In the presence of FSO3D rather than FSO3H, methane has been shown to interchange hydrogen atoms for deuterium atoms, and HD is released rather than H2. This is evidence to suggest that in these reactions, methane is indeed a base, and can accept a proton from the acid medium to form . This ion is then deprotonated, explaining the hydrogen exchange, or loses a hydrogen molecule to form – the carbonium ion. This species is quite reactive, and can yield several new carbocations, shown below.