1. At pH 9.2, seconal absorbs at 239 nm. At pH 13, the absorbance shifts to 254 nm. Of what class of compounds is this characteristic and why?
2. Three compounds were found to have the same empirical formula that is the same number of carbons, hydrogens, oxygens, etc.; however, compound A absorbs at 268 nm, B at 278 nm, and C at 316 nm. What might you conclude about the structures of these three compounds?
3. The spectra of methamphetamine and diazepam are shown in the text of this module. Would you use UV spectrophotometry to screen for either or both of these compounds? Explain why.
4. Tylenol is found to absorb at:
245nm (A 1/1= 668) in aqueous acid and at 257nm (A 1/1= 715) in aqueous akali
If an acid solution in a 1 cm cuvette was found to have an absorbance of 0.669 absorbance units, what was the concentration of tylenol in the solution? If the absorbance of a basic solution of tylenol was 2.0, what would its concentration be? Explain your answer.
5. Why is UV/visible spectrophotometry most often used for screening rather than for confirmation?
6. How can the relative scarcity of drugs that fluorescence be an advantage in some instances and a disadvantage in others?
These solutions may offer step-by-step problem-solving explanations or good writing examples that include modern styles of formatting and construction of bibliographies out of text citations and references. Students may use these solutions for personal skill-building and practice. Unethical use is strictly forbidden.2. Three compounds were found to have the same empirical formula that is the same number of carbons, hydrogens, oxygens, etc.; however, compound A absorbs at 268 nm, B at 278 nm, and C at 316 nm. What might you conclude about the structures of these three compounds [5 points]?
Ans. Compound A, B and C have same empirical formula but their absorption maximum is going towards higher wavelength that means they have increasing number of conjugation (alternating double bonds) when we go from compound A to C. Compound B have slightly increased conjugation than compound A but compound C has considerably higher conjugation than compound A and B because compound A, B and C have absorption maximum 268, 278 and 316 respectively, a higher difference in absorption maximum of compound B and C. In other words we can say that from compound A to C, structure is changing from isolated double bonds or less conjugated double bonds to conjugated or higher number of conjugated double bonds. We can also say that from compound A to C, chromophoric area is increasing....
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