Halogenation of Butyl Rubber—A Model Compound Approach

1984 ◽  
Vol 57 (2) ◽  
pp. 275-283 ◽  
Author(s):  
R. Vukov
Keyword(s):  
Model Compound ◽  
Product Distribution ◽  
Butyl Rubber ◽  
Methyl Groups ◽  
Reaction Site ◽  
Model Compounds ◽  
Reaction Conditions ◽  
Basic Study ◽  
Rubber Model ◽  
Trisubstituted Alkenes

Abstract The study of the halogenation behavior of butyl rubber model compounds has brought about a better understanding of the behavior of these systems. It has been established that the presence of methyl groups, in a position B to the reaction site in the butyl rubber model compound, profoundly influences the course of halogenation. Due to the steric hindrance imposed by these groups, both the products of chlorination and bromination deviate from patterns typical of other trisubstituted alkenes. In the case of chlorination, this deviation is demonstrated by the absence of addition products of chlorine across the double bond. In the case of bromination reactions, the change in product distribution is even more dramatic. Thus, substitution products normally not observed in bromination reactions of other trisubstituted alkenes become predominant products found in yields of between 70–90% depending on the precise reaction conditions. The behavior of the butyl model compound appears to be entirely consistent with the behavior of butyl rubber itself; the model compound approach is therefore a valuable tool for use in the basic study of this type of system.

scholarly journals Stabilization of Fast Pyrolysis Liquids from Biomass by Mild Catalytic Hydrotreatment: Model Compound Study

Catalysts ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 402
Author(s):  
Depeng Han ◽  
Wang Yin ◽  
Ali Arslan ◽  
Tongrui Liu ◽  
Yan Zheng ◽  
...  
Keyword(s):  
Model Compound ◽  
Mixed Model ◽  
Precipitation Method ◽  
Single Model ◽  
Model Compounds ◽  
Reaction Conditions ◽  
Initial Stage ◽  
Uv Raman ◽  
Pyrolysis Liquids

Repolymerization is a huge problem in the storage and processing of biomass pyrolysis liquid (PL). Herein, to solve the problem of repolymerization, mild catalytic hydrotreatment of PL was conducted to convert unstable PL model compounds (hydroxyacetone, furfural, and phenol) into stable alcohols. An Ni/SiO2 catalyst was synthesized by the deposition-precipitation method and used in a mild hydrotreatment process. The mild hydrotreatment of the single model compound was studied to determine the reaction pathways, which provided guidance for improving the selectivity of stable intermediate alcohols through the control of reaction conditions. More importantly, the mild hydrotreatment of mixed model compounds was evaluated to simulate the PL more factually. In addition, the effect of the interaction between hydroxyacetone, furfural, and phenol during the catalytic hydrotreatment was also explored. There was a strange phenomenon observed in that phenol was not converted in the initial stage of the hydrotreatment of mixed model compounds. Thermogravimetric analysis (TGA), Ultraviolet-Raman (UV-Raman), and Brunauer−Emmett−Teller (BET) characterization of catalysts used in the hydrotreatment of single and mixed model compounds demonstrated that this phenomenon did not mainly arise from the irreversible deactivation of catalysts caused by carbon deposition, but the competitive adsorption among hydroxyacetone, furfural, and phenol during the mild hydrotreatment of mixed model compounds.

Actinomin und 4.6-Didesmethyl-4.6-di-tert.-butyl-actinomin-Modellverbindungen zum Studium der Actinomycin/DNA-Wechselwirkung / Actinomine and 4,6-Didemethyl-di-tert-butyl-actinomine-Model Compounds for Studies of the Actinomycin-DNA Interaction

1971 ◽  
Vol 26 (9) ◽  
pp. 875-878 ◽  
Author(s):  
Frank Seela
Keyword(s):  
Model Compound ◽  
Dna Interaction ◽  
Methyl Groups ◽  
Model Compounds ◽  
Base Pairs ◽  
Tert Butyl ◽  
Dna Base ◽  
Dna Base Pairs

The synthesis of actinomine, a model compound for the investigation of the actinomycin-DNA interaction is discribed. In place of the pentapeptide lactone rings, actinomin has N,N-diethyl-ethylenediamine groups; it binds to DNA as strongly as actinomycin C1 (D) does. Additional replacement of the 4,6 methyl groups of the chromophore by tert-butyl residues strongly reduces the binding of actinomine to DNA. This result is consistent with intercalation of the actinomine chromophore between the DNA base-pairs, a reaction that is sterically blocked by the tert-butyl groups.

Combining Fischer-Tropsch (FT) and Hydrocarbon Reactions under FT Reaction Conditions: Model Compound and Combined-Catalyst Studies

2009 ◽  
Vol 7 (1) ◽  
Author(s):  
Alba Mena Subiranas ◽  
Georg Schaub
Keyword(s):  
Model Compound ◽  
Zeolite Catalyst ◽  
Fixed Bed ◽  
Fixed Bed Reactor ◽  
Model Compounds ◽  
Fischer Tropsch ◽  
Reaction Conditions ◽  
Ft Synthesis ◽  
Hydrocarbon Reactions ◽  
Product Specifications

The main objectives of the further downstream operations (product upgrading) of Fischer-Tropsch products are to i) improve yields and selectivities of the desired fractions, and ii) improve fuel properties to meet the fuel product specifications. The present study addresses the combination of low-temperature Fischer-Tropsch (FT) synthesis (with Co or Fe catalysts) and hydrocarbon modification reactions (hydroprocessing) in one reactor.In addition to earlier results with Pt/ZSM-5 in a dual-layer configuration in a fixed-bed reactor (Mena et al. 2007), the objective of the present investigation was to study the influence of CO during hydroprocessing and oligomerisation reactions of hydrocarbon model compounds (1-octene, ethene/propene) on two different bifunctional catalysts (Pt/ZSM-5, Pt/Beta). In addition, the influence of the catalyst-bed configuration for the combination FT synthesis and hydrocarbon reactions was investigated (dual layer/physical mixture).The achieved results indicate a potential of combining FT and hydrocarbons reactions in one reactor. Hydrogenation, isomerisation, cracking and oligomerisation reactions take place on a Pt/zeolite catalyst at FTS temperatures and in the presence of CO and H2O. The most critical point of this combination seems to be the deleterious effect of CO on the cracking reactions of isomers. For that reason, the wax fraction (C21+) was only partially cracked. The experimental results also indicate that the type of zeolite and the catalyst-bed configuration have an influence on the diesel/gasoline ratio obtained. It seems that the final fuel products will be a mixture of gasoline and diesel fuel and C1 to C5 compounds, as long as no diesel-selective hydroprocessing catalyst is found.

Novel Products in the CO2-Laser Induced Reaction of Trichloroethylene

1995 ◽  
Vol 60 (1) ◽  
pp. 104-114 ◽  
Author(s):  
Boyd L. Earl ◽  
Richard L. Titus
Keyword(s):  
Irradiation Time ◽  
Product Distribution ◽  
Incident Power ◽  
Cell Geometry ◽  
Reaction Conditions ◽  
Peak Areas ◽  
Induced Decomposition ◽  
Nmr Methods ◽  
Induced Reaction ◽  
Novel Products

Previous reports on the thermal or CO2-laser induced decomposition of trichloroethylene have identified only one condensible product, hexachlorobenzene (in addition to HCl and mono- and dichloroacetylene). We have found that trichloroethylene vapor exposed to cw irradiation on the P(24) line of the (001 - 100) band of the CO2 laser at incident power levels from 8 - 17 W produces numerous products, of which the 13 major ones have been identified using IR, GC/MS, GC/FTIR, and NMR methods. All of these products have 4, 6, or 8 carbons, are highly unsaturated, and are completely chlorinated or contain a single hydrogen. C4HCl5 and C6Cl6 isomers (three of each) account for S 55% to 85% of total products (based on peak areas in the total ion chromatograms in GC/MS runs), depending on reaction conditions. In addition to characterizing the products, we discuss the dependence of the product distribution on laser power, irradiation time, and cell geometry, and we outline a possible mechanism.

scholarly journals Antibacterial and Photocatalytic Properties of ZnO Nanoparticles Obtained from Chemical versus Saponaria officinalis Extract-Mediated Synthesis

Molecules ◽  
2021 ◽  
Vol 26 (7) ◽  
pp. 2072
Author(s):  
Maria Antonia Tănase ◽  
Maria Marinescu ◽  
Petruta Oancea ◽  
Adina Răducan ◽  
Catalin Ionut Mihaescu ◽  
...  
Keyword(s):  
Microwave Irradiation ◽  
Zno Nanoparticles ◽  
Model Compound ◽  
Size Composition ◽  
Inorganic Nanoparticles ◽  
Bacterial Strains ◽  
X Ray Diffraction ◽  
Zno Nps ◽  
Reaction Conditions ◽  
Saponaria Officinalis

In the present work, the properties of ZnO nanoparticles obtained using an eco-friendly synthesis (biomediated methods in microwave irradiation) were studied. Saponaria officinalis extracts were used as both reducing and capping agents in the green nanochemistry synthesis of ZnO. Inorganic zinc oxide nanopowders were successfully prepared by a modified hydrothermal method and plant extract-mediated method. The influence of microwave irradiation was studied in both cases. The size, composition, crystallinity and morphology of inorganic nanoparticles (NPs) were investigated using dynamic light scattering (DLS), powder X-ray diffraction (XRD), SEM-EDX microscopy. Tunings of the nanochemistry reaction conditions (Zn precursor, structuring agent), ZnO NPs with various shapes were obtained, from quasi-spherical to flower-like. The optical properties and photocatalytic activity (degradation of methylene blue as model compound) were also investigated. ZnO nanopowders’ antibacterial activity was tested against Gram-positive and Gram-negative bacterial strains to evidence the influence of the vegetal extract-mediated synthesis on the biological activity.

A review of lignin hydrogen peroxide oxidation chemistry with emphasis on aromatic aldehydes and acids

Holzforschung ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Ajinkya More ◽  
Thomas Elder ◽  
Zhihua Jiang
Keyword(s):  
Hydrogen Peroxide ◽  
Oxidative Degradation ◽  
Reaction Medium ◽  
Dicarboxylic Acids ◽  
Aromatic Aldehydes ◽  
Product Distribution ◽  
Reaction Conditions ◽  
Alkaline Conditions ◽  
The Stability ◽  
Oxidation Chemistry

Abstract This review discusses the main factors that govern the oxidation processes of lignins into aromatic aldehydes and acids using hydrogen peroxide. Aromatic aldehydes and acids are produced in the oxidative degradation of lignin whereas mono and dicarboxylic acids are the main products. The stability of hydrogen peroxide under the reaction conditions is an important factor that needs to be addressed for selectively improving the yield of aromatic aldehydes. Hydrogen peroxide in the presence of heavy metal ions readily decomposes, leading to minor degradation of lignin. This degradation results in quinones which are highly reactive towards peroxide. Under these reaction conditions, the pH of the reaction medium defines the reaction mechanism and the product distribution. Under acidic conditions, hydrogen peroxide reacts electrophilically with electron rich aromatic and olefinic structures at comparatively higher temperatures. In contrast, under alkaline conditions it reacts nucleophilically with electron deficient carbonyl and conjugated carbonyl structures in lignin. The reaction pattern in the oxidation of lignin usually involves cleavage of the aromatic ring, the aliphatic side chain or other linkages which will be discussed in this review.

scholarly journals Catalytic Hydrogenation, Hydrodeoxygenation, and Hydrocracking Processes of a Lignin Monomer Model Compound Eugenol over Magnetic Ru/C–Fe2O3 and Mechanistic Reaction Microkinetics

Catalysts ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 425 ◽  
Author(s):  
Ana Bjelić ◽  
Miha Grilc ◽  
Sašo Gyergyek ◽  
Andraž Kocjan ◽  
Darko Makovec ◽  
...  
Keyword(s):  
Model Compound ◽  
Annealing Temperature ◽  
Low Cost ◽  
Value Added ◽  
Product Distribution ◽  
Surface Chemical ◽  
Annealing Temperatures ◽  
Microkinetic Model ◽  
Highly Active ◽  
Commercial Carbon

Conversion of waste lignocellulosic (LC) biomass, a widely-available low-cost feedstock, into value-added biobased chemicals (and biofuels) has been gaining much attention recently. Therefore, the present lignin valorisation study was aimed at developing magnetically-separable highly-active catalysts for hydrodeoxygenation (HDO), also proposing surface chemical kinetics. Five carbonaceous substrate-deposited Ru were synthesised and tested for the HDO of monomer moiety eugenol. Their annealing temperatures differed, specifically between 300 and 750 °C, while one was not subjected to calcination. Experiments revealed the substantial influence of annealing temperature on the product distribution. Namely, fresh nonannealed nanocomposites were not active for hydrogenolysis. By further pretreatment increase, hydrogenation and, exclusively, the deoxygenation of saturated cyclic species, were enhanced, these being more promoted considering rates and yields than commercial carbon-supported ruthenium. Over 80 mol% of 4-propyl-cylohexanol and propyl-cyclohexane could be formed over the samples, treated at 500 and 600 °C, for 100 and 125 min, respectively, under 275 °C and 5 MPa of reactor hydrogen pressure. Interestingly, a notable 4-propyl-phenol amount was produced upon 750 °C pretreating. The intrinsic microkinetic model, developed previously, was applied to determine relevant turnover parameters. Calculated modelling results indicated a 47- and 10-fold greater demethoxylation and dehydroxylation mechanism ability upon the reheatingpreheating at 600 °C in comparison to industrial (heterogeneous) Ru/C.

Transition metal-free C(sp3)–H bond coupling among three methyl groups

2017 ◽  
Vol 53 (38) ◽  
pp. 5346-5349 ◽  
Author(s):  
Yufeng Liu ◽  
Xi Zhan ◽  
Pengyi Ji ◽  
Jingwen Xu ◽  
Qiang Liu ◽  
...  
Keyword(s):  
Transition Metal ◽  
Methyl Groups ◽  
Methyl Ketones ◽  
Reaction Conditions ◽  
Methyl Group ◽  
Metal Free

A coupling of multiple C(sp3)–H bonds of the methyl group in methyl ketones with dimethyl sulfoxides was developed under transition metal-free reaction conditions.

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