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Published in Karen D. Sam, Thomas P. Wampler, Analytical Pyrolysis Handbook, 2021
Pyrolysis generally occurs at the sulfonamido group, resulting in the liberation of sulfur dioxide. The other products will include aniline and a heterocyclic aromatic amine. The sulfonamide is generally characterized by the heterocyclic amine since aniline is always a product with these compounds [10]. For example, in the pyrolysis of sulfadiazine, pyrolysis occurs at the sulfonamido nitrogen atom to form an unstable SO2 radical, which readily converts to sulfur dioxide. The other remaining products are aniline and 2-aminopyrimidine. The same process holds for the sulfonamides sulfamerazine and sulfadimidine. The only difference is that the heterocyclic products are 2-amino-4-methylpyrimidine and 2-amino-4,6 dimethylpyrimidine, respectively [11].
Symbols, Terminology, and Nomenclature
Published in W. M. Haynes, David R. Lide, Thomas J. Bruno, CRC Handbook of Chemistry and Physics, 2016
W. M. Haynes, David R. Lide, Thomas J. Bruno
Gra Gri Grn Gro GTO GTP Gua Gul Guo GUT GVB GWS Gy H H H0 h h Ha ha HAM hav Hb HCA HCB hcp Hcy HCZ, HCTZ HDL HDPE HDS HEIS HEP Hepes Hepps HF HFA HFO hfs HHPA HIPS His HMC HMDA HMO HMT HMX HN1 HOAc HOC HOMAS HOMO HOSE Hp hp HPLC glyceraldehyde glyceric acid glycerone [dihydroxyacetone] glycerol gaussian-type orbital guanosine 5'-triphosphate guanine gulose guanosine grand unified theory generalized valence bond (method) Glashow-Weinberg-Salam (theory) gray; gigayear henry; histidine enthalpy; Hamiltonian function; magnetic field Hubble constant helion; hour; hecto (SI prefix for 102) Planck constant Hartmann number hectare hydrogenic atoms in molecules haversine hemoglobin heterocyclic amine; hexachloroacetone hexachlorobenzene hexagonal closed packed homocysteine hydrochlorothiazide high-density lipoprotein high-density polyethylene hydrodesulfurization high-energy ion scattering high energy physics 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid 4-(2-hydroxyethyl)-1-piperazinepropanesulfonic acid high frequency; Hartree-Fock (method) hexafluoroacetone Hartree-Fock orbital hyperfine structure hexahydrophthalic anhydride high-impact polystyrene histidine high strength molding compound hexamethylenediamine Hückel molecular orbital hexamethylenetetramine cyclotetramethylenetetranitramine 2-chloro-N-(2-chloroethyl)-N-ethylethanamine acetic acid halogenated organic compound(s) harmonic oscillator model of aromatic stabilization highest occupied molecular orbital harmonic oscillator stabilization energy heptyl horsepower high-performance liquid chromatography
Tasty and toxic – a culinary risk dilemma
Published in Charlotte Fabiansson, Stefan Fabiansson, Food and the Risk Society, 2016
Charlotte Fabiansson, Stefan Fabiansson
There seem to be no government regulations or guidelines relevant to reduction of exposure to heterocyclic amines. However, although there is no general agreement on the role of heterocyclic amines in relation to human health, authorities in many countries consider the risk high enough to recommend that their presence in our diet should be minimised. This can be achieved through several means. One way could be to follow the recommendations of World Cancer Research Fund International and reduce overall meat consumption (Ferguson 2010). If this is not feasible, changes in cooking techniques have been shown to reduce the level of heterocyclic amines in meat. Differences in heterocyclic amine levels can be more than 100-fold depending on the time and temperature combination used for cooking the meat (Sinha et al. 1998). More heterocyclic amines are formed when pan surface temperatures are higher than 220ºC, so reducing the surface temperature is beneficial in avoiding the creation of burnt crust. The pan drippings and meat residue that remain after meat is fried also have high concentrations of heterocyclic amines and using them for making gravy might best be avoided (Augustsson et al. 1999). Ground beef patties show lower levels of heterocyclic amines if they are flipped every minute until cooked through (Knize and Felton 2005).
Synthesis and properties of double epoxy groups double quaternary ammonium salts
Published in Journal of Dispersion Science and Technology, 2023
Guixin Li, Feng Ma, Junying Li, Guangxu Chen, Pengfei Yang, Ning Yu, Jianhui Chen, Yongle Wang, Xinyu Zhang
Quaternary ammonium salt (QAS, general formula R4N+X−) is a cationic compound that four hydrogen atoms in ammonium are all replaced by organic groups. It is a kind of surfactant with good bactericidal property due to the cationic quaternary ammonium group. QAS commonly used as bactericidal agent and disinfectant, it has a broad-spectrum antibacterial activities,[1] mainly in the inhibition of bacteria and fungi, of course, it also has a certain effect on viruses.[2,3] There are many types of cationic surfactants based on quaternary ammonium salts. Generally, QAS are produced by the nucleophilic substitution reaction of tertiary amines (alkyl amine or heterocyclic amine) with an alkyl halide or similar material.[4,5]
Carbon Dioxide Contamination of Aqueous Morpholine Solutions and Effects on Secondary Coolant Chemistry Under CANDU Conditions
Published in Nuclear Technology, 2022
O. Fandiño, J. S. Cox, C. McGregor, J. Conrad, K. Liao, P. R. Tremaine
Morpholine, O(CH2CH2)2NH, is a heterocyclic amine used in the secondary coolant of nuclear reactors for pH control. Amines similar to morpholine are also used as carbon dioxide (CO2) absorbers in post-combustion carbon-capture technologies, and morpholine itself is known to react with CO2 (Ref. 1). In addition, it has been established that cyclic amines similar to morpholine can have faster absorption rates and a higher capacity for carbon dioxide absorption at low CO2 partial pressures, relative to other amines such as monoethanolamine.2 The concern has been raised that CO2 may be absorbing into the 50 wt% (11.5 mol·kg−1) morpholine solution in the bulk feed drums while in storage at Ontario Power Generation (OPG) sites, thus decreasing the pH and causing the unanticipated addition of carbon dioxide when these solutions are deployed. The possibility for CO2 absorption during transfer/dilution, as well as in the sampling of secondary-side coolant solutions, such as those containing dilute morpholine solution (i.e., 60 ppm/0.006 wt%/7.00 × 10−4 mol·kg−1 or less), is also currently unknown.
Aqueous N-nitrosamines: Precursors, occurrence, oxidation processes, and role of inorganic ions
Published in Critical Reviews in Environmental Science and Technology, 2021
Tahereh Jasemizad, Peizhe Sun, Lokesh P. Padhye
The addition of ammonium to the solutions containing nitrosamines’ precursors during chloramination was found to increase the formation of nitrosamines due to the formation of chloramines (Chen & Young, 2008; Chen & Young, 2009). Comparison between the impact of ammonium, nitrite, and nitrate on NDMA formation during chlorination of diuron showed the highest NDMA formation in the presence of ammonium that was hypothesized to be due to the formation of dichloramine (Chen & Young, 2009). Similarly, an increase in NDMA yield from the oxidation of tetracycline during both chloramination and UV/monochloramine treatment (Cai et al., 2020) and chloramination of chlortoluron in the presence of ammonium was likely due to the inhibition of monochloramine decay (Xu et al., 2012). A recent study by Chen et al. (2021) found that ammonium and nitrite enhanced the NDMA formation from chlorination and chloramination of aromatic and heterocyclic amine-containing pharmaceuticals while the effect of nitrate was negligible. They attributed enhancement by ammonium and nitrite to chloramination and free chlorine-enhanced nitrosation, respectively.