CH. 10 THE CHEMISTRY OF ALCOHOLS AND THIOLSlightcat-files.s3.amazonaws.com/packets/admin... · CH....

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CH. 10 THE CHEMISTRY OF ALCOHOLS AND THIOLS

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:

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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:

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

a.

b.

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CONCEPT: CONVERSION OF ALCOHOLS TO GOOD LEAVING GROUPS

□ Alcohols are terrible leaving groups. If we want to react with them, they need to be transformed.

●They can be converted into ____________ _________________ or ______________ _______________

2o and 3o Alcohols with HX: SN1 mechanism

1o alcohols with HX: SN2 mechanism

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□ SOCl2 and PBr3 are two of the most commonly used reagents to transform alcohols into alkyl halides

●They always proceed with __________________________ of configuration.

1o and 2o Alcohols to RX: SN2 mechanism

EXAMPLE: Determine the mechanism for the following reaction. Draw the final product.

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□ Alcohols can attack sulfonyl chlorides to create sulfonate esters.

●They always proceed with __________________________ of configuration.

Alcohols to Sulfonate Esters:

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Alcohol Conversion Summary:

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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.

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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.

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CONCEPT: OXIDATION MECHANISMS

□ One of the most popular oxidizing agents is the Jones Reagent.

● It can be generated through combination of a strong acid with a Cr6+ reagent.

Mechanism:

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PRACTICE: Predict the product of the following reactions

a.

b.

c.

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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

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PRACTICE: Predict the product of the following reactions

a.

b.

c.

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CONCEPT: 1H NMR – PROTON RELATIONSHIPS

Hydrogens attached to the same carbon actually do have different relationships based on their chirality.

□ The Q-Test is used to determine the specific type of chirality of each hydrogen.

a. Homotopic Protons

Q-Test DOES NOT yield new chiral center

● Protons are always homotopic and are considered ______________________ (They share a signal)

● In general, the three hydrogens on -CH3 groups will always be homotopic

b. Enantiotopic Protons

Q-Test DOES yield new chiral center

.

● No original chiral centers = protons are still _____________________________ (They share a signal)

c. Diastereotopic Protons

Q-Test DOES yield new chiral center

.

● 1+ original chiral centers = protons are now __________________________ (Each proton gets its own signal)

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EXAMPLE: How many signals will each molecule possess in 1H NMR?

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PRACTICE: Identify the indicated set of protons as unrelated, homotopic, enantiotopic, or diastereotopic.



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CONCEPT: 1H NMR – PROTON RELATIONSHIPS

d. E / Z Diastereoisomerism

Q-Test DOES yield new trigonal center on terminal double bonds

● Protons are always diastereotopic and are ____________________________ (Each proton gets its own signal)

EXAMPLE: How many peaks will each molecule possess in 1H NMR?

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CONCEPT: REACTIONS OF THIOLS

□ Thiols contain an _____________ hydrogen, so they become excellent nucleophiles after exposed to __________

● These nucleophiles are called __________________

Sulfide Synthesis:

Disulfide Synthesis:

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CONCEPT: SYNTHESIS OF ALCOHOLS OVERVIEW

There are 4 different techniques commonly used to create alcohols in Organic 1. Thankfully, you already know all of them!

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CH. 10 THE CHEMISTRY OF ALCOHOLS AND THIOLSlightcat-files.s3.amazonaws.com/packets/admin... · CH....

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