9.1-13.6 orgo textbook

Alcohols can act as acids or bases.
Deprotonation of alcohols to form alkoxides requires strong bases stronger than the alkoxide itself.
Strong bases include:
- Lithium diisopropylamide (LDA)
- Butyllithium
- Alkali metal hydrides such as potassium hydride (KH)
These bases can effectively remove a proton from the hydroxy (OH) group.
The reaction with alkali metal hydrides produces hydrogen gas as the sole by-product.

Methods to produce methoxide (NaOCH3) from methanol include:
- Reaction of sodium with methanol
- Use of alkali metals to obtain alkoxides, albeit less vigorous than water reactions.
- Alkali metals react with water to generate alkali metal hydroxides and hydrogen gas, with the following reaction:
  - 2H—OH + 2M (Li, Na, K, Cs) → 2M⁺(OH)⁻ + H2
The reactivity trends show that alcohols with less substitution react more readily with alkali metals.
Methanol has the highest reactivity, while tertiary alcohols are the least reactive.

Alkoxides serve as useful reagents.
Reactions include:
- Hindered alkoxides with haloalkanes result in elimination reactions.
- Less branched alkoxides react with primary haloalkanes via the SN2 mechanism to yield ethers.
A strong base will convert an alcohol to an alkoxide more rapidly with increasing base strength.

Deprotonation of the O–H bond allows substitution or elimination reactions.
Hydroxide (OH⁻) is a very poor leaving group.
Strong acids convert the hydroxy group into a good leaving group by forming alkyloxonium ions through protonation.
Protonation of OH → H2O, facilitating nucleophilic substitution.

Alkyloxonium ions from primary alcohols are attacked by good nucleophiles in reactions with hydrogen halides, like HBr, resulting in formation of haloalkanes.
Example: 1-butanol and HBr gives 1-bromobutane via SN2.

Secondary and tertiary alcohols form carbocations after protonation, leading to SN1 or E1 reactions.
The stability of carbocations influences reaction outcomes.

Carbocations can undergo rearrangements, leading to new products.
- Rearrangements are via hydride and alkyl shifts.
For example, 3-methyl-2-butanol gives 2-bromo-2-methylbutane, a rearranged product.

Alcohols react with carboxylic acids to form esters through a dehydration process (loss of water).
The reaction is catalyzed by strong acids, e.g. H2SO4.
Haloalkanes can be synthesized from alcohols using phosphorus tribromide
- Example: Primary and secondary alcohols → bromoalkane via SN2 pathway.

Ethers: derivatives of alcohols formed by replacing the hydroxy proton with an alkyl group.
IUPAC naming: ethers as alkoxyalkanes (smaller substituent as alkoxy). Common names follow by naming both alkyl groups with 'ether.'

Ethers are generally unreactive but can react with strong acids or undergo cleavage to yield alcohols and alkyl halides.
Acid-induced cleavage can proceed via SN1 or SN2 pathways, depending on the structure.
Tertiary ethers serve as protecting groups during organic synthesis, shielding functionalities from unwanted reactions.

Oxacyclopropanes participate in nucleophilic ring-opening reactions, which are regioselective and stereospecific.
The strain in oxacyclopropane facilitates nucleophilic attack, leading to alcohol formation via SN2 reactions.

Sulfur analogs: Thiol (R-SH) as the sulfur equivalent of alcohols and Thioether (R-SR') as the analog of ethers.
Naming follows similar logic as alcohols, considering the functional group's position in the main carbon chain.