Question

Write line structures for the following compounds. (a) 3-hexanol (b) 2,2 -dimethyl-3-pentanol

Short answer

For 3-hexanol, draw a straight line with six points. The third point from the left should extend to a OH group. For 2,2-dimethyl-3-pentanol, draw a straight line with five points. The second point from the left should extend to two CH3 groups, and the third point should extend to a OH group.

Step-by-step solution

Construct Structure for 3-hexanol

The 'hex' in 3-hexanol means the longest carbon chain in the molecule has six carbons. The 'anol' indicates that there is an alcohol (OH group) attached to the carbon. The '3' indicates that the OH group is attached to the third carbon in the chain. So, starting from the left, draw a straight horizontal line representing six bonded carbons. Number these from left to right from 1 to 6. On the third carbon, draw a dash representing the bond to the OH group. Follow this by a small circle for oxygen and then a horizontal dash to represent hydrogen.

Construct Structure for 2,2 -dimethyl-3-pentanol

In the name 2,2-dimethyl-3-pentanol, the 'pent' denotes a five carbon chain which are numbered from left to right. On the second carbon, the '2,2-dimethyl' indicates that there are two methyl groups (CH3). Draw two dashes at the second carbon going down, each one followed by a C (representing methyl). The '3' before 'pentanol' suggests that there is an alcohol group at the third carbon. Draw a dash upward at the third carbon representing bond to the OH group (a small circle for oxygen followed by a dash for hydrogen).

Verify and finalize line structures

Look at the structures you drew. Make sure that every carbon has four bonds (since carbon forms four bonds), every hydrogen has one bond (since hydrogen forms one bond), and every oxygen has two bonds (since oxygen in alcohol forms two bonds). This is a good step to make sure you've drawn your structure correctly.

Key concepts

Organic Chemistry

Organic chemistry is the branch of chemistry that deals with carbon-containing compounds. Carbon is unique because it can form up to four covalent bonds with different elements including other carbon atoms. This creates a variety of structures, such as straight chains, branched chains, and rings. In organic chemistry, you'll often hear about different types of carbon chains.
These include:

• Straight chains: These chains have a linear arrangement of carbon atoms.
• Branched chains: These have one or more branches coming off a straight chain.
• Rings: Carbon atoms can form closed rings by bonding with themselves.

At the heart of most organic compounds are functional groups. These groups of atoms have specific properties and determine how the compound will react chemically. In organic chemistry, learning the names and properties of these groups is essential. For example, the hydroxyl group (-OH) is key in forming alcohols, which we will explore next.

Alcohol Structure

Understanding the structure of alcohols begins with recognizing the hydroxyl group (-OH).
This functional group consists of:

• One oxygen atom bonded to one hydrogen atom.
• This group is attached to a carbon atom within a hydrocarbon chain.

The presence of this group gives alcohols their distinct properties, such as being able to form hydrogen bonds, which affects their boiling and melting points. In line structures, alcohols are indicated by the 'anol' suffix, as seen with compounds like 3-hexanol or 2,2-dimethyl-3-pentanol.
The number before 'anol' specifies where the hydroxyl group is placed on the carbon chain. For instance, the '3' in 3-hexanol tells you that the OH is attached to the third carbon atom. Paying attention to these details helps in drawing and understanding chemical structures accurately.

Bonding in Compounds

Bonding in chemical compounds is an essential concept in understanding molecular structures. Carbon's ability to form four covalent bonds with other atoms allows it to create diverse and complex molecules.
For instance:

• Carbon forms single, double, and even triple bonds with itself and other elements.
• Single bonds are represented by a single line, while double and triple bonds use double or triple lines, respectively.

Oxygen in alcohols typically forms two bonds, one associated with the carbon and the other with hydrogen. Hydrogen usually forms just one bond. In creating line structures, ensuring that each atom forms the correct number of bonds is crucial. Balancing these bonds ensures stability in the molecule, reflecting the actual chemical behavior of the compound. Properly drawn line structures can provide a simple yet complete view of a compound's molecular formge an understanding of how different atoms fit together within a molecule.