Pressure-Induced Hydrogen Transfer in 2-Butyne via a Double CHAromatic Transition State

Hydrogen transfer (H-transfer) is an importantelementary reaction in chemistry and bioscience. It is oftenfacilitated by the hydrogen bonds between the H-donor andacceptor. Here, at room temperature and high pressure, we foundthat solid 2-butyne experienced a concerted two-in-two-outintermolecular CHmiddotmiddotmiddot pi H-transfer, which initiated the subsequentpolymerization. Such double H-transfer goes through an aromaticHu??ckel six-membered ring intermediate state via intermolecularCHmiddotmiddotmiddot pi interactions enhanced by external pressure. Our work shows that H-transfer can occur via the CHmiddotmiddotmiddot pi route in appropriateconformations under high pressure, which gives important insights into the H-transfer in solid-state hydrocarbons