Formation of By-products in Pure and Aqueous Acrylic Acid - Kinetic Measurements and Formation Mechanisms

2017 ◽  
Vol 40 (4) ◽  
pp. 755-759
Author(s):  
Christian A. Pfeifer ◽  
Cordula Scholz ◽  
Kevin Vogel ◽  
Alfons Drochner ◽  
Herbert Vogel
Keyword(s):  
Acrylic Acid ◽  
Formation Mechanisms ◽  
Kinetic Measurements ◽  
By Products

scholarly journals Formation of NDMA by Chloramination of Nitrogenous Pharmaceuticals

2010 ◽  
Vol 5 (4) ◽  
Author(s):  
J. Le Roux ◽  
H. Gallard ◽  
J.P. Croué
Keyword(s):  
Structural Characteristics ◽  
Haloacetic Acids ◽  
Formation Mechanisms ◽  
Tertiary Amines ◽  
Human Carcinogen ◽  
Conversion Rates ◽  
Water Chlorination ◽  
By Products ◽  
New Formation

Many disinfection by-products (DBPs) are formed during water chlorination, including trihalomethanes (THMs) and haloacetic acids (HAAs). Disinfection with chloramines is often used to reduce the production of regulated DBPs. However, chloramination can lead to the formation of N–nitrosamines, including N–nitrosodimethylamine (NDMA), a probable human carcinogen. The formation mechanisms of NDMA are not fully understood. Proposed mechanisms used dimethylamine (DMA) as a model precursor, but results show that certain widely used tertiary dimethylamines (e.g. the pharmaceutical ranitidine) show much higher conversion rates to NDMA than DMA. These amounts of NDMA cannot be explained by current proposed mechanisms. New formation mechanisms have to be proposed to explain the importance of structural characteristics of tertiary amines for NDMA formation.

scholarly journals Laboratory analogs of carbonaceous matter: Soot and its precursors and by-products

2008 ◽  
Vol 4 (S251) ◽  
pp. 425-432 ◽  
Author(s):  
Cornelia Jäger ◽  
Harald Mutschke ◽  
Isabel Llamas-Jansa ◽  
Thomas Henning ◽  
Friedrich Huisken
Keyword(s):  
Aromatic Hydrocarbons ◽  
Soot Formation ◽  
Formation Mechanisms ◽  
Carbonaceous Matter ◽  
Condensed Carbon ◽  
End Products ◽  
Polycyclic Aromatic ◽  
Experimental Findings ◽  
By Products ◽  
Reactive Gas

AbstractCarbonaceous materials have been prepared in the laboratory by laser-induced pyrolysis of a mixture of hydrocarbons under different conditions and laser ablation of graphite in reactive gas atmospheres. We have investigated the soluble and insoluble parts of the condensed carbon powders with several spectroscopic and chromatographic methods in order to obtain information on the composition of the condensate. The results of these experiments have demonstrated that, at temperatures lower than 1700 K, the pyrolysis by-products are mainly PAHs, whereas at higher temperatures fullerenes and polyyne-based compounds are formed. The experimental findings point to different soot formation mechanisms with variable intermediates and end products. It has been found that soot extracts can contain more than 65 different polycyclic aromatic hydrocarbons (PAHs). Eventually, the study of the condensation pathways of soot particles and their precursors and by-products will permit the prediction of the spectral properties of carbonaceous matter in space.

Kinetic measurements of acrylic acid polymerization in a pendular slug reactor

2020 ◽  
Vol 92 (9) ◽  
pp. 1362-1362
Author(s):  
T. Klement ◽  
T. Röder ◽  
N. Kockmann
Keyword(s):  
Acrylic Acid ◽  
Kinetic Measurements

scholarly journals Synthesis of Boroxine and Dioxaborole Covalent Organic Frameworks via Transesterification and Metathesis of Pinacol Boronates

2021 ◽  
Author(s):  
Ehsan Hamzehpoor ◽  
Antranik Jonderian ◽  
eric mccalla ◽  
Dmitrii F. Perepichka
Keyword(s):  
Kinetic Analysis ◽  
Boronic Acid ◽  
Boronic Acids ◽  
Synthetic Approach ◽  
Covalent Organic Frameworks ◽  
Kinetic Measurements ◽  
H Nmr ◽  
Poorly Soluble ◽  
By Products ◽  
Model Reactions

Boroxine and dioxaborole are the first and some of the most studied synthons of Covalent Organic Frameworks (COFs). Despite their wide application in the design of functional COFs over the last 15 years, their synthesis still relies on the original Yaghi’s condensation of boronic acids (with itself or with polyfunctional catechols), some of which are difficult to prepare, poorly soluble, or unstable in the presence of water. Here we propose a new synthetic approach to boroxine COFs (based on transesterification of pinacol aryl boronates (ArBpin) with methyl boronic acid (MBA) and dioxaborole COFs (through the metathesis of pinacol boronates with methylboryl-protected catechols). The ArBpin and MBA-protected catechols are easy to purify, highly soluble, and bench-stable. Furthermore, kinetic analysis of the two model reactions reveals high reversibility (Keq~1) and facile control over the equilibrium. Unlike the conventional condensation which eliminates water by-products, the by-product of the metathesis (MBA pinacolate) allows for easy kinetic measurements of the COF formation by conventional <sup>1</sup>H NMR. We show the generality of this approach by synthesis of seven known boroxine/dioxaborole COFs whose crystallinity is better or equal to those reported by conventional condensation. We also apply metathesis polymerization to obtain two new COFs, Py4THB and B2HHTP, whose synthesis was previously precluded by their insolubility and hydrolytic instability, respectively, of the boronic acid precursors.<br>

Research Progress of Typical Taste and Odor Compounds Produced by Chlorination in Drinking Water

2013 ◽  
Vol 316-317 ◽  
pp. 698-702 ◽  
Author(s):  
Min Min Mao ◽  
Ke Jia Zhang ◽  
Tu Qiao Zhang ◽  
Hong Liang Yu
Keyword(s):  
Electronic Nose ◽  
Research Progress ◽  
Formation Mechanisms ◽  
Activated Carbon Adsorption ◽  
Common Control ◽  
Taste And Odor ◽  
Pipe Water ◽  
Unpleasant Odor ◽  
Control Technologies ◽  
By Products

As disinfection by-products, the taste and odor (T&O) compounds were produced by chlorination at the end of water treatment. The existence of T&O compounds causes the pipe water with unpleasant odor and reducing water quality. Based on the latest research achievements at home and abroad, the characteristics and formation mechanisms of typical T&O compounds produced by chlorination are introduced. The new analytical method of electronic nose is also expounded. In addition, the common control technologies, such as pre-oxidation, activated carbon adsorption and bio-membrane, are reviewed. Since the precursors of T&O compounds shows small molecular, stable structure and low concentration, some coupling technologies including ozone-GAC, permanganate-PAC, and bio-membrane and GAC treatments, are employed effectively.Key words: chlorination; odor and taste compounds; disinfection by-products; precursor; electronic nose

N-nitrosamines, emerging disinfection by-products of health concern: an overview of occurrence, mechanisms of formation, control and analysis in water

2014 ◽  
Vol 15 (1) ◽  
pp. 11-25 ◽  
Author(s):  
Y. Kadmi ◽  
L. Favier ◽  
D. Wolbert
Keyword(s):  
Drinking Water ◽  
Water Samples ◽  
Formation Control ◽  
Natural Waters ◽  
Current Knowledge ◽  
Health Concern ◽  
Formation Mechanisms ◽  
Mechanisms Of Formation ◽  
Near Future ◽  
By Products

The presence of N-nitrosamines in water bodies used for drinking water purposes may present a more serious risk for humans than regulated disinfection by-products (DBPs) species. Hence, understanding and controlling the incidence of N-nitrosamines represents a contemporary challenge to the water industry. Although many of these molecules potentially formed as DBPs are detected in chlorinated natural waters, few studies have focused on the formation, occurrence, and analysis of N-nitrosamines. Until now, nine N-nitrosamines have been detected in water samples; N-nitrosodimethylamine is the most frequently reported nitrosamine in drinking water. Although there are currently no federal regulations for these molecules in drinking water, this family of N-DBPs is one of three potential groups of contaminants highlighted for possible regulatory action in the near future. This paper gives an overview of the current knowledge concerning the occurrence, precursors, and formation mechanisms of N-nitrosamines in water. In addition, the existing regulations are described and relevant analytical methods used for their quantification in water samples are also discussed.

scholarly journals Synthesis of Boroxine and Dioxaborole Covalent Organic Frameworks via Transesterification and Metathesis of Pinacol Boronates

2021 ◽  
Author(s):  
Ehsan Hamzehpoor ◽  
Antranik Jonderian ◽  
eric mccalla ◽  
Dmitrii F. Perepichka
Keyword(s):  
Kinetic Analysis ◽  
Boronic Acid ◽  
Boronic Acids ◽  
Synthetic Approach ◽  
Covalent Organic Frameworks ◽  
Kinetic Measurements ◽  
H Nmr ◽  
Poorly Soluble ◽  
By Products ◽  
Model Reactions

Boroxine and dioxaborole are the first and some of the most studied synthons of Covalent Organic Frameworks (COFs). Despite their wide application in the design of functional COFs over the last 15 years, their synthesis still relies on the original Yaghi’s condensation of boronic acids (with itself or with polyfunctional catechols), some of which are difficult to prepare, poorly soluble, or unstable in the presence of water. Here we propose a new synthetic approach to boroxine COFs (based on transesterification of pinacol aryl boronates (ArBpin) with methyl boronic acid (MBA) and dioxaborole COFs (through the metathesis of pinacol boronates with methylboryl-protected catechols). The ArBpin and MBA-protected catechols are easy to purify, highly soluble, and bench-stable. Furthermore, kinetic analysis of the two model reactions reveals high reversibility (Keq~1) and facile control over the equilibrium. Unlike the conventional condensation which eliminates water by-products, the by-product of the metathesis (MBA pinacolate) allows for easy kinetic measurements of the COF formation by conventional <sup>1</sup>H NMR. We show the generality of this approach by synthesis of seven known boroxine/dioxaborole COFs whose crystallinity is better or equal to those reported by conventional condensation. We also apply metathesis polymerization to obtain two new COFs, Py4THB and B2HHTP, whose synthesis was previously precluded by their insolubility and hydrolytic instability, respectively, of the boronic acid precursors.<br>

Reaction of 2,3-dihydro-1,3-6H-oxazine-2,6-dione with aliphatic amines and amino acids

1982 ◽  
Vol 47 (11) ◽  
pp. 2932-2945 ◽  
Author(s):  
Jiří Farkaš ◽  
Jaroslav Hapala ◽  
Olga Jindrová ◽  
Jan Škoda
Keyword(s):  
Amino Acids ◽  
Aqueous Medium ◽  
Aliphatic Amines ◽  
Secondary Amines ◽  
Primary Amines ◽  
Kinetic Measurements ◽  
Propenoic Acid ◽  
Tert Butylamine ◽  
By Products

Reaction of 2,3-dihydro-1,3-6H-oxazine-2,6-dione (I) with amines in aqueous medium leads predominantly to N-substituted amides of (Z)-3-carboxylamino-2-propenoic acid. Isomeric 3-(N'-alkylureido)-2-propenoic acids are formed as by-products in the reaction of compound I with ammonia or methylamine; tert-butylamine affords ureido derivative as the sole reaction product. Secondary amines react with compound I substantially more rapidly than primary amines. In both cases the branching on the α-carbon decreases the reactivity distinctly while the branching on the β-carbon does not have a significant effect on the rate of aminolysis. The results of kinetic measurements of the reaction of compound I with amino acids are discussed n connection with the possible interaction of compound I with enzymes.

Hydrogen Cyanide Polymers from the Impact of Comet P/Shoemaker-Levy 9 on Jupiter

1997 ◽  
Vol 161 ◽  
pp. 179-187
Author(s):  
Clifford N. Matthews ◽  
Rose A. Pesce-Rodriguez ◽  
Shirley A. Liebman
Keyword(s):  
Amino Acids ◽  
Solar System ◽  
Hydrogen Cyanide ◽  
Nitrogen Heterocycles ◽  
Laboratory Studies ◽  
Heterogeneous Solids ◽  
The Many ◽  
Comet Halley ◽  
The Impact ◽  
By Products

AbstractHydrogen cyanide polymers – heterogeneous solids ranging in color from yellow to orange to brown to black – may be among the organic macromolecules most readily formed within the Solar System. The non-volatile black crust of comet Halley, for example, as well as the extensive orangebrown streaks in the atmosphere of Jupiter, might consist largely of such polymers synthesized from HCN formed by photolysis of methane and ammonia, the color observed depending on the concentration of HCN involved. Laboratory studies of these ubiquitous compounds point to the presence of polyamidine structures synthesized directly from hydrogen cyanide. These would be converted by water to polypeptides which can be further hydrolyzed to α-amino acids. Black polymers and multimers with conjugated ladder structures derived from HCN could also be formed and might well be the source of the many nitrogen heterocycles, adenine included, observed after pyrolysis. The dark brown color arising from the impacts of comet P/Shoemaker-Levy 9 on Jupiter might therefore be mainly caused by the presence of HCN polymers, whether originally present, deposited by the impactor or synthesized directly from HCN. Spectroscopic detection of these predicted macromolecules and their hydrolytic and pyrolytic by-products would strengthen significantly the hypothesis that cyanide polymerization is a preferred pathway for prebiotic and extraterrestrial chemistry.

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