Aldehydes and ketones I: Electrophilicity and oxidation-reduction ***

Question 1

aldehydes

Answer 1

are terminal functional groups containing a carbonyl bonded to at least one hydrogen. In nomenclature, they use the suffix -al and the prefix oxo-. In rings, they are indicated by the suffix -carbaldehyde.

Question 2

ketones

Answer 2

are internal functional groups containing a carbonyl bonded to two alkyl chains. In nomenclature, they us the suffix -one and the prefix oxo or keto.

Question 3

The reactivity of a carbonyl (C=O) is dictated by

Answer 3

the polarity of the double bond. The carbon has a partial positive charge and is therefor electrophilic.

Question 4

Carbonyl-containing compounds have higher boiling points than

Answer 4

equivalent alkanes because of dipole interactions. Alcohols have higher boiling points than carbonyls because of hydrogen bonding.

Question 5

Aldehydes and ketones are commonly produced by

Answer 5

oxidation of primary and secondary alcohols, respectively.

Question 6

To synthesize aldehydes, what must be used.

Answer 6

PCC cause it is a weaker oxidizing agent because it my oxidize it to a ketone.

Question 7

What is used to form ketones

Answer 7

various oxidizing agents, such as dichromate, chromium trioxide, or PCC because ketones are the most oxidized functional group for secondary carbons.

Question 8

When a nucleophile attacks and forms a bond with a carbonyl carbon,

Answer 8

the electrons in the pi bond are pushed to the oxygen atom. If there is no good leaving group (aldehydes and ketones) the carbonyl will remain open and s protonated to form an alcohol. If there is a good leaving group (carboxylic acids and drivatives), the carbonyl will reform and kick off the leaving group.

Question 9

In hydration reactions

Answer 9

water adds to a carbonyl, forming a geminal diol.

Question 10

when one equivalent of alcohol reacts with an aldehyde (via nucleophilic addition),

Answer 10

a hemiacetal is formed.

Question 11

when one equivalent of alcohol reacts with a ketone,

Answer 11

a hemiketal is formed

Question 12

when another equivalent of alcohol reacts with a hemiacetal (via nucleophilic attack)

Answer 12

an acetal is formed

Question 13

when another equivalent of alcohol reacts with a ketone

Answer 13

a hemiketal is formed .

Question 14

Nitrogen and nitrogen derivatives react with carbonyls to form

Answer 14

mines, oximes, hydrazones, and semicarbazones. Imines can tautermize to form enamines

Question 15

Hydrogen cyanide reacts with carbonyls to form

Answer 15

cyanohydrins

Question 16

Aldehydes can be oxidized to carboxylic acd using agents like

Answer 16

KMnO4, CrO3, Ag2O, or H2O2.

Question 17

Aldehydes can be reduced to primary alcohols by

Answer 17

hydride reagents (LiAlH4, NaBH4)

Question 18

Ketones cannot be further oxidized, but can be reduced by

Answer 18

secondary alcohols using the same hydride reagents