25496-36-0Relevant academic research and scientific papers
Integrating computation and visualization to enhance learning IR spectroscopy in the general chemistry laboratory: Computer-assisted learning of IR spectroscopy
Furlan, Ping Y.,Bell-Loncella, Elisabeth T.
, p. 618 - 625 (2010)
An exercise to compute and visualize the IR spectra of small organic molecules was incorporated into a general chemistry laboratory module on the synthesis of aspirin. The effectiveness of the computation- visualization component was measured by pre- and postquizzes, a survey, and correct interpretation of experimental IR spectra. The assessment results showed that the students' conceptual understanding of IR spectroscopy was enhanced and that their ability to interpret IR spectra improved. Students learned the basics of the Scigress Explorer software package, gained invaluable introductory skills in molecular modeling and computational chemistry, and enjoyed the experience. Taylor & Francis Group, LLC.
Decomposition of aspirin in the solid state in the presence of limited amounts of moisture III: Effect of temperature and a possible mechanism.
Carstensen,Attarchi
, p. 318 - 321 (1988)
In a previous study, we showed that aspirin in the presence of limited amounts of moisture falls to follow Leeson-Mattocks kinetics at 62.5 degrees C. This system has been tested at a series of temperatures, and several plausible models have been tested. It is shown that the data are explained by a model in which the reaction is limited to a surface interaction between aspirin and water from the sorbed bulk moisture layer.
Carbaboranes as pharmacophores: Similarities and differences between aspirin and asborin
Scholz, Matthias,Kaluerovi?, Goran N.,Kommera, Harish,Paschke, Reinhard,Will, Joanna,Sheldrick, William S.,Hey-Hawkins, Evamarie
, p. 1131 - 1139 (2011)
In medicinal chemistry carbaboranes have been used almost exclusively as boron carriers for boron neutron capture therapy (BNCT). Recent developments extended the carrier approach and use carbaboranes as scaffolds for radiodiagnostic or therapeutic agents. Most recent studies, however, focus on carbaboranes as modern hydrophobic pharmacophores. This research employs preferably meta- and para-carbaborane, because these isomers are extremely hydrophobic and very stable. In this paper we therefore investigated the pharmacophoric behavior of the ortho isomer as putative phenyl mimetic by comparing aspirin to asborin, its ortho-carbaborane analogue. Special emphasis is placed on the impact of the cluster properties on the pharmacological profile. Subjects under study are the mode of cyclooxygenase (COX) inhibition, stability, and toxicity. The straightforward syntheses of the corresponding nido compounds as well as their contribution to the pharmacology of the closo precursors will be highlighted. Finally, proof will be given that the ortho-carbaborane core of asborin merits the designation " pharmacophore" by definition and is a multifunctional group rather than just a hydrophobic, bulky spectator.
Decomposition of aspirin in the solid state in the presence of limited amounts of moisture II: Kinetics and salting-in of aspirin in aqueous acetic acid solutions.
Carstensen,Attarchi
, p. 314 - 317 (1988)
The solubility of aspirin in saturated solutions of salicylic acid (and vice versa) was studied in 0 to 16 M aqueous solutions of acetic acid. The solubilities, when expressed in molarity, go through a maximum at an acetic acid concentration of approximately 12 M. The temperature dependence of the solubilities is such that the logarithm of the solubility is linear in reciprocal absolute temperature. The calculated enthalpies are of the order of 11 kcal/mol. The kinetics of aspirin decomposition was also studied at the different acetic acid concentrations, and it was found that the second-order hydrolysis rate constant is fairly independent of acetic acid concentration. Aspirin decomposition follows an Arrhenius equation and has an activation energy of 18 kcal/mol.
Di-tert-butylsilylene as a protecting group for substituted salicylic acids
Pongdee, Gabriel J.,Bell, Kathryn G.,Prestwood, Peri R.,Pongdee, Rongson
, (2020)
The use of di-tert-butylsilyl bis(trifluoromethanesulfonate) has been used to form cyclic protecting groups for substituted salicylic acids. The reaction works well in the presence of a variety of electron-donating groups (EDG) affording the protected compounds in moderate to excellent yields (70–99%) in most cases. In addition, a handful of electron-withdrawing groups (EWG) also provided the corresponding protected silylene derivatives in good yields (77–83%). However, substrates bearing additional ortho -substitution of the carboxylic acid moiety as well as strongly deactivating groups on the aromatic ring did not undergo reaction.
Salicyloyl cyclic phosphate, a 'penicillin-like' inhibitor of β- lactamases
Pratt,Hammar, Ned J.
, p. 3004 - 3006 (1998)
Salicyloyl cyclic phosphate (1-hydroxy-4,5-benzo-2,6- dioxaphosphorinanone (3)-1-oxide) was designed as a 'penicillin-like' inhibitor of β-lactamases. It was anticipated that, after nucleophilic attack on this molecule by the enzyme, the leaving group would remain tethered, and, as in the inhibition of DD-peptidases by penicillins, obstruct hydrolysis of the covalent intermediate back to free enzyme. The target molecule, hitherto only reported as a transient intermediate, was prepared by hydrolysis of the cognate cyclic phosphoryl chloride and isolated and characterized as the dicyclohexylammonium salt. It proved to transiently inhibit the class C β-lactamase of Enterobacter cloacae P99, the class A TEM β-lactamase, and also the DD-peptidase of Streptomyces R61. Most significantly, the half-lives of the complexes formed with these enzymes were 14, 140, and 340 min, respectively. Thus, this cyclic phosphate represents a new class of molecule leading to inert complexes of β-lactam-recognizing enzymes.
Sex differences in the enzymatic hydrolysis of acetylsalicylic acid by microsomes from various rat tissues
Loza, Ana Ma. Julieta Vargas,Sanchez Montes De Oca, Elsa I.,Posadas Del Rio, Francisco A.
, p. 347 - 351 (1997)
We studied the in vitro hydrolysis of acetylsalicylic acid (ASA) to salicylic acid (SA) catalysed by microsomal preparations from liver, kidney, small intestine and stomach mucosas and blood serum of adult female and male rats. Hepatic microsomes from male rats had the highest specific activity: 42.3 ± 6.0 nmol SA mg-1 min-1 (mean ± SEM). Kidney, intestine, stomach and serum activities were 60, 30, 14 and 0.7% with regard to the liver. In contrast, gastric microsomes from female rats showed the highest specific activity: 53 ± 22.1 nmol SA mg-1 min-1 (mean ± SEM) whereas intestine, liver, kidney and serum activities were 60, 43, 40 and 1.7% with regard to the stomach mucosa. Hepatic, renal and intestinal microsomes had a pH, optimum of 5-6. Male rats had V(max) and K(m) values of 95.5, 83.4 and 29.4 nmol SA mg-1 min-1 and 2.9, 1.27 and 6.4 mM, while for female rats they were 54.8, 75.8 and 59.4 nmol SA mg-1 min-1 and 2.6, 1.35 and 3.4 mM for hepatic, renal and intestinal microsomes, respectively. Parathion inhibited the hydrolysis of ASA with an IC50 of 1.2 x 10-5 M for liver and kidney and 5 x 10-6 M for intestine from male rats.
Enzymatic and nonenzymatic in vitro hydrolysis of 2-methyl-2-[2-(methoxy)phenoxy]-4H-1,3-benzodioxin-4-one and 2-methoxyphenyl O-acetylsalicylate
Hundewadt,Senning
, p. 545 - 547 (1991)
This paper is concerned with the synthesis and physical properties as well as the enzymatic and nonenzymatic in vitro hydrolysis of the potential aspirin prodrug MR 693 (5) and the salicylic acid prodrug guacetisalum (6). The half-lives of both prodrugs and the amount of aspirin regenerated in each hydrolytic run for 5 have been estimated over a wide range of pH values.
Phenolic acid glucosides from the seeds of Entada phaseoloides Merill
Singh, Onkar,Ali, Mohd,Akhtar, Nida
, p. 682 - 687 (2011)
Phytochemical investigation of the defatted seeds of Entada phaseoloides Merill. (Mimosaceae) led to the isolation of three new phenolic acid glucosides, which were characterized as 2-hydroxy-5-methylbenzoyl-β-L-glucopyranoside (p-cresotyl glucoside, 1), 2-hydroxy-5-methylbenzoyl-β-L-glucopyranosyl (2 → 1)-β-L-glucopyranosyl (2 → 1)-β-L-glucopyranoside (p-cresotyl triglucoside, 2), and 2-hydroxybenzoyl-β-L-glucopyranosyl (2 → 1)-β-L-glucopyranosyl (2 → 1)-β-L-glucopyranosyl (2 → 1)-β-L-glucopyranoside (salicylic acid tetraglucoside, 5), along with sucrose and triglucoside. The structures of these phytoconstituents have been established on the basis of spectral data analysis and chemical reactions.
Hydrolysis of aspirin studied by spectrophotometric and fluorometric variable-temperature kinetics
Alibrandi, Giuseppe,Micai, Norberto,Trusso, Sebastiano,Villari, Antonino
, p. 1105 - 1108 (1996)
Pseudo-first-order rate constants for the hydrolysis of acetylsalicylic acid as a function of temperature have been obtained by variable-temperature kinetic experiments. A method, based on a generalization of non-isothermal analysis, has been used that takes advantage of the capabilities of modem data collection and processing systems. Both spectrophotometric and, for the first time under non-isothermal conditions, fluorometric measurements have been carried out. The results obtained are identical to those obtained under the same conditions but using traditional constant-temperature kinetic runs. This provides the possibility of reducing the amounts of time and chemicals usually spent in collecting kinetic data in mechanistic studies in solution by an order of magnitude.
