Rules of the Day

2. The general rule of solvation is "like dissovles like", so polar, hydrogen bonding solvents dissolve polar, charged, or hydrogen bonding molecules and non-polar hydrocarbons dissolve nonpolar hydrocarbons. Non-polar material does not dissolve in polar solvents because the polar molecules stick to each other too well.

3. Alcohols are realtively weak acids with pKa's in the 15-19 range. Thiols are more acidic, with pKa's in the 8-12 range since the larger S atom can more easily accomodate the negative charge.

4. Alcohols react with Na° metal to form H2 and alkoxides, which are interesting because they are strong nucleophiles and strong bases.

5. The OH group is not a leaving group, but several reactions involve the conversion of the OH group into a good leaving group, followed by an SN2, E2, E1, or SN1 reaction.

6. 3° and 1° alcohols react with H-X to give haloalkanes via protonation followed by SN1 and SN2 mechanisms, respectively. 2° alcohols give too much rearrangement to be useful. Note the stereochemistry is scrambled for the 3° alcohols (SN1).

7. Alcohols react (dehydrate) with strong acid to give alkenes. 2° and 3° alcohols react via a combination of protonation and an E1 mechanism (carbocation rearrangements possible!) and 1° alcohols react via a combination of protonation and E2. In both cases, remember to make the Zaitzev product when there is a choice.

8. Alcohol dehydration is just the functional reverse of acid-catalyzed alkene hydration. The process is actually an equilibrium, the position of which depends on the reaction conditions.