzene in the temperature range about 170°–238°C were apparently second order with activation energies of approximately 29 and 33.5 kcal. per mole respectively. In the same temperature range the exchange of iodide ion with iodobenzene and m-nitroiodobenzene appeared to be first order reactions, with activation energies of approximately 25 kcal. per mole.

THE EXCHANGE OF IODINE BETWEEN INORGANIC IODIDES AND n-BUTYL IODIDE

1951 ◽  
Vol 29 (1) ◽  
pp. 60-69 ◽  
Author(s):  
G. W. Hodgson ◽  
H. G. V. Evans ◽  
C. A. Winkler
Keyword(s):  
Ion Exchange ◽  
Inorganic Salt ◽  
Activation Energies ◽  
Acetonitrile Solution ◽  
Exchange Reactions ◽  
Complex Ions ◽  
Iodide Ion

Lithium, sodium, and caesium iodides are highly ionized in acetonitrile solution and have practically the same rates and activation energies (18 kcal. per mole) for their exchange reactions with n-butyl iodide in this solvent. There seems little doubt, therefore, that these exchange reactions occur between the organic iodide and iodide ion derived from the inorganic salt. Zinc and cadmium iodides, and iodine, are only slightly ionized in acetonitrile and exchange with n-butyl iodide with rates that are widely different from one another and from the rate of iodide ion exchange. The activation energies are 21.9, 20.6, and 17.5 kcal. per mole respectively. It is concluded that these exchange reactions involve predominantly complex ions.

Adsorption and Reaction of NO on Ni(100)

1987 ◽  
Vol 42 (11) ◽  
pp. 1333-1345 ◽  
Author(s):  
Shikong Shen ◽  
P. Feulner ◽  
E. Umbach ◽  
W. Wurth ◽  
D. Menzel
Keyword(s):  
Heating Rate ◽  
Thermal Desorption ◽  
Low Temperatures ◽  
Activation Energies ◽  
Second Order ◽  
Temperature Range ◽  
Saturation Coverage ◽  
C And N ◽  
Temperature Programmed ◽  
Adsorption Desorption

The adsorption, desorption and decom position of NO on Ni(100 ) was studied with XPS, UPS, XAES, ΔΦ, temperature programmed thermal desorption (TPD) and LEED in the temperature range 80 to 1300 K. NO adsorbs molecularly on Ni(100 ) at low temperatures; dissociation occurs above 200 K. Up to ≈ 1/4 saturation coverage, only N2 desorbs in a second order peak around 1100 K. At saturation three NO desorption states at 350, 420 and 1200 K and two N2 peaks at 660 and 1020 K are observed for a heating rate β of 5 K/s. Activation energies for desorption are obtained by TPD with variable β. Coadsorption experiments show that the NO -TPD peak at 1200 K is due to recombination of N and O on the surface. The relative areas of some TPD maxima depend strongly on coadsorbed O-, C- and N-impurities. At 100 K, ΔΦ increases up to a maximum of 1.1 eV at 3 /4 saturation coverage and drops to 1.0 eV at saturation. Complex LEED patterns are observed for saturated layers adsorbed below 200 K which change during heating. The nature o f the observed binding and desorption states is discussed.

STUDIES ON HOMOGENEOUS FIRST ORDER GAS REACTIONS: IV. THE DECOMPOSITION OF PARA-n-BUTYRALDEHYDE AND PARA-ISOBUTYRALDEHYDE

1933 ◽  
Vol 9 (6) ◽  
pp. 603-609 ◽  
Author(s):  
C. C. Coffin
Keyword(s):  
Experimental Error ◽  
Degrees Of Freedom ◽  
Activation Energies ◽  
Energy Of Activation ◽  
Velocity Constant ◽  
First Order ◽  
Temperature Range ◽  
Measurable Rate ◽  
Gas Reactions ◽  
Internal Degrees Of Freedom

The gaseous decompositions of para-n-butyraldehyde and para-isobutyraldehyde to n-butyraldehyde and isobutyraldehyde respectively are homogeneous and first order over the pressure and temperature range investigated (1.3 to 55 cm. of mercury; 215 to 261 °C). Under these conditions the reactions go to completion at a measurable rate without complications. Within experimental error the activation energies of these reactions are equal and are approximately the same as that of the paracetaldehyde decomposition. This value is between 42,000 and 44,000 calories per mole. The rates of decomposition of the two parabutyraldehydes are very nearly the same at any temperature. At 500° abs. the velocity constant of the iso-compound is about 15% greater than that of the normal and about 100% greater than that of paracetaldehyde. The velocity constants at any temperature are given by the equations: para-n-butyraldehyde, [Formula: see text]; para-isobutyraldehyde, [Formula: see text]. The data are consistent with the idea that, for a series of reactions with the same energy of activation, an increase in the number of contributory internal degrees of freedom of a molecule will increase the probability of reaction.

A VERY LOW-TC SECOND-ORDER TEMPERATURE-COMPENSATED CMOS CURRENT REFERENCE

2014 ◽  
Vol 23 (03) ◽  
pp. 1450042 ◽  
Author(s):  
LIANG LIANG ◽  
ZHANGMING ZHU ◽  
YINTANG YANG
Keyword(s):  
Temperature Compensation ◽  
Supply Voltage ◽  
Design Method ◽  
Current Source ◽  
Second Order ◽  
Cmos Process ◽  
Current Mirror ◽  
First Order ◽  
Temperature Range ◽  
Current Reference

This paper proposes a novel second-order temperature-compensated CMOS current reference which exploits a new self-biased current source for first-order temperature compensation and a resistor-free widlar current mirror for second-order temperature compensation. Moreover, by deriving the temperature coefficient (TC) of the reference current, the temperature compensation condition equations together with a design method of minimizing the thermal drift in a required temperature range are presented. Based on these, the circuit is designed in a standard 0.18 μm CMOS process and achieves a very low TC of only 16.9 ppm/°C in a temperature range between -40°C and 120°C, with 1 μA reference current at 27°C. Besides, the current reference can operate at supply voltage down to 1.3 V, with a good supply regulation of 0.5%/V. At 27°C, its power consumption is 8.93 μW.

scholarly journals The effect of different amino acid side chains on the stereospecificity and catalytic efficiency of the tryptophan synthase-catalysed exchange of the α-protons of amino acids

1996 ◽  
Vol 314 (3) ◽  
pp. 787-791 ◽  
Author(s):  
John J. MILNE ◽  
J. Paul G. MALTHOUSE
Keyword(s):  
Exchange Rate ◽  
Amino Acid ◽  
Exchange Rates ◽  
Catalytic Efficiency ◽  
Second Order ◽  
Tryptophan Synthase ◽  
Exchange Reactions ◽  
First Order ◽  
Allosteric Effector ◽  
Hydrogen Deuterium

1H-NMR has been used to follow the tryptophan synthase (EC 4.2.1.20) catalysed hydrogen–deuterium exchange of the α-protons of L- and D-alanine and -tryptophan. The first-order and second-order rate constants for exchange have been determined at pH 7.8 in the presence and absence of the allosteric effector, DL-α-glycerol 3-phosphate. In the presence of DL-α-glycerol 3-phosphate the stereospecificity of the tryptophan synthase-catalysed first-order exchange rates was in the order tryptophan > alanine > glycine. This increase in stereospecificity was largely due to the decrease in the magnitude of the first-order exchange rate of the slowly exchanged α-proton. A similar increase in the stereospecificity of the second-order exchange rates for alanine was also largely due to the decrease in the magnitude of the first-order exchange rate of the slowly exchanged α-proton of D-alanine. Adding DL-α-glycerol 3-phosphate produced an increase in the stereospecificity of the second-order exchange rate observed with alanine but no significant change in the stereospecificity of the first-order exchange rate with tryptophan. The α-subunits are shown to increase the exchange rates of the α-protons of L-alanine and L-tryptophan. We conclude that the contribution of the R-group of an amino acid to the stereospecificity of the exchange reactions of its α-proton can be similar to or larger than that of its α-carboxylate group. Possible mechanisms that could explain the stereospecificity of these exchange reactions are discussed.

Ligand exchange reactions of vanadium(III) β diketonate complexes

1978 ◽  
Vol 56 (7) ◽  
pp. 1012-1015 ◽  
Author(s):  
A. J. C. Nixon ◽  
D. R. Eaton
Keyword(s):  
Ligand Exchange ◽  
Zero Order ◽  
Second Order ◽  
Exchange Reactions ◽  
Rate Law ◽  
First Order ◽  
Kinetics Of ◽  
Incoming Ligand

The kinetics of ligand exchange reactions of V(III) β diketonates have been studied. The replacement of acetylacetone by hexafluoroacetylacetone involves a rate law with both first- and second-order terms in the incoming ligand. The replacement of acetylacetone by deuteroacetyl-acetone involves terms zero-order and first-order in the incoming ligand. Both reactions are markedly catalyzed by acids and inhibited by bases. A mechanism involving a dangling ligand intermediate is suggested. The rates of ligand exchange are much less than the rates of isomerization.

Nonlinear Analysis of Visual Evoked Potentials Elicited by Color Stimulation

1997 ◽  
Vol 36 (04/05) ◽  
pp. 315-318 ◽  
Author(s):  
K. Momose ◽  
K. Komiya ◽  
A. Uchiyama
Keyword(s):  
Visual System ◽  
Evoked Potentials ◽  
Visual Evoked Potentials ◽  
Normal Subjects ◽  
Second Order ◽  
First Order ◽  
The Relationship ◽  
Perceived Color ◽  
Second Order Nonlinearity ◽  
Visual Evoked

Abstract:The relationship between chromatically modulated stimuli and visual evoked potentials (VEPs) was considered. VEPs of normal subjects elicited by chromatically modulated stimuli were measured under several color adaptations, and their binary kernels were estimated. Up to the second-order, binary kernels obtained from VEPs were so characteristic that the VEP-chromatic modulation system showed second-order nonlinearity. First-order binary kernels depended on the color of the stimulus and adaptation, whereas second-order kernels showed almost no difference. This result indicates that the waveforms of first-order binary kernels reflect perceived color (hue). This supports the suggestion that kernels of VEPs include color responses, and could be used as a probe with which to examine the color visual system.

Imaginings

2017 ◽  
Vol 9 (3) ◽  
pp. 17-30
Author(s):  
Kelly James Clark
Keyword(s):  
Religious Tradition ◽  
Second Order ◽  
Fine Tuning ◽  
Intellectual Humility ◽  
First Order ◽  
Natural Processes ◽  
Empirically Supported ◽  
Group Violence ◽  
The World ◽  
The Universe

In Branden Thornhill-Miller and Peter Millican’s challenging and provocative essay, we hear a considerably longer, more scholarly and less melodic rendition of John Lennon’s catchy tune—without religion, or at least without first-order supernaturalisms (the kinds of religion we find in the world), there’d be significantly less intra-group violence. First-order supernaturalist beliefs, as defined by Thornhill-Miller and Peter Millican (hereafter M&M), are “beliefs that claim unique authority for some particular religious tradition in preference to all others” (3). According to M&M, first-order supernaturalist beliefs are exclusivist, dogmatic, empirically unsupported, and irrational. Moreover, again according to M&M, we have perfectly natural explanations of the causes that underlie such beliefs (they seem to conceive of such natural explanations as debunking explanations). They then make a case for second-order supernaturalism, “which maintains that the universe in general, and the religious sensitivities of humanity in particular, have been formed by supernatural powers working through natural processes” (3). Second-order supernaturalism is a kind of theism, more closely akin to deism than, say, Christianity or Buddhism. It is, as such, universal (according to contemporary psychology of religion), empirically supported (according to philosophy in the form of the Fine-Tuning Argument), and beneficial (and so justified pragmatically). With respect to its pragmatic value, second-order supernaturalism, according to M&M, gets the good(s) of religion (cooperation, trust, etc) without its bad(s) (conflict and violence). Second-order supernaturalism is thus rational (and possibly true) and inconducive to violence. In this paper, I will examine just one small but important part of M&M’s argument: the claim that (first-order) religion is a primary motivator of violence and that its elimination would eliminate or curtail a great deal of violence in the world. Imagine, they say, no religion, too.Janusz Salamon offers a friendly extension or clarification of M&M’s second-order theism, one that I think, with emendations, has promise. He argues that the core of first-order religions, the belief that Ultimate Reality is the Ultimate Good (agatheism), is rational (agreeing that their particular claims are not) and, if widely conceded and endorsed by adherents of first-order religions, would reduce conflict in the world.While I favor the virtue of intellectual humility endorsed in both papers, I will argue contra M&M that (a) belief in first-order religion is not a primary motivator of conflict and violence (and so eliminating first-order religion won’t reduce violence). Second, partly contra Salamon, who I think is half right (but not half wrong), I will argue that (b) the religious resources for compassion can and should come from within both the particular (often exclusivist) and the universal (agatheistic) aspects of religious beliefs. Finally, I will argue that (c) both are guilty, as I am, of the philosopher’s obsession with belief. 

Evidence for general base catalysis by protic solvents in a kinetic study of alcoholyses and hydrolyses of 1-(phenoxycarbonyl)pyridinium ions under both solvolytic and non-solvolytic conditions

2009 ◽  
Vol 74 (1) ◽  
pp. 43-55 ◽  
Author(s):  
Dennis N. Kevill ◽  
Byoung-Chun Park ◽  
Jin Burm Kyong
Keyword(s):  
Second Order ◽  
Base Catalysis ◽  
Substitution Reactions ◽  
Third Order ◽  
Methoxy Derivative ◽  
First Order ◽  
General Base ◽  
Protic Solvents ◽  
Kinetics Of ◽  
Pyridinium Ions

The kinetics of nucleophilic substitution reactions of 1-(phenoxycarbonyl)pyridinium ions, prepared with the essentially non-nucleophilic/non-basic fluoroborate as the counterion, have been studied using up to 1.60 M methanol in acetonitrile as solvent and under solvolytic conditions in 2,2,2-trifluoroethan-1-ol (TFE) and its mixtures with water. Under the non- solvolytic conditions, the parent and three pyridine-ring-substituted derivatives were studied. Both second-order (first-order in methanol) and third-order (second-order in methanol) kinetic contributions were observed. In the solvolysis studies, since solvent ionizing power values were almost constant over the range of aqueous TFE studied, a Grunwald–Winstein equation treatment of the specific rates of solvolysis for the parent and the 4-methoxy derivative could be carried out in terms of variations in solvent nucleophilicity, and an appreciable sensitivity to changes in solvent nucleophilicity was found.

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