New Chitosan-Glyoxal Beads Supported Pd(II) Catalyst: Synthesis, Characterization and Application in Suzuki Coupling Reactions

Abstract

Ö Z E T B u çalışmada, Suzuki çapraz kenetlenme tepkimeleri için yeni bir kitosan boncuk destekli Pd(II) katalizörü hazırlandı ve yapısı FTIR, XRD, TGA, SEM/EDAX ve ICP-OES analizleri ile karakterize edildi. Katalizörün, katalitik ve tekrar kullanılabilirlik performansları mikrodalga ısıtma altında ve çözücüsüz ortamda biaril bileşiklerinin sentezinde araştırıldı. Katalizör basit ve hızlı bir mikrodalga ısıtma yöntemi ileiyi dönüşüm tepkime verimleri ve yüksek TON ve TOF değerleri sağladı. Ayrıca optimum koşullar altında tekrar kullanılabilirlik testleri katalizörün beş çevrime kadar kullanılabileceğini gösterdi. Anahtar KelimelerKenetleme tepkimeleri, biaril, tekrar kullanılabilirlik, kitosan, Schiff bazı. A B S T R A C TI n this paper, a new chitosan bead supported Pd(II) catalyst was prepared and its structure was characterized with FTIR, XRD, TGA, SEM/EDAX and ICP-OES analyses for Suzuki coupling reactions. The catalytic and recyclable performances of the catalyst were explored in the synthesis of biaryl compounds under microwave heating and free solvent media. The catalyst provided good conversion reaction yields and high TON and TOF values with a simple and quick microwave heating procedure. In addition, the recycle tests indicated that the catalyst could be used for up to seven runs under optimum reaction conditions.

Degradation-Dependent Controlled Delivery of Doxorubicin by Glyoxal Cross-Linked Magnetic and Porous Chitosan Microspheres

“… 43 After the cross-linking process, the carbonyl stretching of the amide I band shifted from 1656 to 1643 cm –1 , and the NH 2 bending of amide II has shifted from 1575 to 1554 cm –1 in GS, which is attributed to the stretching of the imine group (C=N) formed by nucleophilic attack of the nitrogen of the amino group (from chitosan) on the carbon of the glyoxal. 44 , 45 The distinctive absorption band at around 1069 cm –1 in the spectrum of GS results from the O–C–O vibration attributed to acetalization between the hydroxyls of glucosamine in chitosan and the aldehyde group of glyoxal. 42 , 43 , 46 Acetalization and Schiff base formation have been further confirmed by the fact that the intensity of peaks in the range 1490–1220 cm –1 is reduced significantly in GS as compared to CS.…”

“…The peaks in the spectrum of CS are specified as follows: 3420 (N–H and O–H stretch), 2920 (CH 3 symmetric stretch), 1656 (CO stretch of amide I), 1575 (NH 2 bend of amide II), 1427 (C–N stretch), 1380 (CH 3 symmetric deformation), 1260 (characteristic amide III stretching vibrations), and 1160 cm –1 (C–O–C bend) . After the cross-linking process, the carbonyl stretching of the amide I band shifted from 1656 to 1643 cm –1 , and the NH 2 bending of amide II has shifted from 1575 to 1554 cm –1 in GS, which is attributed to the stretching of the imine group (CN) formed by nucleophilic attack of the nitrogen of the amino group (from chitosan) on the carbon of the glyoxal. , The distinctive absorption band at around 1069 cm –1 in the spectrum of GS results from the O–C–O vibration attributed to acetalization between the hydroxyls of glucosamine in chitosan and the aldehyde group of glyoxal. ,, Acetalization and Schiff base formation have been further confirmed by the fact that the intensity of peaks in the range 1490–1220 cm –1 is reduced significantly in GS as compared to CS. Different types of Schiff base linkages can contribute biologically relevant properties such as tunable mechanical properties, chemical stability in physiological environments, and remarkable pH responsiveness, which collectively make this linkage of prime importance in biological applications, especially for drug delivery. − …”

CNC pincer palladium complex supported on magnetic chitosan as highly efficient and recyclable nanocatalyst in C─C coupling reactions

“…Palladium nanoparticles immobilized on ligand‐free chitosan or modified chitosan, e.g. thiourea‐modified chitosan, silica–chitosan and chitosan‐ g ‐mPEG hybrid, chitosan/cellulose–Pd(II) catalyst, functionalized chitosan–Pd(II) complexes such as Schiff bases and amino acid derivatives and magnetic‐functionalized chitosan‐supported palladium catalyst have been used as efficient catalyst sources for Suzuki coupling.…”