Editor-in-Chief Hatice Kübra Elçioğlu Vice Editors Levent Kabasakal Esra Tatar Online ISSN 2630-6344 Publisher Marmara University Frequency Bimonthly (Six issues / year) Abbreviation J.Res.Pharm. Former Name Marmara Pharmaceutical Journal
Marmara Pharmaceutical Journal 1990 , Vol 6 , Issue 1
The isolation of hydrochlorides of symmetrical diaminocarbanilides and the determination of their acid constants
Mürşit Pekin,Emre Dölen
In this work, the nitro compounds which are equivalent to symmetrical diaminocarbanilids, are isolated as their hydrochlorides upon reduction with Sn + HCl and their thermodynamic acid constants are determined potentiometrically. The Speakman method which is introduced for the determination of the acid constants of diprotic acids is modified for tetraprotic acids and the conditions in the modification steps are discussed accordingly, 1) The initial pH value must be smaller than pK1; 2) This method could be used separately for the determination of the consecutive acid constant doublets of tetraprotic acids and in this condition for determination K3 and K4, in the calculation of the molar concentration of the base added, the amount of base added for the neutralization of the first two protons is subtracted from the total base amount added, on the other hand, for the determination of the ionic strength the total base amount added must ne considered; 3) In determination of K1 and K2 the titration differences betweed the first equivalent point and the second equivalent point and in calculation of K3 and K4 the third equivalent point and the fourth equivalent point must be used.

The values determinated are for 2’,2’-diaminocarbanilid dihydrochloride (ODAK.2HCl) pK1=3.630, pK2=4.403; for 3’,3’- diaminocarbanilide tetrahydrochloride (MDAK.4HCl) pK1=3.867, pK2=3.277, pK3=5.295; pK4=5.827 and for 4’,4’- diaminocarbanilid tetrahydrochloride (PDAK.4HCl) pK1=3.592, pK2=3.892, pK3=6.547; pK4=6.966. Keywords :

Marmara University