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27 Cards in this Set
- Front
- Back
Thiols (R-S-H) and sulfides (R-S-R') are sulfur analogs of _____ and _____ respectively.
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alcohols, ethers
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ethers
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R-:O-R
-uses: 1. solvents 2. anesthesia |
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alkene to Ether
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1. Hg(OAc)2, R-OH *Markovnikov addn of O-R
2. NaBH4 (Alkoxymercuration) |
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halogen to Ether
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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.) |
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1. NaH
2. CH3-I |
*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. |
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ether to alkyl halide + phenol
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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. |
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Ether to OH
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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 |
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Alkene to epoxide
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MCPBA
*forms epoxide where alkene was |
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:Na- or CH3O:- or HS:-
H2O H2O H+ (note: can use either H2O or H+) |
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. |
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CH3OH
H+ |
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. |
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When epoxide carbon atoms are either primary or secondary, attack of nucleophile occurs at primarily the ___ highly substituted site
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less
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When one of the epoxide carbons is tertiary, nucleophilic attack occurs primarily at the ____ highly substituted site.
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more
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Base-catalyzed epoxide opening is an SN2 reaction in which attack of the nucleophile takes place at the ___ hindered epoxide carbon.
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less
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The importance of crown ethers derives from their extraordinary abiity to:
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solvate metal cations by sequestering the metal in the center of the polyether cavity
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The -SH group is referred to as the:
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mercapto group
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sulfides
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CH3-S-CH3
-similar to alcohol, but sulfur replaces oxygen= thiols |
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thiols
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CH3-S-H
-good nucleophiles -similar rxn to alcohols b/c of hydrogen |
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disulfides
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CH3-S-S-CH3
-uses: 1. protein synthesis 2. beautician |
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alkyl halide to thiol
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-:SH
(SN1 or SN2 depending on substrate) |
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thiol to sulfide
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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) |
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2 thiols to disulfide
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NaOH/H2O *2 thiols to disulfide
Br2 (Oxidation) *See notes for reaction mechanism |
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thiol to CH3
| CH3-S+-H |
CH3-I *thiol to CH3
| CH3-S+-H *S: lone pair from thiol takes CH3, bumping off I, forming product. |
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NaIO4
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*sulfide to sulfoxide (Oxidation)
CH3-S-CH3 NaIO4 --> O (sulfide) || CH3-S-CH3 (sulfoxide) |
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Ex. NaIO4
(note: Ex.= excess) |
*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) |
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Treatment of a sulfide with H2O2 at room temperature yields ____.
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sulfoxide (R2SO)
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Oxidation of sulfoxide with a peroxyacid yields ____.
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sulfone (R2SO2)
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The sulfoxide that is used as a polar aprotic solvent is:
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DMSO (dimethyl sulfoxide)
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