A Generalized Solvent Basicity Scale: The Solvatochromism of 5‐Nitroindoline and Its Homomorph 1‐Methyl‐5‐nitroindoline

Abstract

A total of 202 organic solvents and the gas phase were placed on a solvent basicity scale for hydrogen bond acceptor based on parameter SB. The value of such a parameter can readily be determined from the UV/Vis spectrum for an appropriate acid probe (5‐nitroindoline) (NI) and its non‐acid homomorph (1‐methyl‐5‐nitroindoline) (MNI). The proposed scale can advantageously substitute the more widely used solvent scales such as Gutmann's donor number (DN), the Koppel‐Palm B(MeOD) scale, and the Taft‐Kamlet β scale. While data for the proposed scale are derived only from electronic transitions, they are accurately descriptive of solvent basicity in both spectroscopy (UV/Vis, IR and NMR) and miscellaneous chemical areas (thermodynamic, kinetics, and electrochemistry).

Interactions of polar hydrogen bond donor solvents with ions: a theoretical study

“…2 Complex and for anions D = 2.7; cf., Table S8), but the first difference is slightly higher because cations interact directly with oxygen atoms. The results obtained support the classic view that solute-solvent interactions can be described in terms of Lewis acid-base interactions [8][9][10][11][12][13]. However, these interactions can be considered as a charge transfer, and thus, solvent acidity/basicity is a dynamic property depending not only on the nature of a solvent molecule with its proper acidic and basic centers but also on the acidity/basicity of the interacting ion.…”

“…There is also a thermodynamic approach based on the Hildebrand solubility parameter d, applicable for estimating the solubility of nonelectrolytes in organic solvents [7]. Finally, chemical approaches considering solute-solvent interactions in terms of Lewis acidity/basicity [8][9][10][11][12][13], electron pair donors/acceptors [14,15] and H-bonding donors/acceptors [16,17] should be distinguished there. In some cases, solvent effects on chemical and physicochemical properties were described by mixing physical and chemical approaches [6,18].…”

“…All these problems are widely presented and thoroughly discussed in an excellent monograph by Reichardt and Welton [5]. The results obtained by different chemical approaches, based on various physicochemical solute processes, are quite often correlated [12,13,15,19,20]. However, a problem arises when numerical values of a given scale are considered in detail and examined in particular cases.…”

QSPR Modeling using Catalan Solvent and Solute Parameters

“…19 Catalan has expanded another set of solvatochromic parameters for a generalized treatment of the effects of solvents. 7 Catalan parameters consist of solvent polarity/ polarizability scale (SPP), solvent basicity scale (SB defined as cb in this work), and solvent acidity scale (SA defined as ca in this work), 8,[20][21][22][23] which recently SPP parameter split into two separate scales: solvent dipolarity (SdP defined as cd in this work) and solvent polarizability (SP defined as cp in this work). 7 The approach for measuring these parameters is similar to those of Kamlet and Taft,2,3 where a probe with specific interactions with solvent has been used and variances in spectroscopy data have been recorded and applied for the definition of the solvent scales.…”

“…7 The approach for measuring these parameters is similar to those of Kamlet and Taft,2,3 where a probe with specific interactions with solvent has been used and variances in spectroscopy data have been recorded and applied for the definition of the solvent scales. [2][3][4]8,[20][21][22][23] In formulating the independent solvent scales, the choice of an appropriate probe for the experimental determination of the scales is the major challenge. The selected probe should measure the effect of a single solvent property, for example, hydrogen-bonding basicity, without the interference of any other solvent effects.…”