Chemoselective reagents for derivatization of trace--level volatile carbonyl compounds using a microreactor approach.

Detection and analysis of trace level volatile aldehydes and ketones has become a significant research frontier because of the applicability for environmental monitoring and assessment, noninvasive diseases diagnosis, and in food safety assessment for the US Food and Drug Administration. The number of derivatization reagents for detection of aldehydes and ketones has increased considerably over the last decade. However, the majority of these derivatization reagents are not efficient in derivatizing unsaturated carbonyl compounds due to the presence of electron withdrawing groups adjacent to the reactive functional moieties making them insufficiently nucleophilic. The analysis of trace-level carbonyl compounds challenges existing analytical instrumentation because their concentrations are below current instrument limits of detection. This study shows for the first time the application of an innovative silicon-based microreactor for preconcentration of carbonyl compounds in electronic cigarette aerosols. The microreactor is coated with an aminooxy reagent, typically 4-(2-aminooxyethyl)-morpholin-4-ium chloride (AMAH) or 2-(aminooxy)-N, N, N-trimethylethanammonium iodide (ATM). The aminooxy functional group chemoselectively traps trace aldehydes and ketones generated by aerosolization of electronic liquids by means of oximation reactions. The aminooxy-carbonly adducts and unreacted aminooxy reagent are eluted from the microreactor using 150 μL of methanol followed by addition of an internal standard (for quantification) and then analyzed by Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry (MS) or gas chromatography mass spectrometry (GC-MS), depending on the capture reagent used. Chapter 1 describes different methods of detection and analysis of volatile organic aldehydes and ketones in gaseous samples such as exhaled breath and electronic cigarette aerosols. Chapter 2 presents the analysis and quantification of carbonyl compounds in electronic liquid aerosols. Chapter 3 describes the kinetic studies of oximation reactions of the aminooxy reagents AMAH, ADMH and ATM. It also outlines the synthesis of a cationic hydrazine-based reagent for derivatization of aldehydes and ketones. Chapter 4 describes the quantification of nicotine in e-cig liquids and derived aerosols using both FT-ICR-MS and GC-MS. Chapter 5 provides the overall summary and future direction

Synthesis of Some New Fluorinated Hexahydroquinoline and Acridinedione Derivatives in Trifluoroethanol

This article describes one-pot synthesis of new fluorinated hexahydroquinoline derivatives via unsymmetric Hantzsch reaction involving 5-trifluoromethyl-1,3-cyclohexanedione, aldehydes, acetoacetate ester, and ammonium acetate in trifluoroethanol (TFE). The reaction is simple and rapid with high yield

Synthesis of fluorinated hexahydroquinolines, bis acridinediones, xanthenediones and tetrahydro chromene carboxylates as potential drug candidates

Fluorine-containing building blocks are useful for the preparation of fluorinated pharmaceuticals and agrochemicals. Many of the existing procedures for the preparation employ solvents or reagents that are hazardous. In addition, commercially available fluorine building blocks are expensive. 5-Trifluoromethyl-1, 3-cyclohexanedione (1) was developed by our group as a versatile trifluoromethyl building block. Its reaction with a wide range of substituted aldehydes in a one-pot multicomponent method was studied. Several fluorinated hexahydroquinolines were prepared by reacting 5-trifluoromethyl-1, 3-cyclohexanedione with substituted aromatic aldehydes, beta-ketoesters, and ammonium acetate in trifluoroethanol. Two Bis-trifluoromethyl acridinediones (5) were prepared by reacting two equivalents of 5- Trifluoromethyl-1, 3-cyclohexanedione ( 1), substituted aromatic aldehydes and ammonium acetate. Ten Bis-trifluoromethylated xanthenediones (3) were prepared from two equivalents of 5- Trifluoromethyl-1, 3-cyclohexanedione (1 ) and substituted aromatic aldehydes in HCl-saturated ethanol under microwave irradiation. Eight Tetrahydrochromene carboxylate (6) were prepared from one equivalent of cyclic 1, 3-dicarbonyl (two of which included 5- Trifluoromethyl-1, 3-cyclohexanedione (1) and acetylenedicarboxylate in triethylamine containing dichloromethane at room temperature. All compounds synthesized were characterized by NMR, GC-MS and elemental analysis and will be submitted for in vitro cytotoxicity testing

Aldehyde Detection in Electronic Cigarette Aerosols

Acetaldehyde, acrolein, and formaldehyde are the principal toxic aldehydes present in cigarette smoke and contribute to the risk of cardiovascular disease and noncancerous pulmonary disease. The rapid growth of the use of electronic cigarettes (e-cigarettes) has raised concerns over emissions of these harmful aldehydes. This work determines emissions of these aldehydes in both free and bound (aldehyde–hemiacetal) forms and other carbonyls from the use of e-cigarettes. A novel silicon microreactor with a coating phase of 4-(2-aminooxyethyl)-morpholin-4-ium chloride (AMAH) was used to trap carbonyl compounds in the aerosols of e-cigarettes via oximation reactions. AMAH–aldehyde adducts were measured using gas chromatography–mass spectrometry. ¹H nuclear magnetic resonance spectroscopy was used to analyze hemiacetals in the aerosols. These aldehydes were detected in the aerosols of all e-cigarettes. Newer-generation e-cigarette devices generated more aldehydes than the first-generation e-cigarettes because of higher battery power output. Formaldehyde–hemiacetal was detected in the aerosols generated from some e-liquids using the newer e-cigarette devices at a battery power output of 11.7 W and above. The emission of these aldehydes from all e-cigarettes, especially higher levels of aldehydes from the newer-generation e-cigarette devices, indicates the risk of using e-cigarettes