Organic Chemistry - Ethers, Epoxides, Thiols, And Sulfides (Ch. 18)

Front 1

Thiols (R-S-H) and sulfides (R-S-R') are sulfur analogs of _____ and _____ respectively.

Back 1

alcohols, ethers

Front 2

ethers

Back 2

R-:O-R
-uses:
1. solvents
2. anesthesia

Front 3

alkene to Ether

Back 3

1. Hg(OAc)2, R-OH *Markovnikov addn of O-R
2. NaBH4 (Alkoxymercuration)

Front 4

halogen to Ether

Back 4

CH3OH

*SN2 or SN1 rxn depending on starting substrate.
(SN1= 3 or 2 substrate; halogen leaves on own forming carbocation, -:OCH3 acts as nucleophile & attacks carbocation, forming ether.)
(SN2= methyl or 1 substrate; -:OCH3 acts as nucleophile via backside attack, knocking halogen off, forming ether.)

Front 5

1. NaH
2. CH3-I

Back 5

*OH to ether -or- (Williamson-Ether
*Carboxylic acid to ether Synthesis)


OH to ether:
*Na takes H from OH, makes O- w/ lone pair, lone pair takes CH3 and bumps I off, forming ether.

Carboxylic acid to ether:
*Na takes H from OH, leaves O- w/ lone pair on carbox acid, lone pair takes CH3, bumps I off, forming ether.

Front 6

ether to alkyl halide + phenol

Back 6

H-I (Acidic Cleavage of ethers)

*H protonates ether :O FIRST (O lone pair takes H & bumps I off).
*THEN, :I- acts as nucleophile via backside attack of left side R grp, bumps OH+-benzene ring off
*Final Product= I-R + HO-benzene ring (alkyl halide + phenol.

Front 7

Ether to OH

Back 7

H-I

*H protonates ether :O FIRST (O lone pair takes H & bumps I off)
*THEN :I- acts as nucleophile via backside attack of left side R grp), bumps OH+-R grp off
*Final Product= I-CH3 + HO-R grp

Front 8

Alkene to epoxide

Back 8

MCPBA

*forms epoxide where alkene was

Front 9

:Na- or CH3O:- or HS:-
H2O H2O H+

(note: can use either H2O or H+)

Back 9

Epoxide to OH (Base-Catalyzed Ring Opening)

-Nucleophile MUST have NEGATIVE CHARGE!
-Base attack occurs at opening less hindered.
(attack always occurs at opening easiest to get to.)
*Nucleophile acts via backside attack.

Front 10

CH3OH
H+

Back 10

Epoxide to OH (Acid-Catalyzed Ring Opening)

-Acid attack (regioselective) occurs at tertiary opening IF available.
(attack always occurs at opening easiest to get to.)
*H+ protonates epoxide :O FIRST (O lone pair grab H), THEN CH3O:- acts as nucleophile via backside attack.

Front 11

When epoxide carbon atoms are either primary or secondary, attack of nucleophile occurs at primarily the ___ highly substituted site

Back 11

less

Front 12

When one of the epoxide carbons is tertiary, nucleophilic attack occurs primarily at the ____ highly substituted site.

Back 12

more

Front 13

Base-catalyzed epoxide opening is an SN2 reaction in which attack of the nucleophile takes place at the ___ hindered epoxide carbon.

Back 13

less

Front 14

The importance of crown ethers derives from their extraordinary abiity to:

Back 14

solvate metal cations by sequestering the metal in the center of the polyether cavity

Front 15

The -SH group is referred to as the:

Back 15

mercapto group

Front 16

sulfides

Back 16

CH3-S-CH3
-similar to alcohol, but sulfur replaces oxygen= thiols

Front 17

thiols

Back 17

CH3-S-H
-good nucleophiles
-similar rxn to alcohols b/c of hydrogen

Front 18

disulfides

Back 18

CH3-S-S-CH3
-uses:
1. protein synthesis
2. beautician

Front 19

alkyl halide to thiol

Back 19

-:SH
(SN1 or SN2 depending on substrate)

Front 20

thiol to sulfide

Back 20

1. NaH *thiol to sulfide
2. CH3-I (Williamson-Ether Synthesis)

*FIRST, thiol reacts with NaH
Na takes H on thiol, giving CH3-S:-
*CH3-S:- then reacts with CH3-I
S:- takes CH3, bumping I off
*Final Product= CH3-S-CH3 (sulfide)

Front 21

2 thiols to disulfide

Back 21

NaOH/H2O *2 thiols to disulfide
Br2 (Oxidation)

*See notes for reaction mechanism

Front 22

thiol to CH3
|
CH3-S+-H

Back 22

CH3-I *thiol to CH3
|
CH3-S+-H

*S: lone pair from thiol takes CH3, bumping off I, forming product.

Front 23

NaIO4

Back 23

*sulfide to sulfoxide (Oxidation)

CH3-S-CH3 NaIO4 --> O
(sulfide) ||
CH3-S-CH3
(sulfoxide)

Front 24

Ex. NaIO4


(note: Ex.= excess)

Back 24

*sulfide to sulfone (Oxidation)
(sulfoxide intermediate)
(use excess NaIO4 to get sulfone)

CH3-S-CH3 NaIO4 --> O NaIO4 --> O
(sulfide) || ||
CH3-S-CH3 CH3-S-CH3
(sulfoxide) ||
O
(sulfone)

Front 25

Treatment of a sulfide with H2O2 at room temperature yields ____.

Back 25

sulfoxide (R2SO)

Front 26

Oxidation of sulfoxide with a peroxyacid yields ____.

Back 26

sulfone (R2SO2)

Front 27

The sulfoxide that is used as a polar aprotic solvent is:

Back 27

DMSO (dimethyl sulfoxide)