Formation of flavorant–propylene Glycol Adducts With Novel Toxicological Properties in Chemically Unstable E-Cigarette Liquids

Abstract Introduction “Vaping” electronic cigarettes (e-cigarettes) is increasingly popular with youth, driven by the wide range of available flavors, often created using flavor aldehydes. The objective of this study was to examine whether flavor aldehydes remain stable in e-cigarette liquids or whether they undergo chemical reactions, forming novel chemical species that may cause harm to the user. Methods Gas chromatography was used to determine concentrations of flavor aldehydes and reaction products in e-liquids and vapor generated from a commercial e-cigarette. Stability of the detected reaction products in aqueous media was monitored by ultraviolet spectroscopy and nuclear magnetic resonance spectroscopy, and their effects on irritant receptors determined by fluorescent calcium imaging in HEK-293T cells. Results Flavor aldehydes including benzaldehyde, cinnamaldehyde, citral, ethylvanillin, and vanillin rapidly reacted with the e-liquid solvent propylene glycol (PG) after mixing, and upward of 40% of flavor aldehyde content was converted to flavor aldehyde PG acetals, which were also detected in commercial e-liquids. Vaping experiments showed carryover rates of 50%–80% of acetals to e-cigarette vapor. Acetals remained stable in physiological aqueous solution, with half-lives above 36 hours, suggesting they persist when inhaled by the user. Acetals activated aldehyde-sensitive TRPA1 irritant receptors and aldehyde-insensitive TRPV1 irritant receptors. Conclusions E-liquids are potentially reactive chemical systems in which new compounds can form after mixing of constituents and during storage, as demonstrated here for flavor aldehyde PG acetals, with unexpected toxicological effects. For regulatory purposes, a rigorous process is advised to monitor the potentially changing composition of e-liquids and e-vapors over time, to identify possible health hazards. Implications This study demonstrates that e-cigarette liquids can be chemically unstable, with reactions occurring between flavorant and solvent components immediately after mixing at room temperature. The resulting compounds have toxicological properties that differ from either the flavorants or solvent components. These findings suggest that the reporting of manufacturing ingredients of e-liquids is insufficient for a safety assessment. The establishment of an analytical workflow to detect newly formed compounds in e-liquids and their potential toxicological effects is imperative for regulatory risk analysis.

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Hydrogenolysis of glucose and fructose in glycol solutions over CuO-MgO-ZrO2 catalyst

Catalysis and petrochemistry ◽

10.15407/kataliz2020.30.048 ◽

2020 ◽

pp. 48-55

Author(s):

M.E. Sharanda ◽

◽

E.A. Bondarenko ◽

Keyword(s):

Ethylene Glycol ◽

Propylene Glycol ◽

Flow Reactor ◽

General Trend ◽

Raw Materials ◽

Reaction Products ◽

Renewable Raw Materials ◽

High Partial Pressure ◽

Zro2 Catalyst ◽

Phase Process

Ethylene glycol and propylene glycol are important representatives of polyols. On an industrial scale, they are obtained from petrochemical raw materials. Within a decade, significant efforts were made for the producing of polyols from biologically renewable raw materials - carbohydrates. The general trend for carbohydrate hydrogenolysis includes application of liquid-phase process with the use of modified metal-oxide catalysts, at 120-120 ° C and pressure of 3MPa or above. So high pressure is used for the reason to increase hydrogen solubility, and also due to the high partial pressure of low boiling solvents. We supposed that usage of high boiling solvents could allow hydrogenolysis to be performed at the lower pressure. Ethylene glycol and propylene glycol are of particular interest as such kind of solvent since they are both the main products of glucose hydrogenolysis. In this work, the process of hydrogenolysis of glucose and fructose over Cu / MgO-ZrO2 catalyst have been studied at temperature range of 160-200 °C and a pressure of 0.1-0.3 MPa in a flow reactor. The solvents were simultaneously the target products of the reaction - ethylene glycol and / or propylene glycol. Gas chromatography and 13C NMR were used for the reaction products identification. It was found that the solubility of glucose in propylene glycol is 21 % by weight, and in ethylene glycol 62% by weight. It was pointed out that the process of hydrogenolysis can take place at a pressure close to atmospheric. Under these conditions, the conversion of hexoses reaches 96-100 %. The reaction products are preferably propylene glycol and ethylene glycol. The total selectivity for C3-2 polyols is 90-94 %, that is higher than in the hydrogenolysis of glucose in aqueous solution.

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Non-Toxic Environment for Ferritic Nitrocarburising Process

Revista de Chimie ◽

10.37358/rc.18.9.6587 ◽

2018 ◽

Vol 69 (9) ◽

pp. 2416-2419

Author(s):

Mihai Branzei ◽

Mihai Ovidiu Cojocaru ◽

Leontin Nicolae Druga ◽

Florica Tudose ◽

Roxana Trusca

Keyword(s):

Surface Reaction ◽

Effective Solution ◽

Reaction Products ◽

Toxic Reaction ◽

Wide Range ◽

Toxic Environment ◽

Thermochemical Processing ◽

Surface Saturation ◽

Gas Molecules ◽

Toxic Components

Experimental research aimed to find a solution for replacing components with high toxicity (or generating such components as a result of reactions occurring in the environment at processing temperatures) from the environments used for ferritic nitrocarburising process (FNCP) with non-hazardous components, but extremely active during the process. In the temperature range in which this type of processing is applied (lower than the eutectoid transformation temperature in the Fe-N phase diagram), the most commonly used media are liquid or gaseous; liquid ones contain toxic components (sodium or potassium cyanates/cyanides), and gaseous ones require complex equipments. Packing is extremely rarely used, but in this case pack-mix contain toxic components (15 � 20 wt.% sodium or potassium ferrocyanide). Urea also called carbamide (CO (NH2)2) is the active component in the pack-mixing proposed to be used for FNCP. Carbamide is used in low temperature cyanidation thermochemical heat treatment (liquid FNC), together with sodium or potassium carbonates, resulting in very toxic reaction products (sodium or potassium cyanates). Compared to cyanidation, in the version proposed in the paper, the carbamide does not react with carbonates because they are not found in the composition of the environment but decomposes in the presence or absence of oxygen (by a disproportionation reaction) with the formation of some gas molecules interesting for the process. It has been concluded that the use of carbamide together with two other components, activated charcoal (having a triple role - dispersing, storage, surface saturation) and respectively ammonium chloride as surface reaction activator, is an effective solution for achieving the desired goals by applying this type of thermochemical processing to a wide range of products made of quality steels up to alloy miscellaneous steels.

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Structure and Activity of Pentacyclic Triterpenes Codrugs. A Review

Mini-Reviews in Medicinal Chemistry ◽

10.2174/1389557521666210105110848 ◽

2021 ◽

Vol 21 ◽

Author(s):

Justyna Żwawiak ◽

Anna Pawełczyk ◽

Dorota Olender ◽

Lucjusz Zaprutko

Keyword(s):

Biological Activities ◽

Anticancer Activities ◽

Drug Molecule ◽

Pentacyclic Triterpene ◽

Formation Pathway ◽

Chemical Systems ◽

Drug Molecules ◽

Wide Range ◽

Anti Hiv ◽

Structure And Activity

: Triterpenes are a wide and important group of compounds that have several promising pharmacological properties, such as hepatoprotective, anti-inflammatory, anti-HIV, antioxidant, or anticancer activities. Such potent substances can be successfully incorporated in more complex chemical systems e.g. codrugs or pro-drugs that have better pharmacological profile. The codrug is connected with a drug formation pathway to chemically cohere at least two drug molecules to improve positive therapeutic efficiency or decrease side effects. The codrug can be cleaved in the organism to generate effective compounds previously used as substrates. This article presents an overview of codrugs that consist of pentacyclic triterpene moiety that is chosen as a basic codrug moiety due to their wide range of vital activities and another drug molecule fragment. It was found that triterpenoid codrugs are characterized by a wide range of biological activities. However, most of them have anticancer potency.

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INSPECTOR: free software for magnetic resonance spectroscopy data inspection, processing, simulation and analysis

Scientific Reports ◽

10.1038/s41598-021-81193-9 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Martin Gajdošík ◽

Karl Landheer ◽

Kelley M. Swanberg ◽

Christoph Juchem

Keyword(s):

Magnetic Resonance ◽

Quality Management ◽

Magnetic Resonance Spectroscopy ◽

Data Processing ◽

Biomedical Research ◽

Clinical Diagnostics ◽

Resonance Spectroscopy ◽

User Friendliness ◽

Wide Range

AbstractIn vivo magnetic resonance spectroscopy (MRS) is a powerful tool for biomedical research and clinical diagnostics, allowing for non-invasive measurement and analysis of small molecules from living tissues. However, currently available MRS processing and analytical software tools are limited in their potential for in-depth quality management, access to details of the processing stream, and user friendliness. Moreover, available MRS software focuses on selected aspects of MRS such as simulation, signal processing or analysis, necessitating the use of multiple packages and interfacing among them for biomedical applications. The freeware INSPECTOR comprises enhanced MRS data processing, simulation and analytical capabilities in a one-stop-shop solution for a wide range of biomedical research and diagnostic applications. Extensive data handling, quality management and visualization options are built in, enabling the assessment of every step of the processing chain with maximum transparency. The parameters of the processing can be flexibly chosen and tailored for the specific research problem, and extended confidence information is provided with the analysis. The INSPECTOR software stands out in its user-friendly workflow and potential for automation. In addition to convenience, the functionalities of INSPECTOR ensure rigorous and consistent data processing throughout multi-experiment and multi-center studies.

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Ureido Functionalization through Amine-Urea Transamidation under Mild Reaction Conditions

Polymers ◽

10.3390/polym13101583 ◽

2021 ◽

Vol 13 (10) ◽

pp. 1583

Author(s):

Natalia Guerrero-Alburquerque ◽

Shanyu Zhao ◽

Daniel Rentsch ◽

Matthias M. Koebel ◽

Marco Lattuada ◽

...

Keyword(s):

Aqueous Media ◽

Reaction Times ◽

Reaction Rates ◽

Secondary Amines ◽

Isocyanic Acid ◽

Advantages And Disadvantages ◽

Major Disadvantage ◽

Wide Range ◽

Potential Alternative ◽

Full Conversion

Ureido-functionalized compounds play an indispensable role in important biochemical processes, as well as chemical synthesis and production. Isocyanates, and KOCN in particular, are the preferred reagents for the ureido functionalization of amine-bearing compounds. In this study, we evaluate the potential of urea as a reagent to graft ureido groups onto amines at relatively low temperatures (<100 °C) in aqueous media. Urea is an inexpensive, non-toxic and biocompatible potential alternative to KOCN for ureido functionalization. From as early as 1864, urea was the go-to reagent for polyurea polycondensation, before falling into disuse after the advent of isocyanate chemistry. We systematically re-investigate the advantages and disadvantages of urea for amine transamidation. High ureido-functionalization conversion was obtained for a wide range of substrates, including primary and secondary amines and amino acids. Reaction times are nearly independent of substrate and pH, but excess urea is required for practically feasible reaction rates. Near full conversion of amines into ureido can be achieved within 10 h at 90 °C and within 24 h at 80 °C, and much slower reaction rates were determined at lower temperatures. The importance of the urea/amine ratio and the temperature dependence of the reaction rates indicate that urea decomposition into an isocyanic acid or a carbamate intermediate is the rate-limiting step. The presence of water leads to a modest increase in reaction rates, but the full conversion of amino groups into ureido groups is also possible in the absence of water in neat alcohol, consistent with a reaction mechanism mediated by an isocyanic acid intermediate (where the water assists in the proton transfer). Hence, the reaction with urea avoids the use of toxic isocyanate reagents by in situ generation of the reactive isocyanate intermediate, but the requirement to separate the excess urea from the reaction product remains a major disadvantage.

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On the Chemistry of Tetrabenzyl Thiuram Disulfide and Tetramethyl Thiuram Disulfide with Bis (Triethoxysilylpropyl) Tetrasulfide in Silica Compounds

Rubber Chemistry and Technology ◽

10.5254/1.3547778 ◽

2003 ◽

Vol 76 (4) ◽

pp. 876-891 ◽

Cited By ~ 1

Author(s):

R. N. Datta ◽

A. G. Talma ◽

S. Datta ◽

P. G. J. Nieuwenhuis ◽

W. J. Nijenhuis ◽

...

Keyword(s):

High Performance ◽

Room Temperature ◽

Succinic Anhydride ◽

Dynamic Properties ◽

The Other ◽

Resonance Spectroscopy ◽

Reaction Products ◽

Negative Effect ◽

Higher Temperature ◽

Analytical Tools

Abstract The use of thiurams such as Tetramethyl thiuram disulfide (TMTD) or Tetrabenzyl thiuram disulfide (TBzTD) has been explored to achieve higher cure efficiency. The studies suggest that a clear difference exists between the effect of TMTD versus TBzTD. TMTD reacts with Bis (triethoxysilylpropyl) tetrasulfide (TESPT) and this reaction can take place even at room temperature. On the other hand, the reaction of TBzTD with TESPT is slow and takes place only at higher temperature. High Performance Liquid Chromatography (HPLC) with mass (MS) detection, Nuclear Magnetic Resonance Spectroscopy (NMR) and other analytical tools have been used to understand the differences between the reaction of TMTD and TESPT versus TBzTD and TESPT. The reaction products originating from these reactions are also identified. These studies indicate that unlike TMTD, TBzTD improves the cure efficiency allowing faster cure without significant effect on processing characteristics as well as dynamic properties. The loading of TESPT is reduced in a typical Green tire compound and the negative effect on viscosity is repaired by addition of anhydrides, such as succinic anhydride, maleic anhydride, etc.

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Study of kinetics of reaction of lignin model compounds with propylene oxide

Holzforschung ◽

10.1515/hf.2008.025 ◽

2008 ◽

Vol 62 (2) ◽

pp. 169-175 ◽

Cited By ~ 3

Author(s):

Krishna K. Pandey ◽

Tapani Vuorinen

Keyword(s):

Chemical Reaction ◽

Propylene Oxide ◽

Aqueous Media ◽

Reaction Products ◽

Model Compounds ◽

Rapid Reduction ◽

Visible Absorption ◽

Lignin Model Compounds ◽

Lignin Model ◽

Kinetics Of

Abstract The etherification of phenolic groups has been found to inhibit photodegradation in wood and lignin rich pulps. The precise understanding of kinetics of chemical reaction between lignins or their model compounds and the etherifying agent is the first step for developing a viable modification procedure. In this study, we have investigated the reaction of lignin model compounds (namely, phenol and guaiacol) with propylene oxide in aqueous media. The kinetics of etherification reaction was studied under varying pH conditions in the temperature range 30–60°C. The etherified reaction products were characterized by gas chromatogram-mass spectrum (GC-MS). The extent of etherification of phenols and the rate of chemical reaction was followed by UV-Visible absorption spectroscopy. The reaction between lignin model compounds and propylene oxide was indicated by a rapid reduction in the absorbance accompanied by the development of a new band corresponding to etherified products. The reaction kinetics was investigated at pH ∼12 under the condition of excess concentration of propylene oxide. The reaction followed first order kinetics and rate constants increased linearly with an increase in the temperature and concentration of propylene oxide. The MS fragment data of reaction product support the proposed reaction scheme. The activation energy of the reaction of propylene oxide with phenol and guaiacol, calculated with the Arrhenius equation, was 56.2 kJ mol-1 and 45.4 kJ mol-1, respectively.

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Bis-NHC–Ag/Pd(OAc)2 Catalytic System Catalyzed Transfer Hydrogenation Reaction

Catalysts ◽

10.3390/catal11010008 ◽

2020 ◽

Vol 11 (1) ◽

pp. 8

Author(s):

Hui-Ju Chen ◽

Chien-Cheng Chiu ◽

Tsui Wang ◽

Dong-Sheng Lee ◽

Ta-Jung Lu

Keyword(s):

Functional Groups ◽

Catalytic System ◽

High Efficiency ◽

Aqueous Media ◽

Hydrogenation Reaction ◽

Transfer Hydrogenation ◽

Terminal Alkynes ◽

Wide Range ◽

Transfer Hydrogenation Reaction

The bis-NHC–Ag/Pd(OAc)2 catalytic system (NHC = N-heterocyclic carbene), a combination of bis-NHC–Ag complex and Pd(OAc)2, was found to be a smart catalyst in the Pd-catalyzed transfer hydrogenation of various functionalized arenes and internal/terminal alkynes. The catalytic system demonstrated high efficiency for the reduction of a wide range of various functional groups such as carbonyls, alkynes, olefins, and nitro groups in good to excellent yields and high chemoselectivity for the reduction of functional groups. In addition, the protocol was successfully exploited to stereoselectivity for the transformation of alkynes to alkenes in aqueous media under air. This methodology successfully provided an alternative useful protocol for reducing various functional groups and a simple operational protocol for transfer hydrogenation.

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A Theoretical and Experimental Approach to E-pH Diagram for the Niobium-Water System

CORROSION ◽

10.5006/3871 ◽

2021 ◽

Author(s):

Rodney Santandrea ◽

Simone BRASIL ◽

Leila Reznik ◽

Ladimir Carvalho ◽

Luiz Miranda

Keyword(s):

Experimental Approach ◽

Ph Monitoring ◽

Aqueous Media ◽

Water System ◽

Chemical Species ◽

Polarization Curves ◽

Buffer Solutions ◽

Excellent Corrosion Resistance ◽

Experimental Diagram ◽

Selection Of

E-pH diagrams are usually built from thermodynamic databases available in the literature or from specific software. However, depending on the conditions and the chemical species defined for elaborating a diagram, it may present completely different immunity, passivation, and corrosion domains. In order to obtain a result closer to a real system, experimental E-pH diagrams can be built from polarization curves obtained in the evaluated conditions. This work discloses the construction of a diagram for the Nb-H<sub>2</sub>O system at 25°C from theoretical study and the specific selection of chemical species in the solutions through computer simulations. The polarization curves for the construction of the experimental diagram were gathered without the use of buffer solutions and under pH monitoring in the solution bulk throughout all assays. The methodology proposed was considered adequate since, from experimental data, a final result compatible with the classic diagram for the Nb-H<sub>2</sub>O system and the excellent corrosion resistance of niobium in aqueous media were achieved.

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Leucite-pollucite structure-type variability and the structure of a synthetic end-member calcium wairakite (CaAl2Si4O12·2H2O)

Mineralogical Magazine ◽

10.1180/002646198547558 ◽

1998 ◽

Vol 62 (2) ◽

pp. 165-178 ◽

Cited By ~ 13

Author(s):

C. M. B. Henderson ◽

A. M. T. Bell ◽

S. C. Kohn ◽

C. S. Page

Keyword(s):

Rietveld Analysis ◽

Structure Type ◽

Magic Angle Spinning ◽

Resonance Spectroscopy ◽

Magic Angle ◽

Synthetic Sample ◽

Cation Site ◽

Wide Range ◽

Angle Spinning ◽

Cation Sites

AbstractThe structure of a synthetic end-member wairakite (CaAl2Si4O12·2H2O) has been determined using Rietveld analysis of high-resolution, synchrotron X-ray powder diffraction data, and 29Si and 27Al magic angle spinning nuclear magnetic resonance spectroscopy. The framework in the synthetic sample is more disordered than that in natural wairakite. Ca is distributed over the cavity cation sites M2, M12A, M12B in the approximate proportions 0.8:0.1:0.1, respectively, with M11 being vacant. 29Si MAS NMR data are consistent with about 80% of the Si occupying tetrahedral T11 and T12 sites linked to two Al atoms [Q4(2Al) silicons]. Tetrahedral and cavity cation site disorder are coupled so that Al mainly occupies T2 sites, with Ca in M12A and M12B being balanced by Al in T12A and T12B; T11A and T11B sites appear to only contain Si, in agreement with the M11 site being vacant. The crystal chemistries of the wide range of stoichiometries which crystallize with the leucite/pollucite structure-type are also reviewed, with particular attention being paid to the tetrahedral ordering configurations present in these phases, and the implications to crystallographic phase transitions.

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