Aspirin molecule

The chromatogram and bar graph show results of a study of aspirin metabolism in a rat. Aspirin is converted into salicylic acid by enzymes in the bloodstream. To measure the conversion rate, aspirin was injected into a rat and dialysate from a microdialysis probe in a vein of the rat was monitored by liquid chromatography. If you simply withdrew blood for analysis, aspirin would continue to be metabolized by enzymes in the blood. Microdialysis separates the small aspirin molecule from large enzyme molecules. 

One example that illustrates this is the GPC separation of aspirin and propyl paraben. These two compounds have identical molecular weights (MW = 180) but can be separated using GPC (e.g., on a 100-A jiStyragel columns). From the structures (Fig. 11-3) it can be hypothesized that propyl paraben acts as a larger molecule in solution than does aspirin. Since the side chain on propyl paraben would give the molecules a larger end-to-end size than the more compact aspirin molecule, propyl paraben should elute before aspirin. 

An aspirin molecule, C9Hg04, contains nine carbon atoms, eight hydrogen atoms, and four oxygen atoms. 

Aspirin, Molecule of the Month, February 1996. Featured as the second molecule at MOTM site at URL http //www.bris.ac.uk/Depts/Chemistry/MOTM/aspirin/aspirin.htm. 

Answer E. Aspirin (pKa = 3.5) is absorbed quite readily from the stomach. At a stomach pH of 1.5 (pH - pKa = -2), 99% of aspirin molecules are in the unionized form. Remember, unionized molecular forms of drugs are capable of permeation through biomembranes— ionized forms are trapped . 

Section I covers the more conventional equipment available for analytical scientists. I have used a unified means of illustrating the composition of instruments over the five chapters in this section. This system describes each piece of equipment in terms of five modules - source, sample, discriminator, detector and output device. I believe this system allows for easily comparing and contrasting of instruments across the various categories, as opposed to other texts where different instrument types are represented by different schematic styles. Chapter 2 in this section describes the spectroscopic techniques of visible and ultraviolet spectrophotometry, near infrared, mid-infrared and Raman spectrometry, fluorescence and phosphorescence, nuclear magnetic resonance, mass spectrometry and, finally, a section on atomic spectrometric techniques. I have used the aspirin molecule as an example all the way through this section so that the spectral data obtained from each... 

The high acidity of the gastric juices appears to enhance the rate of absorption of unionized aspirin molecules through the stomach lining. In some cases this can irritate these tissues and cause bleeding. 

The Markush viewer is another module to view R group definitions of a molecule in a hierarchical graphical form. It classifies scaffolds and R groups in a given molecule file. The markush stmcture of aspirin molecules is shown here with R1 and R2 group definitions (Fig. 1.29). 

We can also compute 3D descriptors using the cxcalc option. Draw a structure of aspirin molecule (acetyl salicylic acid) in Marvin Sketch and save it as. smi in the Marvin Beans folder. In the command window, type cxcalc stereoisomers -v true aspirin.mol to generate the stereoisomer of the molecule. Similarly, the command cxcalc lowestenergyconformer -f mrv test aspuin.mol calculates the lowest energy conformer of aspirin (Fig. 2.5). 

Fig. 7.31 NMR spectrum of aspirin molecule as visualized in JSpec ew program...

Edwards [25] investigated the hydrolysis of aspirin in aqueous solution at 17A° and demonstrated that the aspirin is hydrolyzed by general acid-base catalysis and water molecules for ionic and nonionic aspirin, comprising six simultaneous reactions involving H O, O H, and H2O for ionic and nonionic aspirin. The intrinsic hydrolysis rate constant in the heated mixture was comparable with the hydrolysis rate constants of the two-element reactions of nonionic aspirin and H2O or ionic aspirin and H2O in aqueous solution. As aspirin molecules would be adsorbed onto the pore surface of PCC in the molecular state, as a possible mechanism of aspirin hydrolysis in the mixture with PCC it was suggested that the aspirin is dispersed monomolecularly in the heated mixture and reacts with water molecules rather than by acid-base catalysis. 

One promising variant of the aspirin molecule is shown in Figure 1.24(b). The changed portion consists of a sulfur atom (yellow) followed by a "tail" of carbon atoms (black) and attached hydrogen atoms (white). This molecule is a potent COX-2 inhibitor that does not appear to affect COX-1. This and other "super-aspirin" molecules must pass tests of long-term safety before they can appear on the shelves at the drugstore, but in time they may replace aspirin and the other popular nonsteroidal anti-inflammatory drugs. 

A single aspirin tablet contains 0.36 g aspirin. The molecular formula of aspirin is C9H8O4. Identify how many aspirin molecules a single tablet contains. 

Rationale for administering sodium bicarbonate Aspirin is a weak add, pKa = 3.5 (see text). Alkalinizing the urine by administering a weak base like sodium bicarbonate promotes the excretion of weak acids like aspirin. The Henderson-Hasselbalch equation can be used to calculate the fraction of aspirin molecules in charged and uncharged forms. 

There is 1 protonated, or uncharged, aspirin molecule for every... 

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