Preparation, Characterization and Complexationof some HydroxamicAcidswith Iron (III), Vanadium (V), Cobalt (II) and Copper (II), Cations.

Abstract

Five hydroxamic acids were preparedthrough the esterification route. The prepared esterswere reacted with free hydroxylamineunder cold ether process. This method was found to be more applicable than the aqueous process. They were benzohydroxamic acid (BHA),cinnamohydroxamic (CHA) and salicylohydroxamicacid(SHA).β–phenylbenzohydroxamic acid,(β.PBHA) andβ-phenylcinnamohydroxamicacid (β.PCHA),were preparedby the partial reduction of nitrobenzene with zinc dust and ammonium chloride to give β-phenyl hydroxyl amine, which was coupled first with methyl benzoate to giveβ–phenylbenzohydroxamic and thesecond with methylcinnamate to give β-phenylcinnamohydroxamic.The five synthesized ligands were recrystallized by hot water/acetic acid.Thehydroxamic acids were characterized by their standard color test with vanadium (V)and iron (III), melting pointsfor (BHA) (lit131ºCfound127ºC), (β.PBHA)(lit125ºC found 121ºC),(CHA)(lit.114ºC found 114ºC), (β.PCHA)(lit 144-146ºC,found 146ºC),(SHA)(lit.168-170ºC, found 170ºC). I.R. spectra were show the most characteristic bands associated with hydroxamic acids functional group that is due to -OH (BHA 3067,β.PBHA 3082.2,

ii CHA 3260.2,β.PCHA 3266.4,SHA 3288.09)C=O (BHA 1687.38,β.PBHA 1667,CHA1663,β.PCHA1631.67,SHA 1613.64),C-N (BHA 1289,β. PBHA 1289, CHA1350, β.PCHA1348.1, SHA 135.7) N-O (BHA 931,β.PBHA 932,CHA966,β.PCHA 943.1, SHA 907.2) cm-1. The 1H NMR spectra of the hydroxamic acids under investigation show ᵟ(ppm) for (BHA8.0, 7.52 ,7.66.7.97,β.PBHA7.37,7.57,CHA 7.37,7.57,β.PCHA7.38,7.56, 7.66,SHA7.33,7.71) due to (Ar-H's), for (BHA 3.777,β.PBHA3.77,CHA4.93,β.PCHA 3.33, SHA3.78) attributed to NH ,(BHA 6.1,β.PBHA5.74,CHA4.945,β.PCHA 5.00, SHA6.9) assigned to –OH. The 13C NMR spectra exhibit absorption signal due to carbonyl (C=O) nearly (BHA 167.4, β.PBHA 167.4, CHA 169.7, β.PCHA 163, SHA 166) ppm. The peak at (BHA 134, β.PBHA 132, CHA 134, β.PCHA 134, SHA 133) ppm assigned to two carbon atoms 2and 6 of the benzene ring, the peak at (BHA 129, β.PBHA 128, CHA 128, β.PCHA 128, SHA 127) ppm assigned to two carbon atoms 3and 5of the benzene ring.

iii The prepared hydroxamic acids were complexed with Fe (III) to obtain colored complex for (BHA violet,β.PBHA red,CHAbrown,β.PCHAredbrown,SHAdark brown), with V(V) toobtain colored complex for (BHA violet,β.PBHA violet,CHA dark violet,β.PCHAviolet,SHA dark violet), with Co(II) to obtaincolored complex for (BHA pink,β.PBHA pale violet,CHA pink,β.PCHApaleviolet,SHApink ) and with Cu(II)to obtaincolored complex for (BHA blue,β.PBHA blue,CHA green,β.PCHAblue,SHAgreen ).They were recrystallized with ethanol and then, characterized by I.R. spectra, 1H NMR,13 C NMR. Stoichiometric measurements were carried for (SHA) with the metals Fe (III), V(V),Co (II) and Cu(II) ( using continuous variation method (Job's method), the stoichiometric ratio of Fe-salicylhydroxamate,V-salicylhydroxamate, Co-salicylhydroxamate and Cu-salicylhydroxamate, complexes were determined by modified Job's method of continuous variation. The mole ratio of complexes were determined, in different chemical environments, and found to be in ratio of 1:3 forFe-salicylhydroxamate, V-salicylhydroxamate, Co-salicylhydroxamate, and 1:1 forCu-salicylhydroxamate (M:L).