organic - brown 8e ch.11 - ethers, epoxides and...

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ORGANIC - BROWN 8E

CH.11 - ETHERS, EPOXIDES AND SULFIDES

CONCEPT: ETHER NOMENCLATURE

□ Common Name: List alkyl groups in alphabetical order and follow with the word ____________

□ IUPAC: Smaller half of the ether is named as an _________________ substituent on the main alkane chain

EXAMPLE: Provide the correct common and IUPAC name of the following ether

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CONCEPT: SYNTHESIS OF ETHERS

1. Williamson Ether Synthesis (SN2 of 1o or 0o RX)

● Substitution with an oxide base. 2o and 3o alkyl halides will favor _______

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2. Acid-Catalyzed Alcohol Condensation

● Only forms _______________________________ ethers.

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CONCEPT: SYNTHESIS OF ETHERS

3. Alkoxymercuration of alkenes

● Same mechanism as oxymercuration, but using _________________ as the nucleophile instead of H2O.

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4. Acid-Catalyzed Alkoxyation

● Same mechanism as acid-catalyzed hydration, but using ______________ as the nucleophile instead of H2O

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PRACTICE: Predict the product for the following reaction

PRACTICE: Predict the product for the following reaction

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CONCEPT: CLEAVAGE OF ETHERS

□ Ethers are very combustible, but unreactive. They contain two strong C—O bonds that are not easy to break.

● They only undergo one synthetically useful reaction: cleavage in the presence of strong acid.

Mechanism:

EXAMPLE: Predict the product of the following reaction

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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?

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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

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CONCEPT: EPOXIDE NOMENCLATURE

□ Cyclic ethers are named as a unique functional group due to increased reactivity.

● 3-membered ethers are called _________________ or ___________________

□ Cycloalkane Convention: Name the ring as a cycloalkane, adding the prefix ________ and location if necessary

□ Epoxy Convention: Name as a di-located substituent on the longest carbon chain

□ Oxide Convention: Name as an alkene, followed by the word ___________

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PRACTICE: Provide ALL the names applicable for the following molecule

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CONCEPT: EPOXIDATION

□ Epoxides are added to double bonds using _________________ ____________

● Common reagents are _____________ and ___________

Mechanism:

□ Epoxides can also be generated though an intramolecular _______ reaction of halohydrins.

Mechanism:

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CONCEPT: EPOXIDE RING OPENING

1. Acid-Catalyzed Ring Opening

Following protonation of the epoxide, the nucleophile will attack the side of the ring with the most ___________ character:

2. Base-Catalyzed Ring Opening

The strong nucleophile will attack the side of the ring that is ___________ substituted

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CONCEPT: SHARPLESS ASYMMETRIC EPOXIDATION

□ Enantioselective reactions are ones that generate _____ enantiomer in significantly higher yield than another.

□ Converts allyl alcohols into enantioselective epoxides depending on the tartrate used (+) or (-).

General Reaction:

□ Always draw alcohol on the ____________ __________ corner of the double bond. Then determine chirality using DET.

ORGANIC - BROWN 8E


CONCEPT: SULFUR NOMENCLATURE

□ Sulfur is similar to oxygen in its atomic composition, so it forms oxygen compound analogs.

● Alcohol has higher priority than thiols

EXAMPLE: Provide the IUPAC names (and common names if appropriate) for the following compounds.

a.

b.

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CONCEPT: OXIDATION OF SULFIDES

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

□ Sulfides are more reactive than ethers because it has an expanded octet and can form additional bonds with other atoms.

● They are particularly susceptible to oxidation.

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organic - brown 8e ch.11 - ethers, epoxides and...

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