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ORGANIC CONVERSIONS
Muhammad Naseem Khan
1
by
Organic chemistry throws a lot of
different reactions at you. Today I want to
quickly talk about how to learn these
reacti...
A Few Basic Things
1. Generalize
2. Analyze
3. Understand
4. Apply
3
Generalize
• Focus on the functional groups. The rest of the
molecule can usually be ignored.
• Use "R" liberally to organ...
Analyze
• What bonds form and break? (very important:
don’t miss the hydrogens!) Before you understand
the mechanism, you ...
Understand
• Look at the mechanism, if known. What are the
steps? Could you write them out without
looking?
• Do those mec...
Examples
1. Conversion of Carboxylic Acids into Esters
2. Hydrolysis of Esters into Carboxylic Acids
3. Conversion of Carb...
One should try to come up with a good mnemonic for this. “Piranhas Attack People Every Day”
8
9
APPLY
• Given a starting material and the reagent, could you have predicted
the product?
• Could you predict the reagent o...
Identifying the Patterns in Carbonyl Reaction Mechanism
11
USEFULL RESOURCES
1. Summary Sheets ("Cheat Sheets")
2. MAPS
3. Flash Cards
12
Summary Sheets
The key points from each chapter are condensed onto single pages.
13
The use of MAPS…..!!
At one level of organic synthesis you
can think of functional groups as
being like cities on a map, a...
A useful technique is to frame reactions
around functional groups - e.g. what reaction
can transform functional group X (s...
16
Reaction Map: Reactions of Alkanes,
Alkyl Halides, Alkenes, and Alkynes
17
18
How would you build this
Molecule?
19
Building Reaction Map for Ketones
If you look at all these reactions – forward and backward – you can link
functional grou...
Reaction Map for Secondary Alcohol
21
We’re asked to go from an aldehyde to
a tertiary alcohol.
• Go back to the reaction map. Look for the tertiary
alcohol as ...
23
Using Flash Cards to Learn
Reactions in Organic Chemistry
24
Tips on making flashcards:
1) Use unlined 4" by 6" cards.
2) On the front of card write only the name ("title") of the rea...
Tips on studying from Flashcards:
 Carry your reaction flashcards with you everywhere and study from
them whenever you ge...
Sample of Reaction Flashcards
27
28
Write the starting organic compound
and the reagents on one side:
29
A
B
Write the product(s) on the other side:
30
A
B
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Organic Conversions (Learning Organic Reactions)

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Organic Conversions (Learning Organic Reactions)

  1. 1. ORGANIC CONVERSIONS Muhammad Naseem Khan 1 by
  2. 2. Organic chemistry throws a lot of different reactions at you. Today I want to quickly talk about how to learn these reactions without being overwhelmed. 2
  3. 3. A Few Basic Things 1. Generalize 2. Analyze 3. Understand 4. Apply 3
  4. 4. Generalize • Focus on the functional groups. The rest of the molecule can usually be ignored. • Use "R" liberally to organize each reaction by functional group. For example, it's more useful to know that a certain reaction works with carboxylic acids than with, say, CH3(CH2)2COOH in particular. 4
  5. 5. Analyze • What bonds form and break? (very important: don’t miss the hydrogens!) Before you understand the mechanism, you must be able to see this. • What functional groups are present in the starting material and the product? • Does this reaction have anything in common with other reactions you’ve learned? Especially pay attention to the pattern of bonds forming/breaking here. 5
  6. 6. Understand • Look at the mechanism, if known. What are the steps? Could you write them out without looking? • Do those mechanistic steps have names? (they usually do! addition, elimination, protonation/deprotonation, etc) • Are there any other reactions where you’ve seen those mechanistic steps? • Remembering PAPED is a lot easier than remembering the exact way to draw 12 arrows. 6
  7. 7. Examples 1. Conversion of Carboxylic Acids into Esters 2. Hydrolysis of Esters into Carboxylic Acids 3. Conversion of Carboxylic Acids into Amides 4. Hydrolysis of Amides into Carboxylic Acids 5. Formation of Imines from Ketones/Aldehydes and Amines 6. Hydrolysis of Imines to Ketones/Aldehydes and Amines The Six reactions listed might look different, but they actually have EXACTLY THE SAME MECHANISM. So, if you have learned how one of them works___ you’ve actually learned them all. Let’s break it down using the first reaction. 7
  8. 8. One should try to come up with a good mnemonic for this. “Piranhas Attack People Every Day” 8
  9. 9. 9
  10. 10. APPLY • Given a starting material and the reagent, could you have predicted the product? • Could you predict the reagent or the starting material if given the other two pieces of information? • When might this reaction NOT work? [e.g. Grignards don't work on carboxylic acids because they perform an acid base reaction.] • Can you think of reaction you could then do with the product of this reaction? Can you think of a reaction that makes the starting material? [useful for thinking about synthesis] Our textbook might cover 200 reactions, but there are definitely not 200 different plots. Our task is to be able to generalize and recognize the core patterns. (Like described on next Slide) 10
  11. 11. Identifying the Patterns in Carbonyl Reaction Mechanism 11
  12. 12. USEFULL RESOURCES 1. Summary Sheets ("Cheat Sheets") 2. MAPS 3. Flash Cards 12
  13. 13. Summary Sheets The key points from each chapter are condensed onto single pages. 13
  14. 14. The use of MAPS…..!! At one level of organic synthesis you can think of functional groups as being like cities on a map, and reactions that link them are like roads. 14
  15. 15. A useful technique is to frame reactions around functional groups - e.g. what reaction can transform functional group X (say, an alcohol) to functional group Y (say, an alkene). Once you know enough reactions you can start building out little maps. Not all functional groups can be converted to others in 1 step! Often 2, 3 or more steps can be required. 15
  16. 16. 16
  17. 17. Reaction Map: Reactions of Alkanes, Alkyl Halides, Alkenes, and Alkynes 17
  18. 18. 18
  19. 19. How would you build this Molecule? 19
  20. 20. Building Reaction Map for Ketones If you look at all these reactions – forward and backward – you can link functional groups to each other through these types of reactions. 20
  21. 21. Reaction Map for Secondary Alcohol 21
  22. 22. We’re asked to go from an aldehyde to a tertiary alcohol. • Go back to the reaction map. Look for the tertiary alcohol as a product. Then work backwards. How do you get there? One way is from a ketone, in a Grignard reaction. Then think backwards from there – how to get there? One way is to oxidize a secondary alcohol. And if you trace back secondary alcohols, you can get there from the aldehyde and a Grignard reaction. • Once you know what reactions to use, it’s much easier to design your synthesis. Here, the problem is identifying what alkyl groups to use in each of the two Grignard reactions. 22
  23. 23. 23
  24. 24. Using Flash Cards to Learn Reactions in Organic Chemistry 24
  25. 25. Tips on making flashcards: 1) Use unlined 4" by 6" cards. 2) On the front of card write only the name ("title") of the reaction, e.g. "Halogenation of Alkane," “Alcohols from Alkyl Halides," etc. 3) On the back of card write out the general reaction. 4) Be as general as possible in designating organic compounds, e.g. RX rather than CH3Br. 5) Also on the back of card include any other information important to the reaction that are expected to be known; this may include: a) Special conditions, e.g. heat, light, etc. b) Solvents, e.g. DMSO, H2O, etc. c) Catalysts (if any), e.g. H+ , Pyridine, etc. d) General reaction type, e.g. substitution, elimination, addition, oxidation, reduction, etc. 25
  26. 26. Tips on studying from Flashcards:  Carry your reaction flashcards with you everywhere and study from them whenever you get the chance.  Starting with the whole deck (almost 10 cards for phenols in text book), write out from memory the information on the back of each card, then check your answer (NO PEEKING!).  If your answer is 100% correct, set that card aside; if your answer is not 100% correct, put that card on the bottom of the deck  Go through the deck as many times as you need to until you can do all cards 100% correctly; then set aside the deck for a day or two and start all over from the beginning. Repeat the process as many times as possible before the Final Exam.  Test your knowledge and understanding of the reactions by doing all the assigned reaction problems at the end of the chapters; refer to your cards for help if necessary. Redo the problems as many times as necessary until you don't have to refer to your flashcards any more. 26
  27. 27. Sample of Reaction Flashcards 27
  28. 28. 28
  29. 29. Write the starting organic compound and the reagents on one side: 29 A B
  30. 30. Write the product(s) on the other side: 30 A B

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