Chapter 6: Aldehydes & Ketones I

Question 1

a carbonyl group

Answer 1

a functional group consisting of a carbon double bonded to an oxygen

Question 2

what makes a carbonyl group such a common functional group

Answer 2

can behave as either a nucleophile or an electrophile !!

Question 3

ketone

Answer 3

2 alkyl groups bonded to a carbonyl

Question 4

aldehyde

Answer 4

one alkyl group and one hydrogen bonded to a carbonyl

Question 5

characteristic physical property of aldehydes and ketones

Answer 5

they are both often strong smelling compounds

ex. cinnamon, vanilla, cumin, etc.

Question 6

aldehydes suffix

Answer 6

replace -e from alkane name with -al

Question 7

prefix for aldehydes when named as substituents

Answer 7

oxo-

Question 8

ketones suffix

Answer 8

replace -e from alkane name with -one

common names: the 2 alkyl groups are named alphabetically, followed by -ketone

Question 9

prefix for ketones when named as substituents

Answer 9

oxo- or keto-

Question 10

the dipole of a carbonyl is _______ (stronger/weaker) than the dipole of an alcohol. why?

Answer 10

stronger

the double bonded oxygen is more electron-withdrawing than the single bond to oxygen in the hydroxyl

Question 11

boiling points of aldehydes and ketones

Answer 11

higher than their parent alkanes because of the polar carbonyl groups

lower than that of alcohols because there is no hydrogen bonding to occur

Question 12

aldehydes and ketones both act as ___________ (electrophiles/nucleophiles)

Answer 12

electrophiles (electron loving)

due to the electron withdrawing properties of the carbonyl oxygen, which leaves a partial positive charge on the carbon

Question 13

the carbonyl carbon is a ________ (electrophile/nucleophile)

Answer 13

electrophile!!

bears a partial positive charge = electron loving

Question 14

name 1 way an aldehyde can be produced

Answer 14

through the partial oxidation of a primary alcohol (by PCC)

Question 15

name 1 way a ketone can be produced

Answer 15

through the oxidation of an secondary alcohol

reagents: sodium or potassium dichromate salts, or chromium trioxide, PCC, and others

Question 16

nucleophilic addition reactions

Answer 16

a chemical addition reaction in which a nucleophile is added to a carbonyl

recall: the carbonyl carbon is an electrophile, ready for nucleophilic attack

Question 17

nucleophilic addition reaction mechanism (aldehydes and ketones)

Answer 17

the nucleophile attacks; a covalent bond is formed between the nucleophile and the carbonyl carbon, breaking the pi bond in the carbonyl

the electrons from the pi bond are pushed onto the oxygen atom

the new O- will accept H+ from the solvent to form a hydroxyl group, resulting in an alcohol

Question 18

tetrahedral intermediate

Answer 18

a reaction intermediate in which the bond arrangement around an initially double-bonded carbon atom has been transformed from trigonal to tetrahedral

result from nucleophilic addition to a carbonyl group

Question 19

general nucleophilic addition mechanism

Answer 19

Question 20

hydration mechanism of aldehydes and ketones

Answer 20

the nucleophilic oxygen from water attacks the electrophilic carbonyl carbon

requires a small amount of catalytic acid or base

Question 21

in the presence of water, aldehydes and ketones react to form _____

Answer 21

geminal diols: an organic compound with 2 hydroxyl groups attached to the same carbon atom

Question 22

hemiacetals

Answer 22

result when 1 equivalent of alcohol are added to an aldehyde

Question 23

hemiketals

Answer 23

result when 1 equivalent of alcohol are added to a ketone

Question 24

acetals

Answer 24

result when 2 equivalents of alcohol are added to an aldehyde

Question 25

ketals

Answer 25

result when 2 equivalents of alcohol are added to a ketone

Question 26

hemiacetal formation mechanism

Answer 26

the oxygen in the alcohol functions as the nucleophile, attacking the carbonyl carbon and generating a hemiacetal

Question 27

of aldehydes and ketones, which are slightly more reactive than the other?

(toward nucleophiles)

Answer 27

aldehydes are slightly more reactive toward nucleophiles than ketones

Question 28

PCC

Answer 28

pyridinium chlorochromate (an oxidant)

can form aldehydes from primary alcohols

can NOT completely oxidize primary alcohols

can completely oxidize secondary alcohols