17786481
Beschreibung
Karteikarten von John Rivada, aktualisiert more than 1 year ago
|
Erstellt von John Rivada
vor mehr als 5 Jahre
|
|
| Frage | Antworten |
| What is the mechanism for an Sn1 reaction? Include transition states |
Image:
1a (binary/octet-stream)
|
| What is the mechanism for an Sn2 reaction? Include reaction states |
Image:
2a (binary/octet-stream)
|
| If a stable carbocation can be formed,is Sn1 preffered or Sn2? If no carbocation can be formed, what happens? | Stable carbocation = Sn1 None = Sn2 |
| Slide 8 | ** How does HBr prefer S1 and PBr3 prefer Sn2? |
| What kind of cations are stable enough to do Sn1? | -Benzylic -Allylic -3° Alkyl carbocations -2° Alkyl carbocations work but not as good -Heteroatom stabilized |
| Trityl carbocation? | **important? I dunno |
| Why are 3° cabocations stable enough to do Sn1? |
Hyperconjugation with C-H or C-C sigma bonds
Image:
3 (binary/octet-stream)
|
| What reagent can you use to promote Sn1? | Silver salts: AgBF4 AgPF6 AgSbF6 |
| Slide 13 | I think I was asleep for this slide |
| Whats so good about MOM and BOM? | Resonance from oxgen and methoxymeythl cation make it great for Sn1 (?) |
| Order of SN1 reaction rate |
Left is slow, right is fast
Image:
4 (binary/octet-stream)
|
| Why do methyl and 1° alkyl groups always go through an Sn2 pathway? | Low steric hindrance Cation not stable |
| Draw the reaction coordination diagram for an Sn1 and Sn2 Reaction |
Image:
5 (binary/octet-stream)
|
| What happens to the stereochemistry of a chiral atom in an Sn2 and Sn1 reaction? | Sn1: racemic Sn2: inversion |
| Order of Sn2 reaction rate |
Left is slow
Right is fast
Image:
6 (binary/octet-stream)
|
| What does the rate of Sn2 depend on? | 1. Nucleophile -what type of heteroatom is attacking -anionic or neutral -structure of Nu (Pkb and sterically hindered) 2. Electrophile -structure of El (1°, 2°, 3°) LG (lower pkb = better LG) |
| pKb of nucleophile goes up, does rate of Sn2 go up or down? | Rate goes up |
| pkb of LG goes up, does rate of Sn2 go up or down? | Rate goes down |
| Does an EDG promote Sn1 or Sn2? | Promotes Sn1 |
| Does an EWG promote Sn1 or Sn2 | Promotes Sn2 by inhibiting Sn1 |
| Good solvents for Sn1 | -Polar solvents best (transition state in RDS involves formation of ions) -eg. H2O, ROH, RCO2H |
| Good solvents for Sn2 | Less polar solvents are better Polar aprotic solvents are a good compromise |
|
Image:
7b (binary/octet-stream)
|
Trick question! If a Nu is good enough to displace OH then its more than good enough to deprotonate
Image:
7a (binary/octet-stream)
|
| What can you do if you want to perform an Sn rx on an alcohol? |
Protonate it!!!
Image:
8 (binary/octet-stream)
|
| What is the Mitsunobu reaction? |
Image:
9 (binary/octet-stream)
|
|
Mechanism?
Image:
9 (binary/octet-stream)
|
Image:
9a (binary/octet-stream)
|
| What prerequisite does the Nu need for the mitsunobu reaction? | Nu-H must have a pka of less than 11 |
| When performing the mitsunobu reaction, how is the steriochemistry | Stereochemistry gets inverted |
| Whats a good way to turn an OH into a LG? | Sulfur chemistry! Add sulfonates |
| What are common sulfonates that you can use to turn OH into a LG? |
Image:
10 (binary/octet-stream)
|
| What reagent do you use to add a sulfonate group onto an alcohol? | Pyridine I think |
|
Image:
11b (binary/octet-stream)
|
Image:
11a (binary/octet-stream)
|
|
Image:
11c (binary/octet-stream)
|
Image:
11a (binary/octet-stream)
|
|
Image:
12b (binary/octet-stream)
|
Image:
12a (binary/octet-stream)
|
|
Image:
12c (binary/octet-stream)
|
Image:
12a (binary/octet-stream)
|
|
Which more likely to happen and why?
Image:
13 (binary/octet-stream)
|
Blue is because less sterically hindered Red still happens because of the positive charge |
|
Image:
15b (binary/octet-stream)
|
Image:
14a (binary/octet-stream)
|
| What is an old school way of turning 1° and 2° alcohol into a halide? | P-X electrophiles e.g. PBr3 and PCl5 |
| Using 1° and 2° alcohols, how can you use a halide acid (HCl, HBr, HI) to make a 1° or 2° halide? | You can't-ish. It's not that good! |
|
Mechanism?
Image:
16a (binary/octet-stream)
|
Image:
16b (binary/octet-stream)
|
|
Image:
17b (binary/octet-stream)
|
Image:
17a (binary/octet-stream)
|
|
Image:
18b (binary/octet-stream)
|
Image:
18a (binary/octet-stream)
|
|
Image:
18c (binary/octet-stream)
|
Image:
18a (binary/octet-stream)
|
|
Image:
19b (binary/octet-stream)
|
Image:
19a (binary/octet-stream)
|
|
Image:
19c (binary/octet-stream)
|
Image:
19a (binary/octet-stream)
|
|
Image:
20b (binary/octet-stream)
|
Image:
20a (binary/octet-stream)
|
|
Image:
20b (binary/octet-stream)
|
Image:
20a (binary/octet-stream)
|
| What is the Finelstein halide exchange reaction? | RCH2-X + NaI in acetone = RCH2I + NaBr X = Cl, Br, OTs, OMs Na-X is insoluble in acetone |
|
Image:
21c (binary/octet-stream)
|
Image:
21b (binary/octet-stream)
|
|
Image:
22b (binary/octet-stream)
|
Carbonyl attack usually predomanites over attack at ester R-group
Image:
22a (binary/octet-stream)
|
| What do you get when you use a nitrogen nucleophile for Sn2 reactions? | A flippin' mess! |
|
Image:
23b (binary/octet-stream)
|
Image:
23a (binary/octet-stream)
|
|
Image:
23c (binary/octet-stream)
|
Image:
23a (binary/octet-stream)
|
| Are thiolates a good Nu? | Yes! Especially for Sn2 |
| How to make a thiol | ** |
| What is a good carbon nucleophile for Sn2? | -CN! NaCN or KCn |
| What can RCN be transformed into? | Amines Aldehydes Carboxylic Acids |
| What is a useful way to extend a carbon chane by 1 atom? | Use NaCN on an alkyl halide! |
| What is the trend compared to basicity if the atom forming the new bond is the same over a range of nucleohiles? |
Basicity parallels nucleophilicity
Image:
24 (binary/octet-stream)
|
| Nucleohpile rate scale |
Image:
25 (binary/octet-stream)
|
Möchten Sie mit GoConqr kostenlos Ihre eigenen Karteikarten erstellen? Mehr erfahren.