On the primary thermal decomposition pathways of hydroxycinnamic acids

SriBala, Gorugantu; Vijver, Ruben Van de; Li, Liang; Dogu, Onur; Marin, Guy

doi:10.1016/j.proci.2020.06.086

Cited by 10 publications

(12 citation statements)

References 27 publications

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“…Crystalline LH showed its melting point around 260 °C, followed by a small thermal degradation peak (Figure a), which was the same as with our previous report . We found the fusion endotherms of pHCA and CA were 222.8 and 134.3 °C, respectively (Figure b,c), which were consistent with the reported results. , Moreover, it was observed that the physical mixtures of LH and CA exhibited two endothermic peaks, similar to their melting points (Figure S2a–c). However, the physical mixtures of LH and pHCA showed only one melting endotherm in the temperature range of 174–177 °C (Figure S2d–f), probably suggesting that a low eutectic mixture was formed between LH and pHCA.…”

Section: Resultssupporting

confidence: 91%

Influence of the pK_a Value of Cinnamic Acid and P-Hydroxycinnamic Acid on the Solubility of a Lurasidone Hydrochloride-Based Coamorphous System

Guo

et al. 2021

ACS Omega

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Coamorphization of a poorly water-soluble active pharmaceutical ingredient (API) has been proven to be effective in improving its solubility. Generally, API can form multiple coamorphous systems with different coformers. However, it remains unclear how the pK a value of different coformers influences the solubility of the API. In this study, structurally related cinnamic acid (CA, pK a = 4.37) and p-hydroxycinnamic acid (pHCA, pK a = 4.65) were chosen as coformers for the coamorphization of lurasidone hydrochloride (LH). To investigate the influence of the pK a value of the coformers on the solubility of LH, LH-CA/pHCA coamorphous systems were prepared by the vacuum rotary evaporation method and characterized by powder X-ray diffraction and differential scanning calorimetry. Fourier-transform infrared spectroscopy, Raman spectroscopy, and molecular dynamics (MD) simulations were employed to investigate the intermolecular interaction of the coamorphous systems. It was found that the solubility of LH in the coamorphous LH–pHAC with a higher-pK a coformer was higher than that of the coamorphous LH-CA. In addition, according to the solubility product principle-based formula derivation, we established the functional relationship between the solubility of LH and the pK a of the coformers at different-pH buffering solution. It was found that the coformer with a larger pK a value would be more beneficial to improve the solubility profile of LH. Collectively, the current study offers an effective strategy to improve the poor solubility of drugs by increasing the pK a value of the coformer in coamorphous systems.

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Section: Resultssupporting

confidence: 91%

Influence of the pK_a Value of Cinnamic Acid and P-Hydroxycinnamic Acid on the Solubility of a Lurasidone Hydrochloride-Based Coamorphous System

Guo

et al. 2021

ACS Omega

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“…The pyrolysis experiments were performed in a micropyrolysis unit consisting of two sections, viz., reactor and analytics (Figure a) . The reactor is a double-shot tandem micropyrolyzer (Frontier Laboratories, Japan) with two reactors connected in series.…”

Section: Methodsmentioning

confidence: 99%

“…The pyrolysis experiments were performed in a micropyrolysis unit consisting of two sections, viz., reactor and analytics (Figure 2a). 48 The reactor is a double-shot tandem micropyrolyzer (Frontier Laboratories, Japan) with two reactors connected in series. In this study, only the first reactor with a deactivated quartz tube was used to study liquid or solid to gas transformations of hydroxycinnamaldehydes under pyrolysis con-ditions (at 773−1123 K and 2.8 atm).…”

Section: Methodsmentioning

confidence: 99%

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Primary Thermal Decomposition Pathways of Hydroxycinnamaldehydes

Vijver

Eschenbacher

et al. 2021

Energy Fuels

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Hydroxycinnamaldehyde monomers are important intermediates in the lignin biosynthesis and can be incorporated into plants in large quantities via genetic modification. They are also important products formed during pyrolysis or combustion of lignocellulose. In this work, the decomposition of three hydroxycinnamaldehyde model compounds, cinnamaldehyde, p-coumaraldehyde, and coniferaldehyde, was studied in a micropyrolysis reactor equipped with an online GC × GC-FID/TOF-MS coupled with a customized GC for the on-line analysis of all the pyrolysis vapors including permanent gases. The vaporization or sublimation process of these model compounds in the reactor was fitted well based on the experimental time-resolved data. The dominating initial decomposition pathways were elucidated from a first-principles based kinetic model and using rate of production analysis. For cinnamaldehyde (at 773-1123 K) and p-coumaraldehyde (at 873-1123 K), the concerted decarbonylation reactions in the condensed phase are determining the initial decomposition, with almost no contribution from radical chemistry. For coniferaldehyde (at 773-1023 K), the homolysis of O-methyl (O−CH3) bond initiates a radical chain mechanism at temperatures above 773 K, and the H-atom abstraction on the aldehyde group is the most dominant consumption pathway at high temperatures. The presence of methoxy groups on the aromatic rings accelerates the decomposition of hydroxycinnamaldehydes. Models that do not account for these important structural differences will have difficulties to predict the decomposition of real lignocellulosic biomass.

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“…As described previously, the experiments were performed with a double-shot tandem micropyrolyzer. 31 Only the first reactor was used in this work. It is directly connected to the GC inlet to perform solid-to-gas experiments in this study.…”

Section: Micropyrolyzer Unitmentioning

confidence: 99%

New Perspectives into Cellulose Fast Pyrolysis Kinetics Using a Py-GC × GC-FID/MS System

et al. 2022

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Cellulose pyrolysis is reportedly influenced by factors such as sample size, crystallinity, or different morphologies. However, there seems to be a lack of understanding of the mechanistic details that explain the observed differences in the pyrolysis yields. This study aims to investigate the influence of particle size and crystallinity of cellulose by performing pyrolysis reactions at temperatures of 673–873 K using a micropyrolyzer apparatus coupled to a GC × GC-FID/TOF-MS and a customized GC-TCD. Over 60 product species have been identified and quantified for the first time, including water. Crystalline cellulose with an average particle size of 30–50 × 10–6 m produced 50–60 wt % levoglucosan. Predominantly amorphous cellulose with an average particle size of 10–20 × 10–6 m resulted in remarkably low yields (10–15 wt %) of levoglucosan complemented by higher yields of water and glycolaldehyde. A detailed kinetic model for cellulose pyrolysis was used to obtain mechanistic insights into the different pyrolysis product compositions. The kinetics of the mid-chain dehydration and fragmentation reactions strongly influence the total yields of low-molecular weight products (LMWPs) and are affected by cellulose chain arrangement. Levoglucosan yields are very sensitive to the activation of parallel cellulose decomposition reactions. This can be attributed to the mid-chain reactions forming smaller chains with the levoglucosan ends, which remain in the solid phase and react further to form LMWPs. Direct quantification of water helped to improve the description of the dehydration, giving further indications of the dominant role of mid-chain reaction pathways in amorphous cellulose pyrolysis.

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On the primary thermal decomposition pathways of hydroxycinnamic acids

Cited by 10 publications

References 27 publications

Influence of the pK_a Value of Cinnamic Acid and P-Hydroxycinnamic Acid on the Solubility of a Lurasidone Hydrochloride-Based Coamorphous System

Influence of the pK_a Value of Cinnamic Acid and P-Hydroxycinnamic Acid on the Solubility of a Lurasidone Hydrochloride-Based Coamorphous System

Primary Thermal Decomposition Pathways of Hydroxycinnamaldehydes

New Perspectives into Cellulose Fast Pyrolysis Kinetics Using a Py-GC × GC-FID/MS System

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On the primary thermal decomposition pathways of hydroxycinnamic acids

Cited by 10 publications

References 27 publications

Influence of the pKa Value of Cinnamic Acid and P-Hydroxycinnamic Acid on the Solubility of a Lurasidone Hydrochloride-Based Coamorphous System

Influence of the pKa Value of Cinnamic Acid and P-Hydroxycinnamic Acid on the Solubility of a Lurasidone Hydrochloride-Based Coamorphous System

Primary Thermal Decomposition Pathways of Hydroxycinnamaldehydes

New Perspectives into Cellulose Fast Pyrolysis Kinetics Using a Py-GC × GC-FID/MS System

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Influence of the pK_a Value of Cinnamic Acid and P-Hydroxycinnamic Acid on the Solubility of a Lurasidone Hydrochloride-Based Coamorphous System

Influence of the pK_a Value of Cinnamic Acid and P-Hydroxycinnamic Acid on the Solubility of a Lurasidone Hydrochloride-Based Coamorphous System