Aldehydes/Ketones

Question 1

The simplest carbonyl compounds are

Answer 1

Aldehydes and ketones

Question 2

Simplest aldehyde

Answer 2

Formaldehyde (methanal)

Question 3

Ethanal common name

Answer 3

Acetaldehyde

Question 4

Butanal common name

Answer 4

Butyraldehyde

Question 5

40% aqueous solution of formaldehyde is called

Answer 5

Formalin

Question 6

Formalin is formed from

Answer 6

40% formaldehyde
8% methanol
52% water

Question 7

Both the carbon and oxygen in aldehydes/ketones are ___ hybridized

Answer 7

sp2

Question 8

Carbon-oxygen bond length in aldehydes/ketones

Answer 8

120 pm / 1.20 Aº

Question 9

Carbon-oxygen bond length in ethers/alcohols

Answer 9

142 pm / 1.42 Aº

Question 10

Bond angles around carbonyl

Answer 10

120º (CH3=O longest bond) (CH3-CH bond shortest)

Question 11

Most common reaction of aldehydes/ketones

Answer 11

Nucleophilic addition

Question 12

What happens to shape of aldehyde/ketone after nucleophilic additon

Answer 12

From trigonal planar to tetrahedral

Question 13

Why do acid catalyzed addition reactions happen with carbonyls

Answer 13

bc the carbonyl oxygen acts as a lewis base

Question 14

Which molecules follow acid catalyzed addition

Answer 14

Amines, water, ammonia, alcohols

Question 15

What molecules undergo base catalyzed addition reactions

Answer 15

Hydrogen cyanide in the presence of cyanide base (forms cynohydrins)

Question 16

Which are more reactive toward nucleophilic addition reactions, aldehydes or ketones

Answer 16

Aldehydes

Question 17

Which react faster towards nucleophilic addition reactions, aldehydes or ketones

Answer 17

Ketones

Question 18

Which are more electrophilic, aldehydes or ketones

Answer 18

Aldehydes (this is why theyre more reactive)

Question 19

Formaldehydes, when reduced to alcohols give what?
Higher aldehydes?
Ketones?

Answer 19

Formaldehydes = methyl alcohol
Higher aldehydes = Primary alcohols
Ketones = Secondary alcohols

Question 20

Catalysts used to reduce aldehydes/ketones into alcohols

Answer 20

Either: LiAlH4 or NaBH4, ether +H2O
or +H2 and Ni or Pt/Pd

Question 21

Using Grignard Reagant, what are the products

Answer 21

(Grignard Reagants add a C group so its one more than alcohol reduction results)
Formaldehydes give primary
Higher aldehydes give secondary
Ketones give tertiary

Question 22

HCN reaction w carbonyls (and catalyst)

Answer 22

Cyanohydrins (and KCN catalyst)

Question 23

Tollens reagant test

Answer 23

AgNO3 + NH4O4 —> ([Ag(NH3)2]OH) (Tollen’s reagant)
Forms carboxylate ion and silver mirror

Question 24

Fehling’s test

Answer 24

Alkaline solution of cupric ions + tartarate ion
Solution added and heated, and Cu2O forms, which gives red ppt

Question 25

What is Fehling’s solution used for

Answer 25

Estimation of glucose in blood and urine

Question 26

Benedict’s solution test

Answer 26

Solution of cupric ions + citrate ions Gives red ppt Also used to estimate glucose in blood and urine)

Question 27

How to oxidize ketones

Answer 27

Using strong oxidizing agents (KMnO4 / K2Cr2O7 / H2SO4 / V2O5) and applying heat

Question 28

What happens during the oxidation of assymetrical ketones

Answer 28

The longer alkyl chain will leave and the shorter one will stay in the product.

Question 29

Reduction of aldehydes and ketones to alkanes in the presence of zinc and HCl is called

Answer 29

Clemmenson reduction

Question 30

Aldehyde and ketone on reaction with hydroxyamine form

Answer 30

Oxime