Facile synthesis of novel optically active poly(amide‐imide)s containing N,N′‐(pyromellitoyl)‐bis‐l‐phenylalanine diacid chloride and 5,5‐disubstituted hydantoin derivatives under microwave irradiation

Abstract

Pyromellitic dianhydride (1,2,4,5-benzenetetracarboxylic acid 1,2,4,5-dianhydide) (1) was reacted with L-phenylalanine (2) in a mixture of acetic acid and pyridine (3 : 2) at room temperature, then was refluxed at 90 -100°C and N,NЈ-(Pyromellitoyl)-bis-L-phenylalanine diacid (3) was obtained in quantitative yield. The imide-acid (3) was converted to N,NЈ-(Pyromellitoyl)-bis-l-phenylalanine diacid chloride (4) by reaction with thionyl chloride. Rapid and highly efficient synthesis of poly(amide-imide)s (6a-f) was achieved under microwave irradiation by using a domestic microwave oven from the polycondensation reactions of N,NЈ-(Pyromellitoyl)-bis-l-phenylalanine diacid chloride (4) with six different derivatives of 5,5-disubstituted hydantoin compounds (5a-f) in the presence of a small amount of a polar organic medium that acts as a primary microwave absorber. Suitable organic media was o-cresol. The polycondensation proceeded rapidly, compared with the conventional melt polycondensation and solution polycondensation, and was almost completed within 10 min, giving a series of poly(amide-imide)s with inherent viscosities about 0.28 -0.44 dL/g. The resulting poly(amide-imide)s were obtained in high yield and are optically active and thermally stable. All of the above compounds were fully characterized by means of FTIR spectroscopy, elemental analyses, inherent viscosity ( inh ), solubility test and specific rotation. Thermal properties of the poly(amide-imide)s were investigated using thermal gravimetric analysis (TGA).

Microwave‐Assisted Polymer Synthesis: State‐of‐the‐Art and Future Perspectives

“…[36,37] The polymerization reaction was proceeded by the preparation of optically active pyromellitoyl derivatives (under conventional heating), namely N,N 0 -(pyromellitoyl)-bis-L-phenylalanine diacid chloride and the corresponding L-leucine compound. Starting from these monomers, two series of optically active poly(amide imide)s were investigated: The bis-Lphenylalanine compound was reacted with six differently 5,5-disubstituted hydantoin compounds (Scheme 3a) and a bis-L-leucine derivative with six aromatic diamines, respectively.…”

Recent Advances in Microwave-Assisted Polymer Synthesis

“…N,N -(Pyromellitoyl)-bis(amino acid chloride)s from conversion of benzene-1,2,4,5-tetracarboxylic dianhydride with different amino acids were converted with several aromatic diamines [93][94][95] and hydantoin derivatives (Scheme 8). [96][97][98] Because of the chirality of the employed amino acids, optically active poly(amide-imide)s were obtained. It was shown that the polycondensations were completed after short reaction times (<10 min) under MW conditions.…”

Advances in synthetic optically active condensation polymers - A review

“…But the microwave heating is a more efficient method for these step-growth polymerization reactions. Faghihi et al [186][187][188] studied synthesis and characterization of optically active PAIs with hydantoin and thiohydantoin derivatives in the main chain via polycondensation reaction of N,N!-(pyromellitoyl)-bis-l-phenylalanine diacid chloride and six different derivatives of 5,5-disubstituted hydantoin compounds in the presence of a small amount of ocresol as a polar organic media. Polymers were synthesized via two different methods: Classical heating and microwave irradiation method.…”