Table of contents

1. A Review of General Chemistry5h 5m
2. Molecular Representations1h 14m
3. Acids and Bases2h 46m
4. Alkanes and Cycloalkanes4h 17m
5. Chirality3h 39m
6. Thermodynamics and Kinetics1h 22m
7. Substitution Reactions1h 48m
8. Elimination Reactions2h 30m
9. Alkenes and Alkynes2h 9m
10. Addition Reactions3h 19m
11. Radical Reactions1h 58m
12. Alcohols, Ethers, Epoxides and Thiols2h 42m
13. Alcohols and Carbonyl Compounds2h 17m
14. Synthetic Techniques1h 26m
15. Analytical Techniques:IR, NMR, Mass Spect7h 3m
16. Conjugated Systems6h 13m
17. Ultraviolet Spectroscopy51m
18. Aromaticity2h 34m
19. Reactions of Aromatics: EAS and Beyond5h 1m
20. Phenols55m
21. Aldehydes and Ketones: Nucleophilic Addition4h 56m
22. Carboxylic Acid Derivatives: NAS2h 51m
23. The Chemistry of Thioesters, Phophate Ester and Phosphate Anhydrides1h 10m
24. Enolate Chemistry: Reactions at the Alpha-Carbon1h 53m
25. Condensation Chemistry2h 9m
26. Amines1h 43m
27. Heterocycles2h 0m
28. Carbohydrates5h 53m
29. Amino Acids4h 20m
30. Peptides and Proteins2h 42m
31. Catalysis in Organic Reactions1h 30m
32. Lipids 2h 50m
33. The Organic Chemistry of Metabolic Pathways2h 52m
34. Nucleic Acids1h 32m
35. Transition Metals6h 14m
36. Synthetic Polymers1h 49m

4. Alkanes and Cycloalkanes

Naming Alkenes

Organic Chemistry

4. Alkanes and Cycloalkanes

Naming Alkenes

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5:56 minutes

Problem 30a,b

Textbook Question

Draw a condensed structure for each of the following:
a. 2-hexyne
b. 5-ethyl-3-octyne

Verified step by step guidance

Step 1: Understand the naming conventions of alkynes. Alkynes are hydrocarbons containing a triple bond between two carbon atoms. The name indicates the position of the triple bond and any substituents attached to the main chain.

Step 2: For part (a), identify the structure of 2-hexyne. The 'hex-' prefix indicates a six-carbon chain, and the '2-' indicates the triple bond is located between the second and third carbons. Write the condensed structure starting with CH₃ for the first carbon, followed by CH for the second carbon (part of the triple bond), then C≡C for the triple bond, and finally CH₂ and CH₃ for the remaining carbons.

Step 3: For part (b), identify the structure of 5-ethyl-3-octyne. The 'oct-' prefix indicates an eight-carbon chain, and the '3-' indicates the triple bond is located between the third and fourth carbons. The '5-ethyl' indicates an ethyl group (-CH₂CH₃) is attached to the fifth carbon. Begin by writing the main chain with the triple bond at the correct position, then add the ethyl group to the fifth carbon.

Step 4: Ensure the condensed structures are written correctly. For 2-hexyne, the structure should reflect the six-carbon chain with the triple bond at the second position. For 5-ethyl-3-octyne, the structure should reflect the eight-carbon chain with the triple bond at the third position and the ethyl group attached to the fifth carbon.

Step 5: Double-check the structures for accuracy, ensuring the correct number of hydrogens are added to each carbon to satisfy the valency of carbon (four bonds per carbon atom).

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Alkynes

Alkynes are a class of hydrocarbons characterized by at least one carbon-carbon triple bond. They follow the general formula CnH2n-2, where 'n' is the number of carbon atoms. The presence of the triple bond gives alkynes unique properties, including increased reactivity compared to alkenes and alkanes. Understanding the structure and bonding in alkynes is essential for drawing their condensed structures.

Condensed Structural Formula

A condensed structural formula is a way of representing a chemical structure that shows the arrangement of atoms in a molecule without depicting all the bonds explicitly. In this format, groups of atoms are often grouped together to simplify the representation. For example, in 2-hexyne, the condensed formula can be written as CH3C≡CCH2CH2CH3, indicating the positions of the triple bond and the carbon chain.

Nomenclature of Organic Compounds

The nomenclature of organic compounds follows specific rules set by the International Union of Pure and Applied Chemistry (IUPAC). This system provides a standardized way to name compounds based on their structure, including the longest carbon chain, functional groups, and substituents. For instance, in 5-ethyl-3-octyne, the name indicates a carbon chain of eight carbons with an ethyl group at the fifth position and a triple bond starting at the third carbon.

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