Question

MCAT Tutorial: Alcohols & Phenols

Answer 1

\({\bf{Basic~Definition}}\) a compound with a hydroxyl functional group bonded to an sp3 (alcohol) or an sp2 (phenol, alcohol with ring) carbon. If two hydroxyl groups are present the suffix diol may be used.



\({\bf{Nomenclature}}\) replace the e on an alkane with -ol. numbering is typically given to give the C with the -OH the lowest #.

\({\bf{Properties}}\) considering the -OH group, the O is very electronegative making the H very polar and often miscible with water w/ the exception of alcohols w/ long carbon chains. The hydrogen atoms are also very acidic.
If many alkyl chains present --> destabilizing effect, loses H and forms alkoxide, becoming less acidic

\({\bf{Examples}}\) methanol and ethanol are two very common alcohol solvents

Answer 2

\({\bf{Synthesizing~Alcohols}}\)

- convert alkenes to alcohols using addition rxns
- substitution reactions (usu. SN2 for alcohols, using polar aprotic solvents). SN1 possible but tends to produce mixtures and elimination products)

Answer 3

cont.

- addition rxns with carbonyl compounds
- for phenols; use electrophilic substitution

Answer 4

\({\bf{Reactions~with~Alcohols}}\)

1. react with PCC to produce aldehyde (primary) or ketone (secondary). tertiary typically not effective.
2. react with CrO3 and sulfuric acid to produce carboxylic acid (oxidation)
3. react with POCl3 and pyridine to make an alkene (SN2)
4. react with SOCl2 and pyridine to make alkyl chloride (SN2, chlorine attacks the R group). PBr3 can be used to make alkyl bromide using analagous mechanism.
> tosyl chloride can be used to make -OH a better leaving group
5. react with acid chloride Cl(C=O)R and pyirinde to make esther

\({\bf{Alcohol~Protection}}\) chlorotrimethylsilane can be used to shield the -OH group from reactions. makes TMS ether.

Answer 5

*forgot to mention, the TMS group can be removed using an acid

Answer 6

Anyway, that's the end of my tutorial, I hope it was a helpful resource. Source material is the 2nd Edition Barron's Prep book for the new MCAT