Chapter 17: Aldehydes and Ketones (The Carbonyl Group)

Question 1

Carbonyl Group

Answer 1

contains an oxygen atom and two lone parts that allow it to function as a weak Lewis base and has a highly polarized carbon-oxygen bond making the carbonyl group electrophilic
carbon and oxygen are sp2 hybridized and are on the same plane as the two additional groups with bond angles with carbon of 120°

Question 2

Oxidation of Alcohols

Answer 2

PCC, CH2Cl2

forms an aldehyde

Question 3

PCC, CH2Cl2

Answer 3

Oxidation of Alcohols to form Aldehydes

Question 4

Ozonolysis of Alkenes

Answer 4

1. O3, CH2Cl2

2. (CH3)2S

Question 5

1. O3, CH2Cl2

2. (CH3)2S

Answer 5

Ozonolysis of Alkenes to form Aldehydes or Ketones

Question 6

Hydration of Alkynes

Answer 6

H2O, H+, Hg2+

yields enols that tautomerize to carbonyls

Question 7

H2O, H+, Hg2+

Answer 7

Hydration of Alkynes to form Aldehydes or Ketones from Enols

Question 8

Friedel-Crafts Acylation

Answer 8

RCOCl, AlCl3

makes ketone substituent on benzene

Question 9

RCOCl, AlCl3

Answer 9

Friedel-Crafts Acylation

Question 10

Selective Alcohol Oxidation

Answer 10

CrO3, H2SO4, acetone, 0°C

Question 11

CrO3, H2SO4, acetone, 0°C

Answer 11

Selective Alcohol Oxidation

Question 12

Selective Oxidation of Allylic Alcohols

Answer 12

MnO3, CHCl3, 25°C

Question 13

MnO3, CHCl3, 25°C

Answer 13

Selective Oxidation of Allylic Alcohols

Question 14

NaBH4 or LiAlH4

Answer 14

hydride reagents, reduce carbonyls

Question 15

Reduction of Carbonyls

Answer 15

NaBH4 or LiAlH4

Question 16

Nucleophilic Addition-Protonation of Carbonyls

Answer 16

basic conditions, strong nucleophiles
nucleophile attacks carbonyl carbon, pushes e- from DB to oxygen to form alkoxide ion, addition of water, O attacks H in water to form OH

Question 17

Electrophilic Protonation-Addition

Answer 17

acidic conditions, weak or neutral nucleophile

e- on O attack H+, NuH attacks carbonyl C, e- pushed to O to eliminate + charge, H is abstracted from Nu group

Question 18

Carbonyl Hydrates

Answer 18

R2C(OH)2
formed when water attacks a carbonyl facilitated by acid or base
base catalyzed is nucleophilic addition-protonation
acid catalyzed is electrophilic protonation-addition

Question 19

Hydration of Carbonyls

Answer 19

OH is added to carbonyl C to form R2C(OH)2
reversible
EWG increase + charge at C and makes more reactive, ketone equilibrium lies to left and aldehyde equilibrium lies to the right

Question 20

Hemiacetals

Answer 20

OH
R-C-OR’
H
formed from aldehyde reversibly, formation is not favorable
if excess alcohol and H+ is present will form an acetal

Question 21

Hemiketals

Answer 21

OH
R-C-OR’
R
formed from ketone reversibly, formation is not favorable
if excess alcohol and H+ is present will form an ketal

Question 22

Acetals

Answer 22

OR’
R-C-OR’
H
can be isolated by neutralizing the acid catalyst
adding excess H2O will shift equilibrium to the left (acetal hydrolysis)

Question 23

Ketals

Answer 23

OR’
R-C-OR’
R

Question 24

Acetal Protecting Groups

Answer 24

formation is reversible

can be used to protect the carbonyl group using diols

Question 25

Diols

Answer 25

convert aldehydes and ketones to cyclic acetals which are more stable

Question 26

Cyclic Acetalization

Answer 26

aldehyde + diol (OHCH2CH2OH) =(H+)=> cyclic acetal + H2O

Question 27

Thiols

Answer 27

HSCH2CH2SH

react with carbonyl to form thioacetals using a Lewis Acid (BF3, ZnCl2)

Question 28

Thioacetals

Answer 28

sulfur analogs of cyclic acetals

Question 29

Thioacetal Formation

Answer 29

HSCH2CH2SH, ZnCl2, (CH3CH2)2O, 25°C

Question 30

HSCH2CH2SH, ZnCl2, (CH3CH2)2O, 25°C

Answer 30

Thioacetal Formation

Question 31

Thioacetal Hydrolysis

Answer 31

H2O, HgCl2, CaCO3, CH3CH

removes thiol group and restores aldehyde or ketone

Question 32

H2O, HgCl2, CaCO3, CH3CH

Answer 32

Thioacetal Hydrolysis

Question 33

Thioacetal Desulfurization

Answer 33

Raney Ni, H2

removes thiol group and replaces it with 2 H atoms

Question 34

Raney Ni, H2

Answer 34

Thioacetal Desulfurization

Question 35

Imines

Answer 35

RNC(R’)2
formed from hemiaminals by losing H2O and forming CN
can be isolated if water is removed by continuous distillation of the reaction mixture

Question 36

Hemiaminals

Answer 36

R H
N
R2-C-OH
formed from ketones or aldehydes by adding R-NH2

Question 37

Enamine

Answer 37

unsaturated compound derived by the condensation of an aldehyde or ketone with a secondary amine

Question 38

Deoxidation

Answer 38

reduction of the carbonyl group to CH2

can occur by Clemmensen reduction, thioacetal desulfurization or the Wolff-Kishner Reduction

Question 39

Hydrazones

Answer 39

R
R-C=N-NH2
formed by condensation of a hydrazine (H2N-NH2) with aldehyde/ketone

Question 40

H2N-NH2, CH3CH2OH

Answer 40

formation of a hydrazone

Question 41

Wolff-Kishner Reduction

Answer 41

hydrazone decomposes when treated with base at high temperatures
R
R-C=N-NH2 + NaOH =(HOCH2CH2)2O, 180-200°C=> RCH2R’ + N2

Question 42

Cyanohydrins

Answer 42

formed when hydrogen cyanide adds reversibly to a carbonyl
CN
Ph-OH
reagents: NaCN, conc. HCl

Question 43

NaCN, conc. HCl

Answer 43

formation of cyanohydrin from ketone/aldehyde

Question 44

Phosphorous Ylide

Answer 44

reagent in nucleophilic additions that contains a carbocation stabilized by an adjacent positively charged phosphorous group

Question 45

Wittig Reaction

Answer 45

phosphorous ylide attacks ketones/aldehydes to form C=C
produces mostly cis product
conjugation in the ylide produces trans products

Question 46

R=P(C6H5)3, THF

Answer 46

Witting Reaction Reagents

Question 47

Witting Reaction Reagents

Answer 47

R=P(C6H5)3, THF