Synthesis of Aliphatic Polyamides by Direct Polycondensation with Triphenylphosphine

Abstract

ABSTRACT:Direct polycondensation reactions of various nylon salts prepared from diamines and dicarboxylic acids were carried out under mild conditions with triphenylphosphine and halides. Reaction conditions including the monomer concentration, amount of reagents, kind of halides, solvents and organophosphorus compounds, and temperature were investigated. A combination of triphenylphosphine and tetrabromomethane was found to be satisfactory for the aliphatic polyamide synthesis. Nylon 6, 10 having the highest molecular weight was obtained with the molar ratio of triphenylphosphineltetrabromomethanelcarboxyl groups of the monomer= 1.511.511.0 in pyridine at 40°C.KEY WORDSPolycondensation reaction is usually carried out at elevated temperatures above the melting points of the resulting polymers in order to eliminate volatile products so as to shift the equilibrium towards the polymer formation. Several methods have been developed for the synthesis of polyamides under mild conditions1 even at room temperature, where the polycondensation reaction was promoted using active monomers such as dicarboxylic acid chlorides or active diesters.Phosphorylation reaction has been applied1-5 for the polyamide synthesis from diamines and dicarboxylic acids, so that the polycondensation reaction takes place under mild conditions. Although the yield of polyamide was almost quantitative, the solution viscosity of the product did not exceed 0.4. The difficulty of synthesizing aliphatic polyamides under mild conditions may be ascribed to the high basicity of aliphatic diamines which presumably causes significant side reactions such as the formation of P-N linkages and the less solubility in solvents.Recently, an aromatic polyamide of a high molecular weight could be obtained in quantitative yield under mild conditions 5 with triphenylphosphine and hexachloroethane in pyridine. 6 This paper deals with the synthesis of high molecular weight aliphatic polyamides from nylon salts, which are prepared from diamines and dicarboxylic acids, by the direct polycondensation with the combination of triphenylphosphine and a halide.

Synthesis and characterization of polycarbonates based on bisphenol S by melt transesterification

“…The thermal stability of the polycarbonate derived from BPS (PC-1) was slightly less than that of bisphenol A. This phenomenon may reflect the electron-withdrawing characteristic sulfonyl group of BPS, 37,38 which results in smaller inherent viscosity. PC-2 is less stable than the unbrominated one (PC-1), Figure 4 shows stress-strain curves for films of four polycarbonates (PC-3 to PC-6) with varied Brominated aromatic polycarbonate has good flame retardency, as indicated by its high limiting molar ratios of incorporated oxyethylene unit.…”

Synthesis and characterization of polycarbonates based on bisphenol S by melt transesterification

“…The moderate viscosity of polycarbonate based on BPS may be due to not only the electron-withdrawing characteristic of the sulfonyl group, but also the incorporated aliphatic oxyethylene or oxypropylene units. Ogata et al 37 reported that an aliphatic polyamide had a small intrinsic viscosity. As shown in Figure 1, the IR spectrum of polymer (PC-1) showed absorption characteristic of C|O of carbonate at 1776 cm 01 , phenylene at 1589 and 1491 cm 01 , C{O{C at 1239 cm 01 and {SO 2 { at 1310 and 1150 cm 01 .…”

“…The thermal stability of the polycarbonate derived from BPS (PC-1) was slightly less than that of bisphenol A. This phenomenon may reflect the electron-withdrawing characteristic sulfonyl group of BPS, 37,38 which results in smaller inherent viscosity. PC-2 is less stable than the unbrominated one (PC-1), -PC-2 317 372 40 135 56 PC-3 335 397 25 91 -PC-4 326 390 19 60 -PC-5 316 379 17 40 -PC-6 307 367 14 33 -PC-7 324 383 20 62 a Thermogravimetric analyses conducted at a heating rate of 10ЊC min 01 in nitrogen.…”

Synthesis of High Molecular Weight Poly(p-benzamide)s

“…4-Amino-2-((2-ethylhexyl)oxy)benzoic acid (9) (1 g, 3.77 mmol) gave M6 as a transparent oil (390 mg, 0.904 mmol, 24%). 1 (11) (330 mg, 1.323 mmol) with DMAP (32 mg, 265 μmol) and pentafluorophenol (365 mg, 1.985 mmol) in dry DCM (2.2 mL, 0.6 M) at 0 °C. The solution was stirred for 5 min at 0 °C and then allow to stir a further 3 h at room temperature.…”

“…For the synthesis of high molecular weight polymers from amino acid monomers several alternative polymerization methods have been reported. Yamazaki et al showed the direct polycondensation of p -aminobenzoic acid activating the carboxylic acid with triaryl phosphite and a tertiary amine like pyridine. − Similarly, Ogata and co-workers synthesized polyaramides activating the acid moiety using triarylphosophine, a polyhalo compound and a tertiary amine. − In both cases, polyaramides of molecular weights up to 10 000 Da were obtained.…”