Journal Articles (before-1995)

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Kinetic isotope effects: Part 7.—Ionization of (d)-phenylmethylacetophenone
(Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1972, 68 (5), 1972) Earls, D. W.; Jones, J. R.; Rumney, T. G.
Measurements are reported on the hydroxidc-catalyzed ionization of (d)-phenylmethylaceto- phenone in the presence of varying amounts of dimethyl sulphoxide. The kinetic hydrogen isotope effect (kn/kr) increases with increasing basicity until at a H_ value of 16.5 it reaches a maximum. The value of the Bronsted exponent 3 is 0.49 ±0.02 for both isotopes. For several media, activation energies and pre-cxponcntial factors have been determined. The difference Ey—Er reaches a maximum at a H_ value of 16.8. The ratios of JrMt reflect the importance of solvent reorganization contributions.
Microcalorimetric Studies: Enthalpies of Formation of Amino-acid and Peptide Complexes of Coppcr(ll) and Nickel(II)
(Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1972, 68 (9), 1972) Tipping, E. W.; Skinner, H. A.
Measurements of the enthalpies of decomposition by acid at 24–25°C of a number of amino-acid and peptide complexes of CuII and NiII in solution (µ= 0.100 M) have been made using a Beckman microcalorimeter. The enthalpies of formation (from ions in solution) are derived for glycyl-glycinato(2-)copper(II), (glycylglycinato)(glycylglycinato(2-))copper(II) anion, leucylglycinato(2-)-copper(II), glycylglycinatonickel(II) cation, di(glycylglycinato)nickel(II), tri(glycylglycinato)nickel(II) anion, (glycylglycinato)(glycylglycinato(2-))nickel(II) anion, di(glycylglycinato(2-))nickel(II) dianion, glycinamidocopper(II) dication, di(glycinamido)copper(II) dication and di(glycinamido(1-))-copper(II). Equilibrium formation constants for certain of these complexes were measured from pH titration measurements. The bond strength of N→CuII in solution is greater than N→NiII whether the N atom belongs to amino or to peptide groupings.
Colloid and Surface Chemistry of Polymer Latices: Part 1—Adsorption and Wetting Behaviour of n-Alkanols
(Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1972, 68 (8), 1972) Ottewill, R H; Vincent, B
A polystyrene latex, containing particles with a carboxylated surface, has been used as a model system for measurement of the adsorption of the n-alkanols, methanol, ethanol, propanol and butanol. Complementary measurements were made of the wetting properties of polystyrene films, prepared from the latex, by n-alkanol-water mixtures. The critical surface tension of wetting of polystyrene was found to be 27 ± 1 dyn cm-1. The adsorption isotherm of n-butanol on polystyrene differed significantly from that obtained on a typical hydrophobic substrate, Graphon, which suggested that interaction occurred between the hydroxyl group on the butanol molecule and hydrophilic sites on the surface of the latex particle. At concentrations close to the solubility limit of butanol multilayer adsorption was observed.
Flash Photolysis and Electron Spin Resonance Study of p-Chloranil
(Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1972, 68 (12), 1972) Wong, S. K.; Fabes, L.; Green, W. J.
The photochemistry of p-chloranil in dioxan and in isopropyl alcohol was re-investigated by a combination of flash-optical e.s.r.-rotating sector techniques. The transient photoradical is identified as the p-tetrachlorobenzosemiquinone neutral radical based on e.s.r. and kinetic evidence. The radicals decayed by self-disproportionation with a second order rate constant of approximately 8.2 x 108 M-1 s~l in dioxan and about 1.7 x 108 M-1 s-1 in isopropyl alcohol. The combined optical e.s.r. data yielded the following optical molar extinction coefficients for the neutral semiquinone radicals in dioxan: 7.3 x 103 M-1 cm-1 (420 nm); 7 7 x 103 M'1 cm~l (435 nm) and 6.0 x 1000 M-1 cm-1 (448 nm).
Component Interactions in Aqueous Acetone
(Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1972, 68 (7), 1972) Fox, Malcolm F.
νmax and Îµmax for the n–π* transition of acetone in aqueous solution do not vary monotonically with acetone concentration. The Klotz-Worley R parameter for these solutions shows a maximum at 0.05 x2 whereas carbonyl infrared intensities are a linear function of acetone concentration. Hydrophobic hydration of acetone is proposed in the initial region with direct molecular interaction at approximately 0.20 and 0.45 x2.
Aerosol Formation from Sulphur Dioxide in the Presence of Ozone and Olefinic Hydrocarbons
(Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1972, 68 (9), 1972) Cox, R. A.; Penkett, S. A.
The gas phase oxidation of sulphur dioxide in the presence of ozone and olefinic hydrocarbons has been studied at p.p.m. concentrations. The rate of oxidation was determined by measurement of the sulphuric acid aerosol formed from radioactive 35SO2. Sulphur dioxide and ozone do not react at an appreciable rate at low concentration, but in the presence of olefins a rapid oxidation of sulphur dioxide occurs. The kinetics of the reaction are consistent with a mechanism in which sulphur dioxide is oxidized in a fast reaction with a short-lived intermediate produced in the initial reaction of ozone with the olefinic double bond. This oxidation process is of considerable significance in the atmospheric chemistry of sulphur dioxide.
Tonic Association of Some Tetraheptylammonium and Tetraoctylphosphonium Salts in Ethanol Studied by Vapour Pressure Osmometry
(Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1972, 68 (6), 1972) Paligoric, I.; Gal, I. J.
The extent of ionic association of (hcpt)4NCl, (hept)4NBr, (hept)4NI, (hcpt)4NNO3 and (oct)4PNO3 in ethanol at 40 C has been measured by vapour pressure osmometry with matched thermistors. The osmotic coefficients, activity coefficients and association constants have been calculated. Ionic association increases with the increasing size of the anion, contrary to the prediction of electrostatic theory of ion pair formation, but in qualitative agreement with the effect of ionic polarizability based on an approximate hard sphere “ dielectric bubble ” model. The association constants are considerably higher than those predicted by the Denison-Ramsay-Fuoss model of contact ion pairs.
Thermal Isomerization of Cyclobutenes: Part 19.—3,3,4,4-Tetrafluorocyclobutcne
(Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1972, 68 (10), 1972) Frey, H. M.; Hopkins, R. G.; Vinall, I. C.
The thermal isomerization of 3,3,4,4-tetrafluorocyclobutene has been shown to yield 1,1,4,4- tetrafluorobuta-l,3-diene quantitatively. In the temperature range 306 to 36O'C the reaction is a homogeneous first order essentially irreversible reaction which is almost certainly unimolecular. At pressures above 5.3 kN m~2 (~40 Torr) the rate constant is independent of pressure. High pressure rate constants determined at 10 temperatures in the above range yielded the Arrhenius equation, log kls-1 = 14.09±0.05 —200 600± 500 J mol_1/2.303 RT. At 333.7°C the rate constant was determined over a range of pressures from 0.7 to 9000 N m~2 (0.005 to 70 Torr) and a fall-off curve obtained. The isomerization of this compound is discussed in relation to that of perfluorocyclobutcnc and perfluoro-1,2-dimethylcyclobutene. Ricc-Ramspergcr-Kassel-Marcus calculations have been carried out, and found to fit the fall-off curve quite well. In addition, the effect on the calculated fall-off curve of making extreme changes to the vibrational assignment of the activated complex has been investigated. Finally, various computational procedures have been discussed in relation to the calculation of fall-off curves using deconvolution of the experimental results.
Infra-Red Study of the Adsorption of Ammonia on MgO: Part 1.—The Dehydrated Surface
(Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1972, 68 (2), 1972) Tench, A J; Giles, D
The adsorption of ammonia gas has been studied on dehydrated MgO. The symmetrical bending vibration v2 of ammonia is considerably perturbed by the presence of the surface and a doubling of this band is observed at low concentrations of ammonia. Models for the nature of the adsorbed species are discussed and it is concluded that the ammonia molecule is probably hydrogen-bonded to an oxide ion in the surface. There is no evidence for Bronsted or Lewis acid sites on the surface.
Chlorine Abstraction Reactions of Fluorine: Part 3.—Thermochemical Data for Chlorofluoroalkanes
(Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1972, 68 (6), 1972) Foon, Ruby; Tait, K. B.
Radiation Chemistry of Butan-l-ol
(Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1972, 68 (7), 1972) Ackerman, L. G. J; Basson, R. A; Linde, H. J. van der
The radiolysis products of butan-l-ol have been determined at low doses. The effects of total energy input, oxygen and ferric chloride on the yields of the products have been studied. The results are interpreted in terms of primary ionic fragmentations and an attempt has been made to correlate the radiolysis results with mass spectral data. Consideration has also been given to the effect of increasing chain length on the relative radiolytic stability of various bonds in the molecule.
Nanosecond Pulse Radiolysis of Acetone: Kinetic and Thermodynamic Properties of Some Aromatic Radical Cations
(Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1972, 68 (7), 1972) Rodgers, M. A. J
Spectra of the molecular ions of acetone, formed during liquid phase pulse radiolysis arc reported. The kinetic features of the monomer-dimer cation equilibria of some aromatic hydrocarbon solutes have been obtained at a number of temperatures. Equilibrium constants and thermodynamic data are measured and their implications discussed. The data are compared with literature values for the analogous equilibria involving excited singlet monomers and excimers.
Infra-red Study of the Surface Properties of Rutile: Adsorption of Ethanol, n-Butanol and n-Hexanol
(Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1972, 68 (8), 1972) Jackson, P; Parfitt, G D
The vapours of ethanol, n-butanol and n-hexanol chemisorb at room temperature on a variety of rutile surfaces. The adsorption is independent of the nature of the surface, and an estimate of the ethoxide population is 3 groups/nm2. Thermal decomposition of all three alkoxides was complete at 300°C producing surface carbonate species, with water and the respective alk-1-ene in the gas phase. A mechanism is proposed for the formation of the alk-1-ene.
Kinetics and Thermodynamics of the Complex-formation of Nickel(II) and Cobalt(II) Ions with Ammonia and Pyridine- 2-azodimethylaniline in Water, at Pressures from 1 bar to 2 kbar
(Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1972, 68 (12), 1972) Caldin, E. F.; Grant, M. W.; Hasinoff, B. B.
Thermodynamic and kinetic measurements have been made at a series of pressures from 1 bar to 2 kbar on the reactions of nickel(IQ and cobalt(II) ions with ammonia and with the large bidentate ligand PADA (pyridine-2-azodimethylaniline) in aqueous solution. The apparatus consisted of a high-pressure cell and a laser temperature-jump apparatus with spectrophotometric detection. A method is described for determining equilibrium constants at high pressures from the amplitude of the optical-density change on reaction. The values found for AK* are all in the region of 4-5 to + 8 cm3 mol-1. The results are consistent with the interpretation that the transition state involves considerable stretching of the cation-water bond, as postulated in the Eigen-Wilkins mechanism.
Thermodynamics of Autoionization of Methanol+Water Mixtures
(Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1972, 68 (3), 1972) Parsons, G. H.; Rochester, C. H.
The enthalpies of ionization of methanol + water mixtures have been measured calorimetrically and arc used to calculate the entropies of autoionization. The enthalpies arc analyzed in terms of the separate contributions made by transfer of methanol, water, the proton, hydroxide ions and methoxide ions from water to the mixed solvents. Comparison of the relative acidities of water and methanol in the gas phase and in water shows that in water hydroxide ions are more strongly solvated than methoxide ions.
Hydrogenolysis of Ethane on Evaporated Copper-Nickel Alloy Films
(Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1972, 68 (4), 1972) Plunkett, T. J.; Clarke, J. K. A.
The hydrogenolysis of ethane has been studied on a series of copper-nickel film catalysts at temperatures greater than 320°C, where the alloys are single-phased. A gradual fall in activity with nickel content is found with no break at median compositions and, while activity persists to ca. 4 % nickel content, copper films are inactive. This behaviour is not amenable to description by the simple (rigid) band approach to the electronic structure of alloys but emphasizes the retention of catalytic character of individual nickel atoms
Photochemistry of Anhydrides: Part 1.—Photolysis of Perfluoroacetic Anhydride Vapour: A New Source of CF3 Radicals
(Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1972, 68 (1), 1972) Chamberlain, G. A.; Whittle, E.
The photolysis of perfluoroacetic anhydride was studied in the temperature range 19–177°C using wavelengths in the range 254–265 nm. The photolysis is exceptionally simple and is quantitatively described by the reactions (CF3CO)2O +hν→ 2CF3+ CO + CO2, CF3+ CF3 [graphic omitted] C2F6, The anhydride was tested as a source of CF3 radicals by photolyzing it in the presence of CH4 and of cyclohexane. For the reactions CF3+ CH4→ CF3H + CH3(7), CF3+ c-C6H12→ CF3H + c-C6H11, (12), we obtain log(k7/k1c)/(cm3/2 mol–1/2 s–1/2)=(5.93 ± 0.32)–(12500 ± 700)/θ, (logk12/k1/2c)/(cm3/2 mol–1/2 s–1/2)=(5.18 ± 0.15)–(5560 ± 220)/θ, where θ= 2.303 RT/cal mol–1. These results agree with previous ones obtained using conventional sources of CF3 radicals. We conclude that perfluoroacetic anhydride is a convenient new source of CF3 radicals.
Protonation of Aromatic Carboxylic Acids in the First Excited Singlet State
(Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1972, 68 (1), 1972) Watkins, A. R.
Previous methods for determining the excited state acid-base characteristics of molecules from kinetic data are applicable only to molecules which undergo dissociation upon excitation. This paper presents a method of obtaining kinetic data from fluorescence measurements for compounds, which, upon excitation, take on a proton. The kinetic data so obtained can be used to calculate the excited state acidity constants of the protonated molecules. Comparison, for two naphthoic acids, of the results so obtained with data from the spectral method due to Forster and with data from the pH at which the fluorescence spectrum undergoes a transformation reveals considerable discrepancies: these are discussed briefly.
Energy Partition in the y-Radiolysis of Gaseous H2S+N2, H2S+Ar and H2S+Xe Mixtures
(Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1972, 68 (10), 1972) Ahmad, M.; Huyton, D. W.; Woodward, T. W.
Ionization measurements in H24-N2, H2S4-Ar, and H2S4-Xc mixtures arc used to determine apparent stopping power ratios for the mixtures, or “ energy partition parameters ”. The values found for H2S4- N2, H2S4-Ar, and H2S4-Xc are 0.20, 0.95, and 3.60 respectively, as compared to the calculated values of 0.82, 0.95, and 2.46. In H2S4-Ar mixtures a “Jesse effect ” is observed that increases the ion yield by 2 units, this effect being quenched out between stopping power fractions Z = 0.2-0.4. Measurement of sulphur yields in H2S4-N2 mixtures enables an energy partition parameter of 0.5 to be evaluated. The difference from the value obtained by ionization measurements being explained by a small “Jesse effect" In H2S4-Ar mixtures the sulphur yield G(S) was always >G(S) = 7.0 found in pure H2S and approached values as high as 24. The sulphur yield also increased between Z = 0.2 and 0.4 by twice the decrease in the ion yield. G(S) in H2S4-Xe mixtures never rises above 7.0, and the values can be justified by energy transfer from Xe* (G ~ 5.0) to H2S to give H2 4- S*, where S* is not a ground state S(3P) atom. No such simple mechanism will explain the results in H2S4-Ar mixtures. Butadiene was used as an SH and S(3P) scavenger, and the ratio of scavengeablc to non-scavengcablc sulphur in H2 4-Ar mixtures is similar to that in H2S i.e. ^43. In H2S4-Xc mixtures this ratio is ~3-4, and is explained by production of excited S atoms (S*), which react with H2S to give H2 and S2.
Infrared Spectra and Catalytic Activity of Supported Molybdenum Hexacarbonyl
(Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1972, 68 (12), 1972) Howe, R. F.; Davidson, D. E.; Whan, D. A.
Infrared spectroscopy has been used to study the olefin disproportionation catalysts consisting of molybdenum hexacarbonyl supported on silica, alumina and magnesia. Activation of the catalysts is found to cause decomposition of the molybdenum hexacarbonyl. Decomposition occurs most readily on a silica support which is not able to stabilize intermediate sub-carbonyl species. The intermediate sub-carbonyl species observed on alumina and magnesia supports arc not active centres for olefin disproportionation ; the active species is formed by complete loss of all six carbonyl ligands. Indirect evidence suggests the active species is not molybdenum(O) but some higher oxidation state.