Α-haloketones Research Articles

Application of automated solid-phase microextraction to determine haloacetonitriles, haloketones, and chloropicrin in Canadian drinking water

An automated headspace solid-phase microextraction gas chromatography mass spectrometry (HS-SPME-GC-MS) method was developed to monitor the occurrence of selected haloacetonitriles (HANs), haloketones (HKs), and chloropicrin (CP) in drinking water supplies. The method was rapid with analysis time of 30 min, including extraction and chromatographic run. Chemical ionization (CI) was used to increase the sensitivity of the method for the HKs. SPME fibers with seven different coatings including commercial polyacrylate (PA), carbowax/divinylbenzene (CW/DVB), polydimethylsiloxane (PDMS), polydimethylsiloxane/divinylbenzene (PDMS/DVB), carboxen/polydimethylsiloxane (CAR/PDMS), divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS), and a novel custom-made polydimethylsiloxane/divinylbenzene-N-vinylpyrrolidone (PDMS/DVB-NVP) were evaluated. The DVB/CAR/PDMS fiber was found more suitable for the range of the analytes and the novel PDMS/DVB-NVP fiber more efficient for the brominated acetonitriles under the experimental conditions. Method detection limits (MDLs) for the chlorinated acetonitriles and CP varied between 2 and 40 ng/L and for the brominated acetonitriles and HKs between 100 and 180 ng/L. Relative standard deviations (RSD %) of measurements were 4–7%. The method was applied in parallel with a liquid–liquid extraction gas chromatography electron capture detection (LLE-GC-ECD) method (EPA Method 551.1) to the analysis of drinking water samples from eight Canadian water treatment and distribution systems. The results generated by the two methods showed good agreement.

Synthesis and characterization of benzothiazol-2-one derivatives as anti-inflammatory and analgesic agents

A series of new compounds bearing a 1,3-benzothiazol-2-one nucleus have been synthesized using 5,6-dimethyl-3-(2-oxo-propyl)-1,3-benzothiazol-2-one (1) as a key starting compound. The reaction of 1 with some nucleophilic compounds led to the formation of compounds 2, 3, 4, 5a, b, 6 and 7a, b. The thiosemicarbazone derivatives 7a, b were treated with a number of halo ketones to produce the new heterocyclic compounds 9–13, while their reaction with acid anhydrides led to the formation of the derivatives 14 and 15. Also, compound 1 was condensed with different aromatic aldehydes to afford the corresponding chalcones 18–22. The structures of all the novel compounds have been determined by analytical and spectral data. Some of the compounds were selected to be evaluated as anti-inflammatory and analgesic agents.

Formation of disinfection byproducts upon chlorine dioxide preoxidation followed by chlorination or chloramination of natural organic matter

Chlorine dioxide (ClO2) is often used as an oxidant to remove taste, odor and color during water treatment. Due to the concerns of the chlorite formation, chlorination or chloramination is often applied after ClO2 preoxidation. We investigated the formation of regulated and emerging disinfection byproducts (DBPs) in sequential ClO2-chlorination and ClO2-chloramination processes. To clarify the relationship between the formation of DBPs and the characteristics of natural organic matter (NOM), changes in the properties of NOM before and after ClO2 oxidation were characterized by fluorescence, Fourier transform infrared spectroscopy (FTIR), and size and resin fractionation techniques. ClO2 preoxidation destroyed the aromatic and conjugated structures of NOM and transformed large aromatic and long aliphatic chain organics to small and hydrophilic organics. Treatment with ClO2 alone did not produce significant amount of trihalomethanes (THMs) and haloacetic acids (HAAs), but produced chlorite. ClO2 preoxidation reduced THMs, HAAs, haloacetonitriles (HANs) and chloral hydrate (CH) during subsequent chlorination, but no reduction of THMs was observed during chloramination. Increasing ClO2 doses enhanced the reduction of most DBPs except halonitromethanes (HNMs) and haloketones (HKs). The presence of bromide increased the formation of total amount of DBPs and also shifted DBPs to more brominated ones. Bromine incorporation was higher in ClO2 treated samples. The results indicated that ClO2 preoxidation prior to chlorination is applicable for control of THM, HAA and HAN in both pristine and polluted waters, but chlorite formation is a concern and HNMs and HKs are not effectively controlled by ClO2 preoxidation.

A diastereoselective synthesis of pyrano fused coumarins via organocatalytic three-component reaction

A new method for the synthesis of pyran fused coumarins by 3-bromo-4-hydroxycoumarins as cyclic α-halo ketones based on an organocatalyst assisted three-component tandem reaction is investigated. To the best of our knowledge, cyclic α-halo ketones have not yet been used for the synthesis of pyran fused coumarins.

Reactivity of Various α-Halo Ketones in One-Pot Synthesis of γ-Iminolactones

The highly reactive 1:1 intermediate generated in the reaction of tert-butyl isocyanide and dialkyl acetylenedicarboxylate is trapped by α-halo ketones to produce halogenated iminolactones as the sole product in good yields.

Synthesis of 5-arylazothiazoles, pyridines and thieno[2,3-b]pyridines derivatives containing 1,2,3-triazole moiety

1-(2-(4,5-dihydro-3-(5-methyl-1-phenyl-1 H -1,2,3-triazol-4-yl)-5-phenylpyrazol-1-yl)-4-subs-tituted-thiazol-5-yl)-2-phenyldiazene ( 4 ) and substituted pyridines ( 5 - 12 ) were synthesized via reaction of 1-(5-methyl-1-phenyl-1 H -1,2,3-triazol-4-yl)-3-phenylprop-2-en-1-one with hydrazonoyl halides and active methylene compounds. Also, thieno[2,3- b ]pyridines ( 14a - e ) were prepared through reactions of 2-mercapto-6-(5-methyl-1-phenyl-1 H -1,2,3-triazol-4-yl)-4-phenyl-pyridine-3-carbonitrile with halo ester and halo ketones, respectively. The newly synthesized derivetived were elucidated by elemental analysis, spectral data and alternative synthetic routes wherever possobile.

Effects of ozone and ozone/peroxide pretreatments on disinfection byproduct formation during subsequent chlorination and chloramination

Ozone (O3) and ozone/hydrogen peroxide (O3/H2O2) can be used in water treatment facilities to remove many organic micropollutants with taste, odor, and color implications. The effects of O3 and O3/H2O2 on the formation of disinfection byproducts (DBPs) in subsequent chlorination and chloramination processes, however, are not well determined. In this study, we compared the yields of a series of regulated and emerging DBPs during sequenced O3–Cl2, O3/H2O2–Cl2, O3–NH2Cl, and O3/H2O2–NH2Cl oxidation of 11 samples, each with different hydrophobicity, bromide concentration, soluble microbial products, and humic substances. For most water, pretreatment with O3 and O3/H2O2 increased the formation of chloral hydrate (CH), trichloronitromethane (TCNM) and haloketones (HKs) but lowered the yields of haloacetonitriles (HANs) during chlorination processes. Compared with O3 alone, O3/H2O2 in combination generated more CH and HKs during chlorination, and their extents of formation appeared to depend on the O3 doses. In terms of chloramination, both O3 and O3/H2O2 reduced THM, HAA, and HAN formation significantly without increasing CH, TCNM, or HKs. These results suggest that O3 or O3/H2O2 pretreatments may provide some benefits for the chloramination process in controlling regulated and emerging DBPs in waters without high bromide content.

One pot three-component regioselective and diastereoselective synthesis of halogenated pyrido[2,1-b][1,3]oxazines

Three-component reactions of 3-substituted pyridines, dimethyl acetylenedicarboxylate (DMAD), and α-halo ketones led to regioselective and stereoselective synthesis of pyrido[2,1-b][1,3]oxazines in high to excellent yields under mild conditions. All the reactions gave the pyrido[2,1-b][1,3]oxazine derivatives without formation of any indolizine products.

Convenient and simple synthesis of 2-aminothiazoles by the reaction of α-halo ketone carbonyls with ammonium thiocyanate in the presence of N-methylimidazole

Substituted 2-aminothiazole derivatives were obtained as a result of N-methylimidazole catalyzed cyclization of α-halo ketone carbonyls with ammonium thiocyanate in water–alcoholic media. The generality of the method has been demonstrated by screening a series of aromatic/heteroaromatic/aliphatic α-halo ketones, α-halo β-diketones, and α-halo β-ketoesters. The developed method is simple, mild, and general route for the preparation of diversely functionalized 2-aminothiazoles in good to moderate yields from readily available starting materials.

Copper iodide nanoparticles on poly(4-vinyl pyridine): A new and efficient catalyst for multicomponent click synthesis of 1,4-disubstituted-1,2,3-triazoles in water

Polymer supported nanoparticles of copper(I) iodide is reported as a new, efficient and recyclable catalyst for the regioselective multicomponent synthesis of 1,4-disubstituted-1H-1,2,3-triazoles from α-halo ketones, sodium azide and terminal alkynes in water. This catalyst can be recovered by simple filtration and recycled up to 8 consecutive runs without losing its efficiency. ► Click synthesis of triazole derivatives ► High product yields with short reaction times ► Heterogeneous catalysis and recyclability of the catalyst

ChemInform Abstract: Efficient Synthetic Method for the Preparation of Allyl‐ and Propargyl‐Epoxides by Allylation and Propargylation of α‐Haloketones with Organozinc Reagents.

A simple, efficient, and non-metal catalyzed synthetic method for the preparation of substituted allyl- and propargyl-epoxides by allylation and propargylation of α-halo ketones with organozinc reagents in mild conditions is reported in this paper. The present method complements the existing synthetic methods due to some advantageous properties of the organozinc reagents such as availability, selectivity, operational simplicity and low toxicity.

ChemInform Abstract: Synthesis of 3‐Hydroxy‐2‐hydroxy(phenyl)methyl‐3‐methyl‐2,3‐dihydro‐4H‐furo [3,2‐c]chromen‐4‐one from 4‐Hydroxycoumarin.

4-Hydroxycoumarin derivatives include a number of compounds exhibiting biological activity. An important place in this series is occupied by furocoumarins possessing diverse pharmacological properties: antifungal, zoocidal, anticoagulant, spasmolytic, etc. [1–6]. Furocoumarins can be isolated from natural sources [7] or synthesized [8–11]. Methods of synthesis of furocoumarins are based on C-alkylation of 4-hydroxycoumarin with α-halo ketones or halo alkynes with subsequent cyclization [9, 10] or on oxidative addition of olefins to 4-hydroxycoumarin in the presence of silver(I) salts [11].

Addition of Indoles to Oxyallyl Cations for Facile Access to α-Indole Carbonyl Compounds

A direct coupling of unprotected indoles and α-halo ketones via in situ generated oxyallyl cation intermediates is described. The reactions efficiently afford α-indole carbonyl compounds with good to quantitative yields.

Efficient synthetic method for the preparation of allyl- and propargyl-epoxides by allylation and propargylation of α-haloketones with organozinc reagents

A simple, efficient, and non-metal catalyzed synthetic method for the preparation of substituted allyl- and propargyl-epoxides by allylation and propargylation of α-halo ketones with organozinc reagents in mild conditions is reported in this paper. The present method complements the existing synthetic methods due to some advantageous properties of the organozinc reagents such as availability, selectivity, operational simplicity and low toxicity.

Parallel Synthesis of Aminobenzimidazole-Tethered Thiazoles

A multistep approach to construct thiazole-derived aminobenzimidazoles from commercially available amino acids, amines, carboxylic acids, and α-halo ketones is described. Coupling of 9-fluorenylmethoxycarbonyl-protected (Fmoc-protected) amino acids to resin-bound aminobenzimidazoles provides essential intermediates for the construction of an array of thiazoles by utilizing the Hantzsch cyclization strategy. The aminobenzimidazole-tethered thiazoles were isolated in moderate yields.

Synthesis of 3-Hydroxy-2-hydroxy(phenyl)methyl-3-methyl-2,3-dihydro-4H-furo[3,2-c]chromen-4-one from 4-Hydroxycoumarin

4-Hydroxycoumarin derivatives include a number of compounds exhibiting biological activity. An important place in this series is occupied by furocoumarins possessing diverse pharmacological properties: antifungal, zoocidal, anticoagulant, spasmolytic, etc. [1–6]. Furocoumarins can be isolated from natural sources [7] or synthesized [8–11]. Methods of synthesis of furocoumarins are based on C-alkylation of 4-hydroxycoumarin with α-halo ketones or halo alkynes with subsequent cyclization [9, 10] or on oxidative addition of olefins to 4-hydroxycoumarin in the presence of silver(I) salts [11].

ChemInform Abstract: Novel Synthesis and Cytotoxic Activity of Some Chromeno[3,4‐b]pyrrol‐4(3H)‐ones.

AbstractA new synthesis of title chromenopyrrolones (IV) based on the condensation of aminochromenones (I) with α‐halo ketones (II) is given.

New Developments in Putting Waste to Work

Lu and Toy report a tandem Wittig reductive aldol cascade, which combines five reactions in a one-pot operation. In particular, the authors achieved the formation of the stabilized Wittig reagent B from α-halo ketones 1, followed by the Wittig reaction with aldehyde 2, reduction of the resulting enone C with HSiCl3 to silyl enol ether D and the final aldol reaction with aldehydes 2 or 3 to give products 4 or 5, respectively. Yields of up to 85% demonstrate excellent efficiency over five consecutive synthetic steps. Importantly, the silane reduction (C → D) is catalyzed by triphenyl phosphine oxide, a byproduct of the initial ­Wittig reaction.

Synthesis and oxidative cyclization of 3-amino-2-arylazo-5-tert-cycloalkylaminothiophenes

A series of 3-amino-4-arylazo-4,5-dihydrothiophenes has been synthesized by the reaction of arylhydrazonocyanothioacetamides (containing a tert-cycloalkylamino group) with α-halo ketones, 2-chloroacetonitrile, or 4-nitrobenzyl bromide. Their oxidation in the presence of metal acetates was investigated. It was shown that heating in pyridine with Cu(OAc)2 leads to the formation of thieno- [3,4-d]-1,2,3-triazoliumolates.

ChemInform Abstract: Direct and Efficient Conversion of Tertiary Thioamides to S‐2‐Oxo Thioesters under Solvent‐Free Conditions.

E-mail: h.zali@chem.ui.ac.irReceived January 17, 2011, Accepted February 1, 2011A one-pot conversion of tertiary thioamides to S-2-oxo thioesters is reported. Hence, tertiary thioamides werereacted with α-halo ketones or acids under solvent-free conditions to produce the corresponding oxo-thioestersin good to excellent yields.Key Words : Acid derivatives, Thioesters, Thioamide, Solvent-freeIntroductionIt is well known that thioesters are important compoundsdue to their large number of biological activities