Question

Distinguish between primary, secondary and tertiary carbons.

Short answer

Primary, secondary, and tertiary carbons are classified based on the number of carbon atoms they are connected to in an organic molecule. Primary carbon (1°) is attached to one other carbon and three hydrogen atoms, secondary carbon (2°) is attached to two other carbon atoms and two hydrogen atoms, and tertiary carbon (3°) is attached to three other carbon atoms and one hydrogen atom. In butane, the terminal carbon atoms are primary carbons, and the middle carbon atoms are secondary carbons. In isobutane, the central carbon atom is a tertiary carbon.

Step-by-step solution

Define primary, secondary, and tertiary carbons

Primary, secondary, and tertiary carbons are used to classify carbon atoms in an organic molecule based on the number of other carbon atoms they are connected to. 1. Primary carbon (1°): A carbon atom that is attached to only one other carbon atom and three hydrogen atoms. 2. Secondary carbon (2°): A carbon atom that is attached to two other carbon atoms and two hydrogen atoms. 3. Tertiary carbon (3°): A carbon atom that is attached to three other carbon atoms and one hydrogen atom. Now, let's illustrate each type of carbon using examples.

Identify primary carbons

To identify a primary carbon, look for carbon atoms that are connected to only one other carbon atom and three hydrogen atoms. Example: In butane (C₄H₁₀), the molecule is structured as CH₃-CH₂-CH₂-CH₃. The terminal carbon atoms (the leftmost and rightmost ones) are primary carbons because they are each connected to one other carbon atom and three hydrogen atoms.

Identify secondary carbons

To identify a secondary carbon, look for carbon atoms that are connected to two other carbon atoms and two hydrogen atoms. Example: Continuing with butane (C₄H₁₀), the molecule is structured as CH₃-CH₂-CH₂-CH₃. The middle two carbon atoms are secondary carbons because they are each connected to two other carbon atoms and two hydrogen atoms.

Identify tertiary carbons

To identify a tertiary carbon, look for carbon atoms that are connected to three other carbon atoms and one hydrogen atom. Example: In isobutane (C₄H₁₀), the molecule is structured as: CH₃ | CH₃-C-CH₃ | H The central carbon atom is a tertiary carbon because it is connected to three other carbon atoms and one hydrogen atom. Following the above method, you can easily identify primary, secondary, and tertiary carbons in any given organic molecule.

Key concepts

Primary Carbon

When we talk about primary carbon atoms, we're referring to carbon atoms that are connected to just one other carbon atom. These are also attached to three hydrogen atoms. In simpler terms, they're the end-point or the first contact point in various organic molecules.
Think of a primary carbon as a lone player who has only one teammate.

• Example: In the molecule of butane (C₄H₁₀), the ends of the molecule, usually written as CH₃, possess primary carbons.
• Structure: CH₃-CH₂-CH₂-CH₃

Secondary Carbon

Secondary carbon atoms are the next step up. They connect to two other carbon atoms and two hydrogen atoms. Secondary carbons serve as the link in the middle of chains. They are like a player with two teammates, taking the position between them.
If you are looking at a chain of carbon atoms, secondary carbons are the ones in the middle.

• Example: Again, in butane (C₄H₁₀), the two carbon atoms between the end two are secondary carbons.
• Structure: CH₃-CH₂-CH₂-CH₃

Tertiary Carbon

Tertiary carbons are those special carbon atoms connected to three other carbon atoms, with only one hydrogen attached. They are central hubs in molecules, quite literally at the heart of the action.
These carbon atoms have the luxury of forming connections with three different carbon neighbors, resembling a player at the center of a triangle in a team, linking everyone together.

• Example: In isobutane (C₄H₁₀), the central carbon with structure CH₃-C-CH₃ and an OH attached, represents a tertiary carbon.
• Structure: CH₃
  |
  CH₃-C-CH₃
  |
  H

Organic Molecule

An organic molecule is a compound primarily composed of carbon atoms, often bonded with hydrogen, oxygen, nitrogen, and other elements. They are the backbone of life processes, forming the structures of proteins, carbohydrates, and many other life-critical compounds.
In the world of chemistry, organic molecules are plentiful and incredibly diverse, from simple methane molecules to complex arrangements like proteins.

• They are key players in everything from fuels to pharmaceuticals.
• Their classification depends heavily on the carbon atoms' arrangement.

Carbon Atoms

Carbon atoms are fundamental building blocks in chemistry, especially in organic compounds. Their ability to form four bonds makes them incredibly versatile and central to diverse compounds.
Within an organic molecule, carbon atoms form the main skeleton or framework.

• They can form chains, rings, and complex three-dimensional structures.
• This versatility gives rise to endless varieties of organic molecules, each with unique properties.
• Understanding carbon atoms is key to grasping how different organic molecules are classified and behave.