Alcohols Flashcards
what are the precursors for ethers
alkoxides
what happens when an alcohol is a base?
it gains a proton to form oxonium
what happens when alcohol is an acid?
it gains a proton and forms alkoxide
what is the main characteristic of a good leaving group?
weak bases
what are the best leaving groups?
I- > Br- > Cl- ~ H20
what reagent is needed to convert ROH –> Haloalkane
binary acid
what is the purpose of converting ROH into a haloalkane?
turns a bad leaving group into a great leaving group
what is the mechanism for conversion of ROH –> haloalkane for a primary alcohol
proton transfer, then Sn2
what is the mechanism for conversion of ROH –> haloalkane for a secondary/tertiary alcohol
proton transfer, then Sn1 mechanism
what connectivity do carbocations have
sp2, trigonal planar
what of product is generally formed from Sn1 attack
- 50/50 mix of stereoisomers if chiral
what is reaction 1
conversion of ROH –> haloalkane with HX
what is the second reaction
conversion of ROH –> haloalkanes w/o use of HX
what reagents can you use for conversion of ROH –> haloalkane w/o use of HX
PBr3, thionyl chloride + pyridine
what is the mechanism for conversion of ROH –> haloalkanes w/o HX
Sn2
- effective with methanol, primary, and secondary alcohols only
which mechanism results in inversion of product
Sn2
what is the third reaction
conversion of ROH into aryl/alkyl
what reagent does conversion of ROH into aryl/alkyl sulfonates require
TsCl
what mechanism does ROTs undergo
Sn2
does the conversion of -OH into -OTs undergo inversion
no
what is the point of converting ROH into aryl/alkyl sulfonate
turning a poor LG –> great LG
Zaitsev’s rule
the major product of beta-elimination is the most stable alkene = the most substituted alkene
what happens in the E1 mechanism
LG leaves first, forming a carbocation intermediate
- just like Sn1 but a double bond is formed
what happens in the E2 mechanism
no carbocation intermediate forms, bond events occur simultaneously
- just like Sn2
what is the fourth reaction
conversion of ROH –> alkenes (acid-catalyzed dehydration)
what mechanism do primary alcohols undergo in acid-catalyzed dehydration
E2
what mechanism do secondary or tertiary alcohols undergo in acid-catalyzed dehydration
E1
what are the precursors for epoxides
alkenes
redox reactions
involves a transfer of electrons
oxidation
loss of electrons
reduction
gain of electrons
oxidizing agents
perform oxidation upon another species
- they are reduced
reducing agents
perform reduction on another species
- they are oxidized
how do number of C-O bonds affect oxidation
greater C-O bonds = greater oxidation
how do numbers of C-H bonds affect reduction
more C-H bonds = greater reduction
what is the fifth reaction
oxidation of alcohols using chromic acid
what are the three options for reagents for oxidation of alcohols using chromic acid
- K2Cr2O7/H2SO4, 2. CrO3/H2SO4, or KMnO4/OH-/heat
what does a primary alcohol convert to in the oxidation of alcohols using chromic acid
first oxidizes to an aldehyde, then to a carboxylic acid
what does a secondary alcohol form in the oxidation of alcohols using chromic acid
a ketone
what does a tertiary alcohol form in the oxidation using chromic acid
no reaction
what is the sixth reaction
the partial oxidation of primary alcohol
what is the main characteristic of PCC
it is a mild oxidizing agent
what does the partial oxidation of a primary alcohol with PCC form
an aldehyde
when does a hydride shift occur
when there is a tertiary carbon next to a secondary carbocation
when does a methyl shift occur
when there is a quaternary carbon with 1+ methyl groups next to a secondary carbocation
what is Br- good for
good nucleophile
what is I- good for
good nucleophile
what is CH3S- good for
good nucleophile
what is RS- good for
good nucleophile
what is HO- good for
good nucleophile
what is CH3O- good for
good nucleophile
what is RO- good for
good nucleophile
what is R-alkyne - good for
good nucleophile
what is CN- good for
good nucleophile
what is N3- good for
good nucleophile
what is H2N- good for
good nucleophile
