organic - mcmurry 9e ch. 17 - alcohols and...

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ORGANIC - MCMURRY 9E

CH. 17 - ALCOHOLS AND PHENOLS

CONCEPT: ALCOHOL NOMENCLATURE

□ Glycols: Alcohols with two hydroxyls are called ___________; with three hydroxyls are called ____________

● Always give most priority to the –OH group.

EXAMPLE: Provide the correct common and IUPAC name of the following alcohols.

a.

b.



CONCEPT: INTRO TO REDOX

● Oxidation reactions involve an increase in the ______________ content of a molecule

● Reduction reactions involve an increase in the ______________ content of a molecule

EXAMPLE: Label the following transformations as oxidation or reduction.

a.

b.

c.



CONCEPT: OXIDATION

□ Oxidizing agents are used to oxidize molecules

● Most oxidizing agents add as much oxygen as possible while not breaking ANY C-C bonds.

EXAMPLE: Which of the following compounds could be oxidized?

□ These are called strong oxidizing agents. They include KMnO4 and the Cr6+ reagents (H2Cr2O4, CrO3, K2Cr2O7, etc.)

EXAMPLE: Draw the products of the previous molecules with a strong oxidizing agent

□ PCC is a weak oxidizing agent. It reacts similar but can only add ____ equivalent of oxygen to 1º alcohols.



PRACTICE: Provide the major product for the following oxidation reaction.

CH3

CH3 CH3

OHOH

OH PCC

CH2Cl2


CH3CH2 1. O3

2. Zn, CH3CO2H


KMnO4

H+

OH

OH

OH




PRACTICE: Determine the major product for the following reaction.

PRACTICE: Determine the major product for the following reaction.

PRACTICE: Provide the necessary reagents for the following transformation.



CONCEPT: REDUCTION

□ Reducing agents are used to reduce molecules

● These reagents add hydrogens across π-bonds. Unsaturated hydrocarbons and carbonyls can be reduced.

General Mechanism: Nucleophilic addition of hydrogen

□ Reducing agents add to ALL π-bonds present. Multiple equivalents of hydrogen will react if possible.

● LiAlH4 is a strong reducing agent. It is able to reduce ANY carbonyl compound into alcohol

EXAMPLE: Draw the products of the following molecules reacted with LiAlH4

□ NaBH4 is a weak reducing agent. It can only add ____ equivalent of hydrogen and can only reduce CHO and ketones

EXAMPLE: Draw the products of the following molecules reacted with NaBH4



PRACTICE: Predict the product of the following reactions

a.

b.

c.



CONCEPT: NUCLEOPHILIC ADDITION

□ One of the most important ways that carbonyl compounds react is through nucleophilic addition.

● The carbonyl carbon is _____________________________

Nucleophilic Addition General Mechanism:

Nucleophilic Addition General Reactions:



CONCEPT: PREPARATION OF ORGANOMETALLICS

□ Organometallics are alkylating agents that have mostly group IA or group IIA metals bonded to a carbon structure

● They can also react as strong ____________. Beware of cross-reactions with acidic hydrogens.

1. Sodium Alkynides

2. Grignard Reagents

3. Organolithium Reagents

4. Gilman Reagents



CONCEPT: REACTIONS OF ORGANOMETALLICS

1. Substitution/Elimination on Alkyl Halides

2. Nucleophilic Addition on Ketones and Aldehydes

3. Nucleophilic Acyl Substitution on Esters

4. Base-Catalyzed Epoxide Ring Opening



CONCEPT: USE OF PROTECTING GROUPS

□ Organometallics are powerful bases. They will react with any acidic protons available, ruining the reagent.

We can use tert-butyl or silyl ethers to protect alcohols from deprotonation by organometallic reagents

● p-Toluenesulfonic acid is an acid commonly used for this step (abbrev. TsOH or pTSA)

EXAMPLE: Provide the mechanism and final product for the following transformation



PRACTICE: Predict the product of the following reaction.



PRACTICE: Propose a synthesis to accomplish the following transformation.



PRACTICE: Propose a synthesis to accomplish the following transformation (Hint: 4 steps)



CONCEPT: ACID-CATALYZED DEHYDRATION

□ Alcohols are terrible leaving groups, but in the presence of acid, they can be converted into an awesome leaving group

● The more –R groups on the alcohol, the easier to dehydrate: _________________________________

● The specific elimination mechanism depends on how easily the molecule will form a ______________________.

E2 Dehydration: 1o Alcohol Mechanism:

● Protonation:

● E2 β-Hydrogen Elimination:



CONCEPT: ACID-CATALYZED DEHYDRATION

□ Alcohols are terrible leaving groups, but in the presence of acid, they can be converted into an awesome leaving group

E1 Dehydration: 2o and 3o Alcohol Mechanism:

● Protonation:

● Carbocation Formation:

● E1 β-Hydrogen Elimination:



PRACTICE: Provide the mechanism and major product for the following dehydration reactions:

a.

b.



CONCEPT: DEHYDRATION WITH PHOSPHORYL CHLORIDE

□ Alcohol can attack POCl3 to become a good leaving group, which can then be eliminated by base.

Mechanism:

● Nucleophilic Attack + Deprotonation

●E2 β-Hydrogen Elimination:



CONCEPT: FISCHER ESTERIFICATION— MECHANISM

Also known as acid-catalyzed esterification, this is one of the more important mechanisms in this course.

General Reaction:

Mechanism:



CONCEPT: TERT-BUTYL ETHER PROTECTING GROUPS

□ Protecting groups are used to shield reactive moieties while reactions are happening on other parts of the molecule.

● By definition, they must be completely reversible.

EXAMPLE: Will the following reaction proceed efficiently as drawn? Why or why not?



t-Butyl Ether: ● Addition of isobutylene through reversible acid-catalyzed alkoxylation



CONCEPT: SILYL ETHER PROTECTING GROUPS

□ A group used to protect alcohols are silyl (silicon) chlorides.

Mechanism: ● TBDMS is the most common silyl chloride in Organic Chemistry 1

EXAMPLE: Predict the product of the following reaction



organic - mcmurry 9e ch. 17 - alcohols and...

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