Ch.11 Flashcards
What is oxidation?
Addition of O or O2, loss of H2, Addition of X2
What is reduction?
Addition of H2 or H-, Loss of O or O2, loss of X2
What alcohols don’t get oxidized with chromic acid? When does oxidation take place?
Tertiary alcohols don’t get oxidized
Oxidation will only take place when carbon-carbon bonds are broken
Pyridinium Chlorochroate (PCC)
Poisioned, slow reaction
2º alcohol to a ketone, chromium and chromium-free
Chromium: chromic acid or PCC
Chromium-free: NaOCl, Swern, DMP
1º alcohol to aldehyde
Chromium: PCC
Chromium-free: Swern, DMP
1º alcohol to carboxylic acid
Chromium: chromic acid
Chromium-free: NaOCl
When does an alcohol react as a nucleophile?
When the O-H bond breaks
When does an alcohol react as an electrophile?
When the C O bond breaks
Tosylate Ester
An ester of an alcohol with p-toluenesulfonic acid; great leaving group, can undergo both substitution and elimination
What Nucleophiles work with the addition fo Ts
-OH, -CN, Br-, R’O-, NH3, LiAlH4
How can you achieve the reduction of alchols
With two steps and Ts
With HBR/H20 which alchols go by SN2 and which go by SN1
SN2: primary
SN1: secondary and tertiary
What is the lucas reagent
HCl/ZnCl2
How does the Lucas Reagent react with primary, secondary, and tertiary reagents
SN1 with tertiary and secondary
SN2 with primary
What is the lucas test
a test used to determine whether an alcohol is primary, secondary, or tertiary.
<1 min tertiary
1-5 min secondary
>6 min primary
When do phosphorus halides have good yields
With primary and secondary alcohols
What phosphorus haldies react with chloride (primary, secondary, tertiary)
Primary: SOCl2
Secondary SOCl2
Tertiary: HCl
What phosphorus haldies react with bromide (primary, secondary, tertiary)
Primary: PBr3 or HBR
Secondary: PBr3
Tertiary: HBr
What phosphorus haldies react with Iodide (primary, secondary, tertiary)
Primary: P/I2
Secondary P/I2
Tertiary: HI
What does thionyl chloride do
Converts alcohols into the corresponding alkyl chlorides
In alcohol dehydration, what does H2SO4 produce
alkenes
What temperature and mechanism does the dehydration of alcohols occur?
High temperature (180 and above)
E1 Mechanism
What is the rate-limiting step in the dehydration reactions of alcohols
the formation of the carbocation
Bimolecular Dehydration
Two alcohols react by SN2 to form an ether
Favored by low temperatures (140ºC and below)
Pinacol Rearrangement
A vicinal diol converts to a ketone under acidic conditions and heat
Fischer Esterification
the acid-catalysed reaction of an alcohol with a carboxylic acid to form an ester; equilibrium driven
Williamson Ether Synthesis; best results, mechanism
Primary (best result): SN2
secondary of tertiary: E2
