Alcohols Alcohols Methanol and ethanol are industrial chemicals
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Alcohols
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 Diols by hydroxylation of alkenes
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
- Methanol versus ethanol
- Antigentest åre
- Specialty chemicals vs commodity chemicals
- Oxidation of tertiary alcohol
- Alcohols phenols thiols and ethers
- Methanol and propanoic acid
- Mangalore chemicals and fertilizers parent organizations
- You must put all chemicals and drugs in locked cupboards
- светр
- Lucas test mechanism
- Oxidation of alcohol
- These are alcohols containing cppp nucleus
- Secondary alcohols
- Lucas reagent equation
- Preparing haloalkanes from alcohols
- Chemsheets a2 1025 answers
- What does na2cr2o7 do
- Acidity of alcohols
- Sugar alcohol names
- Alcohols nomenclature
- Alcohols nomenclature
- Ethers naming
- Butanone isomers
- Hydroxyl group
- Reduction of alcohol to alkane
- Sample buffer 조성
- Examples of methanol
- Lewisstructuur methanol
- Methanol poisoning
- Methanol vs ethylene glycol
- Npcrt
- Methanol combustion equation