5. Alcohols Flashcards
Alcohols = water soluble, but if the alcohol has a long alkane chain, will it dissolve in water? How does a longer chain affect boiling point?
No. Higher boiling pt; alcs have higher boiling pts than alkanes in general b/c it has more H bonds (so more hydroxyl groups means raising bpt)
How to convert ald/ket into primary/secondary alc w/ NaBH4
1) an H from BH4- attacks carbonyl C
2) carbonyl O and new H = single bond w/ carbonyl C
3) H2O or any H+ gets attacked by single carbonyl O
Primary alc vs secondary alc
C-OH is bonded to 1 other C vs C-OH is bonded to 2 other Cs
What can NaBH4 and LAH reduce?
LAH can reduce all CA, esters (into ald and primary alc), ald and ket; NaBH4 ONLY reduces ald/ket
What type of rxn is going from alc to carbonyl compounds? What about from carbonyl compounds to alcs?
oxidation/[O]; reduction/[H]
How to convert CA and esters into alc with LAH
1) LAH attacks carbonyl C –> single bonds around carbonyl C
2) single carbonyl O becomes a double bond again with carbonyl C and kicks out -OR –> ald
3) more LAH attacks like BH4 –> alc product
ortho vs meta vs para
2 groups on adjacent C of phenols vs 2 groups = separated by a C of phenols vs 2 groups = opposite end of phenol ring
How to name straight chain alcohols and aromatic alcohols?
alkyl alcohol and phenol
PCC can oxidize/[O] primary alc to ald. But can PCC [O] ald to CA? Can PCC [O] secondary alc to ket?
No, you need H2O to [O] ald to CA and PCC doesn’t react w/ H2O –> using PCC stops at ald stage. PCC can [O] sec alc to ket
Can tertiary alc be [O]?
Nope, they’re as oxidized as they can be w/o breaking C-C bonds; there is no H attached to the carbon w/ hydroxyl group (ie. Alpha H)
What do you get when you [O] phenols vs quinones?
quinones vs hydroxyquinones
What are common names of vit K1 and vit K2?
phylloquinone and menaquinone respectively
Hydroquinone vs hydroxyquinone
benzene ring w/ 2 opposite -OH vs almost benzene ring w/ 2 opposite carbonyls and various number of -OH
What’s ubiquinone?
aka Coenzyme Q in ETC; can be reduced to ubiquinol. It’s a small, hydrophobic molec that can move freely in inner mito membrane
A dialcohol can react w/ ald/ket to form what? What about reverse?
acetal (primary C with 2 -OR groups => basically 2 ether groups on primary C)/ketal (secondary C with 2 -OR groups => basically 2 ether groups on secondary C). Acetals/ketals can serve as protecting groups for alcs b/c they don’t react with reducing agents
Acetals/Ketals can be reverted back into ald/ket + diols by reacting with aq acid + heat => deprotection
How to form tosylate? What about reverse?
1) R-OH attacks electrophilic S of tosyl chloride –> Cl = leaving group
2) Pyridine acts as base and grabs H from R-OH-tosyl –> R-O-STosyl => tosylate
Tosylate acts as protecting group for alcs; can be reverted back to alcs by using a strong acid
How to form mesylate? What about reverse?
1) triethylamine acts as base and grabs a methyl H from mesyl chloride –> nucleophilic methyl C
2) double bond forms b/w methyl C and S –> Cl = leaving group
3) R-OH attacks electrophilic S of mesyl –> methyl C = nucleophilic again
4) Methyl C grabs H from R-OH-mesyl –> R-O-mesyl => mesylate
Mesylate acts as protecting group for alcs; can be reverted back to alcs by using a strong acid
Jones reagent (CrO3 with dilute sulfuric acid), salt dichromate (_Cr2O7), chromium, and KMnO4 can convert primary and secondary alcs to what?
Primary to CA, secondary to ket
Geminal vs vicinal diols
Aka hydrates, Diols with -OH’s on same carbon vs aka GLYCOLS, Diols with -OH’s on adjacent carbons
Diols are common protecting groups for which functional groups?
Ald and ket carbonyls
How do you know if a reagent will [O] -OH to ald/ket or CA intentionally?
If they really only want ald/ket, they will use a reagent specific for [O] to ald/ket. Otherwise, it’ll go straight to CA
How acidic are hydroxyl H’s?
Weakly acidic, but phenol H’s = more acidic than those of other alcs —> phenols can form salts w/ inorganic bases like NaOH. Phenols have high Ka/low pKa
Descending acidity: phenols > alkyl alcs > cyclo alcs (cyclo alcs rather donate e- instead of accepting them)
Order of increasing bpt b/w alcs, alkanes and ald/ket
Alkanes < ald/ket < alcs
Can NaBH4 reduce CAs?
Nope, not even to ald
