Chapter 12 - Alcohols Flashcards
What is an alcohol?
Alcohols possess a hydroxyl group (-OH)
What is a phenol?
Phenols possess a hydroxyl group directly attached to an aromatic ring
Alcohol and phenol classification: Nomenclature procedure (5 steps)
- Identify the parent chain, include -OH even if it makes the chain shorter
- Identify, name, and alphabetize substituents
- Assign locants and prefixes to each substituent, give the lowest locant to the -OH
- Place -OH locant just before -ol suffix in parent chain
- Address stereochemistry
* Cyclic alcohols: -OH is assumed to be on carbon 1, locant is assumed
Common alcohol names (3)
Iso-propyl alcohol, turt-butyl alcohol, benzyl alcohol
Properties of alcohols (4)
- Raises boiling point (intermolecular forces)
- Miscible in water if less than eight carbons
- More acidic than amines and alkanes (resonance, induction, solvation)
- Deprotonated by NaH or Na with K/Li
Preparation of alcohols: SN2
(Starting materials, reaction conditions, major products)
Starting material: Primary alkyl halide
Reaction conditions: NaOH
Products: Primary alcohol
Preparation of alcohols: SN1
(Starting materials, reaction conditions, major products)
Starting material: Tertiary alkyl halide
Reaction conditions: H2O
Products: Tertiary alcohol
Preparation of alcohols: Addition (3 types)
(Starting materials, reaction conditions, major products)
- Starting material: Alkene
Reaction conditions: Dilute H2SO4
Products: Secondary alcohol
*Rearrangements - Starting material: Alkene
Reaction conditions: 1) Hg(OAc), H2O | 2) NaBH4
Products: Secondary alcohol - Starting material: Alkene
Reaction conditions: 1) BH3-THF | 2) H2O2, NaOH
Products: Primary alcohol
Preparation of alcohols: Reduction (3 types)
(Starting materials, reaction conditions, major products)
- Starting material: Carbonyls, alkenes, alkynes
Reaction conditions: H2, Pt or Pd or Ni
Products: Secondary alcohol
Will reduce all alkenes and alkynes - Starting material: Ketones, aldehydes, imines
Reaction conditions: NaBH4, EtOH or MeOH or H2O
Products: Secondary alcohol
Will only reduce carbonyl - Starting material: Ketones, aldehydes, imines, esters, carboxylic acids
Reaction conditions: 1) LAH | 2) H2O
Products: primary alcohol
Draw a mechanism for alcohol formation via reduction with BH4
Seriously, draw it.
Draw a mechanism for alcohol formation via reduction with LAH
No skipping!
Calculating carbon oxidation number (2 steps)
- Give electrons heterolytically to more electronegative atom
- Oxidation # = Valence - # of electrons on the carbon
What does an increase in an atom’s oxidation number mean? What about a decrease?
Increase in an atom’s oxidation number means the atom has been oxidized. A decrease means the atom has been reduced.
Why won’t tertiary alcohols undergo oxidation?
There are no hydrogens to remove
How do you name a diol? IUPAC? Common name?
Name using “diol” suffix and give a locant for each hydroxyl for IUPAC
Common names use “glycol”