Problem 14 - General Chemistry

Question

Identify and name the functional group in each of the following. a. \(\mathrm{CH}_{3} \mathrm{COCH}_{3}\) b. \(\mathrm{CH}_{3} \mathrm{OCH}_{2} \mathrm{CH}_{3}\) c. \(\mathrm{CH}_{3} \mathrm{CH}=\mathrm{CH}_{2}\) d. \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{COOH}\) e. \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CHO}\) f. \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{OH}\)

Step-by-Step Solution

Answer

a. Ketone b. Ether c. Alkene d. Carboxylic acid e. Aldehyde f. Alcohol

Step 1: Identify Functional Group in Compound a

The compound given is \( \mathrm{CH}_{3} \mathrm{COCH}_{3} \). It has a carbonyl group (C=O) bonded to two carbon atoms on either side. This indicates the presence of a ketone functional group.

Step 2: Identify Functional Group in Compound b

The compound is \( \mathrm{CH}_{3} \mathrm{OCH}_{2} \mathrm{CH}_{3} \). It contains an oxygen atom bonded to two carbon atoms, signifying an ether functional group.

Step 3: Identify Functional Group in Compound c

The compound \( \mathrm{CH}_{3} \mathrm{CH} = \mathrm{CH}_{2} \) features a carbon-carbon double bond, which is the characteristic of an alkene functional group.

Step 4: Identify Functional Group in Compound d

The compound is \( \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{COOH} \). It has a carboxylic acid group which includes \( \mathrm{-COOH} \). This is the functional group known as carboxylic acid.

Step 5: Identify Functional Group in Compound e

The compound \( \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CHO} \) contains a carbonyl group bonded to at least one hydrogen atom, denoting an aldehyde functional group.

Step 6: Identify Functional Group in Compound f

The compound is \( \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{OH} \). It has an -OH group bonded to a carbon, which identifies the alcohol functional group.

Key Concepts

Ketone Functional Group

A ketone is an organic compound characterized by a carbonyl group \(C=O\) that is bonded to two carbon atoms, serving as key to its identity. The simplest ketone occurs in acetone, represented by \(\mathrm{CH}_{3}\mathrm{COCH}_{3}\). In this case, the carbonyl group is flanked by two methyl groups. Ketones have the general formula R(CO)R', where R and R' can be any carbon-containing substituents. This functional group provides specific properties to the molecule, such as contributing to the boiling and melting points, and its polarity.

• Presence of the carbonyl group makes ketones highly reactive, particularly in nucleophilic addition reactions.
• They often have distinctive odors and are used in various industrial applications.

Understanding the structure of ketones is essential for recognizing their reactivity and role in organic chemistry.

Ether Functional Group

Ethers are compounds containing an oxygen atom bonded to two alkyl or aryl groups, distinguished by their general structure R-O-R'. For instance, \(\mathrm{CH}_{3}\mathrm{OCH}_{2}\mathrm{CH}_{3}\) is diethyl ether, showcasing how an oxygen atom links two carbon chains. The ether linkage provides specific chemical properties and distinguishes ethers from alcohols or water.

• Ethers are known for their relatively inert nature, making them good solvents in many reactions.
• They have higher boiling points than corresponding hydrocarbons due to the possibility of forming weak intermolecular dipole-dipole bonds.

Understanding ethers helps in exploring their usage in anesthesia and as solvents in organic synthesis.

Alkene Functional Group

Alkenes are hydrocarbons with at least one carbon-carbon double bond, exhibiting the general formula CnH2n. The double bond causes these molecules to be unsaturated, meaning they have fewer hydrogen atoms attached than alkanes. A simple alkene is propene \(\mathrm{CH}_{3}\mathrm{CH}=\mathrm{CH}_{2}\), where the double bond introduces distinct reactivity.

• The presence of a double bond allows for reactions such as hydrogenation, where additional hydrogen atoms are added.
• The rigidity of the double bond creates possibilities for different isomers, adding complexity to their chemistry.

Recognizing alkenes' structure and properties is key for grasping their role in polymerization and various industrial applications.

Carboxylic Acid Functional Group

Carboxylic acids contain a carboxyl group \(\mathrm{-COOH}\), combining a carbonyl and hydroxyl group attached to an end carbon. An example is acetic acid, as in \(\mathrm{CH}_{3}\mathrm{CH}_{2}\mathrm{COOH}\). This functional group gives these compounds their characteristic acidic properties.

• The hydrogen in the hydroxyl group can be easily donated, making it an acidic proton, which is why carboxylic acids react with bases to form salts.
• These acids have distinct sour tastes and are found commonly in many living organisms and fermentation products.

Familiarity with carboxylic acids is pivotal for understanding their contributions in biological systems and industrial processes.

Aldehyde Functional Group

An aldehyde contains a carbonyl group attached to a hydrogen atom and a carbon chain, symbolized as \(\mathrm{-CHO}\). Ethanal, represented by \(\mathrm{CH}_{3}\mathrm{CH}_{2}\mathrm{CHO}\), is a simple aldehyde. The positioning of the carbonyl at the end of the carbon chain is a defining feature.

• Aldehydes are generally more reactive than ketones due to the steric and electron-withdrawing effects of the carbonyl group.
• They are key intermediates in the synthesis of alcohols, acids, and other important organic molecules.

Recognizing aldehydes is crucial for understanding their involvement in oxidizing reactions and their occurrence in various natural and synthetic products.

Alcohol Functional Group

Alcohols are characterized by the presence of a hydroxyl \(\mathrm{-OH}\) group bonded to a carbon atom. A classic example is ethanol \(\mathrm{CH}_{3}\mathrm{CH}_{2}\mathrm{CH}_{2}\mathrm{OH}\), where the \(\mathrm{-OH}\) group is clearly present. Alcohols are versatile and found in numerous applications ranging from solvents to beverages.

• Due to the polar nature of the \(\mathrm{-OH}\) group, alcohols can form hydrogen bonds, significantly affecting their boiling points.
• They are reactive, capable of undergoing dehydration, oxidation, and substitution reactions, among others.

Grasping the properties and chemistry of alcohols is essential for their extensive use in industrial, household, and healthcare products.