04/23/24 Flashcards

1
Q

Electrophillic addition

A

follows markovnikov addition where the hydrogen adds to the less substituted carbon and the halogen adds to the more substituted carbon

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2
Q

what is the reasoning behind markovnikovs rule

A

it is driven by carbocation stability, if we add a hydrogen to the less substituted carbon, it leads to the formation of a more stable carbocation

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3
Q

if we treat an alkyne with lindars catalyst and H2, what is the product

A

a cis alkene

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4
Q

when we treat a alkene with hydrogenation, what happens to the saturation

A

the alkene is unsaturated, the alkane is saturated

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5
Q

what is zaitsevs rule

A

when dealing with E2 Eliminations, it is the formation of the more substituted alkene as the major product

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6
Q

what is a regioselective reaction

A

it is when a certain region is favored in a reaction

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7
Q

what is prochiral

A

it is one step before a chiral carbon

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8
Q

what is the stereoselectivity of a electrophillic addition

A

there is no stereoselectivity, the halogen can add from above or below in the empty p orbital of the sp2 carbonation

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9
Q

what is the stereochemical result of an electrophilic addition

A

it is a racemic mixture of enantiomers

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10
Q

what reaction is an electrophillic addition similar to?

A

it is similar to an SN1 mechanism due to the formation of a racemic mixture through the addition to a carbocation

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11
Q

what are the key features of an electrophilic addition?

A

the key features are

formation of the most stable carbocation
markovnikov regioselectivity
no steroselectivity: 50/50 racemic mix

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12
Q

what is anti-markovnikov

A

anti-Markovnikov is the addition of the halogen to the less substituted carbon on the alkene

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13
Q

what is the result of an electrophillic addition with a peroxide

A

it is an anti-markovnikov addition where the hydrogen adds to the more substituted carbon and the halogen adds to the less substituted carbon

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14
Q

why do we see anti-markovnikov with an electrophilic addition with peroxide

A

this mechanism goes through a radical intermediate

by adding a free radical halogen to the less substituted carbon, another radical will form in a more stable location

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15
Q

what are the three ways to hydrate an alkene

A

through acid-catalyzed hydration ( rearrangements)

oxymercuration demercuration (no carbocation, no rearrangement)

hydroboration oxidation (anti markonikov)

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16
Q

what are the key features of a acid-catalyzed hydration

A

it is Markovnikov addition

no stereoselectivity

formation of a carbonation (subject to rearrangements)

17
Q

what are the key features of an oxymercuration demercuration

A

markovnikov addition

no carbocation intermediate

anti stereoselectivity (Oh and H on opposite sides)

18
Q

what are the key features of a hydroboration oxidation

A

anti-markovnikov addition (H adds to more substituted alkene, OH adds to less substituted alkene)

syn addition (OH and H are added to the same side at the same time)

concerted addition

19
Q

what are the key feautres of electrophillic addition of Br2 to an alkene

A

anti-addition (concerted) *added to opposite sides

similar to an Sn2 mechanism with a backside attack of the second bromide ion

cyclicbromonium