18 Additions To Carbonyl

Front 1

True or False: on the carbonyl group, carbon is electrophilic because the more electronegative oxygen pulls electron density away from carbon.

Back 1

True.

Front 2

True or False: on the carbonyl group, carbon is nucleophilic because the more electronegative oxygen pulls electron density away from carbon.

Back 2

False. Carbon becomes electrophilic, not nucleophilic, due to its relationship with oxygen.

Front 3

True or False: on the carbonyl group, oxygen is electrophilic because the more electronegative carbon pulls electron density away from oxygen.

Back 3

False: on the carbonyl group, carbon is electrophilic because the more electronegative oxygen pulls electron density away from carbon.

Front 4

The two mechanisms for carbonyl addition are _________________

Back 4

Acidic & Basic
(or electrophile first, and nucleophile first)

Front 5

In carbonyl addition, what is the first step under acidic conditions? What is the second?

Back 5

protonation of the oxygen, then nucleophile attachment

Front 6

In carbonyl addition, what is the first step under basic conditions? What is the second?

Back 6

nucleophile attachment, then protonation.

Front 7

The rate of reaction for additions to CO double bonds of aldehydes and ketones:

a) is determined by the first step
b) is determined by the second step
c) is determined by how quickly the nucleophile adds
d) is determined the same way as CC double bonds

Back 7

C- the speed of attachment of the nucleophile. This could be the first step or the second step.

Front 8

If the protonation is first under acidic conditions, why isn't it the rate determining step?

Back 8

The addition of an acidic hydrogen to a nucleophilic oxygen is a fast acid-base reaction. The nucleophile adds more slowly, so it determines the rate.

Front 9

True or False: In additions to carbonyl using strong nucleophiles, solvents mustn't have any acidic hydrogens.

Back 9

True

Front 10

True or False: In additions to carbonyl using strong nucleophiles, you must use weak acids as solvent to encourage H to add to O.

Back 10

False, when strong nucleophiles are used, any acidic hydrogens will combine with them and stop the reaction. You must use a solvent such as diethyl ether.

Front 11

True or False: In additions to carbonyl using strong nucleophiles, acid must be added later to finish the reaction.

Back 11

This is true, but you must make sure the reagents have reached the anionic stage before the acid is introduced.

Front 12

True or False: Reactions involving less basic nucleophiles can be conducted with water or alcohol as solvent.

Back 12

True.

Front 13

True or False: Reactions involving strongly basic nucleophiles can be conducted with water or alcohol as solvent.

Back 13

False. Solvents used with strongly basic nucleophiles mustn't contain acidic hydrogens.

Front 14

True or False: In carbonyl addition, equilibrium favors the product.

Back 14

False. The equilibrium may favor the product or the reactants, depending on the strength of the nucleophile and the structure of the carbonyl compound

Front 15

The organic chemist's sources of hydride nucleophile are _____________ & ______________.

Back 15

lithium aluminum hydride & sodium borohydride

Front 16

What are the formulas for lithium aluminum hydride & sodium borohydride.

Back 16

LiAlH4
NaBH4

Front 17

Aldehydes are reduced to _____________ by sources of hydride

Back 17

primary alcohols

Front 18

Ketones are reduced to _____________ by sources of hydride

Back 18

secondary alcohols

Front 19

Reductions employing ________ are usually conducted using ether or THF as solvent

Back 19

LiAlH4

Front 20

Reductions employing LiAlH4 are usually conducted using ____________ as solvent

Back 20

ether or THF

Front 21

One mole of hydride reagent reduces how many moles of carbonyl compound?

Back 21

4

Front 22

True or False: In carbonyl addition, care must be taken, because hydride will attach to any carbons in a structure.

Back 22

False. Hydride nucleophile attacks only electrophilic carbons.

Front 23

The use of LiAlH4 and NaBH4 provides the best way to turn ___________ into alcohols.

Back 23

aldehydes & ketones

Front 24

Water combines with aldehydes & ketones to form ____________

Back 24

hydrates

Front 25

True or False: Addition of water via carbonyl addition can only occur under the acidic pathway.

Back 25

False. Water can add under acidic or basic pathways.

Front 26

True or False: Addition of water via carbonyl addition can occur under either the acidic or basic pathways.

Back 26

True.

Front 27

Addition of water to aldehydes & ketones does not favor the product because ___________________

Back 27

water is a weak nucleophile

Front 28

True or false: in the formation of a hydrate, larger substituents decrease the equilibrium constant.

Back 28

True.

Front 29

True or false: in the formation of a hydrate, larger substituents increase the equilibrium constant.

Back 29

False. in the formation of a hydrate, larger substituents increase the equilibrium constant.

Front 30

In the formation of a hydrate, why do larger substituents decrease the equilibrium constant?

Back 30

Because sp2 carbonyl group (the reactant) is less sterically hindered. When equilibrium points more toward reactants, the equilibrium constant is low.

Front 31

True or false: aldehydes react quicker than ketones, in general.

Back 31

True

Front 32

True or false: ketones react quicker than aldehydes, in general.

Back 32

False. Aldehydes are less sterically hindered, so it is easier for the nucleophile to approach. Aldehydes react quicker.

Front 33

Hydrogen cyanide adds to aldehydes & ketones to form products known as _______________

Back 33

cyanohydrins