12-14 reverse, Flashcards Preview

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Flashcards in 12-14 reverse, Deck (13)
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1

halogenation of OH by HX
O grabs H from H-X, becomes -OH2+
second step X- replaces OH2+
Overall its an a transformation adding X to C

HX
X=Cl, Br, I

2

Halogenation of alcohol
OH replaced by Cl

SOCl2
also requires mild base, poor nucleophile

3

Halogenation of OH
OH replaced by Br

PBr3
requires mild base, poor nucleophile

4

Sn2
LG leaves ( Cl, Br, I, OT)
nucleophile comes on, reagent replaces LG
switches enantiomers (R to S or vis)

SN2
Good Nucleophile ( strong base) Br, Cl, I

5

LG out replaced by OH
enantiomers switch

Sn2
NaOH or KOH

6

LG leaves replaced by OR

Sn2
NaOR (Na+ OR-)

7

R-C (triple bond )C-H
replace H with another group
ex
R-C triplebond C
to r-C TB C-CH2-R

1)strong base NaNH2
2) R-CH2-LG
LG = Cl, Br, I, Ts

8

alkyl halide (r-X) or tosylate (R-OTs) to alkene
good leaving group comes off along with H (x and H)
double bond forms C=C
can form both E and Z

E1

weak base
ethanol (or polar protic solvent ( has Hs on N,O,X))
Heat

E1

9

allylic or benzyllic OH to alkene
OH is secondary or tertiary
OH and H come off
C=C forms between two C's

acid (H2SO4 or H3PO4)
Heat

10

1 step no carbo cation
methyl leaving group or no carbocations or beta-H's
has to be methyl, primary, secondary or 1* w/ allylic/benzyllic LG
not tertiary
Good nuclei-strong base-cool
or Good nuk-weak-aprotic

SN2

11

2 Steps carbo forms,
Only secondary or Tert or 1* if allylic/benzyllic LG
Good nuke-weak base- polar protic ( h on NOX)
or
Poor nuk-weak base or polar protic solvent-cool

Sn1

12

1 Step no carbo forms
1*, 2*, 3*
strong base, poor nuk, hot

E2

13

2 Step, carbo forms
1* if allylic or benzyylic LG, 2*, 3*
WEAK Base only, usually hot,

poor nun, weak base (protic solvent), Hot

E1