Solved Naming Alkynes worksheet #2 Draw the structural | Chegg.com - Free Printable

To solve the problem, we need to draw the structural formulas for the given alkynes based on their IUPAC names. Let's go through each compound step by step.

---

1. 3-ethyl-1-pentyne

#### Step 1: Identify the parent chain
- The parent chain is a pentane (5-carbon chain) with a triple bond.
- The suffix "-yne" indicates a triple bond.
- The triple bond is located at carbon 1 (as indicated by "1-pentyne").

#### Step 2: Add the substituent
- The substituent is an ethyl group (–CH₂CH₃).
- The ethyl group is located at carbon 3 (as indicated by "3-ethyl").

#### Step 3: Draw the structure
- Start with a 5-carbon chain.
- Place the triple bond between C1 and C2.
- Attach the ethyl group to C3.

The structural formula is:
```
CH₃
|
H-C≡C-CH₂-CH(CH₂CH₃)-CH₃
1 2 3 4 5
```

---

2. 3,3-dimethyl-1-butyne

#### Step 1: Identify the parent chain
- The parent chain is a butane (4-carbon chain) with a triple bond.
- The suffix "-yne" indicates a triple bond.
- The triple bond is located at carbon 1 (as indicated by "1-butyne").

#### Step 2: Add the substituents
- There are two methyl groups (–CH₃).
- Both methyl groups are located at carbon 3 (as indicated by "3,3-dimethyl").

#### Step 3: Draw the structure
- Start with a 4-carbon chain.
- Place the triple bond between C1 and C2.
- Attach two methyl groups to C3.

The structural formula is:
```
CH₃
|
H-C≡C-CH(CH₃)₂-CH₃
1 2 3 4
```

---

3. 4,4,5-trimethyl-2-hexyne

#### Step 1: Identify the parent chain
- The parent chain is a hexane (6-carbon chain) with a triple bond.
- The suffix "-yne" indicates a triple bond.
- The triple bond is located at carbon 2 (as indicated by "2-hexyne").

#### Step 2: Add the substituents
- There are three methyl groups (–CH₃).
- Two methyl groups are located at carbon 4, and one methyl group is located at carbon 5 (as indicated by "4,4,5-trimethyl").

#### Step 3: Draw the structure
- Start with a 6-carbon chain.
- Place the triple bond between C2 and C3.
- Attach two methyl groups to C4 and one methyl group to C5.

The structural formula is:
```
CH₃
|
H₂C=CH-CH₂-C(CH₃)₂-CH(CH₃)-CH₃
1 2 3 4 5 6
```

---

4. 4-ethyl-4-methyl-2-pentyne

#### Step 1: Identify the parent chain
- The parent chain is a pentane (5-carbon chain) with a triple bond.
- The suffix "-yne" indicates a triple bond.
- The triple bond is located at carbon 2 (as indicated by "2-pentyne").

#### Step 2: Add the substituents
- There are two substituents: an ethyl group (–CH₂CH₃) and a methyl group (–CH₃).
- Both substituents are located at carbon 4 (as indicated by "4-ethyl-4-methyl").

#### Step 3: Draw the structure
- Start with a 5-carbon chain.
- Place the triple bond between C2 and C3.
- Attach an ethyl group and a methyl group to C4.

The structural formula is:
```
CH₃
|
H₂C=CH-CH₂-C(CH₃)(CH₂CH₃)-CH₃
1 2 3 4 5
```

---

Final Answers

1. 3-ethyl-1-pentyne:
```
CH₃
|
H-C≡C-CH₂-CH(CH₂CH₃)-CH₃
1 2 3 4 5
```

2. 3,3-dimethyl-1-butyne:
```
CH₃
|
H-C≡C-CH(CH₃)₂-CH₃
1 2 3 4
```

3. 4,4,5-trimethyl-2-hexyne:
```
CH₃
|
H₂C=CH-CH₂-C(CH₃)₂-CH(CH₃)-CH₃
1 2 3 4 5 6
```

4. 4-ethyl-4-methyl-2-pentyne:
```
CH₃
|
H₂C=CH-CH₂-C(CH₃)(CH₂CH₃)-CH₃
1 2 3 4 5
```

Boxed Final Answer

\[
\boxed{
\begin{aligned}
1. & \quad \text{CH₃} \\
& \quad \text{|} \\
& \quad \text{H-C≡C-CH₂-CH(CH₂CH₃)-CH₃} \\
& \quad \text{1 2 3 4 5} \\
2. & \quad \text{CH₃} \\
& \quad \text{|} \\
& \quad \text{H-C≡C-CH(CH₃)₂-CH₃} \\
& \quad \text{1 2 3 4} \\
3. & \quad \text{CH₃} \\
& \quad \text{|} \\
& \quad \text{H₂C=CH-CH₂-C(CH₃)₂-CH(CH₃)-CH₃} \\
& \quad \text{1 2 3 4 5 6} \\
4. & \quad \text{CH₃} \\
& \quad \text{|} \\
& \quad \text{H₂C=CH-CH₂-C(CH₃)(CH₂CH₃)-CH₃} \\
& \quad \text{1 2 3 4 5} \\
\end{aligned}
}
\]