Weekly plan 3
Carbonyl compounds
Student book links
Specification links
Link to AS specification
Suggested time allowed (includes contact and non-contact time):
• 1.1.9–12
• 4.1.2 (a)–(f)
• 2.2.1 Alcohols
Four to five hours
Suggested teaching order
Weekly learning outcomes
Students should be able to:
•
Recognise and name aldehydes and ketones.
•
Describe the oxidation of primary alcohols to form aldehydes and carboxylic acids.
•
Describe the oxidation of secondary alcohols to form ketones.
•
Describe the oxidation of aldehydes to form carboxylic acids.
•
Describe the use of 2,4-dinitrophenylhydrazine (2,4-DNPH) to detect and identify a carbonyl
compound.
•
Describe the use of Tollens’ reagent to detect the presence of an aldehyde group.
•
Describe the reduction of carbonyl compounds to form alcohols.
•
Outline the mechanism for nucleophilic addition reactions of aldehydes and ketones with
hydride.
Key words
Aldehyde
Functional group
Electronegativity
Carbonyl
How Science Works
Ketone
Stem redox
Suffix
Reflux
Recrystallisation
Nucleophile
2,4-DNPH
Tollens’ reagent
Addition
Hydride ion
Oxidation
Reduction
Distillation
Learning styles (S = Starter activities, M = Main activities, P = Plenary activities)
Kinaesthetic
Activities S1–3
Activities M1–3
Activities P1&3
1. The carbonyl group and the difference between aldehydes
and ketones
2. The oxidation of primary alcohols to aldehydes and carboxylic
acids
3. The oxidation of secondary alcohols to ketones
4. The oxidation of aldehydes to carboxylic acids
5. The reduction of aldehydes and ketones
6. The mechanism for the reaction of carbonyls with the H– ion
in NaBH4
7. The use of 2,4-DNPH to detect and identify carbonyl
compounds
8. The use of Tollens’ reagent to distinguish between aldehydes
and ketones
Interpersonal
Activity S2
Activities M1–3
Activities P1–3
Auditory
Activity S3
Activities M1–3
Activities P1&3
Visual
Activities S1&3
Activities M1–3
Activity P1
•
•
HSW 1 & 4 The mechanism for nucleophilic addition
HSW 5a & b Testing for and differentiating between
aldehydes and ketones
ICT activities
•
Prepare a PowerPoint presentation to show the nucleophilic
addition reaction between carbonyls and the H– ion.
The web links referred to here are some that the author has found personally helpful but are not intended to be a comprehensive list, many other
good resources exist.
© Pearson Education Ltd 2009
This document may have been altered from the original
1
Weekly plan 3
Suggested starter activities
Equipment
Teacher notes
1. Play What am I?
Cards with names or structures on them
Students must correctly identify them as aldehydes or
ketones.
2. Play Pairs.
Same cards as above, but each name
has a matching structure on another card.
Students play Snap or try to pair up the structure with the
corresponding name.
3. Use molecular models to show the difference between
aldehydes and ketones.
Molecular model kits
Can also be used to practise naming carbonyl compounds.
Suggested main activities
Equipment
Teacher notes
1. Practical activity 2: The characteristic test for a carbonyl
compound and the use of the 2,4-DNPH derivative to identify
an unknown carbonyl compound
See technician worksheet.
See teacher worksheet.
2. Practical activity 3: Oxidation and reduction reactions of
carbonyl compounds
See technician worksheet.
See teacher worksheet.
3. In groups, students produce a flow sheet to distinguish
between aldehydes, ketones and alcohols via simple chemical
tests.
Carboxylic acids and esters may also be added.
Suggested plenary activities
Equipment
Teacher notes
1. Students deliver their PowerPoint presentations.
Data projector
Again, the nucleophile and the carbonyl can be replaced
with others.
2. Devise a key word quiz.
Cards containing key words from the last
three weekly plans
Divide students into pairs or small groups, they then take
turns to draw a card and must explain the word on the card.
3. Play Beach ball game.
Large, plain beach ball
Write keywords from this topic on the ball; more are added
from lesson to lesson. Students sit in a circle and throw the
ball to a friend – the recipient has to explain the word
nearest their right thumb.
© Pearson Education Ltd 2009
This document may have been altered from the original
2
Weekly plan 3
Homework suggestions
• Construct a table that compares and contrasts the key properties of aldehydes and ketones.
• Draw alcohol structures and their oxidation product when given a variety of alcohol names (primary, secondary and tertiary).
• Compare reactions of non-polar C=C bond with the polar carbonyl bond.
Cross-curriculum links
• Biology – reducing sugars that are aldehydes
Stretch and Challenge
• Research how the 2,4-DNPH test was used to identify the alkenes in naturally-occurring rubbers via ozonolysis.
• Research other nucleophilic addition reactions of aldehydes and ketones.
Potential misconceptions
• Students find it difficult to distinguish between aldehydes and ketones – if there is at least one hydrogen attached to the carbonyl carbon then it is an aldehyde.
• In structures, aldehydes are written as –CHO and an alcohol as –CHOH.
Notes
© Pearson Education Ltd 2009
This document may have been altered from the original
3