OCR A Level Chemistry A TEP€¦ · Web viewThis Topic Exploration Pack supports OCR A Level Chemistry A. When distributing the activity section to the students either as a printed

Topic Exploration Pack

Organic Synthesis

Instructions and answers for teachers.....................................................................................1

Introduction.......................................................................................................................2

Suggested activities..........................................................................................................4

Answers for teachers........................................................................................................6

Learner Activity......................................................................................................................18

Activity 1 – Identifying functional groups.........................................................................18

Activity 3 – Two-step synthesis.......................................................................................21

Activity 4 – Test-yourself questions................................................................................24

Instructions and answers for teachers

These instructions cover the student activity section which can be found on page 18. This Topic Exploration Pack supports OCR A Level Chemistry A.

When distributing the activity section to the students either as a printed copy or as a Word file you will need to remove the teacher instructions section.

Version 1 1 © OCR 2017

Learning outcomes 6.2.5(b) for an organic molecule containing several functional groups:

(i) identification of individual functional groups

(ii) prediction of properties and reactions

6.2.5(c) multi-stage synthetic routes for preparing organic compounds

IntroductionThe topic of organic synthesis can be difficult both to teach and to learn. This is not only

because there are a large number of functional groups to recognise, remember and name,

but also because the reagents and conditions for these must be learned too.

The 2015 A Level specification has included some additional reactions which increase the

level of demand of possible questions, most obviously the ability to extend the carbon chain

with CN–/HCN but also the need to consider directing groups when adding to substituted

aromatics.

From experience, the best way to teach these reactions and conditions is in small chunks,

topic by topic, using regular recaps to keep each individual reaction fresh in the mind of the

learner. This is better than trying to teach them all as one section, as many of the groups

and reagents are similar and become mixed up because they are all unfamiliar.

At AS Level the number of reactions is fewer and so easier to recall. Learners who have

taken an AS Level will need to refresh their knowledge of the AS content before taking on

any of the synoptic questions at A Level. If you are teaching the A Level course without

entering learners for AS Levels, it will be worth integrating each new reaction into thinking

about organic synthesis routes as you go along.

This topic exploration pack aims to help teachers and learners to approach organic synthesis

at A level, breaking down the difficult task of multi-stage organic synthesis into its

components:

identifying functional groups in products and reactants

recalling possible reactions and reagents

determining synthetic routes and the correct order of reactions.


This guide does not go into the naming of compounds or go into detail of particular reactions

or directing effects as these are large topics requiring their own exploration.

Identifying functional groups in products and reactantsStart learners off with the ‘Identifying functional groups’ PowerPoint. If more help is needed

have a look at the two web links on the same topic (see Suggested Activities) before trying

the ‘Identifying functional groups’ worksheet (Activity 1). There are also additional links

below to an interactive quiz and a printable worksheet.

Recalling possible reactions and reagentsThis step relies heavily on learners taking responsibility and using their own time to learn the

different reactions. In most cases rote learning at home is best for this, however a teacher

can help by regularly quizzing learners at the start of a lesson.

The ‘Reagents flash cards’ (Activity 2) can be kept on your desk and pulled out at any time

to fill a small gap in a lesson or as a quick starter.

Determining synthetic routes and the correct order of reactionsThe final stage requires progess in both of the previous outcomes and some additional

understanding. The ‘Two-step synthesis’ PowerPoint gives you guidance on how to begin

this process.

Once you have gone through some examples, give learners the ‘Two-step synthesis’

worksheet (Activity 3). The questions get progressively harder but all involve two steps.

Some require thought about order and directing groups which are not covered in detail here.

Once learners are comfortable with the principles of two-stage synthesis, start them thinking

about multi-stage synthetic routes. You could start by having them identify, using the

reaction pathway maps, what multi-stage routes are possible. After that, show learners

different organic compounds, ask them to identify functional groups, and to show what

compounds they could create through multi-stage synthesis routes. This type of work could

be done in mixed-ability groups, with lower achieving learners learning from higher achieving

learners, who in turn consolidate their own understanding by explaining their ideas.

Additional challenge can be added for higher achieving learners by asking them to think

about how a given compound could be synthesised from simpler compounds. They could

also think about the practical aspects of the synthesis, e.g.


http://www.ocr.org.uk/Images/359182-organic-synthesis-topic-exploration-pack-reaction-pathways.pdf

http://www.ocr.org.uk/Images/359181-organic-synthesis-topic-exploration-pack-activity-3.ppt


- How could the product / intermediates be isolated and purified?

- Compare the atom economy of different potential synthesis routes.

- How could you check whether the intended compound has been synthesised, e.g.

think about spectral analysis, functional groups?

Activity 4 in this pack contains test-yourself questions which learners can use to check their

knowledge and understanding of aspects of this topic.

Suggested activities

Identifying functional groups

Activity 1 - Identifying functional groups PowerPoint and worksheet.

This PowerPoint gives learners a way to systematically determine which functional groups

are present in a compound and gives them example questions to test their ability. The

worksheet can be used to follow up.

How to identify functional groups: https://www.youtube.com/watch?v=esJ5MbAHswc

This video also covers similar content in a more visual way. This video include ethers which

are not on specification.

Identify the functional group:

http://www.chem.uiuc.edu/weborganic/Functional%20Groups/Practice%20Problems/

fgDrill09.htm?05

This website has an interactive quiz with which you can test learners. Again look out for off-

spec functional groups like sulfonic acids.

Identifying functional groups worksheet:

http://legacy.jefferson.kctcs.edu/users/kaya.muller/che120/supplements/funcgroups/

worksheet.html

This website has a printable worksheet and answers, more appropriate for high ability

learners. This resource has some off-spec questions too.

Reagents and synthesis



Activity 2 – Reagents and conditions flash cards.

This set of flash cards is designed to be printed back to back, this way the reaction matches

the reagents on the back. Because of this the top left reaction will match the top right

reagent. These can be printed and given to learners to revise at home but can also be used

in lesson to test each other.

There are many ways these cards could be used. One example would be to put learners in

pairs and get one to show the other the reaction and see if they can state the reagents.

Activity 3 – Two-step synthesis PowerPoint and questions.

This PowerPoint gives advice on how to approach synthesis questions and uses worked

examples to show this. The worksheet provides a variety of questions intended to improve a

selection of skills.

Reaction pathway maps for aliphatic, aromatic and phenol compounds are provided in this

pack; these can be used to support the activities in this PowerPoint, as well as any other

practice questions. Differentiate within your group by giving weaker learners the organic

synthesis maps, intermediate learners the blank maps and capable learners no map at all.

Be sensitive to weaker learners, who may be intimidated by the maps at first glance.

Activity 4 – Test-yourself questions

This worksheet is designed to be used at the end of teaching this topic, containing questions

to check learners’ knowledge and understanding of various aspects of organic synthesis.

Answers for teachers

Activity 1 – Identifying functional groups

Basic (one functional group)



Moderate (multiple groups and skeletal formula)


Alkene (hex-2-ene)

Alcohol (6-methyloctan-4-ol)

Phenol(2-methylphenol)

Carboxylic Acid(butanoic acid)

Amine (pentylamine)

Ester (ethyl ethanoate)

Ketone2° amine

Advanced


Phenol Ester

Acyl chloride Nitrile

Alcohol (not phenol)BenzeneHaloalkane

Alkene Alcohol 2° amide

Ester Haloalkane x2

Phenol 1° amine Ketone


Phenol 3° amineKetone Ether (not on specification)

Carboxylic acid 2° amide x2 Haloalkane 1° amine Carboxylate

Activity 2 – Reagents and conditions flash cards

The following flash cards are designed to link the organic reaction with its reagents and

conditions.

To use these cards, you must print them back to back on a double sided printer. This is why

the two sides are ordered as mirror images.

Alternatively, the cards could be printed on separate sheets, the cards cuts out and mixed as two piles. Learners would then need to match the reaction with its reagents and conditions.


Alkene Alkane Aldehyde/ketone Hydroxynitrile

Alkene Haloalkane Aldehyde/ketone Alcohol

Alkene Alcohol Ester Carboxylate salt

Alkane Haloalkane Carboxylic acid Ester

Haloalkane Nitrile Carboxylic acid Acyl chloride

Haloalkane Amine Acyl chloride Carboxylic acid

Haloalkane Alcohol Acyl chloride Primary amide

Alcohol Aldehyde Acyl chloride Secondary amide

Alcohol Carboxylic acid Acyl chloride Ester

Alcohol Alkene Nitrile Amine

Alcohol Haloalkane Ester Carboxylic acid

Alcohol Ester Nitrile Carboxylic acid


NaCN(aq)/H+(aq) H2/Ni, 150 °C

NaBH4 Hydrogen halide

hot aqueous alkali H2O (steam)/H3PO4

Alcohol/conc. H2SO4 Halogen, UV

SOCl2 NaCN or KCN in ethanol

H2O NH3 in ethanol

NH3 NaOH(aq)

Primary amine K2Cr2O7/H2SO4, distil

Alcohol K2Cr2O7/H2SO4, reflux

H2/Ni H2SO4 or H3PO4 /heat

Hot aqueous acid Sodium halide/H2SO4

H2O, HCl, heatCarboxylic acid / conc. H2SO4

OR Acid anhydride OR Acyl chloride


Activity 3 – Two-step synthesis

Show the intermediates, reagents and conditions for the following syntheses.

Problem 1

Problem 2

Problem 3


Step 1: Cl2/UV light

Step 2: NaOH(aq)

Note that the first step in this synthesis would be highly inefficient, with a large number of byproducts.

Step 1: CN–/ethanol

Step 2: H2/Ni

Step 1: dilute H+

Step 2: SOCl2

Problem 4

Problem 5


Step 1: K2Cr2O7/H2SO4/reflux

Step 2: ethanoic acid/conc. H2SO4

The steps must be done in this order to avoid reaction of ethanoic acid with the hydroxyl

group as well as the phenol.

Step 1: Sn/conc. HClStep 2: Cl2/AlCl3 or Fe or FeCl3

The steps must be done in this order due to the directing effect of NO2 to position 3.

Problem 6

Problem 7

Problem 8


Step 1: dilute H+

Step 2: butan-2-ol/conc. H2SO4

Step 1: CN–/ethanol

Step 2: H2O/HCl/heat

Product was rotated to obscure some of the changes, alkene is not affected.

Step 1: H2SO4 or H3PO4 / heat

Step 2: Br2

Activity 4 – Test-yourself questions

1. Identify three functional groups in this compound.

2. This molecule is incomplete. Complete the blank spaces so that it contains- an aldehyde- a tertiary alcohol- an amide.

3. State the reagent needed to convert butanal into butanol.

4. Name the two organic molecules that react in the presence of H2SO4 catalyst to create butyl propanoate.

5. Name the two organic molecules that react to form N-ethylbutanamide.

6. Draw the displayed formula of the product formed when butanal is reacted with NaCN(aq)/H+(aq)


alkene; phenol; ester

NaBH4

Butanol and propanoic acid (or propanoyl chloride or propanoic anhydride)

Butanoyl chloride and ethylamine

7. Look at the organic synthesis below.

a) State the reagent required for step 1.

b) Step 2 involves the reagents H2O/HCl. Draw the skeletal formula of the product X.

c) Step 3 involves an organic reagent.Name the reagent and the catalyst needed.

8. The substance shown reacts with NaOH(aq).

Draw the structure of the product.

9. State the reagents for the two-step synthesis shown below.


CN– or NaCN or KCN (in ethanol)

Ethanol/H2SO4

10. Suggest reagents for the two-step synthesis shown below.


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Step 1: Sn/conc. HClStep 2: Br2

Step 1: dilute H+

Step 2: SOCl2

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Topic Exploration Pack

Organic SynthesisLearner Activity

Activity 1 – Identifying functional groupsFor each compound below identify all of the functional groups

Basic (one functional group)


Moderate (multiple groups and skeletal formula)


Advanced


Activity 3 – Two-step synthesis

Show the intermediates, reagents and conditions for the following syntheses.

Problem 1

Problem 2

Problem 3

Problem 4


Problem 5

Problem 6


Problem 7

Problem 8


Activity 4 – Test-yourself questions1. Identify three functional groups in this compound.

2. This molecule is incomplete. Complete the blank spaces so that it contains- an aldehyde- a tertiary alcohol- an amide.

3. State the reagent needed to convert butanal into butanol.

4. Name the two organic molecules that react in the presence of H2SO4 catalyst to create butyl propanoate.

5. Name the two organic molecules that react to form N-ethylbutanamide.


6. Draw the displayed formula of the product formed when butanal is reacted with NaCN(aq)/H+(aq)

7. Look at the organic synthesis below.

a) State the reagent required for step 1.

b) Step 2 involves the reagents H2O/HCl. Draw the skeletal formula of the product X.

c) Step 3 involves an organic reagent.Name the reagent and the catalyst needed.


8. The substance shown reacts with NaOH(aq).

Draw the structure of the product.

9. State the reagents for the two-step synthesis shown below.


Step 1:

Step 2:

10. Suggest reagents for the two-step synthesis shown below.


Step 1:

Step 2:

Documents

OCR A Level Chemistry A TEP€¦ · Web viewThis Topic Exploration Pack supports OCR A Level Chemistry A. When distributing the activity section to the students either as a printed