What are the physical properties of alcohols?
1. intermolecular H bonding (greater degrees of H bonding with greater #s of OH's present)
2. higher MP and BP
phenol
aromatic alcohols
hydroxy
prefix for an alcohol when it is not the highest priority substituent
ortho meta para
What are the atoms H can bond to in H bonding?
N, O, or F
How acidic is the H of a hydroxyl group?
weakly acidic!
Why are the hydroxyls of phenols more acidic than other alcohols?
aromatic nature of the ring... this allows for resonance stabilization of the neg. charge on O, stabilizing the anion
What else can increase the acidity of an alcohol?
the presence of other substituents! electron
withdrawing
groups (EWG)
increase acidity
and electron
donating
groups (EDG)
decrease acidity
What seems to decrease the acidity of an alcohol?
the presence of alkyl groups in nonromantic alcohols; the more alkyl groups, the less acidic the molecule
Why do alkyl groups reduce the acidity of alcohols?
alkyl groups are EDG's.... they donate e? density, thereby destabilizing a negative charge; also, they help stabilize + charges, so they are more stable the more substituted they are
What are primary alcohols oxidized to?
aldehydes!
What reagent allows primary alcohol -> aldehyde reaction to occur? Are there any other reagents that can complete this reaction?
PCC; this is the ONLY reagent that takes 1� alcohols to aldehydes
How does PCC oxidize the alcohol?
it is a mild anhydrous oxidant that oxidizes the primary alcohol and stops the reactant after this first conversion bc it lacks the water to hydrate the aldehyde
What do hydrated reagents do to aldehydes?
because aldehydes are easily hydrated, a reagent that is hydrated rapidly turns an aldehyde into a geminal diol (1,1-diol)... these can become oxidized to carb acids
Does PCC only work with 1� alcohols?
nope! it also can oxidize 2� alcohols to ketones
What else can oxidize 2� alcohols?
any stronger oxidizing agent
Na2Cr2O7
K2Cr2O7
How do you turn a 1� alcohol into a carb acid?
with chromium(VI) reagent
Na2Cr2O7
K2Cr2O7
What's an even stronger Cr containing oxidizing agent than these?
CrO3 (Jones oxidation)
primary alcohols -> carboxylic acids
secondary alcohols -> ketones
Are the -OH groups of alcohol's good for nucleophilic substiution rxns? Why or why not?
they are NOT! bc they are fairly poor leaving groups
What reactions are alcohols good for?
they can be reacted to form better leaving groups and THEN be used for nucleophillic subst. rxns!
What allows them to be these better leaving groups?
mesylates and tosylates
mesylate
cmpd containing the fxnl group -SO3CH3, derived from methanesulfonic acid; aka MS
How do you prepare a mesylate?
use methylsulfonyl chloride and an alcohol in the presence of a base
tosylate
contains -SO3C6H4CH3; derived from toluenesulfonic acid; produced by rxn of alcohols w/ p-toluenesulfonyl chloride; aka TOS
what else do MS and TOS do besides making -OHs better leaving groups?
they act as
protecting groups
when we don't want our alcohols to react with something
What is a purpose of -OHs similar to MS and TOS?
they can be used as
protecting groups
to other fxnal groups
ex.) acetal or ketal formation via addn of a diol or 2 -OH equivalents to a ketone or aldehyde
When do the acetals and ketals need to be made?
when LiAlH4 will be used to reduce something.... it can easily reduce a carbonyl, but not an acetal or ketal
What happens when you react a phenol with oxidizing agents?
you produce quinones
quinones
resonance-stabilized electrophiles; not always aromatic because not conjugated correctly; serve as e? acceptors (especially in ETC)
What happens when you oxidize quinones?
you form hydroxyquinones
hydroxyquinones
share the same ring and carbonyl backbone as quinones, but
differ by the addn of 1+ hydroxyl groups
ubiquinone
aka: coenzyme Q (CoQ); a biologically active quinone and vital e? carrier associated w/ Complex I, II, & III of the ETC; most oxidized form of the molecule
What is the reduced form of ubiquinone?
ubiquinol
What's the purpose of the long alkyl chain on ubiquinone/ubiquinol?
allows the molecule to be lipid soluble, allowing it to act as an e? carrier w.in the phospholipid bilayer
How do you produce a quinone?
via a Cr containing reagent, i.e. NaCr2O7 w/ H2SO4
How do you produce a hydroxyquinone?
further oxidize a quinone