RAYO ALCOHOLS (R-OH) AND PHENOLS (Ar-OH)

• ALCOHOLS

  • Organic compounds that contain an –OH group attached to a saturated carbon atom
• PHENOLS

  • Carbolic acid
  • A benzene ring with an –OH group directly attached to one of its carbon atom
• MONOHYDRIC ALCOHOLS

  • A.K.A. monohydroxy alcohols
  • Presence of one –OH group
• DIHYDRIC ALCOHOL

  • A.K.A. dihydroxy alcohols
  • Polyhydric/polyhydroxy alcohols  Presence of two –OH group
• TRIHYDRIC ALCOHOLS

  • A.K.A. trihydroxy alcohols
  • Polyhydric/polyhydroxy alcohols
  • Presence of three –OH group
• ALKYL ALCOHOL

  Primary (RCH2OH)

  • Carbon of –OH group is attached to a single alkyl group
• ALKYL ALCOHOL

  Secondary (R2CHOH)

  Carbon of –OH group is attached to 2 alkyl groups – may they be structurally similar or different
• ALKYL ALCOHOL

  Tertiary (R3COH)

  • Carbon of –OH group is attached to 3 alkyl groups
• VINYLIC ALCOHOL

  • Generally unstable in nature
  • Isolated forms: polymer derivatives, Esters, Ether


  Pyrolytic Elimination

  • Elimination of H2O from ethylene glycol (C2H6O2)
  • Production of vinylic alcohol
• BENZYLIC ALCOHOL

  • Aromatic alcohol
  • -OH group attached to a methyl group that is attached to a benzene ring
  • A toluene molecule where 1 hydrogen atoms has been replaced by an –OH group
• PHENOL COMPOUNDS

  • A.K.A. Carbolic acid 
  • The –OH group is directly attached to the benzene ring
• NOMENCLATURE OF ALCOHOL

  A) 1

  B) 2

  
• CHARACTERISTICS

  • Liquid at RT (glycerol = viscous liquid)
  • Colorless
  • Flammable
• BOILING POINT

  • Higher BP compared to hydrocarbons
  • Hydrogen Bond
  • Bond to each other and to water molecules
  • Higher than normal BP
  • Van der Waals force
  • Decrease with decreased surface area
  • 1° ROH has a higher boiling point
  • Increases with increasing carbon atoms
  • Decreases with increase branching
• SOLUBILITY

  • Polar
  • -OH group being hydrophilic in nature
  • Solubility decreases with increased size of alkyl group
  • (Intermolecular) hydrogen bond
  • Explains the solubility of ROH in water
  • Miscible in water
  • ROH ≤ 3C = indefinitely solubility
  • ROH ≥ 4 C = limited solubility (except 2-methypropan-2-ol)
  • Immiscible with nonpolar solvents
• ACIDIC AND BASIC PROPERTIES OF ALCOHOL

  FAVORABLE: Strong acid + Strong base = Weak Acid + Weak base

  • Form: N-H
  • Break: O-H
• ACIDIC AND BASIC PROPERTIES OF ALCOHOL

  UNFAVORABLE: Weak acid + Weak base = Strong acid + Strong base

  • Form: O-H
  • break: N-H
• EQUILIBRIUM

  • Favors the direction where a stronger acid and base produces a weaker acid and base
• ACIDITY

  • Reaction of acid with an active metal leads to formation of alkoxide
  • Reaction points to acidity of ROH in nature
  • Conjugate base should be stabilized in order for ROH to be acidic
• FACTORS THAT STABILIZE THE CONJUGATE BASE

  • Bringing charge closer to the (+) charged nucleus; The more stable a lone pair, the less basic it is; Certain species are made acidic by adjacent electron withdrawing groups
  • Spreading charge out over a larger volume o Diffuse charge is more stable than concentrated charge o The larger atoms are said to be more polarizable (I > Br > Cl > F)
• Combustion

  • O2 is required
  • Heat and light is Produced
  • ALCOHOL → CARBON DIOXIDE + WATER
• Halogenation

  • Phosphorus trichloride (PCl3) and phosphorus tribromide (PBr3) are sources of Halogen
  • Heat is needed.
  • ALCOHOL → ALKYL HALIDE
• Oxidation

  • Potassium permanganate (KMnO4) and potassium dichromate (K2Cr2O7) are oxidizing agents
  • PRIMARY ALCOHOL → ALDEHYDE → CARBOXYLIC ACID
  • SECONDARY ALCOHOL → KETONES
  • TERTIARY ALCOHOL → NO RXN
• Dehydration

  • Sulfuric acid (H2SO4) as catalyst
  • 180 C: Intramolecular Dehydration

  -SEC&TERT ALCOHOL → ALKENE

  • 140 C: Intermolecular Dehydration

  -PRIMARY ALCOHOL→ ETHER
• MOST COMMON MILD OXIDIZING AGENTS

  • PCC (pyridinium chlorochromate): Converts primary alcohols to aldehydes and secondary alcohols to ketones.
  • PDC (pyridinium dichromate): Similar to PCC but more stable for larger scale reactions.
  • Swern oxidation: Uses oxalyl chloride and a tertiary amine to convert alcohols to aldehydes or ketones.
  • Dess-Martin periodinane: A mild and selective oxidizing agent for alcohols to aldehydes or ketones.

  A) PCC (pyridinium chlorochromate)

  B) PDC (pyridinium dichromate)

  C) Swern

  D) Dess-Martin periodinane

  
• MOST COMMON

  • Chromic acid (H2CrO4 or CrO3 in aqueous solution): Oxidizes primary alcohols to carboxylic acids and secondary alcohols to ketones.
  • Potassium permanganate (KMnO4): Oxidizes alkenes to diols, alcohols to carboxylic acids, and other organic compounds.
  • Sodium hypochlorite (NaClO, bleach): Used for oxidizing alcohols to aldehydes or ketones.

  STRONG OXIDIZING AGENTS

  A) Chromic acid

  B) POtassium Permanganate

  C) Sodium Hypochlorite

  
• MECHANISM ALCOHOL OXIDATION

  • Installation of a leaving group on the hydroxyl oxygen
  • Removing the neighboring hydrogen by kicking out the leaving group → formation of C=O pi bond
• MECHANISM OF ALDEHYDE TO CARBOXYLIC ACID

  • Aldehydes react with H2O → aldehyde hydrate resembling a 2° ROH structure
• DEHYDRATION OF ALCOHOL: Heating ROH in the presence of strong acid as a catalyst REQUIRED TEMPERATURE

  • Primary 170°C to 180°C
  • Secondary 100°C to 140°C
  • Tertiary 25 °C to 80 °C
• MECHANISM OF DEHYDRATION OF ALCOHOL

  • -OH group donates 2 electrons to H+ from the acid reagent → alkyloxonium ion (good LG) → carbocation
  • Deprotonated acid (nucleophile) attacks the hydrogen adjacent to the carbocation  Formation of a double bond
• INTRAMOLECULAR HYDROGEN BOND

  • Secondary and tertiary ROH
  • Products: Alkene + H2O
• E1 ELIMINATION MECHANISM

  • Protonation of –OH group → good LG weakening the C-O bond
  • Protonated ROH undergoes elimination
• E2 ELIMINATION MECHANISM

  In E2 elimination, a strong base deprotonates a β-hydrogen adjacent to the leaving group, leading to the formation of a double bond as the leaving group is expelled.
• INTERMOLECULAR DEHYDRATION OF ALCOHOL

  • Exclusive for primary ROH
  • Products: Ether + H2O
  • Nucleophilic Substitution Reaction
  • 2 molecules of ROH undergoes dehydration by condensation, forming an ether
• INTRAMOLECULAR DEHYDRATION

  • 1 molecule of ROH undergoes dehydration within itself to produce alkenes
  • 1 molecule of H2O is eliminated from 1 molecules of ROH
• 1. Aldehydes can be reduced to primary alcohols.
  2. Ketones can be reduced to secondary alcohols.
  3. Carboxylic acids can be reduced to primary alcohols.
  4. Esters can be reduced to primary alcohols.
• Grignard Reactions with Carbonyl Compounds:

  1. Formaldehyde:

  • Formaldehyde reacts with Grignard reagents to form primary alcohols.

  1. Aldehydes:

  • Aldehydes react with Grignard reagents to form secondary alcohols.

  1. Ketones:

  • Ketones react with Grignard reagents to form tertiary alcohols.

  1. Esters:

  • Esters react with Grignard reagents to form tertiary alcohols.
• ETHANOL

  • A.K.A. ethyl alcohol/grain alcohol
  • Most common drug of abuse
  • Most ingested ethanol are converted to acetic acid
• STAGES OF IMPAIRMENT BY ETHANOL

  A) 0.01-0.05

  B) 0.03-0.12

  C) 0.09-0.25

  D) 0.18-0.30

  E) 0.27-0.40

  F) 0.35-0.50

  
• PHYSICAL PROPERTIES OF PHENOL

  • Generally low-melting solids
  • Most are only slightly soluble in water