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

21. Aldehydes and Ketones: Nucleophilic Addition

DIBAL

Organic Chemistry

21. Aldehydes and Ketones: Nucleophilic Addition

DIBAL

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5:20 minutes

Problem 56d

Textbook Question

Show how you would synthesize octanal from each compound. You may use any necessary reagents.
(d) 1-bromoheptane

Verified step by step guidance

Identify the target molecule (octanal) and the starting material (1-bromoheptane). Octanal is an aldehyde with an eight-carbon chain, while 1-bromoheptane is a seven-carbon alkyl halide. The goal is to add one carbon to the chain and introduce the aldehyde functional group.

Perform a nucleophilic substitution reaction to replace the bromine atom in 1-bromoheptane with a cyanide group (-CN). Use a reagent like sodium cyanide (NaCN) in a polar aprotic solvent (e.g., DMSO). This will yield heptanenitrile (C7H15CN).

Hydrolyze the nitrile group (-CN) in heptanenitrile to a carboxylic acid (-COOH). Use acidic hydrolysis (e.g., H2O, H2SO4, and heat) to convert the nitrile into heptanoic acid (C7H15COOH).

Perform a one-carbon homologation to extend the carbon chain by one carbon. Use a reagent like thionyl chloride (SOCl2) to convert heptanoic acid into heptanoyl chloride (C7H15COCl). Then, react heptanoyl chloride with diazomethane (CH2N2) to form an intermediate that rearranges to octanoic acid (C8H16O2).

Reduce the octanoic acid to octanal. Use a selective reducing agent like diisobutylaluminum hydride (DIBAL-H) at low temperature to reduce the carboxylic acid group (-COOH) to an aldehyde (-CHO), yielding octanal.

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Key Concepts

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

Nucleophilic Substitution

Nucleophilic substitution is a fundamental reaction in organic chemistry where a nucleophile replaces a leaving group in a molecule. In the case of synthesizing octanal from 1-bromoheptane, a nucleophile such as a hydride ion (from a reducing agent like lithium aluminum hydride) can attack the carbon atom bonded to the bromine, leading to the formation of an alcohol intermediate that can be further oxidized to yield octanal.

Oxidation-Reduction Reactions

Oxidation-reduction (redox) reactions involve the transfer of electrons between species, resulting in changes in oxidation states. In the synthesis of octanal, after converting 1-bromoheptane to an alcohol, the alcohol can be oxidized using reagents like potassium dichromate or PCC to form the aldehyde, octanal. Understanding the principles of oxidation is crucial for manipulating functional groups in organic synthesis.

Functional Group Interconversion

Functional group interconversion refers to the transformation of one functional group into another, which is essential in organic synthesis. In this case, converting the alkyl bromide (1-bromoheptane) to an aldehyde (octanal) involves first converting the bromide to an alcohol and then oxidizing that alcohol. Mastery of these transformations allows chemists to design synthetic pathways to target molecules.

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