The kinetics of polysulphone formation IV. The isomerization of cis - and trans -2-butene accompanying polysulphone formation

1955 ◽  
Vol 229 (1179) ◽  
pp. 525-536 ◽  
Keyword(s):  
Sulphur Dioxide ◽  
Kinetic Studies ◽  
Ideal Liquid ◽  
Isomerization Reaction ◽  
Kcal Mole ◽  
Geometrical Isomerization ◽  
Ceiling Temperature ◽  
Liquid Sulphur ◽  
Cis And Trans ◽  
Kinetics Of

It has been shown by infra-red spectroscopic measurements that, at temperatures near the ‘ceiling temperature’, the copolymerization of sulphur dioxide with either cis - or trans -2- butene is accompanied by the geometrical isomerization of the 2-butene. The results of some kinetic studies of this latter reaction, using a vapour-pressure technique, are reported. Over the range investigated (25 to 60°C inclusive) the rate of this isomerization reaction increases with temperature according to the normal Arrhenius law, the overall energies of activation using benzoyl peroxide as the initiator being 16·5 ± 0·6 kcal mole –1 for the cis to trans isomerization and 18∙3 ± 0∙4 kcal mole –1 for the trans to cis isomerization. Prolonged reaction leads to the attainment of cis-trans equilibrium, and the value of the relevant thermodynamic functions are cis -2-butene→ trans -2-butene; in liquid sulphur dioxide, x B = 0∙09; ∆ H = – 1∙43 ± 0∙25 kcal mole –1 , ∆ S = – 2∙8 ± 0∙8 cal deg –1 mole –1 . These values differ from the values for an ideal liquid mixture of the cis - and trans -2-butenes. At 100°C and at high catalyst concentrations an additional isomerization reaction is detect­able; namely, that of formation of 1-butene by double-bond migration. The geometrical isomerization data are entirely consistent with the conclusion that the polymers formed from cis - and trans -2-butene are stereoisomeric (see also part III) and that one form of addition in the propagation step has a slightly lower energy of activation than the other.

The kinetics of polysulphone formation III. The formation of the polysulphones of cis and trans - 2 -butene

1955 ◽  
Vol 229 (1179) ◽  
pp. 509-524 ◽  
Keyword(s):  
Sulphur Dioxide ◽  
Heat Content ◽  
Polymer Chains ◽  
Isomerization Reaction ◽  
Thermodynamic Quantities ◽  
Kcal Mole ◽  
Ceiling Temperature ◽  
Liquid Sulphur ◽  
Cis And Trans ◽  
Kinetics Of

The kinetics of the copolymerization of sulphur dioxide with cis -2-butene and trans -2-butene have been investigated dilatometrically. Both reactions show the ‘ceiling temperature’ effect, and from the variation of the reaction rate with temperature and composition of the reaction mixture, the changes in entropy and heat content accompanying the reaction have been determined. The heat content changes have also been measured by adiabatic calori­metry. The thermodynamic quantities obtained for the reaction (2-C 4 H s +SO 2 ) hq.mixt. → 1/ n (—C 4 H 8 SO 2 —) (solution in monomer mixture) cis system: ∆ H = – 19·3 ± 0·3 kcal mole –1 ∆ S 0 = – 66·3 ± 0·9 cal mole –1 deg. C –1 , trans system: ∆ H = – 20·1 ± 0·1 kcal mole –1 ∆ S 0 = – 71·6 ± 0·3 cal mole –1 deg. C –1 , the standard state for ∆ S 0 being 1 mole 1. –1 for each reactant. In calculating the values from the kinetic data allowance has been made for the concurrent cis-trans isomerization reaction described in part IV. The values of ∆ H , together with the known differences in heat content of the cis - and trans -2-butene when dissolved in liquid sulphur dioxide (see part IV), indicate that the heat content of a monomeric segment of the dissolved polymer formed from cis -2-butene exceeds the heat content of a segment of the dissolved polymer derived from trans - 2-butene by 2·33 ± 0·6 kcal mole –1 . Possible stereoisomerism of the polymer chains which might account for the discrepancy is discussed.

The kinetics of polysulphone formation II. The formation of 1-butene polysulphone in the region of the ceiling temperature

1952 ◽  
Vol 212 (1109) ◽  
pp. 207-220 ◽  
Keyword(s):  
Monomer Concentration ◽  
Effect Of Temperature ◽  
Kcal Mole ◽  
Temperature Dependent ◽  
Chain Polymer ◽  
Free Energy Of Formation ◽  
Ceiling Temperature ◽  
Liquid Sulphur ◽  
State 1 ◽  
Kinetics Of

The effect of temperature on the rate of formation of 1-butene polysulphone from mixtures of liquid sulphur dioxide and 1-butene has been investigated dilatometrically. Three methods of initiation were used: photochemical, silver nitrate and benzoyl peroxide, and the temperature range covered was 0 to 70° C. For appreciable rates of reaction, the photochemical rate may be expressed in the form: rate = k 1 [ B ] [ S ] — k 2 , where [ B ] [ S ] denotes the monomer concentration product and k 1 and k 2 are temperature-dependent constants. For each reaction mixture there is a critical temperature defined as the ceiling temperature T c above which the reaction rate and molecular weight of polymer formed are very small. This temperature is independent of the method and rate of initiation. Previous explanations of the ceiling temperature phenomenon are shown to be unsound. The present results may be interpreted on the assumption that the reverse of the propaga­tion reaction, here designated the depropagation reaction, becomes important as the ceiling temperature is approached. The kinetic data permit the evaluation of both the heat and entropy of polymerization, and for the reaction (l - C 4 H 8 + SO 2 ) liq. mixt → 1/ n (C 4 H 8 SO 2 ) n (solution in monomer mixture), — Δ H = 20.7 ± 1.4 kcal mole -1 , — Δ S ° = 68.2 cal mole -1 ° K -1 (standard state 1 mole l. -1 each reactant). The heat change determined by adiabatic calorimetry is 22.0 ± 0.7 kcal mole -1 . In principle, all polymerization systems should exhibit the ceiling temperature effect under suitable conditions. Possible systems for investigation are suggested. The ceiling temperature is the temperature at which the free energy of formation of long-chain polymer is zero. Above the ceiling temperature the polymer is thermodynamically unstable. Depolymerization experiments on I-butene polysulphone indicate that below 130° C the degradation is random in character, whether effected by light or by heat.

[1H,15N] N.M.R. Kinetic Studies of Reactions of cis- and trans-[PtCl2(15NH3)(c-C6H1115NH2)] with Guanosine 5'-Monophosphate

1999 ◽  
Vol 52 (3) ◽  
pp. 173 ◽  
Author(s):  
Sarah J. Barton ◽  
Kevin J. Barnham ◽  
Abraha Habtemariam ◽  
Urban Frey ◽  
Rodney E. Sue ◽  
...  
Keyword(s):  
Trans Isomer ◽  
Active Metabolite ◽  
Kinetic Studies ◽  
Trans Influence ◽  
Trans Complex ◽  
Kinetics Of Reaction ◽  
Cis And Trans ◽  
Kinetics Of ◽  
Cis Isomer ◽  
Amine Ligand

cis-[PtCl2(15NH3)(c-C6H11NH2)] is an active metabolite of the oral platinum(IV) anticancer drug cis,trans,cis-[PtCl2(CH3CO2)2(NH2)(c-C6H11NH2)]. Since it is likely that guanine bases on DNA are targets for this drug, we have analysed the kinetics of reaction of this platinum(II) metabolite with guanosine 5′-monophosphate (5′-GMP) at 310 K, pH 7, using [1H, 15N] n.m.r. methods. Reactions of the trans isomer are reported for comparison. The reactions proceed via aquated intermediates, and, for the cis isomer, the rates of aquation and substitution of H2O by 5′-GMP are 2-5 times faster trans to the amine ligand (c-C6H11NH2) compared to trans to NH3 for both the first and second steps. For the trans complex, the first aquation step is c. 3 times faster than for the cis complex, as expected from the higher trans influence of Cl¯, whereas the rate of the second aquation step (trans to N7 of 5′-GMP) is comparable to that trans to NH3. These findings have implications for the courses of reactions with DNA.

The kinetics of elementary reactions involving the oxides of sulphur II. Chemical reactions in the sulphur dioxide afterglow

1966 ◽  
Vol 295 (1443) ◽  
pp. 363-379 ◽  
Keyword(s):  
Excited States ◽  
Sulphur Dioxide ◽  
Kinetic Studies ◽  
Absolute Intensity ◽  
Third Order ◽  
Elementary Reactions ◽  
The Third ◽  
Dominant Process ◽  
Recombination Reactions ◽  
Kinetics Of

The main recombination reactions in the sulphur dioxide afterglow are shown to be O + SO 2 + M = SO 3 + M (1) and O + SO + M = SO 2 + M , (2) with rate constants of (4·7 ± 0·8) x 10 15 and (3·2 ± 0·4) x 10 17 cm 6 mole -2 s -1 respectively at 300°K for M = Ar. Reaction (2) is the dominant process removing sulphur monoxide (SO) which is otherwise remarkably unreactive. The absolute intensity of the sulphur dioxide afterglow is found to be I = 1·5 x 10 8 [O] [SO] cm 3 mole -1 s -1 for argon carriers at pressures between 0·25 an d 3·0 mmHg. The afterglow emission comes from three excited states of SO 2 . Spectroscopic and kinetic studies show that these are populated subsequent to or by the third order combination reaction (2). Excited SO 2 is removed mainly by electronic quenching.

The kinetics of polysulphone formation - I. The formation of 1-butene polysulphone at 25° C

1952 ◽  
Vol 212 (1108) ◽  
pp. 96-112 ◽  
Keyword(s):  
Sulphur Dioxide ◽  
Primary Process ◽  
Propagation Process ◽  
A Value ◽  
Absorption Of Light ◽  
Rate Of Reaction ◽  
Liquid Sulphur ◽  
Rate Of Absorption ◽  
Photochemical Initiation ◽  
Kinetics Of

The formation of 1-butene polysulphone from mixtures of liquid sulphur dioxide and 1-butene has been investigated dilatometrically at 25° C. Photochemical and silver nitrate initiation have been used, most of the work being carried out in mixtures containing an excess of sulphur dioxide. There is a discrepancy, in the case of photochemical initiation, between the molecular weight as estimated from the intrinsic viscosity of the polymer, and that deter­mined from the rate of reaction and rate of absorption of light. This discrepancy is ascribed to an inefficient primary process. The variation of rate with initiator, monomer and retarder concentrations has been investigated. The initiator exponent has a value intermediate between 0.5 and 1.0, indicating the occurrence of at least two termination processes. Kinetic expressions have been deduced for various possible termination mechanisms, and. in order to obtain agreement with experiment it is necessary to assume that the propagation process involves the addition to the growing chain of a 1:1 molecular complex of 1-butene and sulphur dioxide.

A shock-tube study of the kinetics of decomposition of sulphur dioxide

1963 ◽  
Vol 276 (1367) ◽  
pp. 461-474 ◽  
Keyword(s):  
Activation Energy ◽  
Triplet State ◽  
Sulphur Dioxide ◽  
Direct Reaction ◽  
Kcal Mole ◽  
Absorption Bands ◽  
True Activation Energy ◽  
Rate Of Increase ◽  
Reaction Theory ◽  
Kinetics Of

The rate of increase in strength of absorption bands of SO has been measured in shock-heated mixtures of sulphur dioxide and argon. Arrhenius-type plots indicate a unimolecular first step of the order d [SO]/d t = k [SO 2 ] [ M ], where [SO], [SO 2 ] and [ M ] are concentrations of [SO], [SO 2 ] and total gas. The apparent activation energy at around 3500 °K is 56 kcal/mole. It is shown that on unimolecular reaction theory, if four harmonic modes of oscillation in the SO 2 molecules contribute to the energy available for transformation, the true activation energy is 74 kcal/mole. This agrees with the energy of excitation to a known triplet state of SO 2 , and on this basis it is suggested that the first steps in the decomposition are SO 2 + M = SO* 2 + M — 73.6 kcal/mole (1) and SO* 2 + SO 2 = SO 3 + SO + 25.6 kcal/mole. (2) Step (2) is spin-allowed, whereas the more direct reaction SO 2 + SO 2 = SO 3 + SO —48 kcal/ mole is spin-forbidden. This is an unusual type of decomposition mechanism and occurs because of the high dissociation energy of SO 2 , because the direct step of low-energy is spinforbidden, and because there is a favourably situated triplet state of the molecule.

The kinetics of elementary reactions involving the oxides of sulphur I. The nature of the sulphur dioxide afterglow

1966 ◽  
Vol 295 (1443) ◽  
pp. 355-362 ◽  
Keyword(s):  
Nitrogen Dioxide ◽  
Sulphur Dioxide ◽  
Active Species ◽  
Kcal Mole ◽  
Elementary Reactions ◽  
Kinetics Of

Studies of the sulphur dioxide afterglow in the products of a weak discharge through sulphur dioxide and argon show that the main active species are O and SO. The chemiluminescent combination of these species produces the sulphur dioxide after glow, the intensity of which is proportional to [O] [SO]. Sulphur monoxide reacts rapidly with nitrogen dioxide SO + NO 2 = SO 2 + NO + 59 kcal/mole. (3) Titration of the sulphur dioxide afterglow with nitrogen dioxide yields the sum of the O and SO concentrations, since reaction (2) is also fast, O + NO 2 = NO + O 2 + 46 kcal/mole. (2) The ratio k 2 / k 3 was found to be 0·67 ± 0·07 at 298°K. Klein & Herron’s (1964) value of k 2 yields k 3 = 5 x 10 12 cm 3 mole -1 s -1 at 298°K.

The kinetics of the homogeneous gaseous oxidation of sulphur dioxide

1966 ◽  
Vol 295 (1440) ◽  
pp. 72-83 ◽  
Keyword(s):  
Nitric Oxide ◽  
Sulphur Dioxide ◽  
Collisional Activation ◽  
Catalyst Concentration ◽  
Homogeneous Reaction ◽  
Kcal Mole ◽  
Relative Contribution ◽  
Catalysed Reaction ◽  
High Concentrations ◽  
Kinetics Of

Studies of the gaseous oxidation of sulphur dioxide show that in the absence of added catalysts an apparently homogeneous reaction can be observed only over a rather narrow temperature range (900 to 1050°C). On the basis of the dependence of the rate of this reaction on the concentration of the reactants and of the value of the activation energy (75 kcal/mole), a tentative reaction mechanism is proposed which involves initially the collisional activation of sulphur dioxide. In the presence of nitric oxide, reaction takes place at an appreciable rate at temperatures as low as 400°C. The catalysed reaction is essentially homogeneous and its rate is unaffected by nitrogen and water vapour. At fairly high concentrations of nitric oxide, the rate is approximately proportional to the square of the catalyst concentration and to the first power of the oxygen concentration, but is almost independent of the concentration of sulphur dioxide and of temperature. In the presence of lower concentrations of the additive, the rate is approximately proportional to the first power of both the nitric oxide and oxygen concentrations, increases slightly with the sulphur dioxide concentration, and is appreciably dependent on temperature. The observed kinetic relationships can be satisfactorily explained in terms of a mechanism involving the interaction of sulphur dioxide with the species, NO 2 and NO 3 , the relative contribution of the two reactions: NO 2 + SO 2 = NO + SO 3 and NO 3 + SO 2 = NO 2 + SO 3 varying with the concentrations of the reactants and with temperature.

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