Designer “Quasi-Benzyne”: The Spontaneous Reduction of Ortho-Diiodotetrafluorobenzene on Water Microdroplets
Huan Chen, Ruijing Wang, Tatsuya Chiba, Kathryn Foreman, Kit H. Bowen, Xinxing Zhang
Abstract
It has been widely shown that water microdroplets have a plethora of unique properties that are highly distinct from those of bulk water, among which an especially intriguing one is the strong reducing power as a result of the electrons spontaneously generated at the air–water interface. In this study, we take advantage of the reducing power of water microdroplets to reduce ortho-diiodotetrafluorobenzene (o-C 6 F 4 I 2 ) into a C 6 F 4 I 2 •– radical anion. Photoelectron spectroscopy and density functional theory computations reveal that the excess electron in C 6 F 4 I 2 •– occupies the I–C1–C2–I linkage, which elongates the C–I bonds but surprisingly shortens the C1–C2 bond, making the bond order higher than a double bond, similar to the benzyne molecule, so we named it “quasi-benzyne”. The C 6 F 4 I 2 •– anion was further successfully utilized in a Diels–Alder reaction, a typical reaction for benzyne. This study provides a good example of strategically utilizing the spontaneous properties of water microdroplets and generating an especially exotic anion, and we anticipate that microdroplet chemistry can be an avenue rich in opportunities for new catalyst-free organic reactions.