Certainly! Here is a step-by-step solution for **drawing the most stable conformation of 1-ethyl-4-propylcyclohexane** (considering both ring and substituent conformations), along with the explanation. --- ## **Step 1: Draw the Chair Conformation of Cyclohexane** The chair conformation is the most stable conformation of cyclohexane because it minimizes torsional and steric strain. --- ## **Step 2: Number the Cyclohexane Ring** Number the carbons so that the two substituents (ethyl and propyl) are at positions 1 and 4: - Place **ethyl** at C-1. - Place **propyl** at C-4. --- ## **Step 3: Place Substituents in Axial/Equatorial Positions** The stability of substituted cyclohexane depends on whether large groups are **axial** (up/down, more steric strain) or **equatorial** (out to the side, less steric strain). ### **Guidelines:** - Larger groups prefer the **equatorial position** to minimize 1,3-diaxial interactions. #### **Substituent Sizes:** - Propyl > Ethyl > Hydrogen --- ## **Step 4: Draw Both Possible Chair Conformations** ### **Case 1:** Ethyl at C-1 Equatorial, Propyl at C-4 Axial ### **Case 2:** Propyl at C-4 Equatorial, Ethyl at C-1 Axial --- ## **Step 5: Choose the Most Stable Conformation** Since **propyl** is larger than **ethyl**, the most stable conformation will have the larger group (**propyl**) in the **equatorial** position to reduce steric strain. - **C-1:** Ethyl (axial) - **C-4:** Propyl (equatorial) or - **C-1:** Ethyl (equatorial) - **C-4:** Propyl (axial) **The first choice (propyl equatorial) is more stable.** --- ## **Step 6: Draw the Most Stable Chair Conformation** Below is a schematic (please redraw neatly): ``` 1 (Ethyl, axial up) / \ 6 2 / \ 5 3 \ / 4 (Propyl, equatorial) ``` - Place **ethyl** at C-1 (axial up or down, depending on which chair is drawn). - Place **propyl** at C-4 (equatorial). ### **OR, more clearly:** - **C-1:** Ethyl (axial) - **C-4:** Propyl (equatorial) --- ## **Step 7: Explanation** - **Propyl group** is larger than the ethyl group. - Placing the **propyl group in the equatorial position** minimizes steric (1,3-diaxial) interactions, making this conformation the most stable. - The **ethyl group** will be forced into the **axial position**, but this is less destabilizing than having the propyl group axial. --- ## **Final Answer (Summary)** **The most stable conformation of 1-ethyl-4-propylcyclohexane is the chair conformation in which the larger propyl group is equatorial (at C-4) and the ethyl group is axial (at C-1). This minimizes steric interactions and is the most stable form.** --- **[Sketch for clarity:]** ``` Equatorial propyl at C-4, axial ethyl at C-1 ``` --- If you need a hand-drawn or digital image, let me know!