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Alkyl group
Alkene missing one Hydrogen
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What are the benefits of using PBr3/PCl3 as a nucleophile?
- Good way to convert alcohol to alkyl halide
- Can be converted under relatively mild conditions
- No elimination product
- Stereospecific (specifically inversion)
- No carbocation rearrangements
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What are the conditions for using PBr3/PCl3 as a nucleophile?
- Can only be used on sp3 carbons
- Rxn with a tertiary carbon makes a poor alkyl halide because of steric hinderance
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What is the alpha carbon when talking about alkylation of carbons? Specifically alcohols
The carbon adjacent to the C=O
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Use of LDA in ketones
Low temperature makes alkylation at less substituted alpha carbon
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What does LDA stand for?
Lithium diisopropylamine
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Use of alkoxide bases in ketones
R-O
Causes alkylation at the higher substituted alpha carbon
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What are the Luca Reagents?
- Reagents that react with primary alcohols by SN2
- ZnCl2 and HCl
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What are the reaction times for different substitutions with Lucas Reagents?
- Primary= slowly or not at all
- Secondary- 1-5 minutes
- Tertiary= Less than 1 minute
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What is polyhalogenation and under what conditions does it occur?
Every Hydrogen is replaced with a halogen atom
Basic
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Does polyhalogenation occur in acidic conditions?
No, only halogenation (when a single H is replaced by a halide)
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What is the nucleophile in ammonia/amine alkylations?
NH3
One of the Hydrogens is replaced by an alkyl
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Why are epoxides and oxetanes reactive?
They have ring strain
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What can be used with a tertiary alcohol instead of PBr3/PCl3?
HBr or HCl
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What is alkylation?
When a H is replaced by a an alkyl group
(when a carbon is added to a hetero atom)
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Epoxide regiochemistry (basic)
- Walden inversion from the back
- Attacks the least substituted spot
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Epoxide regiochemistry (acidic)
Attacks the more substituted spot
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Why are epoxides and oxetanes able to open with poor LG's?
The ring strain makes it more favorable to have a poor LG than to stay in the ring formation
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Major factors of Williamson ether synthesis
- Very specific definition of nucleophile/electrophile
- Forms symmetrical, asymmetrical, or cyclic ethers
- Happens via SN2
- Involves an alkyl halide treated with an alkoxide salt
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Under what conditions will larger ether rings open and why?
Under acidic conditions, because the acid will protonate the LG and make them better than without the protonation
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What are the major occurrences in Hofmann elimination?
- Always forms the anti-zaitsev product (less substituted)
- Involves heat and Ag2O
After Ag2O is added to equation, OH- will be present
E2 reaction, so the H and LG must be anticoplanar
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The ____ are stronger in a reaction with electrophilic addition to pi bonds because...
Products
Because the electrons are closer to the atoms in sigma bonds, they are stronger than pi bonds. Therefore, during this reaction, weaker bonds are broken and stronger bonds are formed, making the products more stable than the reactants
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Markovnikov addition
Hydrogen will go to the least substituted areas (that with the most Hydrogen)
This is the regiochemistry of an electrophilic addition
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What is the stereochemistry of an electrophilic reaction?
If there are chiral centers, it is racemic
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For acid hydration reactions, what will be made if there is an alcohol in the starting molecule?
Ether
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For acid hydration reactions, what will be made if there is water in the starting molecule?
Alcohol
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What will conjugated dienes make?
1-2 or 1-4 products
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Electrophilic addition is kinetic or thermodynamic? Irreversible or reversible?
Kinetic and irreversible
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Why is there only a single halogenation under acidic conditions?
The products are more stable than the reactants, so it does not need to be halogenated any more
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What normally happens when the LG is vinyllic?
It makes an alkyne
These reactions are very resistant to substitution or elimination
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What is the priority order for naming this chapter?
Aldehydes, ketones, alcohols, amines
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What are the suffix and prefix for aldehyde?
Al and oxo
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What are the suffix and prefix for ketones?
one and oxo
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What are the suffix and prefix for alcohols?
Ol and hydroxy
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What are the suffix and prefix for amines?
Amine and amino
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What is the only reaction that makes the anti-markovnikov product?
Hydroboration
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What is the stereochemistry of hydroboration oxidation?
Syn, because the two bonds are forming at the same time so that the intermediate makes a square
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What is one place that the carbene is found?
Diazomethane
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What is formed during a hydro-boration oxidation reaction of a terminal alkyne?
An aldehyde
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Which is a more stable form: enol or keto?
Keto, so when there is an enol it should undergo tautomerization to make it into a keto
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