An unknown compound gives a mass spectrum with a weak molecular ion at m/z 113 and a prominent ion at m/z 68. Its NMR and IR spectra are shown here. Determine the structure, and show how it is consistent with the observed absorptions. Propose a favorable fragmentation to explain the prominent MS peak at m/z 68.
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Macrolide antibiotics, including erythromycin and azithromycin (Zithromax®), contain a large ring lactone. One of the largest ever reported is Gargantulide A, the structure of which was determined by the research group of Prof. William Gerwick of the Scripps Institution of Oceanography (Organic Letters, 2015, 17, 1377–1380). Isolated from a Streptomyces bacterium, it kills pathogenic bacteria like MRSA and Clostridium difficile, but it proved too toxic to the test animals to continue further testing.

(a) Identify the lactone that makes this a macrolide structure.

(b) How many rings does this structure contain? How many atoms are in the largest ring?

The structures of four useful polymers are shown, together with some of their best-known products. In each case,

(i) Determine the kind of polymer (polyamide, polyester, etc.).

(ii) Draw the structures of the monomers that would be released by complete hydrolysis.

(iii) Suggest what monomers or stable derivatives of the monomers might be used to make these polymers.

(a)

The structures of four useful polymers are shown, together with some of their best-known products. In each case,

(i) determine the kind of polymer (polyamide, polyester, etc.).

(c)

(d)

The structures of four useful polymers are shown, together with some of their best-known products. In each case,

(i) Determine the kind of polymer (polyamide, polyester, etc.).

(ii) Draw the structures of the monomers that would be released by complete hydrolysis.

(iii) Suggest what monomers or stable derivatives of the monomers might be used to make these polymers.

(b)