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27 Cards in this Set

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Synthesis of Alcohols from Alkenes
Oxymercuration-Demercuration

1) Hg(OAc)2, H2O
2) NaBH4, OH-

Markovnikov
Mercurinium-Ion intermediate
Synthesis of Alcohols from Alkenes
Hydroboration-Oxidation

1) BH3 in THF
2) H2O2, OH- or H2O

Anti-Markovnikov
Syn-Addition
Synthesis of Alcohols from Alkenes via Hydroxylation with OsO4 or KMnO4
Generates cis-diols (1,2 diols)

Syn-Addition
Cyclic Osmate Intermediate

1) OsO4, pyridine
2) NaHSO3, H2O
or
1) KMnO4
2) NaOH, H2O
Synthesis of Alcohols via Reduction with NaBH4
Reduces primary alcohols to aldehydes.

Reduces secondary alcohols to ketones.

NaBH4 acts as a source of the hydride ion H- which is a nucleophile that attacks the carbonyl carbon.

1) NaBH4 in CH3OH
Synthesis of Alcohols from carbonyl compounds via a Grignard reagent reaction.
1) RMgX, ether
2) H3O+

R= alkyl, aryl, vinyl
X= Cl, Br, or I

Nucleophilic addition. Used to extend carbon chain.

Reaction with:
Formaldehyde = primary alcohol
Aldehyde = secondary alcohol
Ketone = tertiary alcohol
Ester = tertiary alcohol (must have 2 equivalents of Grignard to convert ester to tertiary alcohol.)
Synthesis of Alcohols from Esters by Reduction with LiAlH4 (LAH)
Reduction method used for esters. NaBH4 will not work.

Reaction will form 2 alcohols, the carbonyl group will form a primary alcohol, and the -OR group will yield R-OH

1) LiAlH4, ether
2) H3O+

LAH with Carboxylic Acids = primary alcohol.
LAH with Acid Chlorides = primary alcohol.
LAH with acid anhydride = primary alcohol.
Preparation of Alkenes from Alcohols by acid-catalyzed dehydration.
Dehydration of secondary and tertiary alcohols proceeds by the E1 mechanism. PRIMARY alcohols do NOT.

1) H2SO4 (trace)
2) heat

Will form a carbocation intermediate.

Primary alcohols yield alkenes, but via the E2 mechanism.

Overall obeys Zaitsev's rule. (More substituted alkene is major product).
Preparation of Alkyl Halides from TERTIARY alcohols.
1) HBr in Water

SN1 mechanism
Does not work well for primary or secondary alcohols.

Carbocation intermediate.
Preparation of Alkyl Halides from PRIMARY and SECONDARY alcohols.
1) PBr3 (Used primarily to make alkyl bromides)
or
1) SOCl2 in Pyridine (Used to make alkyl chlorides)

Both work through SN2 mechanism.
Stereochemistry Inversion!!!!
Preparations of Aldehydes and Ketones from PRIMARY and SECONDARY alcohols.
Primary Alcohols:
1) PCC (pyridinium chlorochromate) in CH2Cl2

Converts primary alcohols to aldehydes. If done in WATER will yield carboxylic acids.

Secondary Alcohols:
1) NaCr2O7 (Sodium Dichromate) in H3O+

Converts secondary alcohols to ketones.

Note: Chromic Acid or Sodium Dichromate can both cause primary alcohols to go to carboxylic acid.
Williamson ether synthesis from an Alcohol.
SN2 Reaction
1) NaH (strong base)

Alkoxide is formed by removal of proton from alcohol using sodium hydride.
Alkoxide then attacks a PRIMARY Alkyl Halide.

Note: Symmetric Ethers can be synthesized in HOT Sulfuric Acid. You combine the 2 (same) alcohols with the HOT sulfuric acid and it produces R-O-R with H2O.
Synthesis of Ethers via Alkoxymercuration-Demercuration of Alkenes.
1) Hg(O2CCF3)2
2) Alcohol (CH3OH)
3) NaBH4

Reaction runs very similar to oxymercuration-demercuration.

Markovnikov
Mercurinium Ion

Works best with PRIMARY and SECONDARY alcohols and can work with tertiary alcohols as long as the alkene isn't multi-substituted.
Preparation of Alkyl Halides and Alcohols via acidic cleavage.
1) HI, H2O
2) Heat

SN2 Mechanism

PRIMARY and SECONDARY alkyl ethers can be used in this reaction. They yield an alkyl halide and alcohol.

Reaction will only take place in presence of STRONG ACID.

STRONG ACIDS USED : HI, HBr, H2SO4 (HCl and HF are NOT used.)

TERTIARY ethers cause reaction to proceed by SN1 or E1 mechanism.

Continued heating and and excess of HX (for primary and secondary) will further convert the alcohol product into a second alkyl halide.
Synthesis of Epoxides from Alkenes using a peroxycarboxylic acid.
One step Syn-Addition

1) MMPP or MCPBA or any other peroxycarboxylic acid. (Most often the OXIDIZING reagents in a reaction.)
Synthesis of Epoxides from Vicinal Halohydrins.
SN2 Reaction

1) NaOH in Water

Base abstracts proton from OH on halohydrin, and causes epoxide ring formation. As Oxygen bonds to form epoxide ring, the halide is pushed off.
Epoxide Ring-opening via acid or base catalysis.
If an epoxide is reacted with BASE it follows SN2.

If an epoxide is reacted with ACID it follows SN1.

Base :
1) NaOH in Water
Acid :
1) H+ in Water

Bases attack LESS substituted carbon in an asymmetric epoxides.
Acids attack MORE substituted carbon in asymmetric epoxides.

Makes 1,2 diols
Epoxide Ring-opening by the synthesis of extended alcohols by use of Grignard reagents.
Alcohol produced will have 2 more carbon atoms than the R- group of the Grignard reagent.

Grignard + epoxide reacted with H+ in THF = alcohol with 2 more carbons than grignard reagent.

(grignard attacks in SN2 manner).
Synthesis of Sulfides from Thiolate Anions
1) Thiol reacts in Base (NaOH) to yield a thiolate anion.

2) thiolate anion attacks a primary alkyl halide in THF to produce a sulfide.

Very similar to Williamson Ether Synthesis, but only works for PRIMARY and SECONDARY alkyl halides.
Preparation of Carboxylic Acids via Addition of H2O followed by Oxidation.
1) Can use Jones' reagent in acetone at 0 degrees Celcius.
2) Can use Tollen's reagent in aqueous ammonia and ethanol.
3) Can use a peroxycarboxyilc acid.
4) Can use hot Nitric Acid.

Only done with aldehydes because of the hydrogen atom attached to the carbonyl group.
Synthesis of Alkenes from Alkyl Halides by dehydrohalogenation.
alkyl halide is reacted in Base (NaOH)

E2 Mechanism
Preparation of Alkyl Halides via Electrophilic addition of hydrogen halides
1) HCl in Ether

Markovnikov

Carbocation

Can undergo hydride or alkyl shift if necessary to get as close as possible to a TERTIARY intermediate.
Preparation of DiHalides from Electrophilic Addition.
1) Cl2 in CCl4

Produces a vicinal dihalide.

Anti-Addition to produce only trans products.

Cyclic Halonium Intermediate

*commonly a racemic mixture is formed.
Preparation of Halohydrins via electrophilic addition.
1) Cl2 in H2O

Anti-Addition produces Trans Products

Racemic Mixture.
*both Cl2 and Br2 can be used in this reaction, but generally NBS is preferred when trying to create a bromo hydrin.

cyclic halonium ion.
Preparation of Alkenes via catalytic hydrogenation.
Pt, Pd, or Ni catalyst in ethanol with H2

Syn-Addition
Preparation of Alkyl Bromides via free radical addition.
Anti-Markovnikov

Free Radical Chain reaction.

Catalyzed by Peroxides.

1) ROOR + Heat or UV light = alkoxy radicals 2 RO*
2) Alkoxy radicals interact with HBr to form bromine radical which will attack the alkene and form a bromoalkyl radical.
3) bromo alkyl radical will continue process.
Preparation of Aldehydes or Ketones via Oxidative Cleavage with O3.
1) O3 in CHCl2
2) Zn in CH3COOH/ H2O OR Dimethyl Sulfide

Ozonolysis can be performed on alkynes, but it makes carboxylic acids instead.

Ozonide intermediate
Preparation of cyclopropanes via Carbene addition.
1) CHCl3 in KOH

Stereospecific- Cis stays Cis

dichlorocarbene created by deprotonation of chloroform, and an alpha elimination of one of the chlorine atoms.

*If a cyclopropane without halogens is desired, you can do a "Simmons-Smith Reaction" which involves CH2I2 (diiodomethane) and Zn(Cu) in ether.