One-Electron Oxidation of Tetrasubstituted Hydrazides and Dihydrazides

Article abstract of DOI:10.1021/ja00348a027

Cyclic voltammetry curves showing no sign of radical-cation decomposition were observed for eight N,N'-diacyl-N,N'-dialkylhydrazides (7-14) which are Diels-Alder adducts of 1,3-cyclohexadiene and cyclic diacyldiimides or diethyl azodicarboxylate and their olefin-hydrogenated analogues.Protection of the alkyl groups from deprotonation is not requied for long radical-cation lifetime under CV conditions, because 1,4-dioxo-9,10-diazadecalin (15) and N,N'-dimethylphthalhydrazide (16) also show no cation decomposition on the CV timescale.E⁰' values for these compounds fall between 1.26 and 1.48 V vs.SCE.In contrast, 1,2-dicarboethoxytetrahydro- and hexahydropyridazine (17 and 18), biscarbamates with unprotected alkyl groups, show totally irreversible oxidations with peak potentials above 2.3 V.Formyltrimethylhydrazine (19) has E⁰' = 1.14 V, and its radical cation decomposes by deprotonation on the CV timescale, as indicated by observing shorter radical-cation lifetime at a higher concentration of 19, and in the presence of base.Dimethylaminophthalimide (20) has E⁰' = ca. 1.44 V, and fast scan rates must be used to see any radical-cation reduction wave.The alkyl protected N,N'-diacylhydrazine 21 gives a radical cation which is stable on the CV timescale and has E⁰' = 1.17 V.The ESR spectrum of 2,7-diaza-3,6-dioxatricyclo<6.2.2.0^2,7>dodecane (13^+.) has a(2N) = 9.6 G, a(4H) = 2.9 G, and g = 2.0044.