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Chemistry 101 COPY > Reactions of Alkenes > Flashcards

Reactions of Alkenes Flashcards

1
Q

What two things can the reaction of an alkyl halide (R-X) with Na+-OH produce?

A

An alkene or an alcohol

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2
Q

What must an ether (R-OR’) react with in order to form an alkyl halide (R-X)?

A

HX

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3
Q

What state do unsaturated molecules tend to be at room temperature?

A

Liquid

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4
Q

What is the go-to acid catalyst to use in the exam?

A

H2SO4

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5
Q

What must a aldehydes (or ketones) and carboxylic acids react with in order to form an alkyl halide (R-X)?

A

NaBH4

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6
Q

What must an alkene react with in order to form an alkyl halide (R-X)?

A

HX

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7
Q

What are the 3 steps in a hydration reaction?

A
  1. The alkene nucleophile attacks a hydronium ion electrophile, producing a carbocation
  2. Water attacks the positive carbon in the carbocation, producing a protonated alcohol
  3. The alcohol is deprotonated, producing a saturated alcohol and a hydronium ion
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8
Q

Why do saturated molecules have higher melting and boiling points than unsaturated molecules?

A

As they have all single bonds, leading to better intramolecular forces.

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9
Q

What does hydrogenation do to an unsaturated molecule?

A

Saturates it.

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10
Q

What is needed to allow alkenes to react with water?

A

An acid catalyst

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11
Q

What will the reaction of an alkyl halide (R-X) with H2O produce?

A

An alcohol (R-OH)

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12
Q

What are three examples of metal catalysts used in hydrogenation?

A

Pt
Pd
Ni

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13
Q

What will the reaction of an alkene with H2SO4 produce?

A

An alcohol (R-OH)

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14
Q

Do alkenes react with water alone?

A

No

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15
Q

What is hydrogenation?

A

The addition of hydrogen to a molecule

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16
Q

Do the products in a hydration reaction have more or less energy than the reactants?

A

Less

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17
Q

What can the reaction of an alkyl halide (R-X) with RO-Na+ produce?

A

An alkene or an ether

18
Q

What will the reaction of an alkene with H2O produce?

A

An alcohol (R-OH)

19
Q

What is a simple yet effective way to determine which substance is the most acidic out of two?

A

The one that has “acid” in its name

20
Q

What is always the rate-limiting step in a hydration reaction?

A

The formation of a carbocation

21
Q

What is the addition of water to an alkene called?

A

Hydration

22
Q

In the addition of HX to an alkene, how do we know what the H and the X will attach to?

A

The H attaches to the carbon with the fewest substituents and the X attaches to the carbon with the most substituents

23
Q

What is retrosynthesis?

A

The process of working backwards to make something

24
Q

What are the two steps in the synthesis of an alkyl halide from an alkene?

A
  1. The nucleophile (base) attacks the electrophile, creating a carbocation intermediate and isolating the leaving group
  2. The isolated leaving group becomes the nucleophile and attacks the positive carbocation electrophile
25
Q

What will the reaction of an alkyl halide (R-X) with R-OH produce?

A

An ether (R-OR’)

26
Q

What will the reaction of an alkyl halide (R-X) with NaX produce?

A

A different alkyl halide (R-X’)

27
Q

What is needed to make hydrogenation occur?

A

A metal catalyst

28
Q

Why does water not act as an electrophile?

A

The OH bonds are very strong – water is too weakly acidic to allow the hydrogen to act as an electrophile

29
Q

Describe the energy of the 3 transition states in a hydration reaction

A

TS1 highest energy
TS2 middle
TS3 lowest energy

30
Q

Why do we do retrosynthesis?

A

To evaluate the best way to produce something

31
Q

What is an unsaturated organic molecule?

A

An organic molecule that does not have its main chain filled by single bonds

32
Q

What will the reaction of an alkene with H2Pd/C produce?

A

An alkane

33
Q

What state do saturated molecules tend to be at room temperature?

A

Solid

34
Q

What will the reaction of an alcohol (R-OH) with NaBH4 produce?

A

Aldehydes (or ketones) and carboxylic acids

35
Q

What three things can an alcohol (R-OH) react with in order to form an alkyl halide (R-X)?

A

HX
PBr2
SOCl2

36
Q

What will the reaction of an alcohol (R-OH) with PCC produce?

A

Aldehydes (or ketones) and carboxylic acids

37
Q

How is bromine gas used to determine if unsaturated fats are present?

A

Bromine gas is usually brown, but when it forms a bond with carbon it becomes clear. This only occurs in a halogenation reaction, so if only single bonds are present, the gas will remain brown

38
Q

What will the reaction of an alcohol (R-OH) with H2SO4 produce?

A

An Ester

39
Q

Why do alkenes not react with water alone?

A

As there is no electrophile

40
Q

How do we determine if a unsaturated fats (alkenes) are present in a substance?

A

Using bromine gas

41
Q

What is a halogenation reaction?

A

The addition of halogens to a double bond

Chemistry 101 COPY (32 decks)

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