Proton Transfer Kinetics in Medium-strong Inorganic Acids

1973 ◽  
Vol 51 (14) ◽  
pp. 2297-2305 ◽  
Author(s):  
David Charles Hodgkin ◽  
Peeter Kruus
Keyword(s):  
Proton Transfer ◽  
Aqueous Solutions ◽  
Rate Constants ◽  
Reasonable Agreement ◽  
Ultrasonic Absorption ◽  
Absolute Rate ◽  
Absorption Data ◽  
Inorganic Acids ◽  
Diffusion Controlled ◽  
Excess Absorption

A method of obtaining relative and absolute rate constants for proton transfer equilibria is described. It is suitable for equilibria of the type[Formula: see text]in dilute (< 0.1 M) solutions of medium strong inorganic acids. To obtain absolute values of kd, kr it is necessary to know the value of ΔV0 for the equilibrium. Ultrasonic absorption data for aqueous solutions of H3PO4, H3AsO4, and H2SO4 at 20, 10, and 0 °C are presented together with data at 20 °C for H3PO3, H2SeO3, HIO4, NaHSO4, KHSO4, and NH4HSO4. From analysis of the concentration dependence of the excess absorption, values of Ka are calculated for these acids, and values of kd, kr for those where ΔV0 is available. The Ka obtained are in reasonable agreement with literature values except for HIO4 and H2SeO4. The absolute values of kr for H3PO4, H3AsO4, and HSO4− indicate that the diffusion controlled recombination process postulated is complete when the ions are about 15 Å from each other.

Ultrasonic study of hydrochloric acid association in N,N-dimethylformamide

1968 ◽  
Vol 46 (6) ◽  
pp. 853-858 ◽  
Author(s):  
Siu C. Chan ◽  
J. P. Valleau
Keyword(s):  
Hydrochloric Acid ◽  
Sound Velocity ◽  
Hydrogen Chloride ◽  
Rate Constants ◽  
Ultrasonic Absorption ◽  
Frequency Range ◽  
Association Rate ◽  
Reaction Distance ◽  
Ultrasonic Study ◽  
Diffusion Controlled

Ultrasonic absorption and velocity have been measured in anhydrous N,N-dimethylformamide solutions of hydrogen chloride, over the frequency range 13 to 143 mc/s, and the concentration range 0.05 M to 3.5 M. A large relaxation is observed and ascribed to the association of the acid. The rate constants for this reaction are obtained, and their variations with concentration are discussed. The association rate appears to be entirely diffusion controlled, and the corresponding "reaction distance" is large. This may be related to the very large effect on the sound velocity (and hence on the compressibility) that arises from the introduction of these ions.

Direct detection of methylphenylgermylene and 1,2-dimethyl-1,2-diphenyldigermene — Kinetic studies of their reactivities in solution

2006 ◽  
Vol 84 (7) ◽  
pp. 934-948 ◽  
Author(s):  
William J Leigh ◽  
Ileana G Dumbrava ◽  
Farahnaz Lollmahomed
Keyword(s):  
Acetic Acid ◽  
Rate Constants ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Direct Detection ◽  
Kinetic Studies ◽  
Laser Flash ◽  
Absolute Rate ◽  
Hydrocarbon Solvents ◽  
Diffusion Controlled

Photolysis of 1,3,4-trimethyl-1-phenylgermacyclopent-3-ene (5) in hydrocarbon solvents containing isoprene, methanol, or acetic acid affords 2,3-dimethyl-1,3-butadiene (DMB) and the expected trapping products of methyl phenylgermylene (GeMePh) in chemical yields exceeding 90%. The germylene has been detected in hexane solution by laser flash photolysis as a short-lived species (τ ~ 2 µs) exhibiting a UV-vis absorption spectrum centered at λmax = 490 nm. It decays with second-order kinetics and a rate constant close to the diffusion-controlled limit, with the concomitant growth of a second longer-lived transient (λmax = 420 nm) that is assigned to a mixture of (E)- and (Z)-1,2-dimethyl-1,2-diphenyldigermene (4). Absolute rate constants have been determined for the reactions of the germylene with primary and tertiary amines (n-BuNH2 and Et3N, respectively), acetic acid (AcOH), a terminal alkyne and alkene, isoprene, DMB, CCl4, and the group 14 hydrides Et3SiH and Bu3SnH. GeMePh is slightly more reactive than GePh2 towards all the reagents studied in this work; both are significantly less reactive than GeMe2 toward the same substrates. Absolute rate constants for the reactions of 4 have also been measured or assigned upper limits in every case and are compared to previously reported values for tetraphenyl- and tetramethyl-digermene with the same reagents.Key words: germylene, digermene, kinetics, laser flash photolysis, germirane, germirene, vinylgermirane, complex, UV–vis spectrum, insertion, addition.

Protonenübertragungsreaktionen zweibasischer Säuren in wäßriger Lösung: 3-Hydroxypyridin / Proton Transfer Reactions of Dibasic Acids in Aqueous Solution: 3-Hydroxypyridine

1976 ◽  
Vol 31 (5-6) ◽  
pp. 219-224 ◽  
Author(s):  
P. Schuster ◽  
K. Tortschanoff ◽  
H. Winkler
Keyword(s):  
Aqueous Solution ◽  
Relaxation Time ◽  
Proton Transfer ◽  
Aqueous Solutions ◽  
Hydration Shell ◽  
Transfer Reactions ◽  
Diffusion Controlled ◽  
Ultrasound Absorption ◽  
Proton Transfer Reactions

Proton transfer in aqueous solutions of 3-hydroxypyridin (3HP) has been studied by tempera­ture jump relaxation and ultrasound absorption techniques. Two chemical relaxations have been observed. In the range pK1<pH<pK2 the slower of the two processes corresponds to proton transfer between the N and O atoms. A mechanism is proposed which describes the pH and con­centration dependence of the relaxation time measured. Proton transfer involves two types of pro­cesses which operate in parallel: I. pseudomonomolecular, by consecutive diffusion-controlled protonation and deprotonation steps, and 2. bimolecular by diffusion-controlled proton transfer between the neutral 3HP molecule and its corresponding cation or anion. There is no evidence for direct monomolecular proton transfer within the hydration shell of the molecule (k→ ~ k← < 2 × 1O3 sec-1).

Concentration fluctuations in water–methanol mixtures as studied by ultrasonic absorption

1976 ◽  
Vol 54 (3) ◽  
pp. 355-366 ◽  
Author(s):  
William D. T. Dale ◽  
Peter A. Flavelle ◽  
Peeter Kruus
Keyword(s):  
Experimental Data ◽  
Intermolecular Interactions ◽  
Vapour Pressure ◽  
Reasonable Agreement ◽  
Concentration Fluctuations ◽  
Ultrasonic Absorption ◽  
Diffusion Data ◽  
And Diffusion ◽  
Excess Absorption

Measurements of the ultrasonic absorption and velocity, and viscosity have been carried out in the system methanol–water at 0, 15, and 25 °C at frequencies from 10 to 50 MHz. The data show the existence of two maxima in the excess absorption as a function of composition. The existence of the two maxima are predicted by the Romanov–Solovyev theory relating the absorption to concentration fluctuations. The magnitude of the excess absorption is calculated at 25 and 0 °C from density, vapour pressure, and diffusion data. New experimental data on density and vapour pressure are presented for this system at 0 °C. The calculated excess absorption is in reasonable agreement with the measured. This indicates that any specific localized intermolecular interactions present in this system could be responsible for at best a smaller portion of the excess ultrasonic absorption, as longer range concentration fluctuations account for essentially all of the excess. Ultrasonic data on the systems methanol–octanol and n-propanol–water are also presented in the course of examining the generality of these phenomena.

The pulse radiolysis of aqueous solutions of some inorganic compounds

1965 ◽  
Vol 286 (1406) ◽  
pp. 320-336 ◽  
Keyword(s):  
Aqueous Solutions ◽  
Metal Ions ◽  
Absorption Spectra ◽  
Rate Constants ◽  
Pulse Radiolysis ◽  
Inorganic Compounds ◽  
Absolute Rate ◽  
Transient Species ◽  
Temperature Coefficients ◽  
Complex Metal

The reactions of the hydrated electron, e — aq. with a variety of inorganic metal ions, complex metal ions and anions have been investigated with pulses of 4 MeV electrons. Absolute rate constants have been measured in each case and some temperature coefficients have also been determined. Absorption spectra of transient species produced by the pulse have been obtained. Some of these species are unstable valency states produced by reduction withe — aq. , e.g. Ni + , Cr v ; others are the result of oxidation by OH, e.g. Cu 3+ . We have obtained rate constants for the reactions OH+Cu 2+ and H+MnO - 4 . The significance of the rate constants and spectra is discussed.

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