scholarly journals Chemisorption of CO2 on diaminated silica as bicarbonates and different types of carbamate ammonium ion pairs

2021 ◽  
Author(s):  
Anthony E. Szego ◽  
Aleksander Jaworski ◽  
Niklas Hedin
Keyword(s):  
Ion Pairs ◽  
Ammonium Ion ◽  
Carbamic Acid ◽  
Modified Silica ◽  
Direct Excitation ◽  
Different Types

Direct excitation and {1H}13C-CPMAS NMR allowed detecting carbamate–ammonium ion pairs, carbamic acid and bicarbonate species in amine-modified silica sorbents.

Mixing and Comparative Properties of NR Compounds Filled with Different Types of Reinforcing Fillers

2017 ◽  
Vol 266 ◽  
pp. 172-176
Author(s):  
Pattarawadee Maijan ◽  
Nitinart Saetung ◽  
Wisut Kaewsakul
Keyword(s):  
Carbon Black ◽  
Silica Surface ◽  
High Viscosity ◽  
Cure Rate ◽  
Modified Silica ◽  
Reinforcing Fillers ◽  
Silane Coupling ◽  
Different Types ◽  
Cure Time

Mixing behaviors of the compounds filled with different reinforcing fillers were studied in correlation with compound and vulcanizate properties. Four filler systems were used including: 1) silica plus small amount of silane coupling agent; 2) carbon black; 3) pre-modified silica; and 4) silica+silane-carbon black mixed one. The results have shown that silica provides longer optimum cure time and shorter cure rate than carbon black due to accelerator adsorption on silica surface. In addition, owing to highly polar nature on silica surface the silica-based compounds show rather high viscosity, attributed to stronger filler-filler interaction as can be confirmed by Payne effect and reinforcement index. However, the commercial surface treatment or pre-modified form of silica shows superior properties than in-situ modification of silica by silane during mixing, while it gives comparable properties to carbon black-based compound. Tensile properties of vulcanizates show a good correlation with the basic properties of their compounds.

Electron spin resonance observations of photochemically generated contact ammonium ion-pairs of fluoro-substituted ketones

1979 ◽  
Vol 57 (5) ◽  
pp. 600-602 ◽  
Author(s):  
K. S. Chen ◽  
T. Foster ◽  
J. K. S. Wan
Keyword(s):  
Electron Spin Resonance ◽  
Electron Spin ◽  
Ion Pairs ◽  
Esr Spectra ◽  
Ammonium Ion ◽  
Spin Resonance ◽  
Photochemical Systems

Contact radical ion-pairs of ammonium and fluoro-substituted ketones were generated in photochemical systems and their here-to-fore elusive esr spectra were characterized.

Photochemical reactions of fluoro-substituted ketones with amines, tetraphenylborates, and organometals: an electron spin resonance study

1980 ◽  
Vol 58 (6) ◽  
pp. 591-598 ◽  
Author(s):  
Kuang S. Chen ◽  
Terry Foster ◽  
Jeffrey K. S. Wan
Keyword(s):  
Alkali Metal ◽  
Metal Ion ◽  
Ion Pairs ◽  
Photochemical Reactions ◽  
Ammonium Ion ◽  
Electron Spin Resonance Study ◽  
Fluorine Substitution ◽  
Alkali Metal Ion ◽  
Spin Resonance ◽  
Spin Resonance Study

Ammonium ion-pairs, solvent-separated alkali-metal ion-pairs, and Group IVB organometallic adducts of fluoro-substituted ketones were generated photochemically. The structure and the controlling factors for the formation of contact ammonium ion-pair were deduced from the effects of solvent, amine, and fluorine substitution. The effect of fluorine on the formation of the alkali-metal ion-pairs and organometallic adducts was discussed.

The Spectrophotometric Determination of Formaldehyde in Whole Smoke/Eine spektralphotometrische Methode zur Bestimmung von Formaldehyd im Vollrauch von Cigaretten

1971 ◽  
Vol 6 (1) ◽  
Author(s):  
H.P. Stauffer ◽  
J. Bourquin
Keyword(s):  
Gas Phase ◽  
Cigarette Smoke ◽  
Carbonyl Compounds ◽  
Ammonium Ion ◽  
Buffer Solution ◽  
Simple Method ◽  
Different Types ◽  
Volatile Aldehydes ◽  
Whole Smoke

AbstractThe quantitative determination of formaldehyde in the gas phase of cigarette smoke does not permit any conclusion about the actual level in whole smoke. This is due to the fact that a Cambridge filter charged with smoke condensate absorbs up to 50 % of the volatile aldehydes from the gas phase. A simple method is presented making possible the estimation of formaldehyde in whole cigarette smoke. The procedure is based on the Hantzsch reaction between formaldehyde, acetylacetone and ammonium ion in an aqueous buffer solution. The reaction product, 3,5-diacetyl1,4-dihydrolutidine, has an absorption maximum at 412 nm and is measured spectrophotometrically. The operations are simple and there are no separation steps required. Reproducibility is excellent and interference by other carbonyl compounds can be neglected. Acetaldehyde in concentrations 10 times higher than formaldehyde interferes to less than 1 %. Different types of cigarettes have been analysed with respect to their delivery of formaldehyde. Values found range from 40 to 90 µg per cigarette. The concentrations found in whole smoke are significantly higher than the values cited in the Iiterature for gas phase formaldehyde

Article

1999 ◽  
Vol 77 (5-6) ◽  
pp. 1042-1049
Author(s):  
Wlodzimierz Galezowski ◽  
Iwona Grzeskowiak ◽  
Arnold Jarczewski
Keyword(s):  
Proton Transfer ◽  
Salt Effect ◽  
Ion Pairs ◽  
Order Rate Constant ◽  
Transfer Reactions ◽  
First Order ◽  
Organic Bases ◽  
Different Types ◽  
Proton Transfer Reactions ◽  
Guanidinium Cation

The rates of proton transfer reactions between C-acids of different types such as 1-(4-nitrophenyl)-1-nitroalkanes, 4-nitrophenylcyanomethanes, and 2,4,6-trinitrotoluene, and organic bases such as 1,1,3,3-tetrametylguanidine, 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene (MTBD), and tri-n-butylamine have been measured in acetonitrile at pseudo-first-order conditions. A general equation for the rates of proton transfer reactions between C-acids and bases with product existing in two forms, ions and ion pairs, has been derived and its applicability tested. The equation works well except for reactions of 1-(4-nitrophenyl)-1-nitroalkanes with guanidines for which the second-order rate constant is diminished with concentration of guanidinium cation, while tetrabutylammonium salts accelerate the reactions. Possible reasons for this are discussed.Key words: proton transfer, kinetic study, ion pairs, C-acids, organic bases, acetonitrile, salt effect.

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