Synthesis and characterization of oligo‐2‐hydroxy‐1‐naphthaldehyde and its Schiff base oligomers

Abstract

ABSTRACT:In this study, oligo-2-hydroxy-1-naphthaldehyde (OHNA) was synthesized from the oxidative polycondensation of 2-hydroxy-1-naphthaldehyde (HNA) with air oxygen, NaOCl, and H 2 O 2 in an aqueous alkaline medium at 50 -95°C. We determined the products and the oxidative polycondensation reaction conditions of HNA with oxidants such as air oxygen, NaOCl, and H 2 O 2 . In these reactions, H 2 O 2 was more active than air oxygen and NaOCl and their optimum reaction conditions were studied. The products were characterized by 1 H-NMR, FTIR, UV-visible, and elemental analysis. The respective number-average molecular weight, mass-average molecular weight, and polydispersity index values of OHNA and its Schiff base oligomers (compounds 1, 2, and 3) were found to be 500 g mol Ϫ1 , 1880 g mol Ϫ1 , and 3.75 for OHNA; 670 g mol Ϫ1 , 2490 g mol Ϫ1 , and 3.71 for compound 1; 390 g mol Ϫ1 , 1080 g mol Ϫ1 , and 2.77 for compound 2; and 320 g mol Ϫ1 , 670 g mol Ϫ1 , and 1.85 for compound 3. At the optimum reaction conditions, the yields of the reaction products were found to be 77.0% O 2 , 78.0% H 2 O 2 , and 75.4% NaOCl. About 80% of the HNA was converted into OHNA. In addition, new Schiff based oligomers were synthesized from the condensation reaction of OHNA with p-aminophenol, triethyleneglycol bis(4-aminophenyl ether), and aniline and their structures and properties were determined. Thermogravimetric and dynamic thermal analyses showed OHNA and its Schiff base oligomers to be stable against thermooxidative decomposition. The weight losses of OHNA and its Schiff base oligomer compounds 1, 2, and 3 were found to be 5% at 175, 225, 190, and 230°C, respectively; 50% at 900, 590, 650, and 620°C, respectively; and 60, 80, 85, and 82%, respectively, at 1000°C.

Synthesis, characterization, and thermal degradation of new aromatic poly(azomethine-urethane)s and their polyphenol derivatives

“…Polyazomethines (PAMs), with a wide range of applications, have a importance due to having a lot of useful properties such as high thermal stability and excellent mechanical strength as well as their semi-conductivity and optoelectronic properties [8,9]. Because of these properties, they were used to prepare composites with resistance to high temperature and graphite materials, epoxy oligomer and block copolymers adhesives, fotoresists and antistatic materials [10][11][12].…”

Synthesis, Characterization, and Optimum Reaction Conditions of Oligo-3-Aminopyridine and its Schiff Base Oligomer

“….N intramolecular hydrogen bond, which is in agreement with reported values. [12] To identify the structures of OAP and its Schiff base oligomer (Schemes 2 and 7), 1 H NMR spectra were recorded in DMSO-d 6 . The FT-IR spectral data of the OAP and its Schiff bases oligomer confirm the results of the 1 H NMR spectra.…”

“…[1][2][3][4][5][6][7][8] The halogen and sulfur derivatives of oligophenols were used to prepare flame-resistant composite materials such as in lead collecting battery cathodes. [9][10][11][12] Nowadays, despite these advantages, the use of bifunctional oligophenols is limited. Schiff bases derived from the salicylaldehydes are well known polydentate ligands, able to form coordination compounds in deprotonated or neutral forms.…”

The synthesis and thermal properties of oligo‐3‐hydroxybenzaldehyde synthesized by oxidative polycondensation

“…OP method has been used in syntheses of oligophenols and Schiff base oligomers. [5][6][7] Oligomers synthesized by OP method have useful properties such as, paramagnetism, thermal stability, antimicrobial activity, and as antistatic agent. 8 -11 Recently, the OP reaction of salicylaldehyde and 4-hydroxybenzaldehyde was investigated by our research group.…”