6-Butyl-4-hydroxyquinolin-2-(1H)-one as an enol type coupling component for the synthesis of some new azo disperse dyes

Aryl and heteroaryl azo dyes derived from 6, 8‐dichloro‐4‐hydroxyquinolin‐2 (1H)‐one: synthesis, characterisation, solvatochromism and spectroscopic properties

“…The value of p K a = pH i + log[( A b − A i )/( A i − A a )] was calculated from each measurement, where A i is the absorbance of the solution at intermediate pH i , and A a and A b are the absorbance values of the strongest acidic and alkaline buffer solutions of each compound . The p K a values of the dyes were estimated by analysis of the spectral changes and are listed in Table .…”

“…The spectrophotometric results showed that the electron‐withdrawing nature of lactam moiety (quinoline‐2‐one) is responsible for bathochromic shifts in the absorption spectra of dyes with electron‐releasing groups on diazo components (dyes 5 , 6 and 7 ). These results are in accordance with previous research, suggesting that the dyes with electron‐donating groups on the phenyl ring of diazotising components or electron‐withdrawing groups on quinoline‐2‐one moiety exhibit more bathochromic shifts . Substituent and acid‐base influences on the wavelength of maximum absorption were also studied.…”

“…The value of pK a = pH i + log[(A b −A i )/(A i −A a )] was calculated from each measurement, where A i is the absorbance of the solution at intermediate pH i , and A a and A b are the absorbance values of the strongest acidic and alkaline buffer solutions of each compound. 5,[21][22][23][24][25] The pK a values of the dyes were estimated by analysis of the spectral changes and are listed in Table 4. Since the electron density on the aromatic rings can be reduced by the electron-withdrawing groups such as -CN, -NO 2 and -Cl, the pK a values show that the acidity of the hydroxyl group increases (dyes 9-14).…”

“…It was found that the 4‐hydroxyquinolin‐2(1 H )‐one‐based azo dyes have considerable advantages over some known dyestuffs . In particular, the synthesis and spectroscopic properties of some hetaryl azo dyes derived from 4‐hydroxyquinolin‐2(1 H )‐one were investigated by Sener et al In recent years, we have synthesised a series of hydroxyl quinoline‐2‐one derivatives and used them as enol‐type coupling components to prepare some novel disperse azo dyes . Encouraged by the aforementioned results, and as a continuation of an ongoing programme towards synthesising and studying the tautomeric structures of 3‐arylazo‐4‐hydroxyquinolin‐2(1 H )‐ones, the current paper focuses initially on the synthesis of 6, 8‐dichloro‐4‐hydroxyquinolin‐2(1 H )‐one ( 4 ) from ester ( 1 ) or malonamide ( 3 ) via two different methods (Scheme ).…”

“…18 In particular, the synthesis and spectroscopic properties of some hetaryl azo dyes derived from 4-hydroxyquinolin-2(1H)-one were investigated by Sener et al 19 In recent years, we have synthesised a series of hydroxyl quinoline-2-one derivatives and used them as enol-type coupling components to prepare some novel disperse azo dyes. [20][21][22][23][24] Encouraged by the aforementioned results, and as a continuation of an ongoing programme towards synthesising and studying the tautomeric structures of 3-arylazo-4-hydroxyquinolin-2(1H)-ones, 25 the current paper focuses initially on the synthesis of 6, 8dichloro-4-hydroxyquinolin-2(1H)-one (4) from ester (1) or malonamide (3) via two different methods (Scheme 2). Then this compound was allowed to react with a variety of aryl and hetaryl diazonium salts in order to synthesise the corresponding azo dyes (Scheme 3).…”