新试剂AHDHD和DHDHD离解常数的测定与归属

Determination and assignation of acidic dissociation constants of AHDHD and DHDHD

介绍了6-(对氨基苯基偶氮)-2,3-二氢-1,4-酞嗪二酮(简称 AHDHD)和6-(2,4-二羟基苯基偶氮)-2,3-二氢-1,4-酞嗪二酮(简称 DHDHD)的合成方法。以异鲁米诺和亚硝酸钠反应制取相应的重氮盐后,再进一步分别与苯胺和间苯二酚发生偶联反应合成了 AHDHD 和 DHDHD 两种试剂。用分光光度法测定的两试剂的离解常数为;AHDHD pK_1=3.20,pK_2=11.60;DHDHD pK_1=4.96,pK_2=11.64。应用 Hückel 分子轨道(HMO)法研究了试剂各离子在不同酸度下的平衡形式。借助理论计算与分光光度法所测定数据的对照,进行了离解常数的归属。

The synthetic methods of 6-(4-amin-ophenylazo)-2,3-dihydrogen-phthalaz-1,4-dione(AHDHD)and 6-(2,4-dihydroxyphenylazo)-2,3-dihydrogen-phthalaz-1,4-dione(DHDHD)arereported.By diazo-reaction using isoluminol andsodium nitrite,diazonium salt was obtained,which was converted into AHDHD and DHDHDby diazo coupling reactions with aniline and m-dihydroxybenzene.From spectrophotometrie datathe acid dissociation constants of the two reagentshave been determined.These results may besummarized as follows:AHDHD pK_1=3.20,pK_2=11.60;DHDHD pK_1=4.96,pK_2=11.64.Theequilibrium shape of these reagents in media ofvarious acidity has been studied using the Hückelmolecular orbital(HMO)method.By comparisonof these results with experimental data fromabsorption spectra,the assignation of dissociationconstants may be made.