# Solution: Drawing the Structure of 5,5,6,6-Tetramethyl-3-decyne ## Step 1: Analyze the Name - **Decyne:** 10-carbon alkyne (triple bond somewhere). - **3-decyne:** Triple bond between carbons 3 and 4. - **5,5,6,6-tetramethyl:** Four methyl groups, two on carbon 5 and two on carbon 6. ## Step 2: Draw the Main Chain The parent chain is decane (10 carbons, straight chain): ``` C1–C2–C3–C4–C5–C6–C7–C8–C9–C10 ``` ## Step 3: Place the Triple Bond A "3-decyne" means a triple bond between C3 and C4: ``` C1–C2–C≡C–C5–C6–C7–C8–C9–C10 3 4 ``` ## Step 4: Add the Methyl Groups - At **C5**: two methyl groups (–CH₃). - At **C6**: two methyl groups (–CH₃). ## Step 5: Assemble the Structure Below is the condensed structural formula: ``` CH3–CH2–C≡C–C(CH3)2–C(CH3)2–CH2–CH2–CH2–CH3 ``` Or, for clarity, number the carbons: 1. CH₃– (C1) 2. CH₂– (C2) 3. C≡ (C3) 4. C– (C4) 5. C(CH₃)₂– (C5, with two methyls) 6. C(CH₃)₂– (C6, with two methyls) 7. CH₂– (C7) 8. CH₂– (C8) 9. CH₂– (C9) 10. CH₃ (C10) ## Step 6: Draw the Structure Here’s a skeletal structure (line-bond): ``` CH3 CH3 | | CH3–CH2–C≡C–C–C–CH2–CH2–CH2–CH3 | | CH3 CH3 ``` *Alt text: Skeletal structure of 5,5,6,6-tetramethyl-3-decyne, showing a decyne backbone with two methyl groups each on carbons 5 and 6.* ## Step 7: Final Answer **Condensed formula:** `CH3–CH2–C≡C–C(CH3)2–C(CH3)2–CH2–CH2–CH2–CH3` **Skeletal structure:** See diagram above. --- **Summary:** 5,5,6,6-tetramethyl-3-decyne is a 10-carbon chain with a triple bond between C3 and C4, and two methyl branches on each of C5 and C6.