Solvatochromic hydrogen bond donor acidity of aqueous binary solvent mixtures for reversed-phase liquid

Park, Jung Hag; Jang, Myung Duk; Kim, Dong Soo; Carr, Peter W.

doi:10.1016/s0021-9673(01)89429-2

Cited by 77 publications

(15 citation statements)

References 29 publications

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“…We have employed pKa and a S , although they refer to complete-, and partial-proton transfer, respectively (Marcus 1993). We decided to test both descriptors because determination of a S has generated some controversy in the literature (Cheong and Carr 1988;Park et al 1990;Reta et al 1995).…”

Section: Quantitative Correlationsmentioning

confidence: 99%

Cellulose swelling by protic solvents: which properties of the biopolymer and the solvent matter?

Seoud

Fidale

Ruiz³

et al. 2007

Cellulose

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The question posed in the title has been addressed by studying the swelling of celluloses at 20°C by twenty protic solvents, including water; linear-and branched-chain aliphatic alcohols; unsaturated aliphatic alcohols, and alkoxyalcohols. The biopolymers investigated included microcrystalline cellulose, MC, native and never-dried mercerized cotton cellulose, cotton and M-cotton, and native and never-dried mercerized eucalyptus cellulose, eucalyptus and M-eucalyptus, respectively. In most cases, better correlations with the physico-chemical properties of the solvents were obtained when the swelling was expressed as number of moles of solvent/ anhydroglucose unit, nSw, rather than as % increase in sample weight. The descriptors employed in these correlations included, where available, Hildebrand's solubility parameters, Gutmann's acceptor and donor numbers, solvent molar volume, V S , as well as solvatochromic parameters. The latter, employed for the first time for correlating the swelling of biopolymers, included empirical solvent polarity, E T (30), solvent ''acidity'', a S , ''basicity'', b S , and dipolarity/ polarizability, p S * , respectively. Small regression coefficients and large sums of the squares of the residues were obtained when values of nSw were correlated with two solvent parameters. Much better correlations were obtained with three solvent parameters. The most statistically significant descriptor in the correlation equation depends on the cellulose, being p S * for MC, cotton, and eucalyptus, and V S for M-cotton and M-eucalyptus. The best correlations were obtained with the same set of four parameters for all celluloses, namely, solvent pKa (or a S ) b S , p S * , and V S , respectively. These results indicate that the supra-molecular structure of the biopolymer, in particular the average sizes of crystallites and micro-pores, and the presence of its chains in parallel (cellulose I) or anti-parallel (cellulose II) arrangements control its swelling. At least for the present biopolymer/solvent systems, use of solvatochromic parameters is a superior alternative to Hildebrand's solubility parameters and/or Gutmann's acceptor and donor numbers. The relevance of these results to the accessibility of the hydroxyl groups of cellulose, hence to its reactivity, is briefly discussed.

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Section: Quantitative Correlationsmentioning

confidence: 99%

Cellulose swelling by protic solvents: which properties of the biopolymer and the solvent matter?

Seoud

Fidale

Ruiz³

et al. 2007

Cellulose

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“…The δ term is dependent on the class of solvent to be studied; for aromatic solvents δ = 1, for polyhalogenated solvents δ = 0.5, and for all other solvents δ = 0. Such LFER approaches have found success in modeling solution processes as diverse as solubility, partition coefficients, and chromatographic retention . Analysis of the coefficients of the LFER provide insight into the dominant solute/solvent interactions involved in a particular solvent-dependent process.…”

Section: Introductionmentioning

confidence: 99%

UV/Vis Spectroscopic Evaluation of 4-Nitropyridine N-Oxide as a Solvatochromic Indicator for the Hydrogen-Bond Donor Ability of Solvents

1996

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The potential of 4-nitropyridine N-oxide to act as a solvatochromic indicator of the hydrogen-bond donor ability of solvents has been evaluated. A linear free-energy relationship has been established that is predominantly dependent on the Kamlet-Taft alpha parameter of the solvent. In comparison to the previously reported results obtained for pyridine N-oxide, 4-nitropyridine N-oxide possesses a solvatochromic effect that is located in the long wavelength ultraviolet region (lambda = 330-355 nm) of the spectrum, making it a viable probe for hydrogen-bond donation assessment.

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“…No products diagnostic of carbocation formation such as 3-and 4-octanol and the acetamide of 2-octylamine are formed as well. One may conclude that the elimination products are formed by the E2 mechanism and the 2-octanol by a merged mechanism with characteristics of both S N 1 and S N 2 mechanisms [7], but 84 Nicie Conley Murphy, Robert N. Compton and Richard M. Pagni www.scilet.com [9]; c [10]; d [11]; e [12]; f [13]; g [14]; h [15]; i [16]; j [17].…”

Section: Introductionmentioning

confidence: 99%

The Photochemistry of Racemic and Optically Active 2-Iodooctane in Acetonitrile–Water Mixtures

Murphy

Compton

Pagni

2010

Progress in Reaction Kinetics and Mechanism

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Racemic, optically active, and 2-deuterio-2-iodooctane were photolyzed in mixtures of acetonitrile (AN) and water ranging from 95% to 50% AN by volume. The major products in all cases were 1-, (E)-2-, and (Z)-2-octene. Minor products consisting of 2-, 3-, and 4-octanol and N-2-, N-3-, and N-4-(methylheptyl)acetamide were also formed in all cases. These products arise from the reaction of octyl cations with water and acetonitrile, with water being 4 -5 times more reactive with the cations than acetonitrile. Octane was also formed in small yields, but no meso nor d,l 7, 8-dimethyltetradecane, as was seen in significant amounts in previously reported solvents. The behaviour of the 2-deuterio-2iodooctane demonstrated that a small fraction of the reaction occurred through the 2-octyl carbene. The carbene was found to react with AN but not with water, an unusual result. Analysis of all these data showed that approximately 90% of the reaction occurred via the 2-octyl cation, 2 -4% through the 2-octyl radical, and 4 -6% through the 2-octyl carbene. F, the fraction of the intermediates going to 81 product, was determined by examining the behaviour of optically active 2iodoooctane in 95%, 90%, and 80% AN by volume. F goes up in value as the amount of water in the solvent increases, a result consistent with the photoreaction proceeding largely through ion pairs and free ions.

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Solvatochromic hydrogen bond donor acidity of aqueous binary solvent mixtures for reversed-phase liquid

Cited by 77 publications

References 29 publications

Cellulose swelling by protic solvents: which properties of the biopolymer and the solvent matter?

Cellulose swelling by protic solvents: which properties of the biopolymer and the solvent matter?

UV/Vis Spectroscopic Evaluation of 4-Nitropyridine N-Oxide as a Solvatochromic Indicator for the Hydrogen-Bond Donor Ability of Solvents

The Photochemistry of Racemic and Optically Active 2-Iodooctane in Acetonitrile–Water Mixtures

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