Kinetics of the (salen)Cr(iii)- and (salen)Co(iii)-catalyzed copolymerization of epoxides with CO2, and of the accompanying degradation reactions

The catalytic cycle of the (salen)M(iii)-catalyzed copolymerization for a variety of epoxides with CO2 is elucidated using computational chemistry, and factors that control the kinetics and product distribution of these reactions are described.

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ChemInform Abstract: Oxidation of Olefins by Palladium(II). Part 13. Product Distribution and Kinetics of the Oxidation of 2-Cyclohexenol and 2-Cyclohexenol-1-d by PdCl2- 4 in Aqueous Solution.

ChemInform ◽

10.1002/chin.199239114 ◽

2010 ◽

Vol 23 (39) ◽

pp. no-no

Author(s):

K. ZAW ◽

P. M. HENRY

Keyword(s):

Aqueous Solution ◽

Product Distribution ◽

Oxidation Of Olefins ◽

Kinetics Of

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Photodegradation kinetics of alkyd paints: the influence of varying amounts of inorganic pigments on the stability of the synthetic binder

10.21203/rs.2.22609/v1 ◽

2020 ◽

Author(s):

Laura Pagnin ◽

Rita Wiesinger ◽

Manfred Schreiner

Keyword(s):

Alkyd Resin ◽

Physical Stability ◽

Inorganic Pigments ◽

Inorganic Pigment ◽

Degradation Processes ◽

Degradation Reactions ◽

Protection Strategies ◽

Binder Ratio ◽

The Stability ◽

Kinetics Of

Abstract Nowadays, understanding the degradation processes of artworks exposed to outdoor conditions is essential in order to conserve these objects. In fact, the continuous climate changes risk to increasingly affecting their chemical-physical stability, especially for modern and contemporary ones. For this purpose, in this study, the kinetics of photo-oxidation processes occurring in synthetic binders and their stability in mixtures with different inorganic pigments were investigated. The aim was not only to characterize the different degradation reactions over time but to study the photodegradation kinetics according to the different pigments and pigment/binder ratio (P/BM) chosen. A total of 9 paint samples were prepared by mixing the inorganic pigments (artificial ultramarine blue, hydrated chromium oxide green, and cadmium yellow) with alkyd resin, in three different pigment/binder (P/BM) ratios: 1:2, 1:3, and 1:6. The paint samples were exposed to artificial sunlight for up to 1008 h, documented by optical 3D microscopy and analysed by Infrared Spectroscopy (ATR-FTIR) and colourimetry every 168 hours. The results obtained demonstrate that the degradation processes of alkyd resin are influenced by the different inorganic pigment used and its amount/concentration in the mixtures. Evaluation of these different deterioration mechanisms took into account the morphological/colour changes, the chemical reactions, and the physical properties of the materials. This study should contribute to the field of conservation-restoration, such as finding protection strategies for surfaces from degradation agents.

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Deoxydehydration of vicinal diols by homogeneous catalysts: a mechanistic overview

Royal Society Open Science ◽

10.1098/rsos.191165 ◽

2019 ◽

Vol 6 (11) ◽

pp. 191165 ◽

Cited By ~ 5

Author(s):

Kayla A. DeNike ◽

Stefan M. Kilyanek

Keyword(s):

Reaction Mechanism ◽

Product Distribution ◽

Catalytic Cycle ◽

Reaction Conditions ◽

Homogeneous Catalysts ◽

Commodity Chemicals ◽

Reduction Methods ◽

Vicinal Diols ◽

Catalyst Systems

Deoxydehydration (DODH) is an important reaction for the upconversion of biomass-derived polyols to commodity chemicals such as alkenes and dienes. DODH can be performed by a variety of early metal-oxo catalysts incorporating Re, Mo and V. The varying reduction methods used in the DODH catalytic cycle impact the product distribution, reaction mechanism and the overall yield of the reaction. This review surveys the reduction methods commonly used in homogeneous DODH catalyst systems and their impacts on yield and reaction conditions.

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Carbohydrates in alkaline systems. II. Kinetics of the transformation and degradation reactions of cellobiose, cellobiulose, and 4-O-β-D-glucopyranosyl-D-mannose in 1 M sodium hydroxide at 22 °C

Canadian Journal of Chemistry ◽

10.1139/v69-659 ◽

1969 ◽

Vol 47 (21) ◽

pp. 3957-3964 ◽

Cited By ~ 23

Author(s):

Donald J. MacLaurin ◽

John W. Green

Keyword(s):

Sulfuric Acid ◽

Sodium Hydroxide ◽

Column Chromatography ◽

Rate Constants ◽

Reaction Rate ◽

Reaction System ◽

Reaction Rate Constants ◽

Degradation Reactions ◽

Fructose 2 ◽

Kinetics Of

Rates of isomerization, epimerization, and degradation reactions were measured for cellobiose (7), cellobiulose (8), and 4-O-β-D-glucopyranosyl-D-mannose (9) at 0.001 M in 1 M NaOH under N2 in the dark at 22 °C. Reaction system resolution was by column chromatography on anion resins in the borate form. Assay for D-glucose (1), D-fructose (2), D-mannose (3), and 7,8, and 9 was by continuous automated colorimetry of column effluent with orcinol–sulfuric acid as reagent. Reaction rate constants (h−1) found: k78 0.078, k79 0.0005, k7,10 0.002, k87 0.022, k89 0.003 k81 0.065, k8,12 0.023, k97 0.002, k98 0.013, k9,11 0.006 where 10,11, and 12 are other products than 1,2,3,7,8, and 9. Details for preparation of 8 and 9 are given.

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Hydroisomerization of Biomass Derived n-Hexadecane Towards Diesel Pool: Effect of Selective Removal External Surface Sites from Pt/ZSM-22

International Journal of Chemical Reactor Engineering ◽

10.1515/ijcre-2015-0049 ◽

2016 ◽

Vol 14 (1) ◽

pp. 155-165 ◽

Cited By ~ 7

Author(s):

Abhijeet H. Thaker ◽

Mathew John ◽

Kishore Kumar ◽

Mahesh W. Kasture ◽

Snehalkumar Parmar ◽

...

Keyword(s):

Oxalic Acid ◽

Active Sites ◽

External Surface ◽

Space Velocity ◽

Product Distribution ◽

Catalytic Performance ◽

Selective Removal ◽

Cold Flow ◽

External Site ◽

Kinetics Of

AbstractInfluence of dealumination of zeolite ZSM-22 (Si/Al ratio of 45) by treating it with oxalic acid on its catalytic performance in n-hexadecane hydroisomerization reaction was studied. This reaction is an attempt in the direction of green and sustainable source of diesel via improving the cold-flow properties of deoxygenated vegetable oils. Pt (0.5 wt%) on ZSM-22 treated with 1 M oxalic acid afforded highest yields of the mono-branched paraffins. This improved is attributed to selective removal of active sites on external surface of zeolite crystals (responsible for undesired cracking reactions) using the bulkier dealuminating agent, oxalic acid. Thus, pore-mouth key-lock mechanism was brought to play the role to cause high selectivity to mono-branched isomers. Preferential external site deactivation was inferred from mesitylene cracking results. Effects of operating parameters such as temperature, and space velocity on product distribution also were studied. Also, kinetics of the reactions involved too has been in brief reported.

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Products and Kinetics of Flash Pyrolysis of Peg: A Minimum Smoke Binder

MRS Proceedings ◽

10.1557/proc-418-227 ◽

1995 ◽

Vol 418 ◽

Author(s):

H. Arisawa ◽

T. B. Brill

Keyword(s):

Ftir Spectroscopy ◽

Product Distribution ◽

Polymer Structure ◽

Flash Pyrolysis ◽

Volatile Products ◽

Kinetics Of

AbstractFlash pyrolysis of polyethyleneglycol by T-Jump/FTIR spectroscopy to temperatures of the surface during combustion reveals that volatile products arise from approximately equal amounts of C-O and C-C homolysis. Nine volatile products are discussed. The average number of repeating units in the volatile oligomers is 2.5. A shift in product distribution occurs at 420–480°C resulting from a change in the polymer structure. Below 420°C, di- and mono-ether oligomers and diethyleneglycol dominate. Above 480°C, the mono-ethers and ethyleneglycol dominate. The Arrhenius constants for decomposition reflect this difference: Ea=8.8 kcal mol−1, In (A, s−1) =2.0 at 370–420°C and Ea=19 kcal mol−1, In (A, s−1)=10 at 480–550°C.

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