Solvation Structure of 1,3-Butanediol in Aqueous Binary Solvents with Acetonitrile, 1,4-Dioxane, and Dimethyl Sulfoxide Studied by IR, NMR, and Molecular Dynamics Simulation

Abstract

The solvation structure of 1,3-butanediol (1,3-BD) in aqueous binary solvents of acetonitrile (AN), 1,4-dioxane (DIO), and dimethyl sulfoxide (DMSO) at various mole fractions of organic solvent x has been clarified by means of infrared (IR) and H andC NMR. The change in the wavenumber of O-H stretching vibration of 1,3-BD in the three systems suggested that water molecules which are initially hydrogen-bonded with the 1,3-BD hydroxyl groups in the water solvent (x = 0) are more significantly replaced by organic solvent molecules in the order of DMSO ≫ DIO > AN. This agrees with the order of the electron donicities of the organic solvents. The H andC chemical shifts of 1,3-BD also revealed the most remarkable replacement of water molecules on the hydroxyl groups by DMSO. In contrast to the DMSO system, the O-H vibration band of 1,3-BD in the AN and DIO systems suggested the formation of the intramolecular hydrogen bond between the two hydroxyl groups of 1,3-BD above x = ∼0.9. To further evaluate the intramolecular hydrogen bonding of 1,3-BD in AN-water binary solvents, molecular dynamics (MD) simulations and NMR experiments for spin-lattice relaxation times T and H-H nuclear Overhauser effect (NOE) were conducted on 1,3-BD in the AN system. These results showed the intramolecular hydrogen bond within 1,3-BD in the AN-water binary solvents in the high AN mole fraction range of x > 0.9. Especially, the pair correlation functions g(r) of the OH-O interactions of 1,3-BD obtained from the MD simulations indicated that the intramolecular hydrogen bond remarkably increases in the AN solvent as the x rises to the unity.

Site-Selective α-Alkylation of 1,3-Butanediol Using a Thiophosphoric Acid Hydrogen Atom Transfer Catalyst

“…37) The C-H bond abstraction step by this radical species 5 is the rate-limiting step, as shown in Chart 4. Intramolecular hydrogen bonding of 1a is affected by the polarity of the solvent 38) ; in non-coordinating solvents such as DCM, 1a is known to make strong intramolecularly hydrogen bonding. 39) The OH group of the secondary alcohol is particularly prone to hydrogen bonding.…”

“…39) The OH group of the secondary alcohol is particularly prone to hydrogen bonding. 38) This is expected to increase the electron density of the secondary alcohol and lower the bond dissociation energy (BDE) of the C-H bond at the α-position. 40) Therefore, the C-H bond with smaller bond dissociation energy (i.e., secondary α-alkoxy C-H) is selec-…”

Aggregation of the Dipeptide Leu–Gly in Alcohol–Water Binary Solvents Elucidated from the Solvation Structure for Each Moiety

“…The IR spectra of the C–H stretching vibration bands of Leu–Gly in the 100 mmol dm –3 Leu–Gly/HFIP–D 2 O and Leu–Gly/2-PrOH- d 8 –D 2 O solutions (Figure S19 in the Supporting Information) also suggest the interaction of the HFIP F atoms with the alkyl group of Leu–Gly. Figure shows the wavenumbers of the prominent peak of the methyl C–H stretching vibration , at ∼2970 cm –1 as a function of x A . The vibration for the 2-PrOH solutions remarkably red-shifts with increasing x 2‑PrOH .…”

“…The procedures of the simulations were the same as those in the previous reports. , First, the centers of mass for all molecules in each system were randomly distributed in a cubic cell. In the first 500 ps, the molecules in the cell were stirred at 527.0 °C and 1000 atm.…”

Effects of self-hydrogen bonding among formamide molecules on the UCST-type liquid–liquid phase separation of binary solutions with imidazolium-based ionic liquid, [Cnmim][TFSI], studied by NMR, IR, MD simulations, and SANS

“…The procedures for the simulations were the same as those in the previous reports. 1,53,70,71 The production runs lasted 10 ns for neat FA and 20 ns for the neat IL and [C n mim][TFSI]-FA systems. MD snapshots and spatial distribution functions (SDFs) were displayed using the Visual Molecular Dynamics (VMD) program.…”