Acid dissociation reaction of palladium-4-(2-pyridylazo)-resorcinol complexes

Takao Yotsuyanagi, Hitoshi Hoshino, Kazuo Aomura

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21 Citations (Scopus)


Palladium(II) formed four kinds of stable 1:1 chelates with 4-(2-pyridylazo)-esorcinol (PAR or H2R): below pH 4. a green chelate [Pd(H2R)H2O]2+ε= 1.75·104 at 440 nm and ε=8.63·103 at 580 nm); at pH 4-7 two kinds of red helate [Pd( HR)H2O]+ (ε= 2.68·104 at 515 nm) and [Pd(R)H20]0 (ε=2.89·104 at 525 nm); and at pH 8-11 a red chelate [Pd(R)OH]- (ε=3.25·104 at 520 nm). The acid dissociation constants of the chelates were estimated as Ka1=[Pd(HR)H2O+] [H+]/[Pd(H2R)H2O2+]=10-4.35±0.05 and Ka2=[Pd(R)H2O]· [[H+]/[Pd(HR)H2O+]=10-5.38±0.05 in aqueous 50% dioxane solution at 25°, μ=0.1 (NaClO4). At pH 6-11, the red palladium(II)-PAR chelates react with tetradecyldimethylbenzylammonium chloride to form an ion-association complex which is easily extracted into chloroform and has maximal absorbance at 540 nm with a molar absorptivity of 3.29·104.

Original languageEnglish
Pages (from-to)349-354
Number of pages6
JournalAnalytica Chimica Acta
Issue number2
Publication statusPublished - 1974 Aug

ASJC Scopus subject areas

  • Analytical Chemistry
  • Biochemistry
  • Environmental Chemistry
  • Spectroscopy


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