What are the key differences of the IR spectrum of aspirin with that of the starting material salicylic acid?
A key difference is acetylsalicylic acid shows two strong peaks in the carbonyl (C=O) stretching region (1650 – 1800 cm-1), because it has two different carbonyl groups — while salicylic acid has only one.
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How does concentration affect IR spectrum?
More molecules means less light gets through the sample, thus the size of the dip in the IR light intensity at the frequencies of your molecule’s absorption feature is proportional to the concentration.
What are the mechanism for the reaction of aspirin?
Aspirin can be made by reacting salicylic acid with acetic acid in the presence of an acid catalyst. The phenol group on the salicylic acid forms an ester with the carboxyl group on the acetic acid. However, this reaction is slow and has a relatively low yield.
Does aspirin absorb visible light?
Acetylsalicylic acid, commonly known as aspirin, absorbs light in the UV region of the electromagnetic spectrum. The Spectronic 200 operates in the visible region. Therefore, we must perform a series of chemical reactions to convert acetylsalicylic acid to a colored complex, as shown in Figure 5.
What is the absorbance of aspirin?
The UV absorbance of aspirin was determined at 254 nm, and the fluorescence of salicylic acid was measured at 425 nm. Excipients and impurities did not interfere. Recoveries of 100% were obtained for aspirin and salicylic acid from simulated tablet formulations.
What causes IR peaks to shift?
Analyses of IR spectra showed that the apparent positional shifts of peak maxima in these systems are actually due to relative contribution changes of two overlapped bands, instead of the gradual frequency shift of a single band induced by the change in the strength of molecular interactions.
What pathway does aspirin inhibit?
He proved that aspirin and other non-steroid anti-inflammatory drugs (NSAIDs) inhibit the activity of the enzyme now called cyclooxygenase (COX) which leads to the formation of prostaglandins (PGs) that cause inflammation, swelling, pain and fever.
Is aspirin polar or nonpolar?
Aspirin is a polar molecule with dipole-dipole attraction bonds and an -OH (hydroxyl) segment as part of a carboxylic acid group. This makes it easily dissoluble in other polar liquids, such as water (H2O) and blood plasma.
What are the functional groups in aspirin?
The common name of aspirin is acetylsalicylic acid and its IUPAC name is 2-Acetoxybenzoic acid. Between ester and carboxylic acid functional groups the highest priority functional group is carboxylic acid. Hence, in aspirin carboxylic acid is the principal functional group. Therefore, the correct option is B, -COOH.
What wavelength absorbs aspirin?
The absorption spectra of aspirin and salicylic acid in phosphate buffer (pH 6.8) are shown in Fig. 1. The absorption peaks were at 233 nm and 296 nm. At the wavelength of 265 nm, aspirin and salicylic acid had a different absorbance, so it affected the determination of dissolution rate.
Why does aspirin fluoresce?
In order to maximize the detection of ASA in an aspirin tablet, you will first convert it to salicylate ions by the addition of sodium hydroxide. The salicylate ion strongly fluoresces at about 400 nm after it has been excited at about 310 nm.
What is the spectrophotometric analysis of aspirin?
SPECTROPHOTOMETRIC ANALYSIS OF ASPIRIN. Introduction: A colored complex is formed between aspirin and the iron (III) ion. The intensity of the color is directly related to the concentration of aspirin present; therefore, spectrophotometric analysis can be used.
What is red shift in IR spectroscopy?
In physics, a redshift is an increase in the wavelength, and corresponding decrease in the frequency and photon energy, of electromagnetic radiation (such as light). The opposite change, a decrease in wavelength and simultaneous increase in frequency and energy, is known as a negative redshift, or blueshift.
What is the NMR spectrum of the aspirin synthesis reaction?
The two starting materials in the aspirin synthesis reaction were acetic anhydride and salicylic acid. In the reaction between acetic anhydride and water, a gas was released that gave off a smell similar to that of vinegar. This gas was acetic acid; an end product in the aspirin synthesis reaction, thus the NMR spectrum of acetic acid was analyzed.
What is the bioavailability of unhydrolyzed aspirin?
However, the actual bioavailability of the drug as unhydrolyzed aspirin is lower since aspirin is partially hydrolyzed to salicylate in the GI mucosa during absorption and on first pass through the liver. There are relatively few studies of the bioavailability of unhydrolyzed aspirin.
What is the peak concentration of aspirin in the blood?
The mean peak concentration of aspirin was 6.5 micrograms/mL in plasma (range, 4.9-8.9 micrograms/mL), reached in 26 minutes (range, 13-33 minutes). The half-life of aspirin was 31 minutes. The concentration ratio of aspirin (semen/plasma) was 0.12 (except for one subject in whom it was 0.025).