Influence of alkene structure on the formation constants of alkene–ICl molecular complexes

1986 ◽  
Vol 64 (11) ◽  
pp. 2171-2174 ◽  
Author(s):  
George H. Schmid ◽  
James W. Gordon
Keyword(s):  
Molecular Complex ◽  
Formation Constant ◽  
Addition Reaction ◽  
Molecular Complexes ◽  
Formation Constants ◽  
Experimental Conditions ◽  
Rate Law ◽  
Effect Of Substituents

The experimentally determined rate law for the addition of ICl to 22 alkenes in CCl4 at 25 °C under conditions of (alkene)0 [Formula: see text] (ICl)0 is −d(ICl)/dt = kexp(alkene)0(ICl)3/{1 + C2(alkene)0}3. The constant C2 is shown to be equal to Kapp which is a measure of the formation constant or constants of the molecular complexes in this system. Under the experimental conditions used, C2 is a good approximation of the formation constant of the 1:1 alkene–ICl molecular complex. Thus the values of C2 obtained allow an estimate of the effect of alkene structure on the formation constant of the first molecular complex involved in this addition reaction. The contribution of the effect of substituents on C2 is estimated to be approximately 24% of the overall change in rate due to change in the alkene structure.

Evidence for molecular complexes in the mechanism of additions of iodine mono-chloride to alkenes

1984 ◽  
Vol 62 (11) ◽  
pp. 2526-2534 ◽  
Author(s):  
George H. Sçhmid ◽  
James W. Gordon
Keyword(s):  
Absorption Band ◽  
Equilibrium Constant ◽  
Molecular Complex ◽  
Molecular Complexes ◽  
Electrophilic Addition ◽  
Reaction Coordinate ◽  
Rate Law ◽  
Rate Determining Step ◽  
Enthalpy Changes ◽  
Enthalpy Of Activation

Immediately upon mixing ICls and 2,3-dimethyl-2-butene in CCl4 at 25 °C a new absorption band due to an alkene–ICl molecular complex appears at 295 ± 5 nm and decreases rapidly with time. The rate law under conditions of (alkene)0 [Formula: see text] (ICl)0 for the electrophilic addition of ICl to 2,3-dimethyl-2-butene, E- and Z-2-butene, and E- and Z-1-phenylpropene is −d(ICl)/dt = kexpt(alkene)(ICl)3/{1 + kAD(alkene)}3 where KAD is the equilibrium constant for the formation of a 1:1 alkene–ICl molecular complex. The addition of ICl to the Z and E isomers of 2-butene and 1-phenylpropene occurs by anti-stereospecific addition. The negative enthalpy of activation for the addition of ICl to 2,3-dimethyl-2-butene is evidence that one or more complexes are involved on the reaction coordinate prior to the rate-determining step. On the basis of analysis of the enthalpy changes during the reaction, it is proposed that both a 1:1 and a 1:2 alkene–ICl molecular complex is involved in the mechanism prior to the rate-determining step.

scholarly journals Polymer Optical Waveguide Sensor Based on Fe-Amino-Triazole Complex Molecular Switches

Polymers ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 195
Author(s):  
Muhammad Shaukat Khan ◽  
Hunain Farooq ◽  
Christopher Wittmund ◽  
Stephen Klimke ◽  
Roland Lachmayer ◽  
...  
Keyword(s):  
Molecular Complex ◽  
Electromagnetic Interference ◽  
Optical Power ◽  
Uv Curing ◽  
Molecular Complexes ◽  
Core Material ◽  
Absorption Bands ◽  
Electronic Temperature ◽  
Polymer Waveguide ◽  
Temperature Detection

We report on a polymer-waveguide-based temperature sensing system relying on switchable molecular complexes. The polymer waveguide cladding is fabricated using a maskless lithographic optical system and replicated onto polymer material (i.e., PMMA) using a hot embossing device. An iron-amino-triazole molecular complex material (i.e., [Fe(Htrz)2.85(NH2-trz)0.15](ClO4)2) is used to sense changes in ambient temperature. For this purpose, the core of the waveguide is filled with a mixture of core material (NOA68), and the molecular complex using doctor blading and UV curing is applied for solidification. The absorption spectrum of the molecular complex in the UV/VIS light range features two prominent absorption bands in the low-spin state. As temperature approaches room temperature, a spin-crossover transition occurs, and the molecular complex changes its color (i.e. spectral properties) from violet-pink to white. The measurement of the optical power transmitted through the waveguide as a function of temperature exhibits a memory effect with a hysteresis width of approx. 12 °C and sensitivity of 0.08 mW/°C. This enables optical rather than electronic temperature detection in environments where electromagnetic interference might influence the measurements.

Charge Transfer Molecular Complexes of 4-(Dimethylamino)pyridine with Some Conventional and Unconventional Acceptors Involving Fluoroarenes

2006 ◽  
Vol 71 (9) ◽  
pp. 1359-1370 ◽  
Author(s):  
Usama M. Rabie
Keyword(s):  
Charge Transfer ◽  
Nmr Spectra ◽  
Molecular Complexes ◽  
Outer Sphere ◽  
Formation Constants ◽  
Stoichiometric Ratio ◽  
Spectral Bands ◽  
Elemental Analyses ◽  
Ct Complexes ◽  
Solid Complexes

Charge transfer (CT) complexes of 4-(dimethylamino)pyridine (DMAP) with iodine as a typical σ-type acceptor and with typical π-type acceptor, 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), have been synthesized and characterized. Octafluorotoluene (OFT), octafluoronaphthalene (OFN), perfluorophenanthrene (PFP), and 2,3,5,6-tetrafluoropyridine-4-carbonitrile (TFP) were also used as acceptors for interaction with DMAP. Properties of such CT complexes were investigated by UV/VIS and IR spectra, and elemental analyses of the isolated complexes. The systems DMAP-iodine and DMAP-DDQ are characterized by formation of triiodide ions (I3-) and DDQ•- anion radicals, respectively, which is proposed to occur via initial formation of outer-sphere CT complexes. The systems (DMAP-OFT, DMAP-OFN, DMAP-PFP and DMAP-TFP) are characterized by the appearance of new UV/VIS spectral bands assigned as CT bands; they also furnished the corresponding solid complexes with the stoichiometric ratio 1:1. 1H and 19F NMR spectra were used on confirming the formation of the DMAP-PFP CT complexes. The formation constants (KCT) and molar absorption coefficients (εCT) of the latter complex were obtained.

scholarly journals Investigation of the Composition and Formation Constant of Molecular Complexes

1974 ◽  
Vol 71 (4) ◽  
pp. 1499-1503 ◽  
Author(s):  
R. Sahai ◽  
G. L. Loper ◽  
S. H. Lin ◽  
H. Eyring
Keyword(s):  
Formation Constant ◽  
Molecular Complexes

Nonlinear Hammett Relationships in the Reaction of Peroxomonosulfate Anion (HOOSO3-) with meta- and para-Substituted Anilines in Alkaline Medium

2001 ◽  
Vol 66 (6) ◽  
pp. 897-911 ◽  
Author(s):  
Subbiah Meenakshisundaram ◽  
Ramanathan Sockalingam
Keyword(s):  
Nitrogen Atom ◽  
Equilibrium Constant ◽  
Rate Equation ◽  
Kinetic Data ◽  
Formation Constant ◽  
Order Rate Constant ◽  
Reactive Intermediate ◽  
Substituted Anilines ◽  
Experimental Conditions ◽  
First Order

The HOOSO3- oxidation of eleven meta- and para-substituted anilines to the corresponding nitrosobenzenes at pH ≈ 11 was characterized by the rate equation v = kK[OX][An]/(1 + K[An]). Formation constant of the reactive intermediate and its rate of decomposition were evaluated separately for ascertaining the structure-reactivity relationships. Under the experimental conditions the dianion, -O-O-SO3- is probably the effective electrophile. Kinetic data can be rationalized by a bimolecular process which involves the attack of nucleophilic nitrogen atom on the peroxidic oxygen. The highlight of the study is the opposite curvatures observed in the nonlinear Hammett plots of first-order rate constant k and the "equilibrium" constant K, being concave downward and upward, respectively.

scholarly journals Thermodynamics of metal-ligand bond formation. VIII. Pyridine adducts of zinc(II) β-diketonates

1973 ◽  
Vol 26 (11) ◽  
pp. 2537 ◽  
Author(s):  
DR Dakternieks ◽  
DP Graddon
Keyword(s):  
Benzene Solution ◽  
Equilibrium Constants ◽  
Bond Formation ◽  
Formation Constants ◽  
Adduct Formation ◽  
Enthalpies Of Formation ◽  
Calorimetric Titration ◽  
Experimental Conditions ◽  
Metal Ligand ◽  
Ligand Bond

Equilibrium constants and enthalpies in benzene solution are reported for the formation of 1 : 1-adducts of pyridine with four zinc(II) complexes of β-diketones, determined by calorimetric titration. Adduct formation constants at 30�C fall in the range 300-2000 and enthalpies of formation lie between -15 and - 34 kJ mol-1. Though the enthalpies of formation differ little from those of corresponding copper(II) complexes, the adducts are about a hundred times more stable. The pyridine adduct of bis(2,2,6,6-tetramethylheptane-3,5-dionato)zinc(II) is entropy-stabilized relative to those of other complexes. No evidence was obtained for the addition of a second molecule of pyridine under the experimental conditions used.

scholarly journals Understanding the Solution Behavior of Epinephrine in the Presence of Toxic Cations: A Thermodynamic Investigation in Different Experimental Conditions

Molecules ◽  
2020 ◽  
Vol 25 (3) ◽  
pp. 511 ◽  
Author(s):  
Francesco Crea ◽  
Concetta De Stefano ◽  
Anna Irto ◽  
Gabriele Lando ◽  
Stefano Materazzi ◽  
...  
Keyword(s):  
Ionic Strength ◽  
Complex Formation ◽  
Formation Constants ◽  
Titration Calorimetry ◽  
Interaction Theory ◽  
Thermodynamic Investigation ◽  
Experimental Conditions ◽  
Complex Formation Constants ◽  
Specific Ion Interaction Theory ◽  
Enthalpy Changes

The interactions of epinephrine ((R)-(−)-3,4-dihydroxy-α-(methylaminomethyl)benzyl alcohol; Eph−) with different toxic cations (methylmercury(II): CH3Hg+; dimethyltin(IV): (CH3)2Sn2+; dioxouranium(VI): UO22+) were studied in NaClaq at different ionic strengths and at T = 298.15 K (T = 310.15 K for (CH3)2Sn2+). The enthalpy changes for the protonation of epinephrine and its complex formation with UO22+ were also determined using isoperibolic titration calorimetry: ΔHHL = −39 ± 1 kJ mol−1, ΔHH2L = −67 ± 1 kJ mol−1 (overall reaction), ΔHML = −26 ± 4 kJ mol−1, and ΔHM2L2(OH)2 = 39 ± 2 kJ mol−1. The results were that UO22+ complexation by Eph− was an entropy-driven process. The dependence on the ionic strength of protonation and the complex formation constants was modeled using the extended Debye–Hückel, specific ion interaction theory (SIT), and Pitzer approaches. The sequestering ability of adrenaline toward the investigated cations was evaluated using the calculation of pL0.5 parameters. The sequestering ability trend resulted in the following: UO22+ >> (CH3)2Sn2+ > CH3Hg+. For example, at I = 0.15 mol dm−3 and pH = 7.4 (pH = 9.5 for CH3Hg+), pL0.5 = 7.68, 5.64, and 2.40 for UO22+, (CH3)2Sn2+, and CH3Hg+, respectively. Here, the pH is with respect to ionic strength in terms of sequestration.

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