Classification of Alcohol Primary: carbon with –OH is bonded to one other carbon. Secondary: carbon with –OH is bonded to two other carbons. Tertiary: carbon with –OH is bonded to three other carbons. Aromatic (phenol): -OH is bonded to a benzene ring.

Classify these:

IUPAC Nomenclature of Alcohols Name the longest continous chain of carbons containing the –OH group Number which carbon the –OH is attached to Drop the -e from the alkane name, add - ol. If more than one hydroxyl group, use suffixes –diol, -triol, etc.

Name these: 2-methyl-1-propanol 2-methyl-2-propanol 2-butanol 3-bromo-3-methylcyclohexanol =>

Unsaturated Alcohols Hydroxyl group takes precedence. Assign that carbon the lowest number. Use alkene or alkyne name. 4-penten-2-ol (old) pent-4-ene-2-ol (new) =>

Naming Priority 1- Acids 2- Esters 3- Aldehydes 4- Ketones 5- Alcohols 6- Amines 7- Alkynes 8- Alkenes 9- Alkanes 10- Ethers 11- Halides

Common Names Alcohol can be named as alkyl alcohol. Useful only for small alkyl groups. Examples: isobutyl alcohol sec-butyl alcohol

Alcohols (diols, triols) -diols or –triols mean two or three hydroxy groups in the molecule Number the hydroxy group carbons with the lowest possible numbers Prefix uses the full parent name, i.e butane, Ethane-1,2-diol (ethylene glycol) Propane-1,2,3-triol (glycerol)

Nomenclature of phenol -OH group is assumed to be on carbon 1. For common names of disubstituted phenols, use ortho- for 1,2; meta- for 1,3; and para- for 1,4. Methyl phenols are cresols. 3-chlorophenol meta-chlorophenol 4-methylphenol para-cresol =>

Nomenclature of phenol. Phenols are usually named as substituted phenols. The methylphenols are given the special name, cresols. Some other phenols are named as hydroxy compounds.

Nomenclature of phenol. 2,4,6-trinitrophenol (picric acid) 1-naphthol 2- naphthol 2-bromo-1-nitro-3-naphthol (  - naphthol) (  -naphthol)

12 Formation of Alkoxide Ions React methanol and ethanol with sodium metal. Ethanol sodium ethoxide

Formation of Phenoxide Ion Phenol reacts with hydroxide ions to form phenoxide ions. OH + OH O + HOH => Phenol phenoxide

Reactions of Alcohols and phenol

1- Acidity of Alcohols and phenol Alcohols and phenols are weakly acidic pK a range: (water: 15.7) Acidity decreases as alkyl group increases. They dissociate in H2O to give the alkoxide or phenoxide anion Electron withdrawing gps increase the acidity. Phenol is 100 million times more acidic than cyclohexanol!

Number the following acids in decreasing order of acid strength? (let # 1 = most acidic, etc.)

Table of K a Values

2-Nucleophilic substitution (Reaction with HX) The order of reactivity is as follows Hydrogen halide HI > HBr > HCl > HF Type of alcohol 3 o > 2 o > 1 o  methyl

Chapter 11 Mechanism of the Reaction of Alcohols with HX  mechanism for 3 o, 2 o, allylic and benzylic alcohols In step 1 the hydroxyl is converted to a good leaving group In step 2 the leaving group departs as a water molecule, leaving behind a carbocation

–In step 3 the halide, a good nucleophile, reacts with the carbocation Primary and methyl alcohols undergo substitution as follows

3-Dehydration of alcohol Removal of water Catalyst =Sulfuric acid (excess H 2 SO 4 ) Product = Alkene + water

3-Dehydration of alcohols Note:- More substituted alkene will be major product (Saytizive rule)

4- Oxidation Result depends on if alcohol is primary, secondary, or tertiary Primary 1  OH  Produces an aldehyde RCHO  Then goes through further oxidation to produce a carboxylic acid Secondary 2  OH  Produces a ketone RCOR Tertiary 3  OH  No reaction -ve

4-Oxidation Q: What is oxidation reaction for a tertiary alcohol

 Oxidation of Primary Alcohols to Aldehydes A primary alcohol can be oxidized to an aldehyde or a carboxylic acid –The oxidation is difficult to stop at the aldehyde stage and usually proceeds to the carboxylic acid A reagent which stops the oxidation at the aldehyde stage is pyridinium chlorochromate (PCC)

4- Oxidation

4- Oxidation of alcohols ? ?

Special Reactions of Phenols

1-Electrophilic Aromatic Substitution The –OH group is a powerful activating group in EAS and an ortho/para director. a) nitration

b) halogenation

c) sulfonation At low temperature the reaction is non-reversible and the lower Eact ortho-product is formed. At high temperature the reaction is reversible and the more stable para-product is formed.

d) Friedel-Crafts alkylation.

e) Friedel-Crafts acylation

coupling with diazonium salts