scholarly journals Selective synthesis of α-organylthio esters and α-organylthio ketones from β-keto esters and sodium S-organyl sulfurothioates under basic conditions

2021 ◽  
Vol 17 ◽  
pp. 234-244
Author(s):  
Jean C Kazmierczak ◽  
Roberta Cargnelutti ◽  
Thiago Barcellos ◽  
Claudio C Silveira ◽  
Ricardo F Schumacher
Keyword(s):  
Reaction Time ◽  
The Other ◽  
Selective Synthesis ◽  
Selective Method ◽  
Keto Esters ◽  
Other Hand ◽  
Bunte Salts

We described herein a selective method to prepare α-organylthio esters and α-organylthio ketones by the reaction of β-keto esters with sodium S-benzyl sulfurothioate or sodium S-alkyl sulfurothioate (Bunte salts) under basic conditions in toluene as the solvent at 100 °C. When 4 equivalents of a base were used, a series of differently substituted α-thio esters were obtained with up to 90% yield. On the other hand, employing 2 equivalents of a base, α-thio ketones were achieved after 18 h under air. Furthermore, after a shorter reaction time, the isolation of keto–enol tautomers was possible, revealing them as significant intermediates for the mechanism elucidation.

Degradation of chlorpyriphos in water by advanced oxidation processes

2010 ◽  
Vol 10 (1) ◽  
pp. 1-6 ◽  
Author(s):  
R. Murillo ◽  
J. Sarasa ◽  
M. Lanao ◽  
J. L. Ovelleiro
Keyword(s):  
Reaction Time ◽  
Light Source ◽  
Advanced Oxidation Processes ◽  
Advanced Oxidation ◽  
The Other ◽  
Molar Ratio ◽  
Optimum Conditions ◽  
Oxidation Processes ◽  
Other Hand ◽  
Initial Ph

The degradation of chlorpyriphos by different advanced oxidation processes such as photo-Fenton, TiO2, TiO2/H2O2, O3 and O3/H2O2 was investigated. The photo-Fenton and TiO2 processes were optimized using a solar chamber as light source. The optimum dosages of the photo-Fenton treatment were: [H2O2]=0.01 M; [Fe3 + ]=10 mg l−1; initial pH = 3.5. With these optimum conditions total degradation was observed after 15 minutes of reaction time. The application of sunlight was also efficient as total degradation was achieved after 60 minutes. The optimum dosage using only TiO2 as catalyst was 1,000 mg l−1, obtaining the maximum degradation at 20 minutes of reaction time. On the other hand, the addition of 0.02 M of H2O2 to a lower dosage of TiO2 (10 mg l−1) provides the same degradation. The ozonation treatment achieved complete degradation at 30 minutes of reaction time. On the other hand, it was observed that the degradation was faster by adding H2O2 (H2O2/O3 molar ratio = 0.5). In this case, total degradation was observed after 20 minutes.

Effects of Speed and Accuracy of Exertion of Force on the Relationship between Force Output and Fractionated Reaction Time

1991 ◽  
Vol 73 (1) ◽  
pp. 327-334 ◽  
Author(s):  
Shoko Kawabe-Himeno
Keyword(s):  
Reaction Time ◽  
Isometric Contraction ◽  
Light Signal ◽  
The Other ◽  
Force Output ◽  
Motor Time ◽  
Premotor Time ◽  
Other Hand ◽  
The Relationship ◽  
Speed And Accuracy

The present study was designed to investigate the effect of speed and accuracy of force exertion on the relationship between force output and fractionated reaction time. Subjects exerted their force (10% or 40% of maximum isometric contraction) on “accurate” and “fast” tasks as rapidly as possible at the light signal. On the “fast” task, premotor time for the 40% target was lengthened in comparison with that for the 10% target, and motor time was shortened with an increase of force output. On the “accurate” task, on the other hand, premotor time was independent of magnitude of force, and no relation between motor time and force output was found. These findings show that the relationship between force output and fractionated reaction time may be affected by the effort to exert force accurately.

Copolymerization of Ethylene/Diene with Different Metallocene Catalysts

2006 ◽  
Vol 61 (11) ◽  
pp. 1426-1432 ◽  
Author(s):  
Maria de Fátima Vieira Marques ◽  
Fernanda Constantino Rocha ◽  
Narda Juárez Soto
Keyword(s):  
Catalytic Activity ◽  
Thermal Properties ◽  
Reaction Time ◽  
Polymerization Rate ◽  
The Other ◽  
Copolymer Composition ◽  
Metallocene Catalysts ◽  
Ethylene Pressure ◽  
Other Hand ◽  
Catalyst Type

Copolymerizations of ethylene and 1,7-octadiene were carried out employing homogeneous catalysts Cp2ZrCl2, Ph2C(Flu,Cp)ZrCl2 and Et(Ind)2ZrCl2, and methylaluminoxane as cocatalyst. The polymerization characteristics, such as catalytic activity, polymerization rate, copolymer composition, and thermal properties were examined in relation to the catalyst type. Different comonomer concentrations were employed, and the reaction time was varied, ranging from 1 h up to 4 h, at 90°C and at 0.5 bar ethylene pressure. The results showed that the catalyst Cp2ZrCl2 was more efficient than Et(Ind)2ZrCl2 in the preparation of high diene content ethylene/1,7-octadiene copolymers. On the other hand, Et(Ind)2ZrCl2 and Ph2C(Flu,Cp)2ZrCl2 catalysts produced low insaturation content but possibly formed cyclic structures and crosslinking.

Effects of Preparatory Period on a Reaction-Time Followed by a Pointing Movement Either Guided or Not

1973 ◽  
Vol 37 (3) ◽  
pp. 980-982
Author(s):  
Yves Guiard ◽  
Jean Requin
Keyword(s):  
Reaction Time ◽  
Movement Time ◽  
The Other ◽  
Preparatory Period ◽  
Other Hand ◽  
Pointing Movement ◽  
Pointing Task ◽  
The Mean

In a pointing task, the movement-time (MT), as opposed to reaction-time (RT), does not depend upon duration of preparatory period (PP). On the other hand, the mean MT, but not the mean RT, is shortened by guidance of the movement. The timing of preparatory processes in such task is discussed.

Confidence-accuracy dissociation via criterion attraction

2021 ◽  
Author(s):  
Dobromir Rahnev
Keyword(s):  
Reaction Time ◽  
Recent Work ◽  
Strong Evidence ◽  
External Noise ◽  
The Other ◽  
Decision Criteria ◽  
Other Hand ◽  
Objective Performance ◽  
Multiple Tasks ◽  
Criterion Location

Humans often have to use different decision criteria in different tasks such as when detecting a mosquito against a white versus a patterned wall. However, it is debated whether people can maintain independent criteria for different tasks. Early work uncovered suboptimal biases when multiple tasks are performed simultaneously, and concluded that in such situations people inadvertently use the same decision criteria across different perceptual tasks. On the other hand, these studies could not measure the criterion location directly and more recent work has questioned whether the same criteria are indeed used across different tasks. To resolve this debate, here we develop a new external noise paradigm that can objectively quantify criterion location across two tasks that optimally require very different criteria. We find strong evidence of “criterion attraction” where the criteria across the two tasks move towards each other but do not become identical. This criterion attraction leads to a large and consistent confidence-accuracy dissociation in the absence of reaction time differences between the tasks. These results unify the seemingly disparate findings in the literature and establish a robust way of inducing dissociations between subjective and objective performance.

Research on the Application of Laccase to the Treatment of Oily Wastewater

2010 ◽  
Vol 45 (1) ◽  
pp. 91-98 ◽  
Author(s):  
Zhi Lin Li ◽  
Wei Liu ◽  
Xin Fang Chen ◽  
He Sheng Li ◽  
Yun Miao Tian
Keyword(s):  
Reaction Time ◽  
Removal Rate ◽  
Catalytic Performance ◽  
The Other ◽  
Oily Wastewater ◽  
Oil Removal ◽  
Other Hand ◽  
Oil Concentration

Abstract The feasibility of using laccase to treat oily wastewater was examined. When only laccase was added to the synthetic oily wastewater, the suitable technological conditions were laccase at 3 U/mL, pH at 6.0, a temperature of 30°C, and a reaction time of 6 h for the initial oil concentration of 120 mg/L. Under those conditions, the rate of oil removal was as high as 69%. The effects of Mg2+, Mn2+, Cu2+, and Fe2+ ions in wastewater on the rate of oil removal using laccase were investigated. The results showed that Cu2+and Fe2+ ions obviously inhibited the catalytic performance of laccase under the studied concentration. On the other hand, Mg2+ and Mn2+ ions only had slight effects on the rate of oil removal for the range of concentrations studied. A 95% oil removal rate could be obtained when actual wastewaters were treated using laccase with the additive chitosan under the suitable technological conditions.

Total synthesis of the stemodane-type diterpenoids (±)-stemodin and (±)-maritimol. Formal total synthesis of (±)-stemodinone and (±)-2-desoxystemodinone

1985 ◽  
Vol 63 (12) ◽  
pp. 3418-3432 ◽  
Author(s):  
Edward Piers ◽  
Brian F. Abeysekera ◽  
David J. Herbert ◽  
Ian D. Suckling
Keyword(s):  
Total Synthesis ◽  
Room Temperature ◽  
The Other ◽  
Subsequent Reaction ◽  
Total Syntheses ◽  
Keto Esters ◽  
Other Hand ◽  
Synthetic Intermediates ◽  
Separation Of Mixtures ◽  
Hydrolysis Of

Total syntheses of the stemodane-type diterpenoids (±)-stemodin (2) and (±)-maritimol (4), as well as formal total syntheses of (±)-stemodinone (3) and (±)-2-desoxystemodinone (5), are described. The known ketol 12 was converted into the tricyclic enone 7. Photoaddition of aliène to 7 gave (96%) a mixture of the photoadducts 20–23 (40:51:6:3, respectively). Ozonolysis of 20, followed by treatment of the resultant dione 24 with MeONa–MeOH (room temperature, 2.5 h), provided the keto ester 26 (94%). Subjection of 21 to an identical sequence of reactions gave (86%) the same product 26. On the other hand, when the dione 25 was treated with MeONa–MeOH under much milder conditions (0 °C, 5 min), the isomeric keto esters 27 (39%) and 28 (33%) were produced. Both 27 and 28, upon reaction with MeONa–MeOH at room temperature, were converted efficiently into 26. Reduction (NaBH4 or Lisec-Bu3BH) of 26 provided separable mixtures of the ester alcohol 32 and the lactone 33, which could be transformed readily into the dimesylates 35 and 39, respectively. Reaction of 35 and 39 with NaCN in warm hexamethylphosphoramide afforded the dinitriles 37 and 40, both of which, upon treatment with t-BuOK in refluxing t-BuOH, produced the sameenaminonitrile 41. Acid hydrolysis of 41 provided the dione 42. Preparatively, compound 26 could be transformed conveniently into the dione 42 (52% overall yield) without separation of mixtures of isomeric synthetic intermediates. Treatment (CH2Cl2, −95 °C) of 42 with Mc3Sil–Et3N, followed by oxidation of the resultant products 46 and 47 with Pd(OAc)2 in acetonitrile, gave the bis enones 48 (67%) and 49 (19%). Compound 48 was converted into the dione 52 which, upon reaction with (i-PrO)3 TiMe in ether, provided an 86:14 mixture of the keto alcohols 53 and 54 (63% from 48). Reduction (NaBH4) of 53 afforded (±)-maritimol (4). On the other hand, conversion of the 86:14 mixture of 53 and 54 into the p-toluenesulfonylhydrazones 55 and subsequent reaction of 55 with NaH in refluxing toluene gave the alkene alcohols 56 (58%) and 57 (12%). Hydroboration–oxidation (9-BBN, refluxing tetrahydrofuran; NaOH, H2O2) of 56 afforded (88%) (±)-stemodin (2).

scholarly journals Further evidence that the Worst Performance Rule is a special case of the Correlation of Sorted Scores Rule

2020 ◽  
Author(s):  
Kimmo Sorjonen ◽  
Guy Madison ◽  
Tomas Hemmingsson ◽  
Bo Melin ◽  
Fredrik Ullén
Keyword(s):  
Standard Deviation ◽  
Reaction Time ◽  
Large Range ◽  
Rank Order ◽  
Statistical Properties ◽  
The Other ◽  
Other Hand ◽  
Test Rank ◽  
Higher Rank ◽  
Special Case

According to the worst performance rule (WPR), the correlations between intelligence and sorted performances, for example on reaction time tasks, should strengthen from the best to the worst performance. A commonly proposed explanation for the WPR is that poor performances reflect lapses of attention that are particularly strongly related to intelligence. The correlation of sorted scores rule (CSSR), on the other hand, claims that the WPR arises due to certain statistical properties of the data. Specifically, the magnitude of intelligence-performance correlations will change with the rank order of the test when intelligence is correlated with the within-individual standard deviation (WISD) of the tests. If the latter correlation is negative, a WPR is seen, i.e. intelligence-performance correlations will be lower for tests with higher rank order. If the intelligence-WISD correlation is positive, however, intelligence-performance correlations instead increase with test rank order. In the present study, through strategic slicing of two full samples (N = 5467 and N = 43,987, respectively), we created subsamples with a large range of intelligence-WISD correlations. In accordance with the CSSR, but not the WPR, the association between intelligence-performance correlations and test rank order was found to reflect the intelligence-WISD correlation of the subsample. This indicates that the WPR might be a special case of the more general CSSR and that the WPR is crucially dependent on intelligence-WISD correlations. The findings also indicate that the predictions made by the CSSR generalize to other predictors besides intelligence and to other outcomes besides reaction time.

scholarly journals Processing of inflected adjectives

Psihologija ◽  
2003 ◽  
Vol 36 (3) ◽  
pp. 353-378
Author(s):  
Dusica Filipovic ◽  
Aleksandar Kostic
Keyword(s):  
Reaction Time ◽  
Lexical Decision ◽  
Cognitive System ◽  
The Other ◽  
Amount Of Information ◽  
Inflected Form ◽  
Other Hand ◽  
Mean Reaction Time

Processing of inflected Serbian verbs was investigated in two lexical decision experiments. Specifically, the following issues were addressed: a. does the adjectival system contain syntactic functions and meanings, and b. are adjectival gender and case cognitively relevant properties. Each of the above issues could be expressed in terms of alternative equations that generate the amount of information carried by inflected form of an adjective. The informational values were correlated with mean reaction time to inflected adjectival forms. The outcome of the two experiments indicated that number of syntactic functions/meanings is the obligatory term in the equation that generates the amount of information carried by an adjectival inflected form. However, unlike nouns, where the amount information was specified in terms of ratio between a. sum of frequencies of inflected cases encompassed by a given inflected form and b. sum of its functions/ meanings, equation for adjectives includes sum of frequency by number of syntactic functions/meanings ratios for cases encompassed by a given inflected adjectival form. This, on the other hand, suggests that cognitive system when processing inflected adjectives is to some extent sensitive to adjectival case. It was also demonstrated that cognitive system is not sensitive to adjective gender.

THE REDUCTION OF NITROBENZENE BY HYDROSULPHIDE ION IN AQUEOUS MEDIA

1962 ◽  
Vol 40 (12) ◽  
pp. 2317-2328 ◽  
Author(s):  
O. J. Cope ◽  
R. K. Brown
Keyword(s):  
Reaction Time ◽  
Rate Constants ◽  
Aqueous Media ◽  
The Other ◽  
First Order ◽  
Order Dependence ◽  
Other Hand ◽  
Nitrobenzene Reduction ◽  
Autocatalytic Effect

The reduction of nitrobenzene by sodium hydrosulphide and sodium hydrodisulphide in aqueous media at 50° has been examined. Goldschmidt's report of first-order dependence upon both nitrobenzene and hydrosulphide is corroborated. The action of hydrosulphide on nitrobenzene produces phenylhydroxylamine, which is reduced by hydrosulphide much more slowly than is nitrobenzene. As reaction progresses, nitrobenzene reduction produces yellow hydrodisulphide, which is responsible for the observed autocatalytic effect. Hydrodisulphide reduces phenylhydroxylamine more rapidly than it does the original nitrobenzene, and hence as reaction time is extended, phenylhydroxylamine disappears more rapidly than does nitrobenzene, yielding only aniline and some unreacted nitrobenzene towards the end of the reaction. Hydrosulphide reduction of phenylhydroxylamine to aniline produces thiosulphate but apparently no hydrodisulphide. Hydrodisulphide reduction of the phenylhydroxylamine leads only to conversion of the yellow hydrodisulphide to a colorless species, apparently thiosulphate. On the other hand hydrosulphide or hydrodisulphide reduction of nitrobenzene is accompanied by thiosulphate formation and some increase in hydrodisulphide. A comparison of the rate constants shows that under the conditions of the reaction, hydrodisulphide ion reduces nitrobenzene about seven times more rapidly than does hydrosulphide ion while phenylhydroxylamine is reduced two to three times more rapidly by hydrodisulphide than is nitrobenzene.

Sign in / Sign up

Export Citation Format

Share Document