Elimination Of Chloroform Research Articles

Elimination of Chloroform (CHCl3) from Drinking Water via a Synergistic Effect of Stripping, Oxidation and Adsorption Process in Air Lift Loop Reactor

In this work, a modified internal loop airlift reactor has been designed to remove the organic pollutants in synthetic wastewater at an efficient and inexpensive treatment technique by means of a synergistic effect combining of (oxidation, stripping and adsorption). The validation of the current style was experimentally examined in the treatment of synthetic Wastewater contained chloroform. The experimental testing rig was implemented at various air flow rates range (5-20) (L/min), with total variable residence period (5-60 min) with a different molar ratio of CHCl3 to H2O2 i.e. 1:10, 1:15 and 1:20. The results showed that the best molar ratio of chloroform to hydrogen peroxide was 1:20 for the air flow rate 18 L/min and extended retention period (60 min) having the uppermost results (83.3%) to remove chloroform from the contaminated effluent water. This design complements the research objectives with high efficiency through the synergy of stripping, oxidation and adsorption processes to remove contaminated chloroform from wastewater. This work contributes to a part of the solution of the environmental problems of the contaminated water before recycling, reuse or released to our safe environment.

A new, high-yield synthesis of 3-aryl-1,2,4-triazoles

A convenient new synthetic approach to 3-aryl-1,2,4-triazoles has been developed. Chloralamides were obtained by high yield reactions between benzamides and chloral hydrate. These reacted with a phosphorus pentachloride/phosphorus oxychloride mixture undergoing a near quantitative conversion to N-(1,2,2,2-tetrachloroethyl)benzimidoyl chlorides, which were treated with hydrazine hydrate to directly give 3-aryl-1,2,4-triazoles in high to quantitative yields. The formation of these products involves a double condensation process followed by a spontaneous β-elimination of chloroform. The molecular structure of 1-(4-chlorobenzoyl)-3-(4-methoxyphenyl)-1,2,4-triazole was determined by X-ray crystallography. Theoretical computational studies on aromatization of 3-aryl-5-trichloromethyl-1,2,4-triazolines via chloroform elimination and to determine relative stabilities of 3-phenyl-1,2,4-triazole tautomers were performed using ab initio, density functional (B3LYP), Moller–Plesset (MP2), and the thermochemical recipe T1.

ChemInform Abstract: A New Convenient Synthetic Approach to Diarylpyrimidines.

AbstractTwo pathways to the desired compounds are presented: a stepwise and a one‐pot procedure which both are operationally simple.

A new convenient synthetic approach to diarylpyrimidines

A new synthetic method in pyrimidine chemistry has been developed. 2,2,2-Trichloroethylideneacetophenones, easily available from chloral and acetophenones, reacted with benzamidines to provide novel 2,6-diaryl-6-hydroxy-4-trichloromethyl-1,4,5,6-tetrahydropyrimidines in near quantitative yields. Efficient dehydration of these compounds gave previously unknown 2,4-diaryl-6-trichloromethyl-1,6-dihydropyrimidines, which were found able to undergo base-induced chloroform elimination to give 2,4-diarylpyrimidines in high yields. Molecular structures for final and intermediate compounds were determined by single crystal X-ray diffraction. A main improvement of this procedure lies in circumventing the oxidative aromatization of dihydropyrimidine intermediates through a chloroform elimination process. The diarylpyrimidines were also found directly accessible by a fair yield one-pot procedure.

A new improved method for the synthesis of 2,4-diarylpyrimidines starting from 2,2,2-trichloroethylideneacetophenones

An advantageous new approach to 2,4-diarylpyrimidines has been developed. 2,2,2-Trichloroethylideneacetophenones reacted with benzamidines leading to novel 2,6-diaryl-6-hydroxy-4-trichloromethyl-1,4,5,6-tetrahydropyrimidines in near quantitative yields. These compounds were efficiently dehydrated to obtain previously unknown 2,4-diaryl-6-trichloromethyl-1,6-dihydropyrimidines, which were able to undergo aromatisation via chloroform elimination to give 2,4-diarylpyrimidines in high yields. A main improvement of this procedure lies in circumventing the oxidative dehydrogenation of dihydropyrimidine intermediates. This preparative process has also been adapted to a one-pot protocol.

New approach to 5-arylsulfonyl-substituted 1,2-dihydropyrimidin-2-ones via base-induced chloroform elimination from 4-trichloromethyl-1,2,3,4-tetrahydropyrimidin-2-ones

A four-step method for the synthesis of 5-arylsulfonyl-substituted 1,2-dihydropyrimidin-2-ones has been developed. The reaction of readily available N-[(1-acetoxy-2,2,2-trichloro)ethyl]ureas with sodium enolates of α-arylsulfonylketones followed by heterocyclization–dehydration of the oxoalkylureas formed gave 5-arylsulfonyl-4-trichloromethyl-1,2,3,4-tetrahydropyrimidin-2-ones. The latter, in the presence of strong bases, eliminate CHCl 3 to give the target compounds.

Reactions of Ruthenium Vinylidene and Acetylide Complexes Containing Trichloromethyl Groups: Preparation of a Cyclobutenonyl Complex by Solid‐State Photolysis

Solid-state route to a cyclobutenone: Ruthenium perchlorocyclobutenonyl complex 2 is obtained by solid-state photoisomerization of ruthenium trichloroacetyl acetylide complex 1. The four-membered ring is sufficiently robust that transfer of the intact ligand could be readily achieved in a reaction of 2 with an enyne. Cyclobutenedionyl complex 3 was obtained by hydrolysis of 2 in H(2)O/THF.New reactions were observed for the cationic gamma-hydroxyvinylidene complex [Ru(2)]==C==CHC(OH)(CCl(3))(2) (+) (2, [Ru(2)]=CpRu(PPh(3))(2)). A rare chloroform elimination was observed when 2 was treated with nBu(4)NOH to give neutral acetylide complex [Ru(2)]--C[triple chemical bond]CC(==O)CCl(3) (3). Solid-state photoinduced isomerization of 3 generated ruthenium perchlorocyclobutenonyl complex [Ru(2)]--C(4)Cl(3)O (4) in high yield. This transformation was analyzed by DFT calculations, and 4 was found to be 4.22 kcal mol(-1) more stable in terms of Gibbs free energy than 3. In the coupling reaction of 4 with 2-methyl-1-buten-3-yne the four-membered cyclic ligand is transferred to the enyne to give substituted eta(3)-butadienyl complex 5 containing a cyclobutenonyl group. This coupling product could be removed from the metal by HCl. Deprotonation of 2 gave gamma-hydroxyacetylide complex [Ru(2)]--C[triple chemical bond]CC(OH)(CCl(3))(2) (9). In the photolysis of 9 phosphine dissociation is followed by addition of HCl to give neutral vinylidene complex Cl[Ru(1)]==C==CHC(OH)(CCl(3))(2) (10, [Ru(1)]=Cp(PPh(3))Ru). Complex 4 catalyzed the coupling reaction of dimethyl acetylenedicarboxylate with styrene yielding the diene PhCH==CHC(CO(2)Me)==CHCO(2)Me. Solid-state structures of 3-6 and 10 were determined by single-crystal X-ray diffraction analysis.

Microstructural characteristics of calcium hydroxyapatite/poly-L-lactide based composites.

Besides its high osteoinductive properties, hydroxyapatite (HAp) exhibits a relatively low mechanical strength. In order to improve the mechanical properties and reliability of HAp based composites, the addition of selected polymers is highly recommended. The main objective of this work is to study the microstructural characteristics of HAp/poly-L-lactide (PLLA) composites obtained by cold or hot processing. The composites were prepared from a mixture of a chloroform solution of poly-L-lactide with granulated HAp. After elimination of chloroform by vacuum evaporation, dense compacts were obtained by cold or hot pressing. The pressing pressure ranged from 98.10 to 294.3 MPa for both cold and hot pressing. The hot pressing was performed in the temperature region 293-457 K for a time period of 15-60 min. Depending on the PLLA amount and the pressing procedure it is possible to obtain highly porous or nearly fully dense composites. The scanning electron microscopy examination of fracture as well as of free surfaces revealed that the final porosity and wetting are affected to a great extent by the synthesis conditions and amount of polymer added. An increase in temperature to 457 K for a longer period of time results in fully dense compacts. The formation of a nearly continuous polymer network that leads to the hardening of HAp has also been observed. However, it should be pointed out that some layers of HAp may be free of polymer film since PLLA penetrates more deeply into the porous HAp.

Alveolar breath sampling and analysis to assess trihalomethane exposures during competitive swimming training.

Alveolar breath sampling was used to assess trihalomethane (THM) exposures encountered by collegiate swimmers during a typical 2-hr training period in an indoor natatorium. The breath samples were collected at regular intervals before, during, and for 3 hr after a moderately intense training workout. Integrated and grab whole-air samples were collected during the training period to help determine inhalation exposures, and pool water samples were collected to help assess dermal exposures. Resulting breath samples collected during the workout demonstrated a rapid uptake of two THMs (chloroform and bromodichloromethane), with chloroform concentrations exceeding the natatorium air levels within 8 min after the exposure began. Chloroform levels continued to rise steeply until they were more than two times the indoor levels, providing evidence that the dermal route of exposure was relatively rapid and ultimately more important than the inhalation route in this training scenario. Chloroform elimination after the exposure period was fitted to a three compartment model that allowed estimation of compartmental half-lives, resulting minimum bloodborne dose, and an approximation of the duration of elevated body burdens. We estimated the dermal exposure route to account for 80% of the blood chloroform concentration and the transdermal diffusion efficiency from the water to the blood to in excess of 2%. Bromodichloromethane elimination was fitted to a two compartment model which provided evidence of a small, but measurable, body burden of this THM resulting from vigorous swim training. These results suggest that trihalomethane exposures for competitive swimmers under prolonged, high-effort training are common and possibly higher than was previously thought and that the dermal exposure route is dominant. The exposures and potential risks associated with this common recreational activity should be more thoroughly investigated.

A new synthesis of N-sulfinylamines via β-elimination of chloroform from trichloromethanesulfinamides

The synthesis of various N-monosubstituted trichloromethanesulfinamides by two alternative and novel procedures is described. All these compounds have been found to undergo base-induced elimination of chloroform with formation of the corresponding N-sulfinylamines. Reaction proceeds smoothly under mild conditions.

Environmental and biological monitoring of chloroform in indoor swimming pools

The presence of chloroform as the result of disinfection with sodium hypochlorite was demonstrated in the water and ambient air of indoor swimming pools. Environmental monitoring was performed in 12 indoor swimming pools in northern Italy and the level of human exposure was assessed. Biological monitoring performed by gas chromatography on human plasma and alveolar air samples evidenced that the uptake of chloroform in swimmers varies according to the intensity of the physical activity and age. The elimination of chloroform in alveolar air in one subject showed a very short half-life (from 20 to 27 min) and a complete clearance within 10 h after the end of exposure.

Collection of a single alveolar exhaled breath for volatile organic compounds analysis.

Measurement of specific organic compounds in exhaled breath has been used as an indicator of recent exposure to pollutants or as an indicator of the health of an individual. A typical application involves the collection of multiple breaths onto a sorbent cartridge or into an evacuated canister with the use of a relatively complex sampling apparatus. A new method has been developed wherein a single exhaled breath is directly transferred from the mouth into an evacuated 1 l or 1.8 l stainless steel SUMMA canister. The single breath canister (SBC) method avoids the necessity for a complex sampling system requiring maintenance and cleaning and allows easy collection of samples. Additionally, it is possible to collect a rapid sequence of samples from a subject to establish the elimination curve subsequent to an exposure to specific volatile organic compounds with a theoretical resolution of adjacent breaths. The SBC method was compared to an accepted canister based sampling system to assure comparability and then used to demonstrate its utility by measuring the absorption and elimination of chloroform during and after exposure to chlorinated shower water.

A Novel Synthesis of Thioaldehyde S-Oxides Via an Unusual β-Elimination of Chloroform From Allylic and Benzylic Trichloromethyl Sulfoxides

Abstract A new method for the synthesis of thioaldehyde S-oxides including α,β-unsaturated derivatives, by mild base-induced elimination of chloroform from readily available allylic and benzylic trichloromethyl sulfoxides is described.

ChemInform Abstract: A Novel Synthesis of Monosubstituted Sulfines via an Unusual β‐ Elimination of Chloroform from Allylic and Benzylic Trichloromethyl Sulfoxides.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

A novel synthesis of monosubstituted sulfines via an unusual β-elimination of chloroform from allylic and benzylic trichloromethyl sulfoxides

A new method for the synthesis of thioaldehyde S-oxides by base-induced elimination of chloroform from allylic and benzylic trichloromethyl sulfoxides is described. The reaction proceeds smoothly under mild conditions. A mechanism for this remarkable sulfine synthesis and apparently unprecedented β-elimination of chloroform is presented.

A Novel Synthesis of Thioaldehyde S-Oxides Via an Unusual β-Elimination of Chloroform From Allylic and Benzylic Trichloromethyl Sulfoxides

Abstract A new method for the synthesis of thioaldehyde S-oxides including α,β-unsaturated derivatives, by mild base-induced elimination of chloroform from readily available allylic and benzylic trichloromethyl sulfoxides is described.

A Compartmental Model for the Prediction of Breath Concentration and Absorbed Dose of Chloroform After Exposure While Showering

In order to predict the exhaled breath concentration of chloroform in individuals exposed to chloroform while showering, an existing physiologically based pharmacokinetic (PB-PK) model was modified to include a multicompartment, PB-PK model for the skin and a completely mixed shower exposure model. The PB-PK model of the skin included the stratum corneum as the principal resistance to absorption and a viable epidermis which is in dynamic equilibrium with the skin microcirculation. This model was calibrated with measured exhaled breath concentrations of chloroform in individuals exposed while showering with and without dermal absorption. The calibration effort indicated that the expected value of skin-blood partitioning coefficient would be 1.2 when the degree of transfer of chloroform from shower water into shower air was 61%. The stratum corneum permeability coefficient for chloroform was estimated to be within the range of 0.16-0.36 cm/hr and the expected value was 0.2 cm/hr. The estimated ratio of the dermally and inhaled absorbed doses ranged between 0.6 and 2.2 and the expected value was 0.75. These results indicate that for the purposes of risk assessment for dermal exposure to chloroform, a simple steady-state model can be used to predict the degree of dermal absorption and that a reasonable value of skin permeability coefficient for chloroform used in this model would be 0.2 cm/hr. Further research should be conducted to compare the elimination of chloroform via exhaled breath when different exposure routes are being compared. The model results from this study suggest that multiple measurements of exhaled breath concentrations after exposure may be necessary when making comparisons of breath concentrations that involve different exposure routes.

Some aspects of the chemistry of 1,1,1-trihalogenoalk-4-en-2-ols, the ene adducts obtained from reaction of chloral and bromal with alkenes

The chemistry of the title compounds has been explored and previous studies extended. They are inert to a wide range of oxidising agents, and conversion into trihalogenomethyl ketones was effected (CrO3–H2SO4–AcOH) only after hydrogenation of the double bonds. Simple dehydration also failed, but the tosylate esters reacted with NaOEt–EtOH to afford ethyl alka-2,4-dienoates. Reaction of the ene adducts with alcoholic KOH gave α-alkoxy acids in high yield, as noted previously by Weizmann. A similar result was obtained with NaOR–ROH unless excess base was neutralized before work-up when α-alkoxy ester was isolated. It appears that the ester to acid conversion by the BAL2 mechanism is relatively fast at high alkoxide ion concentrations. The trichloromethyl alcohol to α-alkoxy acid or ester conversion has been shown to occur with net retention of stereochemistry, and a mechanism based on a dichloroepoxide intermediate is proposed. The stereochemical results are accommodated by the stereoselective electro-cyclic ring opening rearrangement of the dichloroepoxide. Similar considerations apply to the hydrolysis using aqueous base, when α-hydroxy acids with retention of stereochemistry were obtained; in one instance competing chloroform elimination (to give aldehyde) was observed. The dianions from the α-methoxy acids are readily converted into the corresponding β,γ-unsaturated methyl esters by oxygen-ation and then acidification. Reductive dehalogenation of the ene adducts by LiAlH4 or Bun3SnH was partially successful. The exocyclic chiral centres of the (–)-β-pinene ene adducts were detached, without loss of chirality, by oxidative degradation of the pinenyl ring; enantiometrically pure methyl (S)-3-acetoxy-4,4,4-trichlorobutanoate was obtained by this route.

Distribution of volatile halogenated organic compounds between rat blood serum and adipose tissue.

A 31-day rat-dosing sequence was used to study some aspects of the physiological distribution, metabolism, storage and rate of elimination of chloroform, trichloroethylene, carbon tetrachloride and bromodichloromethane from rat adipose tissue and blood serum. Data points were collected nine times during the dosing period and twice after dosing had ceased. Purge/trap/desorb methodology was employed using a liquid sample concentrator, a gas-liquid chromatograph and a Hall electrolytic conductivity detector in series. Compound identities were confirmed using a GC/MS analytical system. For these volatile compounds, tissue levels fluctuated but did not indicate increased storage with time. Adipose tissue to blood serum levels never differed by more than a factor of three. Within 3-6 days after dosing was terminated, practically all of the halogenated compounds had left the examined tissues. Metabolic conversion of trichloroethylene and carbon tetrachloride into chloroform and/or a chloroform precursor was observed; bromodichloromethane-dosed animals did not have serum chloroform levels exceeding those observed for the control animals.

Zur Reaktion von trimethylsilyl‐substituierten Methyldiphenylphosphanen mit Tetrachlorkohlenstoff

On the Reaction of Trimethylsilyl‐substituted Methyldiphenylphosphanes with TetrachloromethaneIn dichloromethane the [(trimethylsilyl)methyl]‐substituted phosphanes 3a, b undergo a chloroform elimination with CCl4 to give the chloromethylenediphenylphosphoranes 4a, b. The new P‐chloro ylides are remarkably stable and can be isolated as pure substances.