Alcohols Alcohols as Acids Alcohols as Acids Alcohols
- Slides: 33
Alcohols
Alcohols as Acids
Alcohols as Acids
Alcohols as Acids
Alcohols as Acids resonance in phenols
Alcohols Methanol and ethanol are industrial chemicals: solvents, antifreeze, fuel, antiseptic, social / recreational Isopropyl alcohol is prepared by hydration of propene. All alcohols with four carbons or fewer are readily available. Most alcohols with five or six carbons are readily available.
Sources of alcohols Reactions discussed in earlier chapters Hydration of alkenes Hydroboration-oxidation of alkenes Hydrolysis of alkyl halides
Sources of alcohols New methods: Reduction of aldehydes and ketones Reduction of carboxylic acids Reduction of esters Reaction of Grignard reagents
Preparation of Alcohols by Reduction of Aldehydes and Ketones
Reduction of Aldehydes Gives Primary Alcohols R R C H O H C H OH
Example: Catalytic Hydrogenation O CH 3 O CH + H 2 Pt, ethanol CH 3 O CH 2 OH (92%)
Reduction of Ketones Gives Secondary Alcohols R R C R' O H C R' OH
Example: Catalytic Hydrogenation H O + H 2 OH Pt ethanol (93 -95%)
Retrosynthetic Analysis R H C R OH H: – R C R' O C O H H H C R OH H: – R'
Metal Hydride Reducing Agents H H + Na H – B H Li + Al H H H Sodium borohydride H – Lithium aluminum hydride act as hydride donors
Examples: Sodium Borohydride Aldehyde O 2 N O O 2 N Na. BH 4 CH 2 OH CH methanol (82%) Ketone O Na. BH 4 ethanol H OH (84%)
Lithium aluminum hydride more reactive than sodium borohydride cannot use water, ethanol, methanol etc. as solvents diethyl ether is most commonly used solvent
Examples: Lithium Aluminum Hydride Aldehyde O CH 3(CH 2)5 CH 1. Li. Al. H 4 diethyl ether 2. H 2 O CH 3(CH 2)5 CH 2 OH (86%) Ketone O (C 6 H 5)2 CHCCH 3 1. Li. Al. H 4 diethyl ether 2. H 2 O OH (C 6 H 5)2 CHCHCH 3 (84%)
Selectivity neither Na. BH 4 or Li. Al. H 4 reduces isolated double bonds O 1. Li. Al. H 4 diethyl ether 2. H 2 O (90%) H OH
Preparation of Alcohols By Reduction of Carboxylic Acids and Esters
Reduction of Carboxylic Acids Gives Primary Alcohols R R C HO O H C H lithium aluminum hydride is only effective reducing agent OH
Example: Reduction of a Carboxylic Acid O 1. Li. Al. H 4 diethyl ether COH 2. H 2 O CH 2 OH (78%)
Reduction of Esters Gives Primary Alcohols Lithium aluminum hydride preferred for laboratory reductions Sodium borohydride reduction is too slow to be useful Catalytic hydrogenolysis used in industry but conditions difficult or dangerous to duplicate in the laboratory (special catalyst, high temperature, high pressure
Example: Reduction of a Carboxylic Acid O COCH 2 CH 3 1. Li. Al. H 4 diethyl ether 2. H 2 O CH 2 OH + (90%) CH 3 CH 2 OH
Summary
Synthesis of Alcohols Sodium borohydride / Lithium aluminum hydride Reductions
- Alcohol ester reaction
- Acidity of alcohols
- Cppp cholesterol
- Diol oxidation
- Naming alkyl halides
- Chlorination
- Sp
- Formation of alcohols
- Tollens reagent
- Naming ethers
- Hydrogen halide
- Sugar alcohol names
- Oxidation primary alcohol
- Alcohols phenols thiols and ethers
- Pentanal isomers
- Reactions of alcohols 2 chemsheets answers
- Oxidation of alcohols
- Alcohols nomenclature
- Chapter 12 basics of chemistry review questions
- Acids and bases
- Characteristics of acids and bases
- Homemade indicators for acids and bases
- What are the seven strong acids
- What is an anticodon
- Essential lipids
- Beta oxidation of odd chain fatty acids
- Nucleophilic substitution of carboxylic acids
- Nucleoside and nucleotide
- Food that rich in nucleic acid
- How many amino acids are there
- Base water
- Acids
- Essential amino acids arginine
- Naming acids