Influence of packing of the reactants and products in solution on the volume parameters of the Diels-Alder reaction

Kiselev, V. D.; Kashaeva, E. A.; Potapova, L. N.; Shikhab, M. S.; Коновалов, А. И.

doi:10.1007/s11176-005-0054-z

Cited by 5 publications

(6 citation statements)

References 8 publications

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“…On the other hand, the acceleration of the rate of reactions, catalyzed by gallium or aluminum trihalides in inert media, practically coincides with the acceleration of reactions found in the dienophile medium 1, 5. In n ‐donor solvents, the catalytic effect of gallium or aluminum trichloride is almost entirely suppressed 1, 5…”

Section: Introductionsupporting

confidence: 53%

“…It is interesting to note that at the transition of the Diels–Alder reaction of cyclopentadiene with acrylonitrile from diethyl ether solution to a 1 M solution of LP in diethyl ether, the rate of acceleration is even higher than that for the same reaction in the transition from the acrylonitrile to a 1 M solution of LP in acrylonitrile 4. On the other hand, the acceleration of the rate of reactions, catalyzed by gallium or aluminum trihalides in inert media, practically coincides with the acceleration of reactions found in the dienophile medium 1, 5. In n ‐donor solvents, the catalytic effect of gallium or aluminum trichloride is almost entirely suppressed 1, 5…”

Section: Introductionmentioning

confidence: 59%

“…Since the concentration of the solvent is much higher than that of n ‐donor reagent, the part of activated reagent in salt solutions is usually small. This usually explains the relatively weak total salt influence on the acceleration of reactions 3–5. It is interesting to note that at the transition of the Diels–Alder reaction of cyclopentadiene with acrylonitrile from diethyl ether solution to a 1 M solution of LP in diethyl ether, the rate of acceleration is even higher than that for the same reaction in the transition from the acrylonitrile to a 1 M solution of LP in acrylonitrile 4.…”

Section: Introductionmentioning

confidence: 99%

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Solvent effect on the heat of solution and partial molar volume of magnesium perchlorate

Kiselev

Bolotov

Kashaeva

et al. 2010

J of Physical Organic Chem

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For magnesium perchlorate (MP), the solvent effect on the heat of solution and partial molar volumes (PMV) at 25 °C was studied. Since the complete dissociation of magnesium perchlorate is more difficult to achieve as compared with lithium perchlorate (LP), the concentration dependence of the values of the heat of solution and partial molar volume were noted. Only in highly polar solvents with large donor numbers (DN), such as water, dimethyl sulfoxide, N,N‐dimethyl formamide, and formamide, the differential and integral values of the enthalpies of solution were the same in the range of concentrations studied. In all solvents studied, the values of the heat of solution of MP were highly exothermic and exceed that of LP by more than 30 kcal mol−1. The values of the partial molar volume of MP were changed from 82.3 cm3 mol−1 in formamide to −2.4 cm3 mol−1 in acetone, and correlate linearly with that of LP (R = 0.975). Taking into account the significant change in the properties of molecules in the solvate shell of cation Mg2+, the large increase in the reactivity of reactants, activated by such interaction with Mg2+ cation is expected. Copyright © 2010 John Wiley & Sons, Ltd.

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Section: Introductionsupporting

confidence: 53%

Section: Introductionmentioning

confidence: 59%

Section: Introductionmentioning

confidence: 99%

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Solvent effect on the heat of solution and partial molar volume of magnesium perchlorate

Kiselev

Bolotov

Kashaeva

et al. 2010

J of Physical Organic Chem

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“…The observed reaction volume (∆V) by more than a factor of 2 exceeds the van der Waals reaction volume ∆V W due to an addi tional contribution caused by a change in the volume of intermolecular cavities. 1,2,7, 8 This has recently been con firmed experimentally by a comparison of the volumes of several Diels-Alder reactions in the solid phase and in solutions. 9 The intrinsic volume of the Diels-Alder reac tion determined by the difference in the van der Waals volumes V W of the products and reactants is rather con stant (-8±2 cm mol -1 ) for all types of reactants.…”

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confidence: 93%

Volume parameters of some Diels-Alder reactions involving C=C, C=S, and N=N bonds

et al. 2005

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The effect of a hydrostatic pressure of up to 1000 kg cm -2 on the rate constants of the Diels-Alder reactions of maleic anhydride with 1,2,3,4 tetraphenylcyclopentadiene and with 6,13 dichloropentacene, of 4 phenyl 1,2,4 triazoline 3,5 dione with hexachlorocyclo pentadiene, and of thiobenzophenone with isoprene was studied at 25 °С. The volume param eters and ratios of the activation to reaction volumes make it possible to exclude electrostriction of the solvent during transition state solvation in all the reactions studied, which corresponds to the nonpolar nature of the transition state.Elevated pressure facilitates substantially chemical pro cesses if the volume of the system decreases during the reaction. The origin of a volume change is not the main problem for practical purpose. However, the use of vol ume parameters of the reaction to refine the reaction mechanism requires information on the contributions that form these volume parameters. The factors that affect the activation volume (∆V ≠ ) and Diels-Alder reaction vol ume (∆V ) have been considered earlier. 1-4 These volume parameters can be determined from the dependence of the rate (k) or equilibrium (K ) constant on the pres sure (p).Real and imaginary changes in the volume parameters should be distinguished. Real values of the volume pa rameters are caused by the general volume changes in the system (addends, transition state, and solvents) and in clude changes of the intrinsic (van der Waals, ∆V W ) vol umes due to the bond redistribution and changes in inter molecular volumes (∆V solv ) in the solvate shell of the cor responding states (reactants, transition state, products). The reaction volume values can be obtained both by Eq.(2) and directly from the difference between partial molar volumes (PMVs) of the products and reactants. The activation volumes can be calculated only using the dependence (1). If an elevated pressure can induce a change in the properties of the system, which, in turn, affects the free activation or reaction energy, then the volume parameter values including the imaginary contri butions can be obtained from Eqs (1) and (2). With a pressure increase, the rate (k) or equilibrium (K ) con stants can change due to the energy р•∆V ≠ or р•∆V and pressure induced changes: in the dielectric constant of the medium, 3 concentration of active species in the cata lytic process, 5 and viscosity of the medium to a level of the diffusionally controlled rate of the process. 4,6Two new C-C bonds are consistently formed in a nonpolar Diels-Alder reaction. However, the values of the activation and reaction volumes can strongly differ (from -15 to -40 cm 3 mol -1 ), depending on the size and structure of the reactants. 7 The formation of the products from the reactants with elevated packing coefficients (η = V W /V ) was found 8 to be usually accompanied by a weak increase in this parameter, while an increase in the packing coefficients on going to the adducts is much higher in the reactions involving "loose" reactants. The observed reaction...

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“…1,2 It has been shown additionally for the Diels-Alder reac tion that the higher volume parameters are observed for the processes involving small, "loosen" reactants with the low packing coefficient in solution. 3,4 Their transition to the activated complex or adduct is always accompanied by a considerable increase in the packing coefficient. The van der Waals activation (∆V ≠ W ) and reaction (∆V W ) vol umes are often by 2-3 times lower by modulus than the observed volume parameters in solution (∆V ≠ and ∆V ) due to a large contribution of the change in the volume of intermolecular holes in solution.…”

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confidence: 99%

Activation and reaction volumes of the reactions of o-and p-nitrophenylsulfenyl chlorides with styrene and cyclohexene in some solvents

et al. 2007

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The effect of hydrostatic pressure below 1000 kg cm -2 on the rate of reactions of o and p nitrophenylsulfenyl chlorides with styrene and cyclohexene was studied. The activation and reaction volumes (cm 3 mol -1 ) for the reactions of o nitrophenylsulfenyl chloride with styrene in acetonitrile (-23.1 and -23.6), 1,2 dichloroethane (-29.2 and -24.7), chlorobenzene (no, -20.2), and anisole (-25.1 and -21.2) and for the reaction of p nitrophenylsulfenyl chloride with styrene in carbon tetrachloride (-39.5±1.5 and -22.0) were determined. In carbon tetrachloride the activation volumes for the reactions of cyclohexene with o and p nitrophenylsulfenyl chlorides (-37.7±2.0 and -40.9±1.2 cm 3 mol -1 , respectively) are almost the same and coincide with the data for the reactions with styrene. The considerable decrease in the volume of the transition state in the nonpolar solvent is considered as a consequence of the enhanced electrostriction of carbon tetrachloride in the solvate sphere of the transition state of the reaction, which excludes the nonpolar transition state of the sulfuran type.Complex investigation of the nonpolar Diels-Alder reaction free of electrostriction of the medium during solvation of the transition state made it possible to find that in the series of solvents a noticeable change in the activation or reaction volume is observed only for strong specific interactions of the reactants with the medium. 1,2 It has been shown additionally for the Diels-Alder reac tion that the higher volume parameters are observed for the processes involving small, "loosen" reactants with the low packing coefficient in solution. 3,4 Their transition to the activated complex or adduct is always accompanied by a considerable increase in the packing coefficient. The van der Waals activation (∆V ≠ W ) and reaction (∆V W ) vol umes are often by 2-3 times lower by modulus than the observed volume parameters in solution (∆V ≠ and ∆V ) due to a large contribution of the change in the volume of intermolecular holes in solution. The experimental con firmation has been obtained recently 5 from comparison of the reaction volumes in the solid phase and in solution. It has been shown 6 for lithium perchlorate used as a model of the ion state that the change in the partial molar vol ume (PMV) due to electrostriction of the solvent reaches tens of cubic centimeters per mole, resulting in even nega tive PMV value in acetone (-2 cm 3 mol -1 ). The activa tion and reaction volumes can be determined from the equations -RT(∂lnk/∂p) Т = (∂G ≠ /∂p) Т = ∆V ≠ = ∆V ≠ W + ∆V ≠ sol , (1)where ∆V ≠ sol and ∆V sol are the parameters of the solvent. Taking into account the aforesaid, we should expect low ∆V ≠ W and ∆V W values and their differences for both polar and nonpolar processes. More substantial contribu tions to the observed ∆V ≠ and ∆V values and their differ ences are formed due to a change in the solvent packing (∆V ≠ sol and ∆V sol ), especially in the solvate shell of charged states.Considerable attention was given to studying the el eva...

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Influence of packing of the reactants and products in solution on the volume parameters of the Diels-Alder reaction

Cited by 5 publications

References 8 publications

Solvent effect on the heat of solution and partial molar volume of magnesium perchlorate

Solvent effect on the heat of solution and partial molar volume of magnesium perchlorate

Volume parameters of some Diels-Alder reactions involving C=C, C=S, and N=N bonds

Activation and reaction volumes of the reactions of o-and p-nitrophenylsulfenyl chlorides with styrene and cyclohexene in some solvents

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