Effect of solvent structure on electron reactivity: 2-propanol/water mixtures

1988 ◽  
Vol 66 (7) ◽  
pp. 1706-1711 ◽  
Author(s):  
Yadollah Maham ◽  
Gordon R. Freeman
Keyword(s):  
Electron Transfer ◽  
Secondary Alcohol ◽  
Mixed Solvents ◽  
Trap Depth ◽  
Large Change ◽  
Solvent Composition ◽  
Solvated Electrons ◽  
Tertiary Alcohols ◽  
Alcohol Water ◽  
Small Change

The reactivity of solvated electrons [Formula: see text] with efficient (nitrobenzene, acetone) and inefficient (phenol, toluene) scavengers is affected greatly by the solvent composition in 2-propanol/water mixed solvents. 2-Propanol is the only secondary alcohol that is completely miscible with water. The variation of the nitrobenzene rate constant k2 with solvent composition displays four viscosity zones, as in primary and tertiary alcohol/water mixtures. In zone (c), where the Stokes–Smoluchowski equation applies, the nitrobenzene k2 values in the secondary alcohol/water mixtures are situated between those in the primary and tertiary alcohols, due to the relative values of the dielectric permittivity ε. The charge–dipole attraction energy varies as ε−1.The two water-rich zones (c) and (d) are characterized by a large change of viscosity η and a small change in [Formula: see text] solvation energy (trap depth) Er; here k2 for all the scavengers correlates with the inverse of the viscosity. In the two alcohol-rich zones (a) and (b) the change of η is small but that of Er is large; here k2 of inefficient scavengers correlates with the inverse of Er, due to the difficulty of electron transfer out of deeper traps. Activation energies E2 and entropies [Formula: see text] also show composition zone behaviour. The value of [Formula: see text] is more negative for less efficient scavengers; E2 varies less and does not correlate with reactivity or Er. Electron transfer from solvent to inefficient scavenger is driven by solvent rearrangement around the reaction center, reflected in [Formula: see text].

Composition effects on optical absorption spectra of solvated electrons in alcohol/water mixed solvents

1982 ◽  
Vol 60 (18) ◽  
pp. 2342-2350 ◽  
Author(s):  
Ah-Dong Leu ◽  
Kamal N. Jha ◽  
Gordon R. Freeman
Keyword(s):  
Optical Absorption ◽  
Pure Water ◽  
High Energy ◽  
Band Width ◽  
Primary Alcohols ◽  
Solvated Electrons ◽  
Tertiary Butyl ◽  
Composition Effects ◽  
Tertiary Alcohols ◽  
Alcohol Water

Addition of a few percent of water to an alcohol has a relatively large effect on the shape of the optical absorption spectrum of solvated electrons in the liquid. This occurs whether the optical absorption energy in the pure alcohol is greater or smaller than that in water. Addition of up to 10 mol% of water causes EAmax in methanol and primary alcohols to decrease, while it increases in secondary and tertiary alcohols. At around 10 mol% water in primary alcohols EAmax passes through a minimum and increases again at higher water concentrations, reaching a plateau at about 30 mol% and remaining constant up to about 95 mol% water; over the last part of the composition range to pure water EAmax decreases slightly. The behavior in secondary and tertiary alcohols containing > 30 mol% water is similar to that in primary alcohols. The width of the band at half height W1/2 is divided at EAmax into "red side" and "blue side" portions Wr, and Wb, respectively. In methanol and in primary and secondary alcohols, addition of up to 30 mol% of water greatly reduces Wb but has relatively little effect on Wr. At > 30 mol% water Wb and Wr are similar to those in pure water. In tertiary butyl alcohol the band width is similar to that in pure water, so addition of water to the alcohol makes little change in the band width. The water/alcohol composition effects on the es− absorption band parameters are attributed to changes in solvent structure. This is especially evidenced by the minimum in EAmax at 10 mol% water in a primary alcohol. The changes in band asymmetry Wb/Wr indicate that the types of electronic transition on the low and high energy sides of the band are different.

Effects of solvent structure on electron reactivity and radiolysis yields: 2-propanol/water mixed solvents

1984 ◽  
Vol 62 (7) ◽  
pp. 1265-1270 ◽  
Author(s):  
Joanna Cygler ◽  
Gordon R. Freeman
Keyword(s):  
Pure Water ◽  
Mixed Solvents ◽  
Water Structure ◽  
Trap Depth ◽  
Solvent Structure ◽  
Solvated Electrons ◽  
Absorption Energy ◽  
Diffusion Controlled ◽  
Free Ion ◽  
Different Temperatures

Reaction of solvated electrons with nitrobenzene, N, is nearly diffusion controlled in both pure solvents; kN ~ 1010 dm3/mol s. The value of kN is approximately proportional to the inverse viscosity η−1 in the pure solvents, and in the mixed solvents at different temperatures. However, on going from zero to 74 mol% water at the same temperature kN is independent of the 40% increase of η. Electron diffusion in the mixed solvents is not a simple function of fluidity.Reaction with the inefficient scavengers tryptophane (kS ~ 109 dm3/mol s) and phenol (kS ~ 107–108 dm3/mol s) correlates inversely with the electron optical absorption energy. The latter is related to the trap depth in the solvent; electrons in deeper traps have less tendency to react with molecules of low electron affinity.Addition of 3 mol% 2-PrOH to water at 296 K increases the value of Gεmax by 16%, although the value in pure 2-PrOH is three-fold smaller than that in pure water. The increase is attributed to an increase in the free ion yield, caused by an increase in the product of the electron thermalization range and the microscopic dielectric constant of the fluid between the ion and electron, averaged over the time that they exist as a correlated pair. Addition of a small amount of alcohol to water increases the orderliness of the water structure.

scholarly journals The Additive Influence of Propane-1,2-Diol on SDS Micellar Structure and Properties

Molecules ◽  
2021 ◽  
Vol 26 (12) ◽  
pp. 3773
Author(s):  
Martina Gudelj ◽  
Paola Šurina ◽  
Lucija Jurko ◽  
Ante Prkić ◽  
Perica Bošković
Keyword(s):  
Mixed Solvents ◽  
Sodium Dodecyl ◽  
Shielding Effect ◽  
Bulk Solution ◽  
Structure And Properties ◽  
Micellar Structure ◽  
Related Substances ◽  
Micellar Systems ◽  
Small Change ◽  
Additive Influence

Micellar systems are colloids with significant properties for pharmaceutical and food applications. They can be used to formulate thermodynamically stable mixtures to solubilize hydrophobic food-related substances. Furthermore, micellar formation is a complex process in which a variety of intermolecular interactions determine the course of formation and most important are the hydrophobic and hydrophilic interactions between surfactant–solvent and solvent–solvent. Glycols are organic compounds that belong to the group of alcohols. Among them, propane-1,2-diol (PG) is a substance commonly used as a food additive or ingredient in many cosmetic and hygiene products. The nature of the additive influences the micellar structure and properties of sodium dodecyl sulfate (SDS). When increasing the mass fraction of propane-1,2-diol in binary mixtures, the c.m.c. values decrease because propane-1,2-diol is a polar solvent, which gives it the ability to form hydrogen bonds, decreasing the cohesivity of water and reducing the dielectric constant of the aqueous phase. The values of ΔGm0 are negative in all mixed solvents according to the reduction in solvophobic interactions and increase in electrostatic interaction. With the rising concentration of cosolvent, the equilibrium between cosolvent in bulk solution and in the formed micelles is on the side of micelles, leading to the formation of micelles at a lower concentration with a small change in micellar size. According to the 1H NMR, with the addition of propylene glycol, there is a slight shift of SDS peaks towards lower ppm regions in comparison to the D2O peak. The shift is more evident with the increase in the amount of added propane-1,2-diol in comparison to the NMR spectra of pure SDS. Addition of propane-1,2-diol causes the upfield shift of the protons associated with hydrophilic groups, causing the shielding effect. This signifies that the alcohol is linked with the polar head groups of SDS due to its proximity to the SDS molecules.

scholarly journals An electron transfer driven magnetic switch: ferromagnetic exchange and spin delocalization in iron verdazyl complexes

2018 ◽  
Vol 47 (18) ◽  
pp. 6351-6360 ◽  
Author(s):  
David J. R. Brook ◽  
Connor Fleming ◽  
Dorothy Chung ◽  
Cardius Richardson ◽  
Servando Ponce ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Spin Crossover ◽  
Large Change ◽  
Single Electron ◽  
Spin Multiplicity ◽  
Magnetic Switch ◽  
Ferromagnetic Exchange ◽  
Spin Delocalization ◽  
Electron Reduction

A single electron reduction of an iron bis(verdazyl) complex results in a large change in spin multiplicity resulting from a combination of spin crossover and exceptionally strong ferromagnetic exchange.

Electron-transfer reactions in non-aqueous media. VII. Reduction of CoF(NH3)52+ and Co(HCOO)(NH3)52+ by copper(I) in dimethyl sulfoxide-water mixtures

1983 ◽  
Vol 36 (10) ◽  
pp. 1923 ◽  
Author(s):  
JMB Harrowfield ◽  
L Spiccia ◽  
DW Watts
Keyword(s):  
Electron Transfer ◽  
Dimethyl Sulfoxide ◽  
Aqueous Media ◽  
Mixed Solvents ◽  
Transfer Reactions ◽  
Aprotic Solvents ◽  
Aqueous Mixtures ◽  
Electron Transfer Reactions ◽  
Dipolar Aprotic Solvents ◽  
Sphere Mechanism

Previous work on the reduction of a series of cobalt(III) complexes by iron(II) in dipolar aprotic solvents and in aqueous mixtures has been extended to reduction by copper(I). The greater stability of copper(I) to disproportionation in these media has permitted the study of the reduction of CoF(NH3)52+ and Co(HCOO)(NH3)52+ in range of solvents over a number of temperatures with a precision not possible in previous studies in water. The results are consistent with an inner-sphere mechanism in which the copper(I) reductant is preferentially solvated by dimethyl sulfoxide to the exclusion of water in mixed solvents.

scholarly journals Minimizing the Impacts of Desertification in an Arid Region: A Case Study of the West Desert of Iraq

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Khamis Naba Sayl ◽  
Sadeq Oleiwi Sulaiman ◽  
Ammar Hatem Kamel ◽  
Nur Shazwani Muhammad ◽  
Jazuri Abdullah ◽  
...  
Keyword(s):  
Land Degradation ◽  
Vegetation Index ◽  
Rainwater Harvesting ◽  
Large Change ◽  
Cost Effective ◽  
Western Desert ◽  
Gis Environment ◽  
Small Change ◽  
Western Desert Of Iraq ◽  
Suitable Land

Currently, desertification is a major problem in the western desert of Iraq. The harsh nature, remoteness, and size of the desert make it difficult and expensive to monitor and mitigate desertification. Therefore, this study proposed a comprehensive and cost-effective method, via the integration of geographic information systems (GISs) and remote sensing (RS) techniques to estimate the potential risk of desertification, to identify the most vulnerable areas and determine the most appropriate sites for rainwater conservation. Two indices, namely, the Normalized Differential Vegetation Index (NDVI) and Land Degradation Index (LDI), were used for a cadastral assessment of land degradation. The findings of the combined rainwater harvesting appropriateness map, and the maps of NDVI and LDI changes found that 65% of highly suitable land for rainwater harvesting lies in the large change and 35% lies in the small change of NDVI, and 85% of highly suitable land lies in areas with a moderate change and 12% lies in strong change of LDI. The adoption of the weighted linear combination (WLC) and Boolean methods within the GIS environment, and the analysis of NDVI with LDI changes can allow hydrologists, decision-makers, and planners to quickly determine and minimize the risk of desertification and to prioritize the determination of suitable sites for rainwater harvesting.

Inclusion Behavior of Chemical Modified β-cyclodextrin in Alcohol/Water Mixed Solvents

2000 ◽  
Vol 16 (03) ◽  
pp. 248-252
Author(s):  
Jie Hong-Zhi ◽  
◽  
Wu Shi-Kang
Keyword(s):  
Mixed Solvents ◽  
Alcohol Water

Application of Supercritical Carbon Dioxide for Solar Water Heater

2017 ◽  
pp. 215-234
Author(s):  
Yuhiro Iwamoto ◽  
Hiroshi Yamaguchi
Keyword(s):  
Heat Exchanger ◽  
Solar Collector ◽  
Supercritical Co2 ◽  
Large Change ◽  
Solar Water Heater ◽  
Water Heater ◽  
Solar Water ◽  
Small Change ◽  
And Performance ◽  
Main Components

For supercritical CO2, a small change in temperature or pressure can result in large change in density, especially in the state close to the critical point. The large change in density can easily induce the natural convective flow. In this chapter, a solar water heater using supercritical CO2 which is originally designed and constructed will be introduced. The solar water heater is a closed loop system with main components of an evacuated solar collector and a heat exchanger. The working fluid of CO2 is naturally driven by the large change in density with absorbing and transporting heat in the solar collector. And the heat energy (hot water) is produced by exchanging the transferred heat with water in the heat exchanger. This chapter will describe the typical system operation and performance at different season and climates.

scholarly journals Reflections on the outer-sphere mechanism of electron transfer

1996 ◽  
Vol 74 (5) ◽  
pp. 631-638 ◽  
Author(s):  
Thomas W. Swaddle
Keyword(s):  
Electron Transfer ◽  
Large Change ◽  
Outer Sphere ◽  
Pressure Effects ◽  
Spherical Approximation ◽  
Mean Spherical Approximation ◽  
Redox Kinetics ◽  
Electron Transfer Processes ◽  
Low Pressures

The quantitative efficacy of the Stranks–Marcus–Hush theory of volumes of activation ΔV‡ for outer-sphere electron transfer between metal complexes in solution is assessed. The theory predicts ΔV‡ accurately for several couples in aqueous solution, but is satisfactory for polar nonaqueous solvents only at pressures of ca. 100 MPa and above, and accuracy is not improved when the molecular nature of the solvent is allowed for through the Mean Spherical Approximation approach. At low pressures, the calculations become numerically unstable when the isothermal compressibility of the solvent is high and its relative permittivity is low, particularly for the more highly charged couples. For aqueous systems, departures from the predicted ΔV‡ afford insights into the role of the counterions, the incursion of inner-sphere pathways, the enhanced reactivity of CoIII/II cage complexes relative to conventional chelates, and the question of "spin forbiddenness" of electron transfer processes that involve a large change in spin multiplicity. Key words: redox kinetics, inorganic reaction mechanisms, pressure effects, Marcus–Hush theory, activation volumes.

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