scholarly journals Model Discrimination for Hydrogen Peroxide Consumption towards γ-Alumina in Homogeneous Liquid and Heterogeneous Liquid-Liquid Systems

Processes ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 1476
Author(s):  
Daniele Di Menno Di Bucchianico ◽  
Wander Y. Perez-Sena ◽  
Valeria Casson Moreno ◽  
Tapio Salmi ◽  
Sébastien Leveneur
Keyword(s):  
Hydrogen Peroxide ◽  
Ring Opening ◽  
Oxidation Mechanism ◽  
Liquid System ◽  
Side Reactions ◽  
Hydroxyl Groups ◽  
Homogeneous Liquid ◽  
Liquid Systems ◽  
Kinetics Of

The use of hydrogen peroxide as an oxidizing agent becomes increasingly important in chemistry. The example of vegetable oil epoxidation is an excellent illustration of the potential of such an agent. This reaction is traditionally performed by Prileschajew oxidation, i.e., by the in situ production of percarboxylic acids. Drawbacks of this approach are side reactions of ring-opening and thermal runaway reactions due to percarboxylic acid instability. One way to overcome this issue is the direct epoxidation by hydrogen peroxide by using γ-alumina. However, the reaction mechanism is not elucidated: does hydrogen peroxide decompose with alumina or oxidize the hydroxyl groups at the surface? The kinetics of hydrogen peroxide consumption with alumina in homogeneous liquid and heterogeneous liquid-liquid systems was investigated to reply to this question. Bayesian inference was used to determine the most probable models. The results obtained led us to conclude that the oxidation mechanism is the most credible for the heterogeneous liquid-liquid system.

scholarly journals Effect of Na- and Organo-Modified Montmorillonite/Essential Oil Nanohybrids on the Kinetics of the In Situ Radical Polymerization of Styrene

Nanomaterials ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 474
Author(s):  
Ioannis S. Tsagkalias ◽  
Alexandra Loukidi ◽  
Stella Chatzimichailidou ◽  
Constantinos E. Salmas ◽  
Aris E. Giannakas ◽  
...  
Keyword(s):  
Essential Oil ◽  
Radical Polymerization ◽  
Food Packaging ◽  
In Situ Polymerization ◽  
Average Molecular Weight ◽  
Monomer Conversion ◽  
Hydroxyl Groups ◽  
Modified Montmorillonite ◽  
Kinetics Of

The great concern about the use of hazardous additives in food packaging materials has shown the way to new bio-based materials, such as nanoclays incorporating bioactive essential oils (EO). One of the still unresolved issues is the proper incorporation of these materials into a polymeric matrix. The in situ polymerization seems to be a promising technique, not requiring high temperatures or toxic solvents. Therefore, in this study, the bulk radical polymerization of styrene was investigated in the presence of sodium montmorillonite (NaMMT) and organo-modified montmorillonite (orgMMT) including thyme (TO), oregano (OO), and basil (BO) essential oil. It was found that the hydroxyl groups present in the main ingredients of TO and OO may participate in side retardation reactions leading to lower polymerization rates (measured gravimetrically by the variation of monomer conversion with time) accompanied by higher polymer average molecular weight (measured via GPC). The use of BO did not seem to affect significantly the polymerization kinetics and polymer MWD. These results were verified from independent experiments using model compounds, thymol, carvacrol and estragol instead of the clays. Partially intercalated structures were revealed from XRD scans. The glass transition temperature (from DSC) and the thermal stability (from TGA) of the nanocomposites formed were slightly increased from 95 to 98 °C and from 435 to 445 °C, respectively. Finally, better dispersion was observed when orgMMT was added instead of NaMMT.

Feasibility Study of Raman Spectroscopy as a Tool to Investigate the Liquid-Phase Chemistry of Aliphatic Organic Peroxides

1997 ◽  
Vol 51 (1) ◽  
pp. 74-80 ◽  
Author(s):  
Peter Jacob ◽  
Bernhard Wehling ◽  
Wieland Hill ◽  
Dieter Klockow
Keyword(s):  
Hydrogen Peroxide ◽  
Raman Spectroscopy ◽  
Liquid Phase ◽  
Chemical Processes ◽  
Organic Peroxides ◽  
Time Resolved ◽  
In Situ Investigation ◽  
Phase Chemistry ◽  
Kinetics Of

The described investigations are focused on peroxides occurring as products in atmospheric chemical processes, namely, hydrogen peroxide, methylhydroperoxide, hydroxymethylhydroperoxide, bis-(hydroxymethyl)peroxide, 1-hydroxyethylhydroperoxide, bis-(hydroxyethyl)peroxide, and hydroxymethylmethylperoxide. The compounds are identified and determined through the position and intensity of their characteristic O–O stretching bands in the range between 767 and 878 cm−1. Time-resolved Raman spectroscopy of peroxide solutions permits the in situ investigation of pathways and kinetics of reactions between peroxides and aldehydes.

scholarly journals Oxirane Ring Opening of Rubber (Hevea Brasiliensis) Seed Oil by Perfomic Acid

2019 ◽  
Vol 9 (1) ◽  
pp. 5070-5073
Keyword(s):  
Hydrogen Peroxide ◽  
Formic Acid ◽  
Hevea Brasiliensis ◽  
Ring Opening ◽  
Seed Oil ◽  
Ftir Analysis ◽  
Rubber Seed Oil ◽  
Renewable Source ◽  
Rubber Seed

Studies on the epoxidation of rubber (Hevea brasiliensis) seed oil, a renewable source with formic acid was performed in the presence of 30% hydrogen peroxide at a of temperature 40, 50,60,70 oC. The process is favoured by an increase in temperature forming a product with high oxirane content which is as a result of mole ratios of formic acid and hydrogen peroxide. Products of high oxirane content are commercialy viable in the production of polyvinyl chloride (PVC). Natural rubber and other products can be obtained from this in- situ technique. Studies in this research shows that the rate of epoxidation increases with an increase in temperature.Oxirane values of 2.30, 3.62 and 4.73 for the various temperature. However high oxirane content of 6.22 was obtained at 70 oC which is in line with literature. FTIR analysis was also carried out on the epoxidized rubber seed oil which shows the peaks of oxirane cleavage.

scholarly journals Kinetics of glycoalkaloid hydrolysis and solanidine extraction in liquid-liquid systems

2002 ◽  
Vol 56 (12) ◽  
pp. 521-525 ◽  
Author(s):  
Mihajlo Stankovic ◽  
Nada Nikolic
Keyword(s):  
Liquid Phase ◽  
Organic Liquid ◽  
Liquid System ◽  
Liquid Systems ◽  
One Step ◽  
Kinetics Of

The kinetics of glycoalkaloid hydrolysis and solanidine extraction in Analyzed in this study. obtained from dried and milled potato haulm to to which hydrochlotic acid was added is the first liquid phase, while chloroform trichloroethylene or carbon tetrachlondeisthe second organic, liquid phase. The purpose of this paper was to combine the processes of glycoalkaloid hydrolysis to solanidine and solanidine extraction into one step, and to find the optimal liquid-liquid system for such a process.

scholarly journals Kinetika reaksi hidroksilasi epoksi minyak jarak pagar menggunakan katalis bentonit

2018 ◽  
Vol 12 (2) ◽  
pp. 257
Author(s):  
Ratni Ariatmi Nugrahani ◽  
Flora Elvistia Firdaus ◽  
Yeti Widyawati ◽  
Hana Firginia ◽  
Riris Purnama
Keyword(s):  
Jatropha Curcas ◽  
Ring Opening ◽  
Reaction System ◽  
Chemical Properties ◽  
Oxirane Ring ◽  
Hydroxyl Groups ◽  
Jatropha Oil ◽  
Jatropha Curcas Oil ◽  
Ring Opening Reaction ◽  
Kinetics Of

Hydroxylation kinetics of jatropha oil epoxy using bentonite catalyst. Based on chemical properties such as fatty acid compositions and iodium value, jatropha curcas oil can potentially be applied as lubricant. Unsaturation of this oil decreases its  oxidative stability. Improvement of this property may be done by chemical modification involving epoxidation and oxirane ring opening with bentonite catalyst, forming polyol by hydroxylation. The purpose of this research is to characterize the products and kinetics of the oxirane ring opening reaction. The results of chemical analysis by titration for residual oxiranes and hydroxyl formed in the reaction system, was showed using ir spectroscopy. Their effects were to reduce epoxy groups at 824-842 cm−1 and appearance of hydroxyl groups at the oh characteristic absorption peak from 3450-3800 cm−1. The oxirane number of epoxidized jatropha oil was reduced from 4.7% to 0.05% by ring opening. The kinetics of the oxirane ring opening of epoxidized jatropha curcas oil by methanol with bentonite was studied at 50, 60, and 65 oc. The oxirane ring opening analyzed by the pseudo-homogeneous approach followed a pseudo-first order kinetics. From the temperature dependence of the  rate, reaction enthalpy (δh) and activation energy (δea) were found to be 8,27 kcal mol−1 and 7,63 kcal mol−1, respectively.Keywords: epoxidized jatropha curcas, hydroxyl, oxirane, bentonite, kinetic AbstrakBerdasarkan sifat-sifat komposisi asam lemak dan bilangan iodium, minyak jarak pagar (Jatropha curcas) berpotensi menjadi bahan dasar pelumas. Meskipun demikian, kandungan ikatan tidak jenuh minyak ini menurunkan kestabilan oksidasinya. Kestabilan oksidasi ini dapat diperbaiki melalui modifikasi kimiawi dengan reaksi epoksidasi yang menghilangkan ikatan rangkap.  Ini dilakukan melalui reaksi hidroksilasi dengan membuka ikatan gugus oksirana epoksi. Tujuan penelitian ini adalah mengkarakterisasi produk, serta mempelajari kinetika reaksi pembukaan cincin oksirana oleh metanol dengan katalis bentonit untuk membentuk poliol. Hasil analisis FTIR produk reaksi menunjukkan penurunan intensitas gugus epoksi pada bilangan gelombang 824-842 cm−1 dan munculnya gugus hidroksil pada bilangan gelombang 3450-3800 cm−1. Bilangan oksirana epoksi jarak pagar berkurang dari 4,7% menjadi 0,05% setelah pembukaan cincin. Bilangan hidroksil poliol adalah sebesar 165,77. Pengukuran kinetika pembukaan cincin pada gugus oksirana dari epoksi jarak pagar dilakukan pada 50, 60, dan 65oC. Analisis data laju reaksi yang dianalisis dengan pendekatan sistem pseudohomogen menunjukkan bahwa reaksi mengikut kinetika orde-1 semu. Dari perubahan laju reaksi terhadap temperatur diperoleh nilai entalpi reaksi dan energi aktivasi sebesar masing-masing 8,27 kkal mol-1 dan 7,63 kkal mol-1.Kata kunci: epoksi jarak pagar, hidroksil, oksirana, bentonit, kinetika

scholarly journals Microwave-assisted in situ ring-opening polymerization of ε-caprolactone in the presence of modified halloysite nanotubes loaded with stannous chloride

RSC Advances ◽  
2022 ◽  
Vol 12 (3) ◽  
pp. 1628-1637
Author(s):  
Gang Yang ◽  
Rui Ma ◽  
Shifan Zhang ◽  
Ziying Liu ◽  
Dexuan Pei ◽  
...  
Keyword(s):  
Ring Opening ◽  
Catalytic Effect ◽  
Stannous Chloride ◽  
Halloysite Nanotubes ◽  
Ring Opening Polymerization ◽  
Composite Catalyst ◽  
Chain Growth ◽  
Hydroxyl Groups ◽  
Microwave Assisted

For the composite catalyst, there existed synergetic catalytic effect between the hydroxyl groups and the metal center. All chain growth simultaneously proceeded between the layers or on the surface of HNTs, conducting the in situ ROP.

scholarly journals Benzothiazole Degradation by Rhodococcus pyridinovorans Strain PA: Evidence of a Catechol 1,2-Dioxygenase Activity

2002 ◽  
Vol 68 (12) ◽  
pp. 6114-6120 ◽  
Author(s):  
Nicolas Haroune ◽  
Bruno Combourieu ◽  
Pascale Besse ◽  
Martine Sancelme ◽  
Thorsten Reemtsma ◽  
...  
Keyword(s):  
Ring Opening ◽  
High Performance ◽  
Reversed Phase ◽  
Culture Conditions ◽  
Ionization Mass ◽  
Structure Detection ◽  
Catechol 1,2 Dioxygenase ◽  
Kinetics Of ◽  
C Nmr

ABSTRACT The pathway for biodegradation of benzothiazole (BT) and 2-hydroxybenzothiazole (OBT) by Rhodococcus pyridinovorans strain PA was studied in detail. The kinetics of biodegradation were monitored by in situ 1H nuclear magnetic resonance (NMR) in parallel with reversed-phase high-performance liquid chromatography (HPLC). Successive oxidations from BT to OBT and then from OBT to dihydroxybenzothiazole were observed. Further insight was obtained by using a mutant strain with impaired ability to grow on BT and OBT. The precise structure of another intermediate was determined by in situ two-dimensional 1H-13C NMR and HPLC-electrospray ionization mass spectrometry; this intermediate was found to be a ring-opening product (a diacid structure). Detection of this metabolite, together with the results obtained by 1H and 19F NMR when cells were incubated with 3-fluorocatechol, demonstrated that a catechol 1,2-dioxygenase is involved in a pathway for biodegradation of BTs in this Rhodococcus strain. Our results show that catechol 1,2-dioxygenase and catechol 2,3-dioxygenase activities may both be involved in the biodegradation of BTs depending on the culture conditions.

Sign in / Sign up

Export Citation Format

Share Document