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  • Physical Chemistry  (11)
  • [abr] Tris tris (hydroxymethyl) amino-methane  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Effects of low temperatures on formation and conservation of high energy state (X"e) appearing in spinach chloroplasts during the light step of the two-stage phosphorylation: I. - Formation of X"e below 0^oC II. - Conservation of X"e between -30^oC and -196^oC
    Amsterdam : Elsevier
    Biochemical and Biophysical Research Communications 65 (1975), S. 1400-1408 
    Details
    ISSN: 0006-291X
    Keywords: [abr] ADP; adenosine diphosphate ; [abr] ATP; adenosine triphosphate ; [abr] Tris tris (hydroxymethyl) amino-methane
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/S0006-291X(75)80385-8
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  • 2
    Electronic Resource
    Electronic Resource
    Effects of low temperatures on formation and conservation of high energy state (X"e) appearing in spinach chloroplasts during the light step of the two-stage phosphorylation: I. - Formation of X"e below 0^oC II. - Conservation of X"e between -30^oC and -196^oC
    Amsterdam : Elsevier
    Biochemical and Biophysical Research Communications 65 (1975), S. 1400-1408 
    Details
    ISSN: 0006-291X
    Keywords: [abr] ADP; adenosine diphosphate ; [abr] ATP; adenosine triphosphate ; [abr] Tris tris (hydroxymethyl) amino-methane
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/S0006-291X(75)80385-8
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  • 3
    Electronic Resource
    Electronic Resource
    Bond dissociation energies and radical heats of formation in CH3Cl, CH2Cl2, CH3Br, CH2Br2, CH2FCl, and CHFCl2 (1987)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 19 (1987), S. 15-24 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An analysis of thermochemical and kinetic data on the bromination of the halomethanes CH4-nXn (X = F, Cl, Br; n = 1-3), the two chlorofluoromethanes, CH2FCl and CHFCl2, and CH4, shows that the recently reported heats of formation of the radicals CH2Cl, CHCl2, CHBr2, and CFCl2, and the C—H bond dissociation energies in the matching halomethanes are not compatible with the activation energies for the corresponding reverse reactions. From the observed trends in CH4 and the other halomethanes, the following revised ΔH°f,298 (R) values have been derived: ΔH°f(CH2Cl) = 29.1 ± 1.0, ΔH°f(CHCl2) = 23.5 ± 1.2, ΔHf(CH2Br) = 40.4 ± 1.0, ΔH°f(CHBr2) = 45.0 ± 2.2, and ΔH°f(CFCl2) = -21.3 ± 2.4 kcal mol-1. The previously unavailable radical heat of formation, ΔH°f(CHFCl) = -14.5 ± 2.4 kcal mol-1 has also been deduced. These values are used with the heats of formation of the parent compounds from the literature to evaluate C—H and C—X bond dissociation energies in CH3Cl, CH2Cl2, CH3Br, CH2Br2, CH2FCl, and CHFCl2.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/kin.550190103
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  • 4
    Electronic Resource
    Electronic Resource
    Kinetics of the thermal decomposition of CF3CHCL2 in a single-pulse shock tubeWork supported by the National Research Council of Canada. (1973)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 5 (1973), S. 363-373 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The pyrolysis of 2,2-dichloro-1,1,1-trifluoroethane was studied over the temperature range of 1120-1260°K at total reflected shock pressures from ∼2800 to 3100 torr. Below 1260°K, the decomposition leads to three reaction products which were identified as CF2CFCl, CF2CFH, and CF3CCl3. The results are interpreted in terms of a parallel C—Cl bond rupture process which becomes competitive with the molecular HCI elimination. The rate constant for the α,α-elimination process \documentclass{article}\pagestyle{empty}\begin{document}$$ CF_3 CHCl_2 \to CF_2 CFCl + HCL $$\end{document} has been deduced to be \documentclass{article}\pagestyle{empty}\begin{document}$$ \log \left( {K_1 ^\infty /\sec ^{ - 1} } \right) = \left( {13.4 \pm 0.7} \right) - \left( {63.1 \pm 3.8kcal} \right)/2.303RT $$\end{document} It was also possible to obtain the overall rate constant for the formation of CF2CFH, which is given by \documentclass{article}\pagestyle{empty}\begin{document}$$ \log \left( {K^{''} /\sec ^{ - 1} } \right) = \left( {11.5 \pm 0.8} \right) - \left( {54.1 \pm 3.8kcal} \right)/2.303RT $$\end{document} Some evidence for hydrogen fluoride elimination was found at temperatures above 1260°K. However, at these higher temperatures C—C bond scission also occurs and the kinetics of the system become untractable.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/kin.550050307
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  • 5
    Electronic Resource
    Electronic Resource
    Application of the modified semi-ion pair model for the evaluation of activation energies for HX (X = F, Cl, Br, I, OH) addition to olefins (1975)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 7 (1975), S. 363-379 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The modified semi-ion pair model for four-center reactions initially developed to treat the addition of hydrogen halides to olefins, including polar olefins, has been extensively applied to these systems. In addition, the restriction that the species added be a hydrogen halide has been relaxed and addition of HOH to olefins is treated within the same frame-work. Input parameters, transition state properties, and calculated activation energies are presented for 111 such reactions. Calculated activation energies for the elimination reactions agree to better than ±2 kcal/mole, on the average, with experimental values where these areknown.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/kin.550070306
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  • 6
    Electronic Resource
    Electronic Resource
    Model for a three-center decomposition reaction. I. Perfluorodiazirine (1975)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 7 (1975), S. 649-660 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A semiempirical approach has been used to evaluate rate parameters for a three-center decomposition reaction from the point of view of transition state theory, with perfluorodiazirine serving as the prototype molecule. Several activated complex models are considered in which the reaction coordinate is chosen as the ∡ NCN bending mode. The constraints imposed include the principle of concerted bond-order conservation in passing from the initial to the final state, and use is made of empirical bond order-bond length and bond order-force constant relationships. The geometric configuration of the transition state sought is one which conforms with the lowest energy path and is also consistent with the observed entropy of activation. The potential energy of activation is taken as the optimum difference in binding energies (based on the INDO method) between the transition and initial states, and the critical energy is obtained by applying a correction for the zero-point energy difference, derived from normal coordinate analysis. Satisfactory agreement is found in the case of the activated complex model for which the total bond order is conserved and bonds undergoing rupture are assigned a fractional bond order (FBO) of 2/3, derived from the postulate (FBO) = α/β whe re α(=2) is the number of bonds breaking, and β(=3) is the number of bonds undergoing change in the ring opening.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/kin.550070503
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  • 7
    Electronic Resource
    Electronic Resource
    Photolysis of 1,1,1-difluorochloroethane (Freon 142) at 147 nm (1977)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 9 (1977), S. 697-703 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1,1,1-Difluorochloroethane (Freon 142) was photolyzed at 147 nm in the pressure range of 3.6-20.6 torr. The effects of added NO, H2S, and CF4 were investigated. The extinction coefficient at 147 nm and 296°K was determined to be 64 ± 8 atm-1 · cm-1.The molecule photodecomposes largely by α,β elimination of HCl to give 1,1-difluoroethylene (Φ = 0.74 ± 0.06). There is no observable elimination of HF, but there is strong evidence for the elimination of the elements of FCl though the relative importance of this process is minor, as are contributions from carbon—carbon and carbon—halogen bond fission.The 1,1-difluoroethylene formed is undoubtedly vibratonally excited and is the source of a pressure-dependent small yield of fluoroacetylene. Over the pressure range studied there is no evidence that the major primary process itself is affected by changes in total pressure as is the case in the 147-nm photolysis of ethyl chloride.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/kin.550090502
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  • 8
    Electronic Resource
    Electronic Resource
    Primary processes in the 147-nm photolysis of 1,1-dichloroethane (1977)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 9 (1977), S. 619-628 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The room temperature photolysis of 1,1-dichloroethane at 147 nm in the pressure range of 1.34-196.2 torr is characterized almost entirely by the molecular elimination of HCl, Cl2, and small quantities of H2. Acetylene is also produced. While it is possible that the C2H2 arises, in part, from the decomposition of vibrationally excited ground states of C2H3Cl and/or C2H4, in this particlar case serious consideration has to be given to alternative explanations where the products of the primary processes are formed in electronically excited states. The ±, elimination of molecular chlorine is not inconsistent with an increased degree of Cl—Cl interaction predicted for a «Rydberg «state of 1,1-C2H4Cl2. Varying small yields of CH4 are observed in the presence and absence of NO. The effect of large pressures of CF4 on the quantum yields of the major products is extremely small. The extinction coefficient for 1,1-C2H4Cl2 at 147 nm and 296°K is 246 ± 29 cm-1 ± atm-1.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/kin.550090410
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  • 9
    Electronic Resource
    Electronic Resource
    A comparison of two single-pulse shock-tube techniques: The thermal decomposition of ethyl chloride and n-propyl chloride (1978)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 10 (1978), S. 855-869 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This investigation presents a detailed examination of the relative reliability of the comparative and absolute rate methods as they are applied to kinetic studies in the single-pulse shock tube. For this purpose two previously studied reactions, the thermal elimination of HCl from ethyl chloride and n-propyl chloride, were selected and mixtures of these compounds were shock heated to temperatures in the range of 960°-1100°K. The experimental results were analyzed by both methods and the rate constants obtained from these analyses are compared with those of previous studies. The advantages and shortcomings of both methods are noted and it is concluded that reliable kinetic data can be obtained by the absolute rate (isolation technique) method with careful examination of the gas-dynamic flow conditions and taking cognizance of the incident shock deceleration. The limitations of the comparative rate technique encountered in the present study were similar to those detailed in previous investigations.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/kin.550100806
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  • 10
    Electronic Resource
    Electronic Resource
    Hydrogen/deuterium abstraction by chlorine atoms from gaseous ethyl chlorides. Secondary kinetic isotope effects in the system CH3CH2Cl, CH3CHDCl, CH3CD2Cl (1984)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 16 (1984), S. 621-631 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The abstraction of hydrogen/deuterium from CH3CH2Cl, CH3CHDCl, and CH3CD2Cl by photochemically generated ground-state chlorine atoms has been investigated over the temperature range of 8-94°C using methane as a competitor. Rate constant data for the following reactions have been obtained:The temperature dependence of the relative rate constants ki/kj was found to conform to the Arrhenius rate law, where the stated error limits are one standard deviation:\documentclass{article}\pagestyle{empty}\begin{document}$$ k_1 /k_2 = (1.099 \pm 0.015)\exp [(429 \pm 2)/T] $$ $$ k_1 /k_r = (1.422 \pm 0.026)\exp [(1113 \pm 3)/T] $$ $$ k_2 /k_r = (1.295 \pm 0.029)\exp [(684 \pm 3)/T] $$ $$ k_3 /k_r = (1.177 \pm 0.025)\exp [(717 \pm 4)/T] $$ $$ k_4 /k_r = (1.115 \pm 0.023)\exp [(732 \pm 2)/T] $$ $$ k_5 /k_r = (0.978 \pm 0.020)\exp [(985 \pm 2)/T] $$\end{document} and kr is the rate constant for the reference reaction (CH4 + Cl → CH3 + HCl). The β secondary kinetic isotope effects (k2/k3/k4) are close to unity and show a slight inverse temperature dependence. Both preexponential factors and activation energies decrease as a result of deuterium substitution in the adjacent chloromethyl group. The trends are well outside the limits of experimental error.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/kin.550160602
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