الفهرس 
Chapter 1 : IntroductionOnly 14 pages are availabe for public view
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Abstract
ade for these· componds to define the The calculated LUMO’s have been confirmed through the experimental cathodic reduction which reveal the responsible reducing azo group. It has been noticed that the reduction rate of TAR is higher than that in case of TAS.
Chapter three : In this chapter the experimental details are given on the preparation of solutions. Instrumentation and working procedures are also described. This chapter includes also, the results and discusssion of the spectrophotometric study of the acid-base equilibria of 22benzothiazolylazoresorcinol (BTAR) and 2-benzothiazolylazosalicylic acid (BTAS) in binary water-organic solvent systems contaning 20ro, 40% and 60% (v/v) methanol, ethanol, n-propanol, iso-propanol, aceetone, dioxane or DMF. The solution spectra of the reagents have been recorded at different pH values. The spectral changes are explained in terms of shifts in equilibria amongst different molecular and ionic species existing in solutions. The ionization constants correesponding to the various acid-base equi libria have been determined. The pKa values of the benzothiazolylazophenol derivatives were correelated in the light of molecular structure of the reagents and the nature of the organic co-solvent used. The elemination of the protons from the compounds investigated is enhanced as the amount of dioxxane or DMF increases but to the contrary decreases as the proportion of methyl, ethyl, n-propyl or iso-propyl is increased. This behaviour may be explained on the basis that the former solvent act as proton acceptor”’ rather than donors and cause protona tion of the lone pairs of-OH and -COOH groups and facilitate the proton dissociation from these compounds. The pK2 values of (BTAS) are higher than those of (BTAR). This can be attributed to the ease of ionization of-COOH group in (BTAS) at lower pH values forming the monoanonic species of (BTAS). This renders the ionization of the-OH group becomes more difficult (Le higher pKa value).