From the protodediazoniation of p-nitrobenzenediazonium fluoroborate in DMF, DMF-d1, DMF-d6 and DMF-d7 the ratios of nitrobenzene to nitrobenzene-4d1 are directly related to the relative rates of abstraction of methyl and formyl protons, convoluted with the deuterium kinetic isotope effect for abstraction at the two sites.

We have also carried out high level, ab initio electronic structure calculations characterizing dimethyl formamide and the methyl and formyl radicals derived from it. These calculations establish the bond dissociation energies for the methyl and formyl hydrogen bonds in DMF. The formyl bond is found to be essentially unchanged from its value in formaldehyde, while the methyl bond is seen to be considerably weaker than in dimethyl amine. The weakening of the methyl hydrogen bond reflects the stability of the HC(O)N(CH3)CH2 radical, due to delocalization of the radical center over the OCNC backbone.

Introduction || Experimental || Theory || Conclusions || References

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