Question

The correct statement regarding smallest ketone is/are (A) Only \(1^{\circ} \mathrm{C}\) present (B) Only 1 DBE (C) Only six \(1^{\circ} \mathrm{H}\) (D) Only 1 two degree carbon

Short answer

The correct statements regarding the smallest ketone, acetone (CH3-CO-CH3), are (B) Only 1 DBE (double bond equivalent), (C) Only six \(1^{\circ} \mathrm{H}\), and (D) Only 1 two-degree carbon.

Step-by-step solution

Identifying the Smallest Ketone

The smallest possible ketone contains three carbons, which form acetone, with the structure CH3-CO-CH3. This is because a ketone has a carbonyl group (C=O) bonded to two alkyl groups and the smallest possible alkyl group is the methyl group (CH3).

Analyzing the Properties of Acetone

Now that we have identified the smallest ketone structure, we can analyze the properties of acetone and check the given statements: (A) Only \(1^{\circ} \mathrm{C}\) present Acetone has two primary carbons (methyl groups) and one secondary carbon (carbonyl functional group). So, this statement is false. (B) Only 1 DBE (double bond equivalent) Acetone has a carbonyl group (C=O), which is only one double bond or one DBE. So, this statement is true. (C) Only six \(1^{\circ} \mathrm{H}\) Acetone has two methyl groups, with three hydrogen atoms in each. As a result, there are six primary hydrogen atoms in the substance. Therefore, this statement is true. (D) Only 1 two-degree carbon Acetone has only one secondary or two-degree carbon (the carbonyl group). So, this statement is true. In conclusion, the correct statements regarding the smallest ketone are (B), (C), and (D).

Key concepts

Acetone Properties

Acetone, often touted as the simplest and smallest ketone, is a colorless liquid with a distinctive sweetish odor. It is a volatile, flammable substance and has unique physical and chemical properties that make it an indispensable solvent in industrial and laboratory settings.

Notable for its effectiveness at dissolving organic substances, acetone is also used in the production of plastics, fibers, drugs, and other chemicals. Moreover, as the exercise suggests, acetone contains two primary carbon atoms (the methyl groups) and one secondary carbon (attached to the carbonyl group). This structure makes it a fascinating molecule from a chemical standpoint. It can be used as a solvent in reactions due to its polarity and ability to dissolve many other substances.

Carbonyl Group

The carbonyl group, denoted by the chemical formula C=O, is a critical functional group in organic chemistry. Characterized by a carbon atom double-bonded to an oxygen atom, this group has polar characteristics, which influence the reactivity and interaction of compounds containing it.

Found in several types of compounds like aldehydes, ketones, carboxylic acids, and amides, it is central to the behavior and properties of these molecules. In ketones, like acetone, the carbonyl group is flanked by carbon atoms, which shapes the molecule's chemical reactivity. The presence of the carbonyl group allows for various chemical reactions, such as nucleophilic addition or condensation, which are used in forming more complex organic molecules.

Double Bond Equivalent (DBE)

Double Bond Equivalent (DBE), also known as the degree of unsaturation, quantifies the saturation level of a compound by counting the number of pi bonds and rings. For a given molecular formula, the DBE tells us about the number of double bonds, triple bonds, and/or rings present in its structure.

The formula to calculate DBE is as follows:
\[\text{DBE} = 1 + \frac{{2C + 2 - H - X + N}}{2}\]
where C is the number of carbon atoms, H is the number of hydrogens, N is the number of nitrogens, and X is the number of halogen atoms.

Acetone has a DBE of 1 because it contains one double bond (the carbonyl group) and no rings. The DBE concept helps chemists understand structural aspects of molecules, which is crucial for deducing molecular structures, particularly in complex compound analysis.