The Influence of β‐Ammonium Substitution on the Reaction Kinetics of Aminooxy Condensations with Aldehydes and Ketones

Ogunwale, Mumiye A.; Knipp, Ralph J.; Evrard, Clint N.; Thompson, Lee M.; Nantz, Michael H.; Fu, Xiao‐An

doi:10.1002/cphc.201801143

Cited by 3 publications

(3 citation statements)

References 47 publications

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“…The apparent kinetic constant of n -7ONEs is quite similar, where the 2–7ONE oximation reaction rate is slightly lower than the 3–7ONE oximation rate. This fact could be explained assuming that the activation energy of the oximation reaction of 2–7ONE is lower because of steric impediments. , …”

Section: Resultsmentioning

confidence: 99%

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: Resultsmentioning

confidence: 99%

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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“…On the contrary, the BR of the trans isomer requires the breakage of the bond C 1 – C 2 . This last bond corresponds to an imine vinyl group with a higher electronic density that avoids the attack of the free electron pair of the nitrogen atom. − For this reason, this stereoisomer of the oxime is less reactive than the ( Z ) oxime isomer. It could therefore be concluded that ( E )-2-cyclohexen-1-one oxime conversion is almost negligible in the BR step.…”

Section: Resultsmentioning

confidence: 99%

Transformation of Cyclic Ketones as Impurities in Cyclohexanone in the Caprolactam Production Process

Lorenzo

Salvador

Del-Arco

et al. 2019

Ind. Eng. Chem. Res.

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Nylon 6 fibers are produced by polymerization of caprolactam obtained after oximation and Beckmann rearrangement of cyclohexanone. For this reason, the purity of cyclohexanone used is an important parameter to control the quality of final nylon 6 products. The poor quality of cyclohexanone is related to the presence of some cyclic ketone impurities, such as 2-methylcyclopentanone, n-methylcyclohexanones (n = 2, 3, and 4), and 2-cyclohexen-1-one, which can remain after the purification process of cyclohexanone. In this study, the first step was to study the products promoted during the oximation of these cyclic impurities. The oximation of each impurity was carried out at T = 80 °C and pH = 5, and the reaction products were identified using gas chromatography−mass spectrometry (GC/MS) and NMR. Each cyclic oxime promoted a mixture of cis and trans stereoisomers, and the relative production ratio was determined. Additionally, the operating conditions that can affect the oximation step were studied. To do that, cyclohexanone was spiked with the mentioned cyclic impurities, and the oximation reaction was carried out using an aqueous solution of hydroxylammonium sulfate. The effects of experimental conditions, such as temperature (353.15−358.15 K) and pH (3.5−6), were studied. It was found that the higher the temperature, the higher the impurity conversion. However, when the pH was studied, the conversion of impurities presented a maximum due to the oximation mechanism. Additionally, a kinetic model of oximation reaction of cyclohexanone spiked with the cyclic impurities, based on an apparent constant to take into account that the reaction was carried out in two liquid phases, was proposed to explain the experimental results. The apparent kinetic constants obtained for 2-methylcyclohexanone and 2-cyclohexen-1-one were similar but lower than that for 2methylcyclopentanone. The study was completed promoting the Beckmann rearrangement of the oxime mixtures obtained from the oximation of pure cyclic impurities under mild conditions (sulfuric media at 100 °C). The amides produced were identified by gas chromatograph/mass selective detector (GC/MSD). Cis/trans oxime stereoisomers from n-methylcyclohexanones (n = 2 and 3) and 2-methylcyclopentanone presented the same reactivity to the corresponding amides, but only (Z)-2-cyclohexen-1one oxime reacts in the Beckmann rearrangement to produce its cyclic amide.

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“…The whole training procedure stops till it reaches the set iterations. The bounds for first-principle parameters are set according to the literature study (Ogunwale et al, 2019;Thotla et al, 2007), while the data-driven coefficients were searched in the range of [-0.1, 0.1]. A small range [-0.1, 0.1] was chosen because the first-principle parts play the primary role in the hybrid modeling to explain the complex reaction processes.…”

Section: Hybrid Modelsmentioning

confidence: 99%

SI-M/O: Swarm Intelligence-based Modeling and Optimization of complex synthesis reaction processes

Wu,

Di Caprio,

Elmaz

et al. 2023

Computers & Chemical Engineering

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The Influence of β‐Ammonium Substitution on the Reaction Kinetics of Aminooxy Condensations with Aldehydes and Ketones

Cited by 3 publications

References 47 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

Transformation of Cyclic Ketones as Impurities in Cyclohexanone in the Caprolactam Production Process

SI-M/O: Swarm Intelligence-based Modeling and Optimization of complex synthesis reaction processes

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