Issue 8, 2011

Direct conversion of polyamides to ω-hydroxyalkanoic acid derivatives by using supercritical MeOH

Abstract

We examined the decomposition of polyamides such as nylon-6 and nylon-12 by using supercritical MeOH as the reaction media. The treatment of waste nylon-6 with supercritical MeOH resulted in smooth depolymerization, forming caprolactam as the first product which was then converted to a mixture of methyl 6-hydroxycapronate and methyl 5-hexenoate in a ratio of approximately 1 : 1. The reaction progress was traced using gas chromatography (GC) analyses, and precise product distribution was estimated. During the decomposition of nylon-6, N-methylcaprolactam and methyl 6-(N,N-dimethylamino)capronate were detected as intermediates. The sum of the all detectable products and intermediates exceeded 80%. In addition, we examined the decomposition reaction initiating from caprolactam, N-methylcaprolactam, and methylN,N-dimethylcapronate under similar reaction conditions, and observed that the final two products were formed in similar yields and ratios. Kinetic analyses by using a simulation study based on the experimental data were performed, and kinetic parameters for each step were estimated. Nylon-12 underwent similar conversion to produce methyl 12-hydroxydodecanoate in good yield. Because methyl ω-hydroxyalkanoate is known to be an important intermediate in the chemical industry, the present method has the potential for producing valuable compounds from waste material. Thus, the first upgrade in the chemical recycling of plastics was accomplished.

Graphical abstract: Direct conversion of polyamides to ω-hydroxyalkanoic acid derivatives by using supercritical MeOH

Article information

Article type
Paper
Submitted
15 Feb 2011
Accepted
20 Apr 2011
First published
16 Jun 2011

Green Chem., 2011,13, 2055-2061

Direct conversion of polyamides to ω-hydroxyalkanoic acid derivatives by using supercritical MeOH

A. Kamimura, K. Kaiso, S. Suzuki, Y. Oishi, Y. Ohara, T. Sugimoto, K. Kashiwagi and M. Yoshimoto, Green Chem., 2011, 13, 2055 DOI: 10.1039/C1GC15172J

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