Special Issue Reviews and Accounts ARKIVOC 2008 (i) 153-194
The nomenclature applied to compounds of type 74 has been somewhat confusing, and sometimes the name hydrazidine68-70 has also been used. Besides this, the name hydrazidine has been applied to compounds of type 76 which are also termed as hydrazide-hydrazones or dihydroformazans. These names cover, respectively, amidrazones of the types 77 and 78 (R' . H) which are incapable of tautomerism. It is intended to adhere to the name amidrazone for all compounds of type 74 and furthermore to employ the nomenclature introduced by Rapoport and Bonner71 as it is the least ambiguous. Amidrazone is named after the acid theoretically obtained from it by hydrolysis.71 Hence, CH3C(=NNH2)NH2 is acetamidrazone, In addition, in compounds containing N substituents, the nitrogen atoms are numbered71 as shown in formula 79 which is therefore named N1-phenyl-N1 ,N3 ,N3-trimethylpropionamidrazone. Compound 80 is thus a true diamidrazone (oxaldiamidrazone).
C2H5 NNC6H5(CH3) NNH2H2NN 12 N(CH3)2 H2N NH2 3 79 80
Related compounds having the structure of 81 were initially termed dihydrazidines, but have become known as amide-azines.72 Again difficulty arises with these compounds when their structures preclude tautomerism (e.g., compound 82, R = C6H5; R' = CH3), and it may well be more convenient to consider compounds 81 and 82 as N,N'-diamidines. Formula 81 thus represents N1,N1'-dimethyl-N2,N2'-diphenyl-N1,N1'-diformamidine. Otherwise, these compounds might be described as 1,2-seco-4,5-dihydro-syn-tetrazines 82 or diazabutadienes 81.
N N RN NR' RR HH NH2 H2N NR RN
81 82
5.1 General properties Amidrazones are, in general, monoacid bases which form salts with inorganic acids, the hydrochlorides being most commonly described, although carbonates, nitrates, picrates, benzoates, sulfates, and chloroplatinates have all been reported.72-74 In the free state, amidrazones tend to be either liquids or low-melting solids, and unsubstituted amidrazones show strong reducing properties akin to hydrazine itself.75 Indeed these amidrazones are almost unknown in the free state, the perfluoroalkyl compounds being almost unique in having been successfully characterized.76 Thus amidrazones in general tend to be unstable in alkaline solution undergoing hydrolysis but are much more stable in acid;77,78 e.g., heating N1-phenylcyanoformamidrazone at
ISSN 1551-7012 Page 172 ©ARKAT USA, Inc.
