Solved Naming Alkenes Worksheet HyC-CH-CH=C-CH | Chegg.com - Free Printable

It looks like you've uploaded a "Naming Alkenes Worksheet" with several alkene structures and their corresponding IUPAC names. Some of the names are already filled in, and there appear to be some annotations (like circles around groups labeled "methyl" or "ethyl") to help identify substituents.

Let’s go through each structure carefully, verify the IUPAC naming, and explain the logic behind naming alkenes according to IUPAC rules.

---

🔹 IUPAC Rules for Naming Alkenes:

1. Find the longest carbon chain that includes the double bond.
2. Number the chain to give the double bond the lowest possible number.
3. Name the parent hydrocarbon by replacing the "-ane" suffix with "-ene".
4. Identify and name any substituents (alkyl groups).
5. Assign numbers to the substituents based on their position.
6. List substituents in alphabetical order (ignoring prefixes like di-, tri-).
7. Use hyphens to separate numbers from words, commas to separate numbers.

---

Let's analyze each compound:

---

1.

```
CH₃
|
H₃C–C≡C–CH₃
|
CH₃
```
Structure: A triple bond between C2 and C3 (not an alkene — it's an alkyne).
But the name written is: 2,3-dimethylbut-2-ene

⚠️ Error: This molecule has a triple bond, not a double bond. So it should be named as an alkyne, not an alkene.

Correct name: 2,3-dimethylbut-2-yne

✔ But since the worksheet says "Naming Alkenes", perhaps this is a typo in the structure? Or maybe it was meant to be a double bond?

If it were a double bond instead of a triple bond:
```
CH₃
|
H₃C–C=C–CH₃
|
CH₃
```
Then yes, it would be 2,3-dimethylbut-2-ene — correct.

So assuming it's a double bond, this name is correct.

---

2.

```
CH₃
|
H₃C–CH–CH=CH–CH₃
|
CH₃
```
Name given: 2,4-dimethylpent-2-ene

Let’s check:
- Longest chain with double bond: 5 carbons → pentene
- Double bond starts at C2 → pent-2-ene
- Substituents: methyl group on C2 and C4 → 2,4-dimethyl

Wait! But C2 already has a methyl group and is part of the double bond. That makes it a tertiary carbon.

But the carbon at C2 has:
- One H (if we assume standard bonding)
- CH₃ (methyl group)
- CH₃ (from left)
- Double bond to C3

That’s four bonds — okay.

But wait: C2 is sp² hybridized, so it can have only three atoms attached.

Actually, let’s write the full structure:
```
CH₃
|
CH₃–CH–CH=CH–CH₃
|
CH₃
```

Carbon 2 is bonded to:
- CH₃ (left)
- CH₃ (branch)
- CH (C3)
- H? Wait — that's four bonds. No!

Hold on: The carbon at position 2 is CH–, so it must have one hydrogen.

So structure:
- C1: CH₃–
- C2: CH(CH₃)– (so it has a methyl group)
- C3: =CH–
- C4: –CH(CH₃)–
- C5: –CH₃

Wait, no — the chain is:
- C1: CH₃–
- C2: CH(CH₃)–
- C3: =CH–
- C4: –CH(CH₃)–
- C5: –CH₃

But the double bond is between C2 and C3?

No — the double bond is between C3 and C4?

Wait, the structure shows:
```
H₃C–CH–CH=CH–CH₃
| |
CH₃ CH₃
```

So:
- C1: CH₃–
- C2: CH(CH₃)–
- C3: CH=
- C4: =CH–
- C5: –CH₃

And C4 also has a methyl group? No — the methyl is on C2 and C4?

Wait, the structure shows:
- On C2: one methyl group
- On C4: one methyl group

So:
- C1: CH₃–
- C2: CH(CH₃)–
- C3: CH=CH–
- C4: CH(CH₃)–
- C5: CH₃

But the double bond is between C3 and C4.

So the chain is: C1–C2–C3=C4–C5 → 5 carbons, double bond at C3-C4 → pent-3-ene

But we number to give the double bond the lowest number.

So if we number from right to left:
- C1' = original C5
- C2' = C4
- C3' = C3
- C4' = C2
- C5' = C1

Double bond between C2' and C3' → pent-2-ene

Substituents:
- Methyl on C2' (original C4)
- Methyl on C4' (original C2)

So: 2,4-dimethylpent-2-ene — same as before.

But now, C2' has a methyl group and is part of the double bond.

Is that valid? Yes.

So the name 2,4-dimethylpent-2-ene is correct.

✔ Correct.

---

3.

```
CH₃
|
H₃C–CH–CH–C≡CH
| |
CH₃ CH₂
|
CH₃
```

Wait — the structure shows:
- C1: H₃C–
- C2: CH–
- C3: CH–
- C4: C≡CH
- And branches: CH₃ on C2, CH₃ on C3, and CH₂–CH₃ on C4?

Wait — the drawing says:
```
CH₃
|
H₃C–CH–CH–C≡CH
| |
CH₃ CH₂
|
CH₃
```

So:
- C4 is C≡CH
- C3 is CH– with a CH₃
- C2 is CH– with a CH₃
- C1 is CH₃

And C3 has a CH₂–CH₃ group?

Wait — the branch on C3 is CH₂–CH₃ → ethyl

But the name written is: 3-ethyl-2,4-dimethylpent-1-ene

But the double bond is at C4≡C5? It’s a triple bond!

Again — this is an alkyne, not an alkene.

The name says “pent-1-ene” — but it has a triple bond.

So unless it’s a typo, this is wrong.

But the structure has a triple bond at the end: C≡CH

So it should be named as an alkyne.

Also, the chain includes the triple bond.

Longest chain: C1–C2–C3–C4≡C5 → 5 carbons

Numbering: triple bond at C4–C5 → but we want the lowest number.

So number from right: C1’ = C5, C2’ = C4, C3’ = C3, C4’ = C2, C5’ = C1

Triple bond between C1’ and C2’ → pent-1-yne

Now substituents:
- On C3’: CH₃ (on original C2)
- On C4’: CH₃ (on original C3)
- On C2’: CH₂–CH₃ (ethyl) → but wait, C2’ is the triple-bonded carbon?

No — C2’ is C4 (original), which is part of the triple bond.

But C4 (original) has a CH₂–CH₃ group? Yes.

So C2’ has a CH₂–CH₃ group → ethyl

But C2’ is part of the triple bond — can it have two substituents?

Yes — terminal alkyne: R–C≡C–H

But here: R–C≡C–H → but R is CH₂–CH₃?

Wait — no:

Original structure:
```
H₃C–CH–CH–C≡CH
| |
CH₃ CH₂
|
CH₃
```

So:
- C1: CH₃–
- C2: CH(CH₃)–
- C3: CH(CH₂CH₃)–
- C4: C≡CH

So C4 is ≡C–H, and has one bond to C3

So C4 is: C≡C–H → terminal alkyne

C3 is CH– with a CH₂CH₃ group

So chain: C1–C2–C3–C4≡C5 → 5 carbons

But C3 has an ethyl group → so total carbons: 7

But the longest chain including triple bond is 5 carbons.

So name: pent-1-yne with substituents

Substituents:
- On C2: methyl → 2-methyl
- On C3: ethyl → 3-ethyl

So: 3-ethyl-2-methylpent-1-yne

But the name given is 3-ethyl-2,4-dimethylpent-1-ene — which is wrong.

✘ Incorrect.

Also, it says “pent-1-ene” — should be “pent-1-yne”

And there is no methyl on C4 — C4 is C≡CH, so it has no methyl.

So the name is incorrect.

---

4.

```
CH₃
|
H₃C–CH–CH–CH–CH₃
| | |
CH₃ CH₃ CH₃
```

Wait — the structure is:
```
H₃C–CH–CH–CH–CH₃
| | |
CH₃ CH₃ CH₃
```

But the double bond is missing.

Wait — the name says: 3-ethyl-4-methylpent-2-ene

So double bond must be present.

Looking back: the structure shows:
```
H₃C–CH–CH=CH–CH₃
| |
CH₃ CH₃
```

Wait — no — the original drawing says:
```
H₃C–CH–CH=CH–CH₃
| |
CH₃ CH₃
```

But then the name is 3-ethyl-4-methylpent-2-ene

But there is no ethyl group — both branches are methyls.

So either:
- The name is wrong, or
- The structure is wrong.

Let’s recheck:

The structure shown is:
```
H₃C–CH–CH=CH–CH₃
| |
CH₃ CH₃
```

So:
- C1: CH₃–
- C2: CH(CH₃)–
- C3: CH=CH–
- C4: CH(CH₃)–
- C5: CH₃

Wait — C4 has a methyl group? Yes.

But the double bond is between C3 and C4.

So chain: C1–C2–C3=C4–C5 → 5 carbons → pentene

Double bond at C3–C4 → pent-3-ene

Number from right: C1'=C5, C2'=C4, C3'=C3, C4'=C2, C5'=C1

Double bond at C2'–C3' → pent-2-ene

Substituents:
- On C2': CH₃ (original C4)
- On C4': CH₃ (original C2)

So: 2,4-dimethylpent-2-ene

But the name written is 3-ethyl-4-methylpent-2-ene

This implies an ethyl group — but there is no ethyl.

So ✘ Incorrect name

Should be 2,4-dimethylpent-2-ene

---

5.

```
H₂C=CH–CH–CH–CH₃
| |
CH₃ CH₃
```

With a methyl on C3 and C4.

Wait — the structure shows:
```
H₂C=CH–CH–CH–CH₃
| |
CH₃ CH₃
```

So:
- C1: H₂C=
- C2: =CH–
- C3: CH(CH₃)–
- C4: CH(CH₃)–
- C5: CH₃

Double bond between C1 and C2 → pent-1-ene

Substituents:
- Methyl on C3 → 3-methyl
- Methyl on C4 → 4-methyl

So: 3,4-dimethylpent-1-ene

But the name written is: 3,4,4-trimethylpent-1-ene

There is only two methyl groups — one on C3, one on C4.

So why "trimethyl"? Unless there’s another methyl.

Wait — the drawing shows:
```
H₂C=CH–CH–CH–CH₃
| |
CH₃ CH₃
```

So only two methyls.

But the name says 3,4,4-trimethyl — implying two methyls on C4

But in the structure, C4 has only one methyl.

So ✘ Incorrect

Should be 3,4-dimethylpent-1-ene

---

6.

```
H₃C–CH–C=CH–CH₃
| | |
CH₃ CH₃ CH₃
```

Wait — the structure is:
```
H₃C–CH–C=CH–CH₃
| | |
CH₃ CH₃ CH₃
```

So:
- C1: CH₃–
- C2: CH(CH₃)–
- C3: C(CH₃)=
- C4: =CH–
- C5: CH₃

Double bond between C3 and C4

Chain: C1–C2–C3=C4–C5 → 5 carbons → pentene

Numbering: double bond at C3–C4 → pent-3-ene

But number from right: C1'=C5, C2'=C4, C3'=C3, C4'=C2, C5'=C1

Double bond at C2'–C3' → pent-2-ene

Substituents:
- On C3': CH₃ (original C3)
- On C4': CH₃ (original C2)
- On C3': also CH₃? Wait — C3 has two methyl groups?

Wait — C3 is C(CH₃)= — so it has a methyl group and is part of double bond.

But in the structure, C3 has:
- Bond to C2
- Bond to CH₃ (branch)
- Double bond to C4
- So only three bonds — needs fourth?

Wait — C3 is carbon with:
- C2
- CH₃
- =C4
- and what? Must have H?

But it’s written as C(CH₃)= — so likely it has a methyl group and is quaternary?

But carbon can't have five bonds.

Wait — the structure is:
```
H₃C–CH–C=CH–CH₃
| | |
CH₃ CH₃ CH₃
```

So C3 is:
- Bonded to C2
- Bonded to CH₃ (branch)
- Double bond to C4
- So only three bonds — missing one.

Ah — probably a typo.

Maybe it’s:
```
H₃C–CH–C(CH₃)=CH–CH₃
| |
CH₃ CH₃
```

Then C3 has:
- C2
- CH₃ (branch)
- CH₃ (another branch?)
- Double bond to C4

No — still too many.

Wait — perhaps:
```
H₃C–CH–C(CH₃)=CH–CH₃
| |
CH₃ CH₃
```

Then C3 has:
- C2
- CH₃ (branch)
- CH₃ (branch?) — no, only one methyl shown

Wait — the drawing shows:
- On C3: one CH₃
- On C4: one CH₃

So:
- C1: CH₃–
- C2: CH(CH₃)–
- C3: C(CH₃)=
- C4: =CH–
- C5: CH₃

But C3 has only three bonds: C2, CH₃, and double bond to C4 → missing one.

So unless it has a hydrogen, it’s invalid.

Perhaps it’s:
```
H₃C–CH–C(CH₃)=CH–CH₃
| |
CH₃ CH₃
```

Then C3 has:
- C2
- CH₃ (branch)
- CH₃ (branch?) — no, only one CH₃ shown

Wait — the drawing says:
```
H₃C–CH–C=CH–CH₃
| | |
CH₃ CH₃ CH₃
```

So:
- C2 has CH₃
- C3 has CH₃
- C4 has CH₃

So:
- C1: CH₃–
- C2: CH(CH₃)–
- C3: C(CH₃)=
- C4: =CH(CH₃)–
- C5: CH₃

Now C3 has:
- C2
- CH₃
- =C4
- and must have H → so it’s CH(CH₃)– but no — it’s C(CH₃)= — so it’s quaternary?

No — carbon can’t have four single bonds and a double bond.

A double bond counts as two bonds.

So C3 has:
- Single bond to C2
- Single bond to CH₃
- Double bond to C4 → total 4 bonds → okay

So C3 is sp² hybridized, has no H.

So structure:
- C1: CH₃–
- C2: CH(CH₃)–
- C3: C(CH₃)=
- C4: =CH(CH₃)–
- C5: CH₃

So chain: C1–C2–C3=C4–C5 → 5 carbons → pentene

Double bond at C3–C4 → pent-3-ene

Number from right: C1'=C5, C2'=C4, C3'=C3, C4'=C2, C5'=C1

Double bond at C2'–C3' → pent-2-ene

Substituents:
- On C3': CH₃ (original C3)
- On C4': CH₃ (original C2)
- On C2': CH₃ (original C4)

So:
- C2': methyl group → 2-methyl
- C3': methyl group → 3-methyl
- C4': methyl group → 4-methyl

So: 2,3,4-trimethylpent-2-ene

But the name written is 3,3-dimethylbut-1-ene

That’s completely different.

But the structure has 5 carbons in chain — but the name says "but-" → 4 carbons.

So ✘ Incorrect

Should be 2,3,4-trimethylpent-2-ene or something similar.

But the name given is wrong.

---

7.

```
H₃C–CH–CH–C=CH₂
| | |
CH₃ CH₃ CH₃
```

Wait — the structure is:
```
H₃C–CH–CH–C=CH₂
| | |
CH₃ CH₃ CH₃
```

So:
- C1: CH₃–
- C2: CH(CH₃)–
- C3: CH(CH₃)–
- C4: C(CH₃)=CH₂

Double bond between C4 and C5 → terminal

Chain: C1–C2–C3–C4=C5 → 5 carbons → pentene

Double bond at C4–C5 → pent-4-ene

But number from right: C1'=C5, C2'=C4, C3'=C3, C4'=C2, C5'=C1

Double bond at C1'–C2' → pent-1-ene

Substituents:
- On C2': CH₃ (original C4)
- On C3': CH₃ (original C3)
- On C4': CH₃ (original C2)

So: 3-ethyl-2,4-dimethylhex-1-ene — wait, name says that.

But chain is only 5 carbons — but name says "hex" → 6 carbons.

So inconsistency.

Wait — the structure shows:
- C1: CH₃–
- C2: CH(CH₃)–
- C3: CH(CH₃)–
- C4: C(CH₃)=CH₂

So C4 has a methyl group and is part of double bond.

So total carbons: 5 + 3 methyls = 8 carbons

But longest chain: C1–C2–C3–C4–C5 → 5 carbons

But if we go through the methyl on C4: C4–CH₃ → only 2 carbons

So longest chain is 5.

But the name says hex-1-ene — 6 carbons.

So ✘ Incorrect

Unless there’s a longer chain.

Wait — the structure might be:
```
H₃C–CH–CH–C=CH₂
| | |
CH₃ CH₃ CH₃
```

But C4 has a methyl group — so it's C(CH₃)=CH₂

So the chain is only 5 carbons.

But the name is 3-ethyl-2,4-dimethylhex-1-ene

That implies a 6-carbon chain.

So either the structure is wrong, or the name is wrong.

Possibly the structure has an ethyl group.

But in the drawing, all branches are methyl.

So ✘ Incorrect

---

8.

```
H₃C–CH–CH=CH–CH₃
| | |
CH₃ CH₃ CH₃
```

Wait — the structure is:
```
H₃C–CH–CH=CH–CH₃
| | |
CH₃ CH₃ CH₃
```

So:
- C1: CH₃–
- C2: CH(CH₃)–
- C3: CH(CH₃)=
- C4: =CH(CH₃)–
- C5: CH₃

Double bond between C3 and C4

Chain: C1–C2–C3=C4–C5 → 5 carbons → pentene

Numbering: double bond at C3–C4 → pent-3-ene

From right: C1'=C5, C2'=C4, C3'=C3, C4'=C2, C5'=C1 → double bond at C2'–C3' → pent-2-ene

Substituents:
- On C2': CH₃ (original C4)
- On C3': CH₃ (original C3)
- On C4': CH₃ (original C2)

So: 2,3,4-trimethylpent-2-ene

But the name written is 5,5-diethyl-2,2,3-trimethylhept-3-ene

That’s a 7-carbon chain — much longer.

So ✘ Incorrect

---

✔ Summary of Corrections:

| Structure | Given Name | Correct Name | Reason |
|---------|------------|--------------|-------|
| 1 | 2,3-dimethylbut-2-ene | 2,3-dimethylbut-2-ene | Correct (assuming double bond) |
| 2 | 2,4-dimethylpent-2-ene | 2,4-dimethylpent-2-ene | Correct |
| 3 | 3-ethyl-2,4-dimethylpent-1-ene | 3-ethyl-2-methylpent-1-yne | Has triple bond, not double; name should reflect alkyne |
| 4 | 3-ethyl-4-methylpent-2-ene | 2,4-dimethylpent-2-ene | No ethyl group |
| 5 | 3,4,4-trimethylpent-1-ene | 3,4-dimethylpent-1-ene | Only two methyl groups |
| 6 | 3,3-dimethylbut-1-ene | 2,3,4-trimethylpent-2-ene | Chain is 5 carbons, not 4 |
| 7 | 3-ethyl-2,4-dimethylhex-1-ene | 3,4-dimethylpent-1-ene | Chain is 5 carbons, not 6; no ethyl |
| 8 | 5,5-diethyl-2,2,3-trimethylhept-3-ene | 2,3,4-trimethylpent-2-ene | Chain is 5 carbons |

---

Final Answer:

The worksheet contains several incorrect names due to:
- Misidentifying double vs. triple bonds
- Incorrect chain length
- Wrong substituent identification
- Misnumbering

Only structures 1 and 2 are correctly named.

All others need correction.

Would you like me to redraw the correct structures and names?