Enhanced nucleophile selectivity in the photoaddition to styrene. Comparison with the thermal addition

1988 ◽  
Vol 66 (9) ◽  
pp. 2412-2421 ◽  
Author(s):  
Steven W. Anderson ◽  
Keith Yates
Keyword(s):  
Acetic Acid ◽  
Fluorescence Quenching ◽  
Aqueous Solutions ◽  
Irradiation Time ◽  
The Other ◽  
Ring Substituent ◽  
Thermal Addition ◽  
Carbenium Ion ◽  
Medium Acidity

The reactivity–selectivity properties of the sec-phenethyl carbenium ion and its analogues have been examined in binary-aqueous solutions of alcohols (ROH; R = Me, Et, CF3CH2, n-Bu, t-Bu, n-Pr, i-Pr), acetic acid, and in solutions containing external nucleophiles such as thiophenol, ethanethiol, acetate, and benzenesulfinate. Selectivity (S = k(Nuc)/k(H2O)) is observed to be a function of the nucleophile, the ring substituent, thermal or photochemical conditions, irradiation time, and medium acidity. In the case of styrene, the photochemically generated (usually 254 nm, 1 h) species exhibits greater selectivity (up to two orders of magnitude) than its thermal counterpart, generated (usually 80 °C, 2−4 d) in identical media, particularly in aqueous-rich solvent compositions. A rationale for these differences, supported by fluorescence quenching experiments, and the other effects upon selectivity will be discussed.

Disinfection of Fruits with Activated Water

2019 ◽  
Vol 10 ◽  
pp. 1864-1872
Author(s):  
Prof. Teodora P. Popova
Keyword(s):  
Antimicrobial Activity ◽  
Aqueous Solutions ◽  
Antimicrobial Properties ◽  
The Other ◽  
Gram Negative Bacteria ◽  
High Antimicrobial Activity ◽  
Gram Negative ◽  
E Coli ◽  
Number Of Microorganisms ◽  
Lower Effect

The effect of ionized aqueous solutions (anolytes and catholyte) in the processing of fruits (cherries, morellos, and strawberries) for decontamination has been tested. Freshly prepared analytes and catholyte without the addition of salts were used, as well as stored for 7 months anolytes, prepared with 0.5% NaCl and a combination of 0.5% NaCl and 0.5% Na2CO3. The anolyte prepared with a combination of 0.5% NaCl and 0.5% Na2CO3, as well as the anolyte obtained with 0.5% NaCl, exhibit high antimicrobial activity against the surface microflora of strawberries, cherries, and sour cherries. They inactivate E. coli for 15 minutes. The other species of the fam. Enterobacteriaceae were also affected to the maximum extent, as is the total number of microorganisms, especially in cherries and sour cherries. Even stored for 7 months, they largely retain their antimicrobial properties. Anolyte and catholyte, obtained without the addition of salts, showed a lower effect on the total number of microorganisms, but had a significant effect on Gram-negative bacteria, and especially with regard to the sanitary indicative E. coli.

Aromatic Transformation in Fluidized Bed Reactors

2008 ◽  
Vol 73 (8-9) ◽  
pp. 1061-1088
Author(s):  
Sule Rabiu ◽  
Sulaiman Al-Khattaf
Keyword(s):  
Fluidized Bed ◽  
The Other ◽  
Fluidized Bed Reactors ◽  
Y Zeolite ◽  
Y Zeolites ◽  
Toluene Disproportionation ◽  
Xylene Isomerization ◽  
Toluene Methylation ◽  
Toluene Conversion ◽  
Medium Acidity

In this work three important aromatic transformations, namely: toluene disproportionation, toluene methylation and m-xylene isomerization, were investigated in a riser simulator which closely mimics the operation of commercial fluidized bed reactors. The transformations were studied over a ZSM-5 based catalyst with medium acidity of 0.23 mmol/g and a series of Y zeolites of acidities between 0.55 and 0.03 mmol/g. For pure toluene feed, it was observed that conversion over the ZSM-5 based catalyst and the weakly acidic Y zeolite (USY-1) was very low. However, with the highly acidic Y zeolite (H-Y), significant toluene conversion was observed with paring reaction more prominent than disproportionation. On the other hand, when toluene was alkylated with methanol, higher toluene conversions were achieved over both the ZSM-5 based and the weakly acidic USY-1 catalysts as compared to when pure toluene feed was used. In addition, p-xylene/o-xylene (P/O) ratios higher than the equilibrium values were obtained in the reaction product over both catalysts. Finally, for m-xylene isomerization it was found that m-xylene conversion increased initially as the acidity of the catalyst increased up to 0.1 mmol/g beyond which any further increase in acidity resulted in a slight decrease in the m-xylene conversion.

scholarly journals Synthesis of spiro[dihydropyridine-oxindoles] via three-component reaction of arylamine, isatin and cyclopentane-1,3-dione

2013 ◽  
Vol 9 ◽  
pp. 8-14 ◽  
Author(s):  
Yan Sun ◽  
Jing Sun ◽  
Chao-Guo Yan
Keyword(s):  
Acetic Acid ◽  
Reaction Mechanism ◽  
Room Temperature ◽  
The Other ◽  
Other Hand ◽  
Three Component Reaction ◽  
High Yields

A fast and convenient protocol for the synthesis of novel spiro[dihydropyridine-oxindole] derivatives in satisfactory yields was developed by the three-component reactions of arylamine, isatin and cyclopentane-1,3-dione in acetic acid at room temperature. On the other hand the condensation of isatin with two equivalents of cyclopentane-1,3-dione gave 3,3-bis(2-hydroxy-5-oxo-cyclopent-1-enyl)oxindole in high yields. The reaction mechanism and substrate scope of this novel reaction is briefly discussed.

scholarly journals Effect of Photofunctionalization with 6 W or 85 W UVC on the Degree of Wettability of RBM Titanium in Relation to the Irradiation Time

2021 ◽  
Vol 11 (12) ◽  
pp. 5427
Author(s):  
Arturo Sanchez-Perez ◽  
Nuria Cano-Millá ◽  
María José Moya Villaescusa ◽  
José María Montoya Carralero ◽  
Carlos Navarro Cuellar
Keyword(s):  
Light Source ◽  
Ultraviolet Light ◽  
Irradiation Time ◽  
Contact Angles ◽  
The Other ◽  
Control Group ◽  
Hydrophilic Surface ◽  
Biological Ageing ◽  
Ultraviolet C ◽  
Group A

Photoactivation with ultraviolet C light can reverse the effects derived from biological ageing by restoring a hydrophilic surface. Ten titanium discs were randomly divided into three groups: a control group, a 6 W group, and an 85 W group. A drop of double-distilled, deionized, and sterile 10 µL water was applied to each of the discs. Each disc was immediately photographed in a standardized and perpendicular manner. Measurements were taken based on the irradiation time (15, 30, 60, and 120 min). UVC irradiation improved the control values in both groups. There was no difference in its effect between the 6 W group and the other groups during the first 30 min. However, after 60 min and up to 120 min, 85 W had a significantly stronger effect. The contact angles with the 85 W ultraviolet light source at 60 and 120 min were 19.43° and 31.41°, respectively, whereas the contact angles for the 6 W UVC source were 73.8° and 61.45°. Power proved to be the most important factor, and the best hydrophilicity result was obtained with a power of 85 W for 60 min at a wavelength of 254 nm.

Valorization of a natural residue (sawdust) as adsorbent to remove the acetic acid in aqueous solutions

2015 ◽  
Vol 56 (10) ◽  
pp. 2731-2738 ◽  
Author(s):  
Kamel Rida ◽  
Atika Bouanika ◽  
Meriem Boudellal ◽  
Ali Boukhemkhem
Keyword(s):  
Acetic Acid ◽  
Aqueous Solutions

Preparations, sulphinate coordination, and thermal decomposition of some bismuth triarenesulphinates

1972 ◽  
Vol 25 (10) ◽  
pp. 2107 ◽  
Author(s):  
GB Deacon ◽  
GD Fallon
Keyword(s):  
Thermal Decomposition ◽  
Acetic Acid ◽  
Sulphur Dioxide ◽  
Glacial Acetic Acid ◽  
The Other

Bismuth triarenesulphinates, Bi(02SR)3 [R = Ph, p-MeC6H4, p-ClC6H4, 2,4,6-(Me2CH)3C6H2, and p-MeCONHC6H4], have been prepared by reaction of bismuth triacetate with the appropriate arenesulphinio acids in glacial acetic acid, and the first two compounds have also been obtained by reaction of triphenyl-bismuth with the appropriate mercuric arenesulphinates. The sulphur-oxygen stretching frequencies of the bismuth sulphinates are indicative of O-sulphinate coordination, and the compounds are considered to be polymeric with bridging O-sulphinate groups and six-coordinate bismuth. Thermal decomposition of Bi(O2SR)3 (R = Ph, p-MeC6H4, or p-CIC6H4) under vacuum gave the corresponding triarylbismuth compounds and sulphur dioxide, the preparation of tri-p-chlorophenylbismuth being accompanied by formation of di-p-chlorophenyl sulphone and S-p-chlorophenyl p-chlorobenzenethiosulphonate. Pyrolysis of the other triarenesulphinates did not yield organobismuth compounds.

Changes in protein spectra of bean seed during germination

1970 ◽  
Vol 48 (7) ◽  
pp. 1347-1350 ◽  
Author(s):  
Pei-Show Juo ◽  
G. Stotzky
Keyword(s):  
Acetic Acid ◽  
Phaseolus Vulgaris ◽  
Basic Protein ◽  
The Other ◽  
Globulin Fraction ◽  
Bean Seed ◽  
Basic Proteins ◽  
Number Of Components ◽  
Red Kidney Bean ◽  
Protein Spectra

Globulins, albumins, and basic proteins were extracted from seeds of red kidney bean (Phaseolus vulgaris), and their distribution was in a ratio of about 3:2:1, respectively. The globulin fraction constituted a major portion of the reserve proteins and was hydrolyzed rapidly during germination. More than 90% of the basic proteins, extractable with 0.05 N acetic acid, disappeared 12 days after germination. Although the decrease in total albumin was not as marked as with the other two fractions, a number of components of this fraction disappeared during the early stages of germination, but several new components were detected about 8 days after germination. The apparent synthesis of new globulin components during germination was also observed, but no synthesis of basic protein could be detected.

Fluorescence quenching of tryptophan in aqueous solutions by pyruvate

1987 ◽  
Vol 47 (5) ◽  
pp. 1127-1131 ◽  
Author(s):  
G. A. Gachko ◽  
I. L. Zubko ◽  
V. K. Zybel't ◽  
L. N. Kivach ◽  
S. A. Maskevich ◽  
...  
Keyword(s):  
Fluorescence Quenching ◽  
Aqueous Solutions

GROWTH OF STAPHYLOCOCCUS AUREUS IN ACIDIFIED PASTEURIZED MILK1

1970 ◽  
Vol 33 (11) ◽  
pp. 516-520 ◽  
Author(s):  
T. E. Minor ◽  
E. H. Marth
Keyword(s):  
Staphylococcus Aureus ◽  
Acetic Acid ◽  
Lactic Acid ◽  
Hydrochloric Acid ◽  
Ph Value ◽  
The Other ◽  
Antagonistic Effects ◽  
Pasteurized Milk ◽  
Ph Values ◽  
Effect On Growth

The effect of gradually reducing the pH of pasteurized milk with acetic, citric, hydrochloric, lactic, and phosphoric acids over periods of 4, 8, and 12 hr on growth of Staphylococcus aureus 100 in this substrate was determined. In addition, 1: 1 mixtures of lactic acid and each of the other acids, and of acetic and citric acids were evaluated for their effect on growth of this organism. To achieve a 90% reduction in growth over a 12 hr period, a final pH value of 5.2 was required for acetic, 4.9 for lactic, 4.7 for phosphoric and citric, and 4.6 for hydrochloric acid. A 99% reduction during a 12 hr period was obtained with a final pH value of 5.0 for acetic, 4.6 for lactic, 4.5 for citric, 4.1 for phosphoric, and 4.0 for hydrochloric acid. A pH value of 3.3 was required for a 99.9% reduction with hydrochloric acid, whereas the same effect was produced at a pH value of 4.9 with acetic acid. Correspondingly lower pH values were required to inhibit growth within 8 and 4 hr periods. Mixtures of acids adjusted to pH values at the borderline for growth (12 hr period) exhibited neither synergistic nor antagonistic effects between two acids.

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