1,2,4,5-Benzenetetracarbonitrile (TCB) is irradiated in the
presence of adamantane (1) and some
of its derivatives. The singlet excited state of TCB is a strong
oxidant, and there is various evidence,
including time-resolved spectroscopy, to prove that SET from the alkane
to TCB1* takes place and
yields the corresponding radical ions. The adamantane radical
cation deprotonates from the
bridgehead position, and the resulting radical couples with
TCB-•. Deprotonation via the
radical
cation occurs with a number of substituted adamantanes and remains the
exclusive or predominating reaction also with derivatives containing a potential electrofugal
group, such as one of the
following carbocations: t-Bu, CH2OMe,
CH2OH (notable here is that C−H deprotonation is
more
efficient than O−H deprotonation). A carboxy group is lost more
efficiently than a proton, however.
In contrast, detaching of such cations is the main process when
the radical cations of substituted
adamantanes is produced anodically. This different behavior is
explained on the basis of
thermochemical calculation and of the different environments
experienced by the radical cation in
the two cases, viz reaction from the solvated radical cation in the
first case and from the substrate
adsorbed on the anode in the latter one. 1-Methoxyadamantane
deprotonates from the methyl
group, a reaction explained by the different structure of the radical
cation. On the other hand, the
radical NO3
•, conveniently produced by
photolysis of cerium(IV) ammonium nitrate, reacts by
hydrogen abstraction with selective attack at the bridgehead position
and little interference by
substituents and thus offers a useful way for the selective oxidative
functionalization of adamantanes.
SynopsisTwo classes of resins, having a poly(amid+amine) structure, have been synthesized. The basicity constants and the complexing abilities toward copper (11) and nickel (11) ions have been investigated by potentiometric $chniques. The influence of the nature of the crosslinking agent on the basicities and the complexing abilities has been studied.
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