Write a condensed structural formula for each of the following: \((\mathbf{a})\) an amide with the formula $\mathrm{C}_{4} \mathrm{H}_{9} \mathrm{NO},(\mathbf{b})\( a cyclic ether with the formula \)\mathrm{C}_{4} \mathrm{H}_{8} \mathrm{O},(\mathbf{c})$ a diketone compound with the formula \(\mathrm{C}_{5} \mathrm{H}_{8} \mathrm{O}_{2}\), (d) a phenyl carboxylic acid with the formula \(\mathrm{C}_{7} \mathrm{H}_{6} \mathrm{O}_{2}\)

Identify the functional groups associated with each type of compound: a) Amide: -CONR₂ b) Cyclic ether: C-O-C in a ring structure c) Diketone: Two carbonyl groups (C=O) within the same molecule d) Phenyl carboxylic acid: -COOH group connected to a phenyl ring

a) Amide with the formula C₄H₉NO: Since we have 4 carbon atoms, the longest carbon chain will have 3 carbons, with the amide functional group (-CONH₂) located at one end of the chain. The condensed structural formula for the amide will be: CH₃CH₂CONH₂ b) Cyclic ether with the formula C₄H₈O: A cyclic ether will have oxygen bridging two carbon atoms in a ring structure. For a 4-carbon molecule, the structure will be a tetrahydrofuran ring. The condensed structural formula for the cyclic ether will be: CH₂OCH₂CH₂CH₂ (with the O atom forming the ring) c) Diketone compound with the formula C₅H₈O₂: Since there are two carbonyl groups, we can't have them at the ends of the molecule. The diketone structure would have a carbonyl group on the second and fourth carbon atoms. The condensed structural formula for the diketone compound will be: CH₃COCH₂COCH₃ d) Phenyl carboxylic acid with the formula C₇H₆O₂: A phenyl carboxylic acid will have a carboxylic acid (-COOH) group attached to a phenyl ring. Since there are 6 carbon atoms in a phenyl ring, the carboxylic acid group is attached to one of those carbon atoms. The condensed structural formula for the phenyl carboxylic acid will be: C₆H₅COOH (with the COOH group attached to the phenyl ring)