Question

Draw structures of compounds that fit the following descriptions:

1. An $\mathit{\alpha }$,$\mathbf{\beta }$-unsaturated ketone, ${\mathbf{C}}_6{\mathbf{H}}_8\mathbf{O}$
2. An $\mathit{\alpha }$-diketone
3. An aromatic ketone,${\mathbf{C}}_9{\mathbf{H}}_{10}\mathbf{O}$
4. A diene aldehyde,${\mathbf{C}}_7{\mathbf{H}}_8\mathbf{O}$

Short answer

(a)

(b)

(c)

(d)

Step-by-step solution

Step-by-Step SolutionStep 1: Nomenclature of aldehydes and ketones

The aldehydes and ketones have a common carbonyl group (-C=O), but the groups attached on both sides are different for ketone and aldehyde.The aldehyde has at least one hydrogen on one side of the carbonyl group (RCHO), whereas ketones have both alkyl groups ( $\text{RCOR'}$).

The structures of an α,β-unsaturated ketone,C6H8O

(a)The $\mathrm{\alpha }$,$\mathrm{\beta }$-unsaturated ketone with chemical formula ${\text{C}}_{\text{6}}{\text{H}}_{\text{8}}\text{O}$is drawn by placing the double bond adjacent to the ketone group. The closest carbon with a double bond is labelled as $\mathrm{\alpha }$, and the second carbon of a double bond is labelled as $\mathrm{\beta }$.

There are five structures of an $\mathrm{\alpha }$,$\mathrm{\beta }$-unsaturated ketone ${\text{C}}_{\text{6}}{\text{H}}_{\text{8}}\text{O}$, and are shown below,

Structures of an $\alpha$,$\beta$-unsaturated ketone with a chemical formula ${\text{C}}_{\text{6}}{\text{H}}_{\text{8}}\text{O}$

The other possible structures can be cyclobutenones and cyclopropenones.

The structure of an α-diketone

(b)The structure of an $\mathrm{\alpha }$-diketone is drawn by keeping the two ketone groups on the adjacent carbons. There are many other structures possible, and one of the structures for $\mathrm{\alpha }$-diketone is shown below,

Structure of an $\alpha$-diketone

The structure of an aromatic ketone, C9H10O

(c) Aromatic ketones are those which are having ketone groups attached to the aromatic ring-like benzene. There are four structures possible for an aromatic ketone with chemical formula ${\text{C}}_{\text{9}}{\text{H}}_{\text{10}}\text{O}$, and these are shown below,

Structure of an aromatic ketone,${\text{C}}_{\text{9}}{\text{H}}_{\text{10}}\text{O}$

The structure of a diene aldehyde, C7H8O

(d) The structure of a diene aldehyde with chemical formula ${\text{C}}_{\text{7}}{\text{H}}_{\text{8}}\text{O}$is drawn with one cyclohexene ring has two double bonds and one aldehyde (-CHO) group attached to the ring.

Structure of a diene aldehyde,${\text{C}}_{\text{7}}{\text{H}}_{\text{8}}\text{O}$