The Sulfinatodehalogenation Reaction of α,α-Difluorobenzyl Halides with Sodium Dithionite

The sulfinatodehalogenation reaction of α,α-difluorobenzyl handes, ArCF_2X (Ar = CAFS, C_6H_5; X = Br, I ), with sodium dithionite took place readily in aqueous acetonitrile under mild conditions. giving the corresponding sodium sulfinate. The 1: 1 adducts were obtained when alkenes were added to the reaction system in some cases.

Dechlorination of DDT and DDE by Dithionite in Dicofol Type DDTs-Contaminated Soil

Dicofol type DDTs-contamination is of great concern as environmental organochlorine pollutant. In the present study, dechlorination time-course ofp,p＇-DDT and p,p＇-DDE in dithionite treated waterlogged DDTs-contaminated soil, non-contaminated soil solution and citrate-bicarbonate buffer （0, 50, 100 mmol L^-1, dithionite） for 72 hrs was investigated based on residual amount of p,p＇-DDTs （p,p＇-DDT and p,p＇-DDE） analyzed by GC-ECD. The metabolites ofp,p＇-DDTs in dithionite treated non-contaminated soil solution, and citrate-bicarbonate buffer were detected by GC-MSD. The dechlorination time-course of p,p＇-DDT and p,p＇-DDE exhibited rapid dechlorination at the first 3.0 hrs, slow dechlorination after 3.0 hrs. For 50 mmol L^-1 dithionite treatments, the dechlorination ratios ofp,p＇-DDT and p,p＇-DDE were 36.42% and 35.08% respectively at 3.0 hrs. For 100 mmol L^-1 dithionite treatments, the dechlorination ratios of p,p＇-DDT and p,p＇-DDE were 58.62% and 57.39% respectively at 3.0 hrs in DDTs-contaminated soils. Significant differences of dechlorination ratio were also confirmed in dependence on dithionite concentrations, reaction systems and the chemical structure of DDTs. The dechlorination ratio ofp,p＇-DDT/DDE increased with the increasing of dithionite concentrations irrespective of reaction systems. Dithionite-induced dechlorination ratio of p,p＇-DDT was higher than that of p,p＇-DDE. The p,p＇-DDD （1,1-dichloro-2,2-bis（4-chlorophenyl）-ethane）, p,p＇-DDE and p,p＇-DDMU （1-chloro-2,2-bis（4-chloropheny）-ethylene） were identified to be metabolites ofp,p＇-DDT in buffer and non-contaminated soil solution, however, no metabolites ofp,p＇-DDE treated by dithionite were detected. The possible pathways explaining the dechlorination of p,p＇-DDT and p,p＇-DDE by dithionite were also proposed. Dithionite could be used to develop an effective and fast remediation option for DDTs-contaminated soils and sediments.

Assessment of Dithionite and Oxalate Extractable Iron and Aluminium Oxides on a Landscape on Basement Complex Soil in South-Western Nigeria

The study investigats the morphological, physical and chemical characteristic of a toposequence on basement complex in Ejioku area, south-western Nigeria on latitude 07°28.675'N;and longitude 004°07.219'E;180 m above sea level at the upper slope. It terminates at the valley bottom on latitude 07°28.756'N;and longitude 004°07.229'E;175 m above sea level. The topography of the site is moderately slope (not greater than 10%). The aim is to examine the two forms of sesquioxides (crystalline-dithionite extractible Fe & Al and amorphous-oxalate Fe & Al) and their distribution on the toposequence. The crystalline form of Fe oxide dominates all the positions and ranges from 7.2 g/kg at the valley bottom to 444.3 g/kg at the crest compared to the amorphous forms that range from 2.7 g/kg to 10.9 g/kg. The crystalline and amorphous aluminium oxide contents of the soils are low (2.9 g/kg - 43.3 g/kg and 1.3 g/kg - 8.7 g/kg respectively). There is significant negative relationship between Fed and Fed/Feo (r =-0.15;P n = 16). There is also a correlation between Feo and Ald (r = 0.63;P n = 16), FeO and FeO/Fed (r = 0.44;P n = 16), signifying a high level of weathering. The relatively high amount of Fed virtually at all the horizons indicates that the crystalline and less active forms of the oxides exist more on the landscape and may be responsible for the non-availability of some nutrient like phosphorus that may be sorbed to their crystals lattice. All forms of Al in the soils are low especially, the oxalate extractable forms, when compare with the dithionite extractable forms. However, there is a significant correlation between Ald and Feo/Fed (r = 0.57;P < 0.01). As a result of high accumulation of crystalline form of Fe and Al oxide with increasing depth, most especially, at the crest/upper slope, there is greater amount of concretions, nodules and plinthites which will lead to further deterioration of the soil for agricultural purposes.

Removal of arsenite by reductive precipitation in dithionite solution activated by UV light

This study investigates the removal of arsenite（As（III）） from water using dithionite activated by UV light. This work evaluated the removal kinetics of As（III） under UV light irradiation as affected by dithionite dose and light intensity, and characterized the nature of the precipitated solids using XPS and SEM-EDS. Photolysis of dithionite was observed by measuring dithionite concentration using UV absorbance at 315 nm. This study also investigated the effect of UV light path length on soluble As concentrations to understand resolubilization mechanisms. Total soluble As concentrations were observed to decrease with reaction time due to reduction of arsenite to form solids having a yellow-orange color.The removal mechanism was found to be reductive precipitation that formed solids of elemental arsenic or arsenic sulfide. However, these solids were observed to resolubilize at later times after dithionite had been consumed. Resolubilization of As was prevented and additional As removal was obtained by frequent dosing of dithionite throughout the experiment. As（III） removal is attributed to photolysis of dithionite by UV light and production of reactive radicals that reduce As（III） and convert it to solid forms.

Sulfonylation from sodium dithionite or thiourea dioxide

The cheap and easily available sodium dithionite and thiourea dioxide have been used as the source of sulfonyl group in the synthesis of sulfones and sulfonamides recently.Compared with other methods for the sulfonylation reactions,the strategies using sodium dithionite or thiourea dioxide provide an alternative and complementary route to diverse sulfonyl compounds.During the reaction process,sulfur dioxide anion radical is the key intermediate,which is usually generated from a single electron transfer under suitable conditions.The advantages using sodium dithionite or thiourea dioxide in the sulfonylation reactions include mild conditions and broad substrate scope with excellent functional group compatibility.Further applications by using sodium dithionite and thiourea dioxide in organic transformations will be anticipated.

Radical Addition of Perfluoroalkyl Iodides to Alkenes and Alkynes Initiated by Sodium Dithionite in an Aqueous Solution in the Presence of a Novel Fluorosurfactant

A new fluorinated anionic surfactant Cl（CF2）6O（CF2）2SO3N（C2H5）4 was prepared and characterized. The application of the fluorosurfactant allowed the fluoroalkylation to occur in the water without adding organic solvent. The addition of perfluoroalkyl iodides with olefins and alkynes under the initiation of Na2S2O4 in water in the presence of the fluorosurfactant gave the corresponding adducts in good to excellent yields. The fluorosurfactant was suitable for a radical addition process.

Evaluation of gastric lavage efficiency and utility using a rapid quantitative method in a swine paraquat poisoning model

BACKGROUND:Gastric lavage(GL)is one of the most critical early therapies for acute paraquat(PQ)poisoning;however,details of the treatment protocol remain to be established.METHODS:A rapid quantitative method involving sodium dithionite testing was developed.It was validated for the determination of the PQ concentrations in gastric juice and eluate samples from a swine acute PQ poisoning model with early or delay GL,or without.The vital signs,laboratory testing,and PQ plasma concentrations were collected for therapeutic effect evaluation.RESULTS:The reaction conditions of the test were optimized for two types of samples.Early GL at one hour(H1)could improve the signs and symptoms after acute PQ poisoning at 24 hours(H24).In contrast,GL at 6 hours(H6)could only partially relieve the vital signs.The H1 GL group effectively reduced the peak of the plasma PQ concentration.In addition,the PQ concentrations in the plasma and the gastric juice were significantly decreased in both the GL groups as compared to the untreated group at H24.Moreover,there was no significant difference in the washing efficiencies calculated from the total eluates between the two GL groups.However,the washing efficiency of the first 10 L eluate is superior to that of the additional 10 L eluate.CONCLUSION:GL only at early stage may it benefit PQ poisoning in an animal model.The currently used 20 L GL volume may need to be reduced in view of the low washing efficiency in the later 10 L eluate.The rapid quantitative method can be used for gastric juice sample and has a certain value for clinical GL practices.

A Convenient Method of Polyfluoroalkyl-lactonization

A novel synthesis of polyfluoroalkyl substituted -butyrolactones from the reaction of polyfluoroalkyl iodides with 4-pentenoic acid initiated with sodium dithionite was realized in good yields.

IMPROVEMENT OF BLEACHING OF KAOLIN USING CHELATING AGENTS

Bleaching of the kaolin ore from Shaziling Kaolin Mine in Jiangxi Province of China was studied with the aim of enhancing the quality and value of the ore to meet the requirements from the ceramics manufacturers. Factors affecting the reductive bleaching of kaolin ore with sodium dithionite as the bleaching agent were studied and optimized to increase the whiteness of the kaolin ore from 38. 5% to about 65%. However, it was found that in the conventional bleaching process, a washing step to remove the ferrous ions from the bleached kaolin suspension was indispensable, which made the process complicated and restricted the capacity of the production. In addition, the whiteness of the bleached kaolin products was unstable. To solve the above problems, a new technique with the application of chelating agents in the bleaching process was developed to remove ferrous ions and get rid of the washing step. The bleaching process of kaolin was simplified. The whiteness of the bleached kaolin products was stabilized as well as increased to about 70%. The mechanism of the bleaching process and the action of the chelating agents were discussed.

Reduced Species （HSO2^-, SO2^·-） Promoted One-Pot Efficient Synthesis of Phenyl Alkyl Selenides

Reduced species （HSO2^-, SO2^·-） promoted one-pot synthesis of phenyl alkyl selenides has been developed. This synthetic method was achieved by reactions of diphenyl diselenide with alkyl halides at room temperature. It is noteworthy that the reactions were operated under mild reaction conditions, required short time, and got good resuits. A single electron transfer reaction mechanism was proposed for the reaction.