Oxidation-and-Reduction-in-Aldehydes-Ketones-and-Carboxylic-Acids (1).pptx

Oxidation-and-Reduction-in-Aldehydes-Ketones-and-Carboxylic-Acids (1).pptx

1. Oxidation and Reduction in Aldehydes, Ketones, and Carboxylic Acids Exploring chemical transformations in organic functional groups

2. Identifying Functional Groups Aldehydes Contain the -CHO group at the end of carbon chains. Examples include formaldehyde and acetaldehyde. Ketones Feature the C=O group within the carbon chain. Common examples are acetone and butanone. Carboxylic Acids Distinguished by the -COOH group, including acetic acid and benzoic acid.

3. Learning Objective By the end of this lesson, you will be able to: Identify oxidation and reduction reactions in aldehydes and ketones Write balanced chemical equations for these transformations Explain the mechanisms behind these important organic reactions Apply your knowledge to solve practical chemistry problems

4. Understanding Oxidation and Reduction Oxidation Addition of oxygen atoms OR removal of hydrogen atoms from a molecule. Results in increased oxidation state. Memory tip: OIL - Oxidation Is Loss (of electrons/hydrogen) Reduction Addition of hydrogen atoms OR removal of oxygen atoms from a molecule. Results in decreased oxidation state. Memory tip: RIG - Reduction Is Gain (of electrons/hydrogen)

5. Oxidation of Aldehydes and Ketones Aldehydes undergo oxidation easily, while ketones are resistant Aldehyde Oxidation R-CHO + [O] → R-COOH Example: CH₃CHO + [O] → CH₃COOH Acetaldehyde becomes acetic acid Ketone Resistance Ketones resist oxidation under normal conditions due to their structural stability Harsh conditions required to break C-C bonds

6. Question Time: Identify the Reactions Analyse these equations: 1. CH₃CH₂CHO + [O] → CH₃CH₂COOH2. HCHO + [O] → HCOOH3. CH₃COCH₃ + [O] → No reaction Which compounds are being oxidised? What products are formed? Think and discuss: Why do aldehydes oxidise easily whilst ketones don't?

7. Tollens' Test for Aldehydes The Tollens' test specifically identifies aldehydes by producing a distinctive silver mirror coating inside the test tube when aldehydes react with Tollens' reagent. 01 Add Tollens' Reagent Mix aldehyde sample with ammoniacal silver nitrate solution 02 Gentle Heating Warm the mixture carefully in a water bath 03 Observe Silver Mirror Positive test shows shiny silver coating on glass surface

8. Reduction of Aldehydes and Ketones Both aldehydes and ketones can be reduced using appropriate reducing agents like sodium borohydride (NaBH₄) or lithium aluminium hydride (LiAlH₄). 1 Aldehyde → Primary Alcohol R-CHO + 2[H] → R-CH₂OH Example: CH₃CHO + 2[H] → CH₃CH₂OH 2 Ketone → Secondary Alcohol R-CO-R' + 2[H] → R-CHOH-R' Example: CH₃COCH₃ + 2[H] → CH₃CHOHCH₃

9. Group Activity: Choice Board Challenge Select one activity from each row to explore oxidation and reduction reactions: Experiment Design Design an experiment to distinguish between aldehydes and ketones using oxidising agents Mechanism Explanation Create a visual presentation explaining why aldehydes oxidise more readily than ketones Equation Balancing Balance complex redox equations involving organic compounds and explain electron transfer

10. Assessment and Plenary Fill in the blanks: 1. Aldehydes can be oxidised to form _______ 2. The functional group in ketones is _______ 3. Tollens' test produces a _______ mirror Challenge Questions: Explain why primary alcohols can be oxidised to aldehydes, then to carboxylic acids Compare the ease of oxidation in aldehydes versus ketones Predict the products when propanal undergoes reduction Plenary Summary: Today we explored how aldehydes readily undergo oxidation whilst ketones resist it, and how both can be reduced to form alcohols.