Nomenclature-Alkanes - Free Printable
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Step-by-step solution for: Nomenclature-Alkanes
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Show Answer Key & Explanations
Step-by-step solution for: Nomenclature-Alkanes
To find the correct answer, we need to determine the IUPAC name for each molecule shown in the image. Let's break them down one by one.
1. Analyze Molecule A:
* Structure: It is a straight chain with branches.
* Longest Chain: Counting the carbons in the longest continuous chain gives us 6 carbons (hexane).
* Numbering: We number from left to right to give the branches the lowest numbers.
* Carbon 2 has a methyl group ($CH_3$).
* Carbon 4 has a methyl group ($CH_3$).
* Name: 2,4-dimethylhexane.
2. Analyze Molecule B:
* Structure: Straight chain with branches.
* Longest Chain: 7 carbons (heptane).
* Numbering: Numbering from left to right gives substituents at positions 2, 3, and 5.
* Carbon 2: methyl
* Carbon 3: methyl
* Carbon 5: methyl
* Name: 2,3,5-trimethylheptane.
3. Analyze Molecule C:
* Structure: Straight chain with branches.
* Longest Chain: 8 carbons (octane).
* Numbering: Numbering from left to right.
* Carbon 2: methyl
* Carbon 4: methyl
* Carbon 6: methyl
* Name: 2,4,6-trimethyloctane.
4. Analyze Molecule D:
* Structure: Branched alkane.
* Longest Chain: If we trace the longest path, it goes from the top ethyl group down to the bottom right. That is 5 carbons (pentane).
* Numbering: Numbering from the top/left side gives lower numbers.
* Carbon 2: ethyl group
* Carbon 3: methyl group
* Carbon 4: methyl group
* Name: 2-ethyl-3,4-dimethylpentane.
5. Analyze Molecule E:
* Structure: Branched alkane.
* Longest Chain: 5 carbons (pentane).
* Numbering: Numbering from left to right.
* Carbon 2: methyl
* Carbon 3: methyl
* Carbon 4: ethyl? No, let's look closer. The main chain is actually horizontal.
* Left end: Isopropyl-like start. Let's trace carefully.
* Longest chain is 5 carbons.
* At C2: methyl. At C3: methyl. At C4: ethyl? No, looking at structure E: It looks like 2,3-dimethylpentane but with an ethyl group? Let's re-examine.
* Actually, let's look at the options usually provided for this specific set of molecules. Often these questions ask to identify a specific isomer or name. Since there is no specific question text like "Which one is...", I will assume the task is simply to identify the names or perhaps find a match if this were a multiple choice question. However, without a specific question prompt (e.g., "Find the isomer of..."), I will provide the systematic name for each to ensure accuracy.
* Let's re-evaluate E: Longest chain is 5. Substituents: 2-methyl, 3-methyl. Wait, the group on the right is an ethyl group attached to the chain? No, it's a sec-butyl group attached to an isopropyl?
* Let's trace the longest chain in E again. Start left: $CH_3-CH(CH_3)-CH(CH_3)-CH_2-CH_3$. That is 2,3-dimethylpentane.
6. Analyze Molecule F:
* Structure: Cyclohexane ring with two methyl groups on the same carbon.
* Name: 1,1-dimethylcyclohexane.
7. Analyze Molecule G:
* Structure: Straight chain.
* Longest Chain: 6 carbons (hexane).
* Numbering: Symmetrical. Methyls at 2 and 5.
* Name: 2,5-dimethylhexane.
8. Analyze Molecule H:
* Structure: Straight chain.
* Longest Chain: 6 carbons (hexane).
* Numbering: Ethyl at 3, Methyl at 3? No.
* Chain: $CH_3-CH_2-CH(CH_3)-CH(C_2H_5)-CH_2-CH_3$? No, looking at H:
* It looks like 3-ethyl-2-methylpentane? Let's trace.
* Longest chain: 5 carbons.
* Pos 2: Methyl. Pos 3: Ethyl.
* Name: 3-ethyl-2-methylpentane.
9. Analyze Molecule I:
* Structure: Cyclopentane ring.
* Substituents: Two methyls at position 1, one ethyl at position 2.
* Name: 2-ethyl-1,1-dimethylcyclopentane.
10. Analyze Molecule J:
* Structure: Cyclohexane ring.
* Substituents: Two methyls at position 1.
* Name: 1,1-dimethylcyclohexane. (Note: This is identical to F).
11. Analyze Molecule K:
* Structure: Cyclopentane ring.
* Substituents: Two methyls at position 1, one ethyl at position 2.
* Name: 2-ethyl-1,1-dimethylcyclopentane. (Note: This is identical to I).
12. Analyze Molecule L:
* Structure: Short chain.
* Longest Chain: 4 carbons (butane).
* Substituents: Methyls at 2 and 3.
* Name: 2,3-dimethylbutane.
Conclusion:
Since the user did not specify a particular question (like "Which molecule is an isomer of X?" or "Name molecule A"), but simply uploaded the image with labels A-L, the most helpful response is to provide the IUPAC name for each labeled structure. This covers all potential homework questions related to naming these specific alkanes.
Here is the summary of names:
* A: 2,4-dimethylhexane
* B: 2,3,5-trimethylheptane
* C: 2,4,6-trimethyloctane
* D: 2-ethyl-3,4-dimethylpentane
* E: 2,3-dimethylpentane
* F: 1,1-dimethylcyclohexane
* G: 2,5-dimethylhexane
* H: 3-ethyl-2-methylpentane
* I: 2-ethyl-1,1-dimethylcyclopentane
* J: 1,1-dimethylcyclohexane
* K: 2-ethyl-1,1-dimethylcyclopentane
* L: 2,3-dimethylbutane
Final Answer:
A: 2,4-dimethylhexane
B: 2,3,5-trimethylheptane
C: 2,4,6-trimethyloctane
D: 2-ethyl-3,4-dimethylpentane
E: 2,3-dimethylpentane
F: 1,1-dimethylcyclohexane
G: 2,5-dimethylhexane
H: 3-ethyl-2-methylpentane
I: 2-ethyl-1,1-dimethylcyclopentane
J: 1,1-dimethylcyclohexane
K: 2-ethyl-1,1-dimethylcyclopentane
L: 2,3-dimethylbutane
1. Analyze Molecule A:
* Structure: It is a straight chain with branches.
* Longest Chain: Counting the carbons in the longest continuous chain gives us 6 carbons (hexane).
* Numbering: We number from left to right to give the branches the lowest numbers.
* Carbon 2 has a methyl group ($CH_3$).
* Carbon 4 has a methyl group ($CH_3$).
* Name: 2,4-dimethylhexane.
2. Analyze Molecule B:
* Structure: Straight chain with branches.
* Longest Chain: 7 carbons (heptane).
* Numbering: Numbering from left to right gives substituents at positions 2, 3, and 5.
* Carbon 2: methyl
* Carbon 3: methyl
* Carbon 5: methyl
* Name: 2,3,5-trimethylheptane.
3. Analyze Molecule C:
* Structure: Straight chain with branches.
* Longest Chain: 8 carbons (octane).
* Numbering: Numbering from left to right.
* Carbon 2: methyl
* Carbon 4: methyl
* Carbon 6: methyl
* Name: 2,4,6-trimethyloctane.
4. Analyze Molecule D:
* Structure: Branched alkane.
* Longest Chain: If we trace the longest path, it goes from the top ethyl group down to the bottom right. That is 5 carbons (pentane).
* Numbering: Numbering from the top/left side gives lower numbers.
* Carbon 2: ethyl group
* Carbon 3: methyl group
* Carbon 4: methyl group
* Name: 2-ethyl-3,4-dimethylpentane.
5. Analyze Molecule E:
* Structure: Branched alkane.
* Longest Chain: 5 carbons (pentane).
* Numbering: Numbering from left to right.
* Carbon 2: methyl
* Carbon 3: methyl
* Carbon 4: ethyl? No, let's look closer. The main chain is actually horizontal.
* Left end: Isopropyl-like start. Let's trace carefully.
* Longest chain is 5 carbons.
* At C2: methyl. At C3: methyl. At C4: ethyl? No, looking at structure E: It looks like 2,3-dimethylpentane but with an ethyl group? Let's re-examine.
* Actually, let's look at the options usually provided for this specific set of molecules. Often these questions ask to identify a specific isomer or name. Since there is no specific question text like "Which one is...", I will assume the task is simply to identify the names or perhaps find a match if this were a multiple choice question. However, without a specific question prompt (e.g., "Find the isomer of..."), I will provide the systematic name for each to ensure accuracy.
* Let's re-evaluate E: Longest chain is 5. Substituents: 2-methyl, 3-methyl. Wait, the group on the right is an ethyl group attached to the chain? No, it's a sec-butyl group attached to an isopropyl?
* Let's trace the longest chain in E again. Start left: $CH_3-CH(CH_3)-CH(CH_3)-CH_2-CH_3$. That is 2,3-dimethylpentane.
6. Analyze Molecule F:
* Structure: Cyclohexane ring with two methyl groups on the same carbon.
* Name: 1,1-dimethylcyclohexane.
7. Analyze Molecule G:
* Structure: Straight chain.
* Longest Chain: 6 carbons (hexane).
* Numbering: Symmetrical. Methyls at 2 and 5.
* Name: 2,5-dimethylhexane.
8. Analyze Molecule H:
* Structure: Straight chain.
* Longest Chain: 6 carbons (hexane).
* Numbering: Ethyl at 3, Methyl at 3? No.
* Chain: $CH_3-CH_2-CH(CH_3)-CH(C_2H_5)-CH_2-CH_3$? No, looking at H:
* It looks like 3-ethyl-2-methylpentane? Let's trace.
* Longest chain: 5 carbons.
* Pos 2: Methyl. Pos 3: Ethyl.
* Name: 3-ethyl-2-methylpentane.
9. Analyze Molecule I:
* Structure: Cyclopentane ring.
* Substituents: Two methyls at position 1, one ethyl at position 2.
* Name: 2-ethyl-1,1-dimethylcyclopentane.
10. Analyze Molecule J:
* Structure: Cyclohexane ring.
* Substituents: Two methyls at position 1.
* Name: 1,1-dimethylcyclohexane. (Note: This is identical to F).
11. Analyze Molecule K:
* Structure: Cyclopentane ring.
* Substituents: Two methyls at position 1, one ethyl at position 2.
* Name: 2-ethyl-1,1-dimethylcyclopentane. (Note: This is identical to I).
12. Analyze Molecule L:
* Structure: Short chain.
* Longest Chain: 4 carbons (butane).
* Substituents: Methyls at 2 and 3.
* Name: 2,3-dimethylbutane.
Conclusion:
Since the user did not specify a particular question (like "Which molecule is an isomer of X?" or "Name molecule A"), but simply uploaded the image with labels A-L, the most helpful response is to provide the IUPAC name for each labeled structure. This covers all potential homework questions related to naming these specific alkanes.
Here is the summary of names:
* A: 2,4-dimethylhexane
* B: 2,3,5-trimethylheptane
* C: 2,4,6-trimethyloctane
* D: 2-ethyl-3,4-dimethylpentane
* E: 2,3-dimethylpentane
* F: 1,1-dimethylcyclohexane
* G: 2,5-dimethylhexane
* H: 3-ethyl-2-methylpentane
* I: 2-ethyl-1,1-dimethylcyclopentane
* J: 1,1-dimethylcyclohexane
* K: 2-ethyl-1,1-dimethylcyclopentane
* L: 2,3-dimethylbutane
Final Answer:
A: 2,4-dimethylhexane
B: 2,3,5-trimethylheptane
C: 2,4,6-trimethyloctane
D: 2-ethyl-3,4-dimethylpentane
E: 2,3-dimethylpentane
F: 1,1-dimethylcyclohexane
G: 2,5-dimethylhexane
H: 3-ethyl-2-methylpentane
I: 2-ethyl-1,1-dimethylcyclopentane
J: 1,1-dimethylcyclohexane
K: 2-ethyl-1,1-dimethylcyclopentane
L: 2,3-dimethylbutane
Parent Tip: Review the logic above to help your child master the concept of naming alkanes worksheet.
