Synthetic transformations part 2 Flashcards Preview

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Flashcards in Synthetic transformations part 2 Deck (11)
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1

HX on an alcohol

X replaces alcohol
makes H2O
R-CH2-OH to R-CH2-X
halogenation of alcohol (X= Cl, Br, I)

2

SOCl2 (mild base, poor nucleophile, pyridine)

Cl replaces alcohol
halogenation of alcohol
R-CH2-OH to R-CH2-Cl

3

PBr3 (mild base, poor nucleophile, pyridine)

Br replaces alcohol
Halogenation of alcohol
R-CH2-OH to R-CH2-Br

4

Any common nucleophile

replaces LG(leaving group) attached to carbon with Nucleophile
R-CH2-LG to R-CH2-Nuc
SN2 rxn

5

What are Common nucleophiles

Best: RS-, NC-. I-, PR3, R3C-, R2N-, RC-trip bond-C-, RO-
Good: Br-, R2S, NR3, Cl-, RCO2-, N3-
Poor: strong acids, F-, HCO3-, R2O

6

NaOH or KOH

replaces leaving group with OH
R-CH2-LG to R-CH2-OH
SN2 rxn

7

Na metal + ROH = NaOR (sodium alcohol)

replaced LG with OR
R-CH2-LG to R-CH2-OR
SN2 rxn

8

NaNH2 (any strong base) + R-CH2-LG
(LG = Cl, Br, I, OTs)

R- C triple bond C-CH2-R
create triple bonded CC
SN2 rxn

9

What are Common Leaving groups

Great: RSO3- (R= CF, tol, CH3)
Good: R2O ( H2O, OH, ether)
Poor: Strong bases, F-, RO-, R2N-, R3C-

10

E2 Small base

zaitsev elimination
most substituted c gets double bond
due to small molecule

11

E2 big base

hoffman elimination
least sub c gets double bond
more easily accessible
steric hindrance