Problem 17 - Chemistry: Principles and Reactions

Question

In each of the following, name the functional group (i.e., ester, aldehyde, ...). (a) \(\mathrm{CH}_{3}-\mathrm{CH}=\mathrm{CH}-\mathrm{CH}_{2}-\mathrm{OH}\)

Step-by-Step Solution

Answer

Based on the given information, the functional groups present in the compound \(\mathrm{CH}_{3}-\mathrm{CH}=\mathrm{CH}-\mathrm{CH}_{2}-\mathrm{OH}\) are alkene (due to the double bond between two carbon atoms) and alcohol (due to the hydroxyl group at the end of the compound).

Step 1: Identify the functional group present in the compound

The given compound is \(\mathrm{CH}_{3}-\mathrm{CH}=\mathrm{CH}-\mathrm{CH}_{2}-\mathrm{OH}\). Let's break it down: 1. There is a double bond between two carbon atoms: \(\mathrm{CH}=\mathrm{CH}\). 2. There is an alcohol group (hydroxyl group) at the end: \(\mathrm{OH}\). Therefore, it has an alkene functional group and an alcohol functional group.

Step 2: Name the functional group

Since the compound has an alkene functional group and an alcohol functional group, we can say that the given compound has two functional groups: 1. Alkene: Due to the presence of the double bond between two carbon atoms. 2. Alcohol: Due to the presence of the hydroxyl group at the end of the compound. Thus, the functional groups present in the given compound are alkene and alcohol.

Key Concepts

Alkene

An alkene is a type of hydrocarbon that contains at least one carbon-to-carbon double bond. In the compound \[\mathrm{CH}_{3}-\mathrm{CH}=\mathrm{CH}-\mathrm{CH}_{2}-\mathrm{OH}\], the presence of the double bond is a defining feature of the alkene functional group. Each carbon in the double bond is hybridized as sp2, leading to a planar structure around the double bond area.Alkenes are unsaturated compounds, meaning they have fewer hydrogen atoms than the corresponding alkanes with the same number of carbon atoms. This is because of the double bond, which reduces the number of bonded hydrogens.

• Characterized by a C=C bond
• Unsaturated hydrocarbons
• Typically ends in '-ene' in systematic naming

When naming alkenes, the longest continuous carbon chain containing the double bond forms the base name, and the position of the double bond is indicated by the lowest possible locant number.

Alcohol Group

The alcohol functional group is characterized by the presence of an -OH group, also known as a hydroxyl group. In our compound, \[\mathrm{CH}_{3}-\mathrm{CH}=\mathrm{CH}-\mathrm{CH}_{2}-\mathrm{OH}\], the hydroxyl group is attached to the last carbon in the chain. This gives the molecule its alcohol characteristics.The alcohol group has a broad range of chemical reactions and properties. For instance, they can undergo deprotonation to form alkoxides or participate in substitution and elimination reactions.

• Contains the hydroxyl group (-OH)
• Slightly polar, capable of forming hydrogen bonds
• Has higher boiling points than alkanes and alkenes of similar size due to hydrogen bonding

The naming of alcohols involves replacing the -e ending of the parent alkane with -ol, with the number indicating the position of the hydroxyl group.

Hydroxyl Group

The hydroxyl group, comprised of an oxygen and hydrogen atom bonded together ( -OH), forms the backbone of alcohols. This group is a key player in determining the physical and chemical properties of the molecule. In chemical reactions, the hydroxyl group can act either as a nucleophile, where it donates a pair of electrons, or as a base, removing a proton (H+) from an acid. The polarity of oxygen leads to differences in characteristicsamong compounds containing hydroxyl groups as compared to those that don't.

• Consists of an oxygen and hydrogen atom
• Polar and capable of forming hydrogen bonds
• Increases solubility of the molecule in water compared to hydrocarbons

The presence of the hydroxyl group significantly impacts the boiling and melting points due to its hydrogen bonding capability. It influences the molecule’s solubility, usually leading to a greater solubility in polar solvents like water.