Alcohols, Ethers, Epoxides - DAT

R—OH + HX ————>

R—X + H2O (alkyl halide formation)

PBr3 / Pyridine ————>

R—Br + HPR (alkyl bromide formation)

Can alkyl bromide/chloride formation occur on a 3* alcohol?

No, 1* and 2* only

SOCl2 / Pyridine ————>

Alkyl chloride formation with R—Cl

TsCl/pyridine ————>

Alkyl tosylate formation with R—OTs —— OTs is a better leaving group than OH

H2SO4 or H3PO4 ————>

Alcohol dehydration to form alkenes or ethers

What mechanism is used in alcohol dehydration of 1* alcohols

E2

What mechanism of dehydration is used for 2* or 3* alcohols

E1 (favors most substituted product)

NaCr2O7/H2SO4 or H2CrO4/ or CrO3/H2SO4 ————>

Carboxylic acid formation (oxidizing alcohol)

NaCr2O7/H2SO4 or H2CrO4/ or CrO3/H2SO4 ————>

Ketone formation (oxidizing alcohol)

Does chromium alchohol oxidation work on 3* alcohols and phenols?

No!

PCC / or periodinane ————>

Aldehyde formation (PCC oxidation)

PCC / or periodinane ————>

Ketone formation (PCC oxidation)

Does PCC/periodinane work on 3* alcohols or phenols?

NO

1. DMSO, (COCl)2 / 2. NEt3 ————>

aldehyde formation (Swern oxidation)

1. DMSO, (COCl)2 / 2. NEt3 ————>

1. 
   

Ketone formation (Swern oxidation)

Alcohol + NaH, Na, or K (base) ——> Alkoxide + alkyl halide ———> ?

Formation of an ether (williamson ether synthesis)

What is the primary way that an ether will split up?

it will split up to make the alkyl halide as close to a 1* carbon as possible → encourages SN2

Can eliminations occur in williamson ether synthesis

Yes, if the alkyl halide is 2* or 3*

ether + H—X ————>

alkyl halide + alcohol (xs H-X gives 2 alkyl halides)

if R or R’ on an ether is 2* or 3*, what mechanism will the rxn do?

SN1

Alkene + peroxy acid (mCPBA) ————>

epoxide

Under acidic conditions, what carbon will the nucleophile attach to in a nuc/epoxide addition

Carbon 1 (more substituted)

Under basic conditions, what carbon will the nucleophile attach to in a nuc/epoxide addition

Carbon 2 (less substituted)

what would the stereochemistry be of the dihydroxide? (in acidic and basic conditions)

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