1. Alcohols and Ethers

2. Important Alcohols in Nature
(-) Menthol
Vanillin

3. Important Ethers in Nature
Eucalyptol

4. IUPAC Substitutive Nomenclature
An IUPAC name may have up to 4 features: locants, prefixes, parent compound and suffixes
Numbering generally starts from the end of the chain which is closest to the group named in the suffix

5. Alcohols R-OH IUPAC Nomenclature of Alcohols
Select the longest chain containing the hydroxyl and change the suffix name of the corresponding parent alkane from -ane to -ol
Number the parent to give the hydroxyl the lowest possible number
The other substituents take their locations accordingly

6. Common Names of simple alcohols are still often used and are approved by IUPAC

7. Penta-2,3,4-triol 4-Methyl-hex-1-en-3-ol Pent-2-yne-1,4-diol
Alcohols with two hydroxyls are called diols in IUPAC nomenclature and glycols in common nomenclature
Alcohols with two or more hydroxyls , use the prefixes (di, tri, tetra,....) to indicate the numbers of hydroxyl group.
Penta-2,3,4-triol
4-Methyl-hex-1-en-3-ol
Pent-2-yne-1,4-diol

8. Alcohols R-OH Classification of Alcohols 1° Primary Alcohol
2° Secondary Alcohol
3° Tertiary Alcohol

9. Ethers R-O-R Nomenclature of Ethers Common Names IUPAC
The groups attached to the oxygen are listed in alphabetical order
IUPAC
Ethers are named as having an alkoxyl substituent on the main chain

10. Cyclic ethers can be named using the prefix oxa-
Three-membered ring ethers can be called oxiranes;
Four-membered ring ethers can be called oxetanes
Oxacyclopropane
Or oxirane
(ethylene oxide)
Oxacyclobutane
Or oxetane
Oxacyclopentane
(tetrahydrofurane)
1,4-Dioxacyclohexane
(1,4-dioxane)

11. Hydrogen bonding between molecules of Methanol
Physical Properties of Alcohols and Ethers
Ether boiling points are roughly comparable to hydrocarbons of the same molecular weight
Molecules of ethers cannot form hydrogen bond to each other
Alcohols have considerably higher boiling points
Molecules of alcohols connect with hydrogen bond to each other
Both alcohols and ethers can form hydrogen bond to water and have similar solubilities in water
Diethyl ether and 1-butanol have solubilites of about 8g /100 mL in water
Hydrogen bonding between molecules of Methanol

12. Physical properties of Alcohol and Ethers
Steric factors affect hydrogen bonding.
Physical properties of Alcohol and Ethers

14. Synthesis of Alcohols Via Acid-Catalyzed Hydration of Alkenes
Via Reduction of Cabonyl Compounds
Via Grignard Reagents

15. Synthesis of Alcohols Via Acid-Catalyzed Hydration of Alkenes
This is a reversible reaction with Markovnikov regioselectivity

16. Reactions of Carbonyl Compounds
with Nucleophiles
Carbonyl groups can undergo nucleophilic addition
The nucleophile adds to the d+ carbon
The p electrons shift to the oxygen
The carbon becomes sp3 hybridized and therefore tetrahedral
Hydride ions and carbanions are two examples of nucleophiles that react with the carbonyl carbon

17. Synthesis of Alcohols by Reduction of Carbonyl Compounds
A variety of carbonyl compounds can be reduced to alcohols
Carboxylic acids can be reduced to primary alcohols
These are difficult reductions and require the use of powerful reducing agents such as lithium aluminum hydride (LiAlH4 also abbreviated LAH)

18. Esters are also reduced to primary alcohols
LAH or high pressure hydrogenation can accomplish this transformation

19. Aldehydes and ketones are reduced to 1o and 2o alcohols respectively
Aldehydes and ketones are reduced relatively easily; the mild reducing agent sodium borohydride (NaBH4) is typically used
LAH and hydrogenation with a metal catalyst can also be used

20. Aldehydes and ketones are reduced to 1o and 2o alcohols respectively

21. Carboxylic acids and esters are considerably less reactive to reduction than aldehydes and ketones and require the use of LAH
Lithium aluminium hydride (LiAlH4) is very reactive with water and must be used in an anhydrous solvent such as ether
Sodium borohydride (NaBH4) is considerably less reactive and can be used in solvents such as water or an alcohol

22. Synthesis of Alcohols from Grignard Reagents
Organometallic Compounds
Carbon-metal bonds vary widely in character from mostly covalent to mostly ionic depending on the metal
The greater the ionic character of the bond, the more reactive the compound
Organopotassium compounds react explosively with water and burst into flame when exposed to air

23. Grignard Reagents
Grignard reagents are prepared by the reaction of organic halides with magnesium turnings
An ether solvent is used because it forms a complex with the Grignard reagent which stabilizes it

24. Synthesis of Alcohols from Grignard Reagents
Aldehydes and ketones react with Grignard reagents to yield different classes of alcohols depending on the starting carbonyl compound

26. Alcohols as Acids Alcohols have acidities similar to water
Sterically hindered alcohols such as tert-butyl alcohol are less acidic (have higher pKa values)
Why?: The conjugate base is not well solvated and so is not as stable
Alcohols are stronger acids than terminal alkynes and primary or secondary amines
An alkoxide can be prepared by the reaction of an alcohol with sodium or potassium metal

27. Reactions of Alcohols Reactions of R----OH bond
The oxygen atom of the hydroxyl group is nucleophilic and weakly basic.
The hydroxyl group can be converted to a leaving group so as to allow subsyitution or elimination reactions.
Reaction with HX
Reaction with PX3
Reaction with SOCl2
Reactions of RO----H bond
The hydrogen atom of the hydroxyl group is weakly acidic
Combusition
Oxidation
Esterfication

28. Reactions of R----OH bond
Hydroxyl groups are poor leaving groups, and as such, are often converted to alkyl halides when a good leaving group is needed.
Three general methods exist for conversion of alcohols to alkyl halides, depending on the classification of the alcohol and the halogen desired.
The most commonly used reagents for for conversion of alcohols to alkyl halides are the following:
Hydrogen halides (HCl, HBr, HI).
Phosphorus tribromide (PBr3).
Thionyl chloride (SOCl2).

29. Reaction with Hydrogen Halides (HX)
The order of reactivity of alcohols is 3° > 2° > 1° > methyl .
The order of reactivity of the hydrogen halides is HI > HBr > HCl (HF is generally unreactive.
The reaction is acid-catalized, but they do not react with nonacidic NaCl, NaBr or NaI.

30. Reaction with Phosphorus Trihalide (PX3).
Primary 1°,secondary 2° and tertiary 3° alcohols react with phosphorus trihalide to yield alkyl halides with inversion (D ↔ L) .
Reaction Thionyl Chloride (SOCl2).
Primary 1°,secondary 2° and tertiary 3° alcohols react with phosphorus tribromide to yield alkyl chlorides with retention (D ↔ D) or (L ↔ L)

31. Starting with alcohols, outline a synthesis of each of the following:
(a) Benzyl bromide
(b) Cyclohexyl chloride
(c) Butyl bromide

32. Reactions of RO----H bond
1- Combusition Reaction of Alcohol
2- Oxidation Reaction of Alcohol
Alcohol can oxidized by warming an acidic potassium dichromate(VI) (K2Cr2O7)
Ethanol
Ethanal
Ethanoic
acid
Primary alcohol 1°
- H2
+ O
Aldehyde
Carboxylic
acid
secondary alcohol 2°
- H2
+ O
Ketone
tertiary alcohol 3°
- H2

33. Oxidation of Alcohols Oxidation of 1° 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)
PCC is made from chromium trioxide under acidic conditions
It is used in organic solvents such as methylene chloride (CH2Cl2)

34. Oxidation of 1° Primary Alcohols to Carboxylic Acids
Potassium permanganate (KMnO4) is a typical reagent used for oxidation of a primary alcohol to a carboxylic acid
The reaction is generally carried out in aqueous solution; a brown precipitate of MnO2 indicates that oxidation has taken place
Oxidation of 2° Secondary Alcohols to Ketones
Oxidation of a secondary alcohol stops at the ketone
Many oxidizing agents can be used, including chromic acid (H2CrO4) and Jones reagent (CrO3 in acetone)

35. Esterification Reaction
Reaction of alcohols with carboxylic acids in the presence of conc. H2SO4
forms esters as shown in the following general equation:
carboxylic
acid
alcohol
ester
Example:

36. A Chemical Test for Primary and Secondary Alcohols
Chromium oxide in acid has a clear orange color which changes to greenish opaque if an oxidizable alcohol is present

37. Synthesis of Ethers 1. Ethers by Intermolecular Dehydration of Alcohol
Primary alcohols can dehydrate to ethers
This reaction occurs at lower temperature than the competing dehydration to an alkene
This method generally does not work with secondary or tertiary alcohols because elimination competes strongly
1° Alcohol

38. Synthesis of Ethers 2. Williamson Ether Synthesis
This is a good route for synthesis of unsymmetrical ethers

39. Reactions of Ethers
Acyclic ethers are generally unreactive, except for cleavage by very strong acids to form the corresponding alkyl halides