Transient nitronic acid formation in the protonation of the carbanion of 2,2′,4,4′-tetranitrodiphenylmethane in acidic methanol

1987 ◽  
Vol 65 (8) ◽  
pp. 1980-1986 ◽  
Author(s):  
François Terrier ◽  
Jacques Lelièvre ◽  
Alain-Pierre Chatrousse ◽  
Robert Schaal ◽  
Patrick G. Farrell
Keyword(s):  
Carboxylic Acid ◽  
Solvent Effects ◽  
Rate Constants ◽  
Intrinsic Rate ◽  
Low Ph ◽  
The Other ◽  
Acid Formation ◽  
Other Hand ◽  
Protonated Species ◽  
Nitronic Acid

Rates of deprotonation of 2,2′,4,4′-tetranitrodiphenylmethane (1) by a variety of bases B− and of protonation of the resulting carbanion (2) by the conjugated acids BH in methanol have been measured at 20 °C. The Brønsted αBH coefficients for protonation of 2 by phenol and carboxylic acid buffers are equal to 0.58 and 0.43, respectively, as compared with αBH values of 0.59 and 0.52 respectively, for the same reactions in 50% H2O – 50% DMSO. On the other hand, a comparison of the intrinsic rate constants [Formula: see text] (in the Marcus sense) in the two solvents reveals that the effect of going from 50% H2O – 50% DMSO to methanol is to lower [Formula: see text] for the phenol reactions by a factor of 2 but to increase [Formula: see text]for carboxylic acid reactions by a factor of 5. It is shown that the solvent effects on αBH and [Formula: see text] can all be understood in the context of the Principle of Imperfect Synchronisation (PIS) recently proposed by Bernasconi. In addition, a fast equilibrium protonation of the carbanion 2 is found to precede its conversion to 1 at low pH, i.e., pH < 5. The resulting protonated species is suggested to be the nitronic acid 2,H arising from fast protonation of a para NO2 group of 2. The [Formula: see text] value associated with the ionization of 2,H is ∼4.25.

Methylene. III. Gas phase reactions with 1-chloropropane

1969 ◽  
Vol 312 (1509) ◽  
pp. 141-161 ◽  
Keyword(s):  
Gas Phase ◽  
Rate Constants ◽  
Hydrogen Abstraction ◽  
The Other ◽  
Gas Phase Reactions ◽  
Other Hand ◽  
Chlorine Substituent ◽  
High Degree ◽  
Singlet Methylene

The work described in this and the following paper is a continuation of that in parts I and II, devoted to elucidation of the mechanism of the reactions of methylene with chloroalkanes, with particular reference to the reactivities of singlet and triplet methylene in abstraction and insertion processes. The products of the reaction between methylene, prepared by the photolysis of ketene, and 1-chloropropane have been identified and estimated and their dependence on reactant pressures, photolysing wavelength and presence of foreign gases (oxygen and carbon mon­oxide) has been investigated. Both insertion and abstraction mechanisms contribute significantly to the over-all reaction, insertion being relatively much more important than with chloroethane. This type of process appears to be confined to singlet methylene. If, as seems likely, there is no insertion into C—Cl bonds under our conditions (see part IV), insertion into C2—H and C3—H bonds occurs in statistical ratio, approximately. On the other hand, the chlorine substituent reduces the probability of insertion into C—H bonds in its vicinity. As in the chloroethane system, both species of methylene show a high degree of selectivity in their abstraction reactions. We find that k S Cl / k S H >7.7, k T Cl / k T H < 0.14, where the k ’s are rate constants for abstraction, and the super- and subscripts indicate the species of methylene and the type of atom abstracted, respectively. Triplet methylene is discriminating in hydrogen abstraction from 1-C 3 H 7 Cl, the overall rates for atoms attached to C1, C2, C3 being in the ratios 2.63:1:0.

scholarly journals Role of Vitamin E on Indomethacin induced low pH of Seminal Fluid in Long Evans Rats

1970 ◽  
Vol 8 (1) ◽  
pp. 13-15
Author(s):  
Md Jahangir Alam ◽  
Humaira Naushaba ◽  
Uttam Kumar Paul ◽  
Tahmina Begum ◽  
Sunjida Shahriah ◽  
...  
Keyword(s):  
Body Weight ◽  
Vitamin E ◽  
Seminal Fluid ◽  
Low Ph ◽  
The Other ◽  
Testicular Damage ◽  
Other Hand ◽  
Long Evans ◽  
Different Doses

Context: Indomethacin is the most commonly and widely used nonsteroidal antinflammatory analgesic and antipyretic drug. Though it is effective drug in various diseases, indomethacin causes inhibition of spermatogenesis by lowering the pH of seminal fluid leading to infertility. On the other hand, vitamin E enhances spermatogenesis by increasing pH of the seminal fluid. Therefore, the present study was designed to observe the protective role of vitamin E on indomethacin induced low pH of seminal fluid in testicular damage. Objective: To observe the effects of vitamin E on indomethacin induced low pH of seminal fluid in testicular damage in Long Evans rats. Study design: An experimental study. Place and period of study: The study was carried out in the Department of Anatomy, Sir Salimullah Medical College, Dhaka in the period of August, 2005 to June, 2006. Materials and methods: Eightyfour mature Long Evans male rats were divided into four groups (I, II, III and IV). The rats of group I, II and III were treated with indomethacin at different doses and duration. Group IV rats were treated with indomethacin plus vitamin E at different doses for 49 days. The pH of seminal fluid were measured biochemically. Results: There was significant reduction (P<0.001) of pH of seminal fluid when the rats were treated with indomethacin at low (2 mg/kg body weight/day) and high (10 mg/kg body weight/day) doses for 7, 14 and 42 days, respectively. On the other hand, rats treated with indomethacin plus vitamin E for 49 days showed increase in pH of seminal fluid compared to other groups (P<0.001). Conclusion: It can be concluded from the study that vitamin E has potential role in the prevention of the antispermatogenic effects of indomethacin by increasing the pH of seminal fluid. Key words: seminal fluid; indomethacin; vitamin E   DOI: 10.3329/bja.v8i1.6103 Bangladesh Journal of Anatomy January 2010, Vol. 8 No. 1 pp. 13-15

scholarly journals Spectroscopy Study of Honey Pineapple Peels Extracted in Different Solvents

2021 ◽  
Vol 3 (1) ◽  
pp. 32-35
Author(s):  
Yehezkiel Steven Kurniawan ◽  
Edi Setiyono ◽  
Marcelinus Alfasisurya Setya Adhiwibawa ◽  
Krisfian Tata Aneka Priyangga ◽  
Leny Yuliati
Keyword(s):  
Carboxylic Acid ◽  
Visible Region ◽  
Water Extract ◽  
Ethanolic Extract ◽  
Acetone Extract ◽  
The Other ◽  
Distilled Water ◽  
Spectroscopy Study ◽  
Absorption Signal ◽  
Other Hand

In the present work, we investigated the extract of honey pineapple peels in distilled water, ethanol, and acetone solvents. The spectroscopy study of each extract was performed using a Fourier transform infrared (FTIR) spectrometer, an ultraviolet-visible (UV-Vis) spectrophotometer, and a spectrofluorometer. The FTIR spectrum of the distilled water extract indicated that the distilled water extract may contain alcohol or carboxylic acid compounds. Meanwhile, the ethanolic extract may contain alcohol or carboxylic acid, or ether compounds. On the other hand, the acetone extract may contain alcohol or ether or aromatic or aliphatic compounds. The UV-Vis spectrum of the honey pineapple peels extracted in the distilled water, ethanol, and acetone showed a broad absorption signal at UV region (< 300 nm), four absorption signals at UV region (232-368 nm), and four absorption signals at UV region (231-368 nm) with a weak absorption signal at the visible region at 559 nm, respectively. The distilled water and acetone extracts gave fluorescence signals, however, the ethanolic extract showed no fluorescence intensity. From the FTIR, UV-Vis, and fluorescence spectra characterization, the extracted natural pigments from the honey pineapple peels in distilled water, ethanol, and acetone solvents were identified. The distilled water extract may contain polar flavonoid or steroid compounds while the ethanolic extract may contain polar carotenoid pigments. On the other hand, the acetone extract may contain carotenoid and chlorophyll pigments as shown by an emission signal at 670 nm.

scholarly journals The Effects of pH on the Labellar Sugar Receptor of the Fleshfly

1969 ◽  
Vol 53 (4) ◽  
pp. 450-470 ◽  
Author(s):  
Akio Shiraishi ◽  
Hiromichi Morita
Keyword(s):  
Receptor Site ◽  
Low Ph ◽  
The Other ◽  
High Ph ◽  
Sugar Receptor ◽  
Other Hand ◽  
Wide Range ◽  
Effects Of Ph ◽  
Ionizable Groups ◽  
Inhibition Curve

Reproducible results describing the effects of pH on the response of the labellar sugar receptor of the fleshfly, Boettcherisca peregrina, were obtained. The response to sucrose was independent over a wide range of pH (3.0 to 10.0 for sucrose stimulation), but was inhibited fairly sharply on both sides of this range. Similar results were obtained for monosaccharide stimulation. The receptor was excited on stimulation by water above pH 12.0. The effects of high pH, both inhibitory and excitatory, were affected by the presence of salts. In the presence of 0.5 molar NaCl, for example, the pH-inhibition curve was shifted toward lower pH's by about one pH unit. The effects of low pH, on the other hand, were not affected by salts. Following Dixon's theory, it was concluded that at least five ionizable groups (loosing positive charges above pH 10.5) were located at the receptor site.

Fibrinogen-Induced Polymerization Via the Process of Methylation

1979 ◽  
Vol 42 (05) ◽  
pp. 1398-1410
Author(s):  
A J Osbahr
Keyword(s):  
Carboxylic Acid ◽  
Thionyl Chloride ◽  
Acid Group ◽  
Fibrin Clot ◽  
Spectrophotometric Analysis ◽  
The Other ◽  
Amino Group ◽  
Methyl Sulfate ◽  
Carboxylic Acid Groups ◽  
Other Hand

SummaryFibrinogen is polymerized by a number of group specific reagents including diazomethane, thionyl chloride and di-methyl sulfate at pH 7.4. The relationship between the number of methyl groups incorporated into fibrinogen and the extent of polymerization was evaluated. With diazomethane and thionyl chloride as modifying agents, polymerization ensued in approximately IV2 hr with extensive modification of fibrinogen. On the other hand, m�thylation via di-methyl sulfate-induced polymer formation occurs in approximately 35 min with primarily carboxylic acid group esterification. The polymerized fibrinogen formed under these conditions exhibited properties that were closely similar with the physiological fibrin clot.Amino group determinations revealed the m�thylation of amino acid residues other than the expected esterification of carboxylic acid groups. Diazomethane induced both N- methylation of lysine, as well as O-methylation of tyrosine, as estimated from spectrophotometric analysis. On the other hand, thionyl chloride modified only a small number of amino groups, and di-methyl sulfate modification resulted in no significant amounts of amino group methylation during the process of modification induced polymerization of fibrinogen.The profile of the number of methoxyl groups incorporated into fibrinogen with time for diazomethane modification may reflect a conformational change in the protein due to a more nonspecific m�thylation. Both the reagent and the conditions of modification were found to be important in achieving a selective modification of fibrinogen.A possible interpretation of these results is the esterification of carboxylic acid groups in the fibrinogen with reduction in the prevailing carboxylate ion negative repulsion, thereby achieving an increased protein-protein interaction with a resulting polymerization.

Über die Umsetzung von Benzylmalonylchlorid mit verschiedenen Natriumsalzen von Carbonsäuren / The Reaction of Benzylmalonyl Chloride with Sodium Salts of Carboxylic Acids

1972 ◽  
Vol 27 (5) ◽  
pp. 528-530 ◽  
Author(s):  
Helga Wittmann ◽  
Helmut Rathmayr
Keyword(s):  
Carboxylic Acid ◽  
Carboxylic Acids ◽  
Acid Chloride ◽  
Sodium Benzoate ◽  
Sodium Acetate ◽  
The Other ◽  
Carboxylic Acid Chloride ◽  
Sodium Salts ◽  
Other Hand ◽  
Sodium Phenylacetate

Benzylmalonyl Chloride reacts in the presence of sodium acetate in boiling benzene to give tribenzyl-phloroglucinol-triacetate, however with sodium chloroacetate to 3,5-dibenzyl-6-phenethylpyran-2,4-dion. In both cases trimerisation of benzylketene or benzylketene carboxylic acid chloride occurs. On the other hand, benzylmalonylchloride reacts with sodium benzoate and sodium phenylacetate via a dimeric benzylketene carboxylic acid chloride under the loss of phosgene to yield cyclopentadienyl derivatives.

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.

A Simple Rapid Method for Isolating Soluble Fibrin Complexes from Fibrinogen by Treatment with Thrombin and t-AMCHA

1979 ◽  
Vol 42 (05) ◽  
pp. 1388-1397
Author(s):  
Shigeru Hayashi ◽  
Kaneo Yamada
Keyword(s):  
Carboxylic Acid ◽  
Rapid Method ◽  
Recovery Rate ◽  
Gel Filtration ◽  
The Other ◽  
Recovery Rates ◽  
Soluble Fibrin ◽  
Other Hand

SummaryUsing treatment with thrombin associated with trans-aminomethylcyclohexane carboxylic acid (t-AMCHA), a simple and rapid method for isolating soluble fibrin complexes (SFC) from fibrinogen in the plasma was developed. By this procedure, the recovery rates of SFC and early FDP (mainly X) increased according to the concentration of t-AMCHA, reaching a maximum at 286 mM t-AMCHA. On the other hand, the recovery rate of fibrinogen remained below 1.5% and that of late FDP was almost 100% at all concentrations of t- AMCHA. These results suggested that SFC and FDP could be isolated from fibrinogen by thrombin and t-AMCHA (286 mM) treatment. Moreover, it was possible to isolate SFC from FDP using gel filtration after treatment with thrombin and t-AMCHA. The SFC could be quantified by assay of the eluted fractions containing SFC by the staphylococcal clumping test.

The Reaction of β-Cyanoethylhydrazine with Diethyl Phenylthiocarbamoylmalonate

1976 ◽  
Vol 31 (7) ◽  
pp. 989-992 ◽  
Author(s):  
Mohamed Mohamed Mohamed Sallam ◽  
Mohamed Helmy Elnagdi ◽  
Daizy Hanna Fleita ◽  
Eric Hartmann
Keyword(s):  
Carboxylic Acid ◽  
Hydrazine Hydrate ◽  
The Other ◽  
Diethyl Ester ◽  
Reaction Intermediates ◽  
Ethanolic Solution ◽  
Other Hand

Diethyl phenylthiocarbamoylmalonate (2) reacts with β-cyanoethylhydrazin (1) to yield ethyl 3-anilino-2-pyrazolin-5-one (3) via decyanoethylation of the reaction intermediates.Whereas 2 reacts with hydrazine hydrate in refluxing ethanol to yield a mixture of 3-anilino-2-pyrazolin-5-one (4) and the hydrazide (5), the diethyl ester (6) is formed on treatment of 2 with the same reagent in a cooled ethanolic solution. On the other hand, 2 reacts with hydrazine hydrate in the absence of a solvent to yield the carboxylic acid (7).Benzoylacetonitrile reacts with phenylisothiocyanate to yield the thioanilide (8). The latter compound neither reacts with hydrazine hydrate not β-cyanoethylhydrazine.

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