Examination of organic trace contamination and thermo-oxidative deterioration of ε-caprolactam by high-performance liquid chromatography

Eppert, Günter; Liebscher, Gert; Stief, Claus

doi:10.1016/s0021-9673(00)91248-2

Cited by 9 publications

(12 citation statements)

References 18 publications

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“…These byproducts can be attributed to the evolution of the impurities originally present in ONE stream 19−21 as well as those formed from cyclohexanone oxime or CPL through the oximation, 19,20,22 rearrangement, purification, or storage steps. 7,23,24 The quality of the nylon-6 fibers is closely related with the impurities present in CPL. The type and amount of impurities have marked negative effects on the quality of the nylon-6.…”

Section: Introductionmentioning

confidence: 99%

“…The impurities in commercial caprolactam has been widely studied applying different analysis techniques, mainly by GC/MSD 18,19,21,25−27 HPLC. 23 As mentioned before, one of the key parameters used to evaluate CPL quality is the volatile base (VB) content, measured by the ISO 8661 method. This method is based on the reaction of a CPL sample with sodium hydroxide producing the hydrolysis of the amide impurities and generating amines (volatile bases) that are distilled and collected in a HCl solution.…”

Section: Introductionmentioning

confidence: 99%

“…19,21,23,25 Therefore, in this work, the oximation and BR of the linear ketones mentioned above is studied. Furthermore, while hexanamide has been found as an impurity in CPL, 23,27 oximation and BR of hexanal (6AL) have also been achieved.…”

Section: Introductionmentioning

confidence: 99%

“…After oximation, the Beckmann rearrangement (BR) of cyclohexanone oxime in oleum media produces CPL. ,, However, besides CPL, other byproducts are formed in the Beckmann rearrangement process. These byproducts can be attributed to the evolution of the impurities originally present in ONE stream − as well as those formed from cyclohexanone oxime or CPL through the oximation, ,, rearrangement, purification, or storage steps. ,, …”

Section: Introductionmentioning

confidence: 99%

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Linear Amides in Caprolactam from Linear Ketone Impurities in Cyclohexanone Obtained from Cyclohexane: Kinetics and Identification

Lorenzo

Salvador

Del-Arco

et al. 2019

Ind. Eng. Chem. Res.

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Caprolactam obtained after oximation and Beckman Rearrangement of cyclohexanone is the monomer of nylon-6. As the quality of the nylon-6 fibers is affected by the impurities present in ε-caprolactam, the type and amount of impurities in the cyclohexanone production process should be studied. Characterization of the purity of ε-caprolactam is accomplished using different parameters. Among them, volatile bases evaluate the presence of linear amides as impurities. They act like chain terminations and have a strong impact on average molecular weight and the size of nylon fibers. In ε-caprolactam from cyclohexane oxidation, these linear amides are frequently found, and N-pentylacetamide is one of the most abundant. In this work, it has been proposed and proven that ketones or aldehydes, such as n-heptanones, n-octanones, and hexanal present in cyclohexanone from cyclohexane oxidation, are the precursors of the most linear amides found in CPL. Special attention has been paid to the reactivity of 2-heptanone and 3heptanone in the oximation and Beckmann rearrangement steps since they have a boiling point similar to that of cyclohexanone and are difficult to remove by distillation. To do this, oximation (T = 80 °C and pH = 5) and further rearrangement (in sulfuric media at 100 C) of the aforementioned ketones or aldehydes has been carried out. Oximes and amides produced have been identified by using NMR and/or GC/MSD techniques. The kinetic model for oximation of 2-heptanone and 3-heptanone has been obtained at two temperatures (80 and 85 °C) within the pH range 3.5−6, simulating industrial conditions. In addition, the relative rearrangement rates of the linear oximes have been analyzed, showing the reaction rate to N-pentylacetamide for the production of the linear amides.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Linear Amides in Caprolactam from Linear Ketone Impurities in Cyclohexanone Obtained from Cyclohexane: Kinetics and Identification

Lorenzo

Salvador

Del-Arco

et al. 2019

Ind. Eng. Chem. Res.

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“…Therefore, it is the critical issue to determine the impurities in caprolactam and thereby to understand their influence on the products. Lots of analytical work has been done on the impurities of caprolactam, such as Raman spectroscopy,6 gas chromatography (GC),4, 7–9 high performance liquid chromatography (HPLC)10 and gas chromatography–mass spectrometry (GC–MS),11 etc. However almost all of work was focused on analyzing impurities in caprolactam produced from cyclohexanone.…”

Section: Introductionmentioning

confidence: 99%

Determination of impurities in industrial caprolactam produced from toluene by SPME and GC–MS

Li¹,

Zou²

2006

J of Applied Polymer Sci

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Solid-phase microextraction (SPME) in combination with gas chromatography-mass spectrometry (GC-MS) was applied to study the impurities in industrial caprolactam produced from toluene. Various nitriles, lactones, amides, and alcohols were detected to be the main impurities in caprolactam products. Trace amounts of heterocyclic compounds, which had great effects on the quality of caprolactam, were also successfully detected. Those were pyrrole, 2-ethyl-3-methyl pyrazine, 5,6,7,8-tetrahydroquinoxaline, quinoxaline, 2,3-dimethyl quinoxaline, 2-pyridinamide, etc. The effects of some impurities on caprolactam quality and the polymerization of caprolactam as well as the possible origin of the main impurities were also discussed. This could be of great importance to the industrial purity control of caprolactam.

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Study of adsorption behavior using activated carbon for removal of colored impurities from 30% caprolactam solution produced by means of SNIA-toluene-technology

Zhang

Yuan

et al. 2006

Korean J. Chem. Eng.

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Examination of organic trace contamination and thermo-oxidative deterioration of ε-caprolactam by high-performance liquid chromatography

Cited by 9 publications

References 18 publications

Linear Amides in Caprolactam from Linear Ketone Impurities in Cyclohexanone Obtained from Cyclohexane: Kinetics and Identification

Linear Amides in Caprolactam from Linear Ketone Impurities in Cyclohexanone Obtained from Cyclohexane: Kinetics and Identification

Determination of impurities in industrial caprolactam produced from toluene by SPME and GC–MS

Study of adsorption behavior using activated carbon for removal of colored impurities from 30% caprolactam solution produced by means of SNIA-toluene-technology

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