Discovering and Evaluating the Reducing Abilities of Polar Alkanes and Related Family Members as Organic Reductants Using Thermodynamics

In this work, the pKa values of 69 polar alkanes (YH2) in acetonitrile were computed using the method developed by Luo and Zhang in 2020, and representative 69 thermodynamic network cards on 22 elementary steps of YH2 and related polar alkenes (Y) releasing or accepting H2 were naturally established. Potential electron reductants (YH???), hydride reductants (YH???), antioxidants (YH2 and YH???), and hydrogen molecule reductants (YH2) are unexpectedly discovered according to thermodynamic network cards. It is also found that there are great differences between YH2 and common hydrogen molecule reductants (XH2), such as Hantzsch ester (HEH2), benzothiazoline (BTH2), and dihydro-phenanthridine (PH2), releasing two hydrogen ions to unsaturated compounds. During the hydrogenation process, XH2 release hydrides first, then the oxidation state XH+ release protons. However, in the case of YH2, YH2 release protons first, then YH??? release hydrides. It is the differences on acidic properties of YH2 and XH2 that result in the behavioral and thermodynamic differences on YH2 and XH2 releasing two hydrogen ions (H??????H+). The redox mechanisms and behaviors of Y, YH???, and YH2 as electron, hydrogen atom, hydride, and hydrogen molecule donors or acceptors in the chemical reaction are reasonably investigated and discussed in this paper using thermodynamics. GW WG GW e WG GW WG _H+ H R1nR2 +H+ R1 R2 R1 R2 H ......-. YH2 Y Polar Alkanes Polar Alkane Anions Polar Alkenes 0 Based on 22 Thermodynamic Data 4 YH2: Potential Antioxidants and 112 Reductants, Medium Strong Acids 4 YH: Potential Hydride Reductants and Electron Reductants Potential Antioxidants, Medium Strong Bases Superscript/Subscript Available

Automated summary

In this study, the pKa values of 69 polar alkanes in acetonitrile were calculated, and unexpected reduction and antioxidant properties were discovered in some of these compounds. Unlike common hydrogen molecule reductants, polar alkanes release protons first and then hydrides. This difference in acidity results in their behavioral and thermodynamic differences.