Write all the isomers for the simplest alkane having only one 4 (deg.), one 3 (deg.) and one 2 (deg.) carbons.

To tackle your question about the isomers of the simplest alkane with one 4-degree, one 3-degree, and one 2-degree carbon, we first need to clarify what we mean by these terms. In organic chemistry, the degree of a carbon atom refers to the number of other carbon atoms it is directly bonded to. A 4-degree carbon is bonded to four other carbons, a 3-degree carbon to three, and a 2-degree carbon to two. The simplest alkane that meets these criteria is butane (C4H10), which can exist in different structural forms known as isomers.

Identifying the Isomers of Butane

Butane has two structural isomers:

• n-Butane: This is the straight-chain form where all four carbon atoms are connected in a single line. The structure can be represented as:
• CH3-CH2-CH2-CH3
• Isobutane (or methylpropane): This is the branched form where three carbon atoms are in a chain, and one carbon is attached as a branch. The structure can be represented as:
• CH3-CH(CH3)-CH2-

Understanding the Structures

In n-butane, each carbon is connected in a linear fashion. The terminal carbons (the ones at each end) are 3-degree carbons because they are each bonded to two hydrogens and one carbon. The two middle carbons are 2-degree carbons, each bonded to two other carbons and two hydrogens. This arrangement allows for a simple, unbranched structure.

On the other hand, isobutane has a more complex structure. The central carbon is a 4-degree carbon because it is bonded to three other carbons and one hydrogen. The two terminal carbons are still 3-degree carbons, while the branching introduces a different arrangement of hydrogen atoms, leading to a different physical and chemical behavior compared to n-butane.

Conclusion on Isomers

In summary, the simplest alkane that fits your criteria is butane, which has two isomers: n-butane and isobutane. Each isomer has distinct properties and structures, showcasing the diversity of organic compounds even among simple alkanes. Understanding these variations is crucial for grasping more complex organic chemistry concepts.