Reactions of Ketones And Aldehydes

Question 1

Describe the onolysis of alkenes

Answer 1

O3 and (CH3)2 react with alkynes to form an aldehyde and ketone by oxidatively cleaving the double bond(depending on the Alkene an oxygen is placed on each new double bond)

Question 2

Explain the mechanism for hydration of alkynes

Answer 2

Markivnikov hydration- terminal alkyne reacts with terminal alkyne. Solution to br used is mercury ions (Hg2+, sulfric acid and water) which forms an Enol intermediate but tautomorizes(relocation of a proton)to its keto form

Question 3

What is a Gilman reagent?

Answer 3

A lithium dialkylcuprate (R2CuLi)

Question 4

How can ketone be formed from Gilman reagents?

Answer 4

Gilman reagent reacts with acid chloride

One of the alkyl groups of the Gilman reagent will replace the chloride in the acid chloride to form a ketone, LiCl and R-Cu

Question 5

NaBH4 can reduce ketones to ____________ _________ and aldehydes to ____________ _________

Answer 5

Secondary alcohols

Primary alcohols

Question 6

NaBH4 can reduce ketones and aldehydes but not ___________, ______________, ____________ or __________

Answer 6

Esters, carboxylic acids, acyl chlorides or amides

Question 7

Unlike NaBH4, LiAlH4 can reduce ______ _______ but is …..

Answer 7

Any carbonyl

Difficult to handle

Question 8

Addition of Grignard reagents to an aldehyde along with a hydronium ion forms….

Answer 8

A secondary alcohol

Question 9

A ketone reacts with a Grignard reagent and a hydronium ion to form….

Answer 9

A tertiary alcohol

Question 10

How is an aryl ketone produced?

Answer 10

Benzene reacts with an acid halide (catalyze by a Lewis acid such as AlCl3) to produce an aryl ketone and hydrogen halide

Question 11

What type of reaction is the preparation of of aryl ketones by fruedel crafts acylation?

Answer 11

Aromatic electric substitution

Question 12

The addition of Grignard reagents to form alcohols from carbonyl compounds is…,

Answer 12

Irreversible

Question 13

How can a nitrile be converted to a ketone?

Answer 13

Addition of a Grignard reagents or organolithium to a nitrile which forms an iimine which is hydrolyzed to form a ketone

Question 14

What is the mechanism for nucleophilic addition reactions under basic conditions?

Answer 14

A negatively charged nucleophile attaches to the carbonyl carbon to form an alkoxide ion intermediate

The alkoxide ion is pronates by added acid Ir solvent to form an alcohol

Question 15

Explain the mechanism of nucleophilic addition under acidic conditions

Answer 15

the carbonyl oxygen is protonated by an acid to make it more electrophilic

A neutral nucleophile attaches to the electrophilic carbonyl carbon. The oxygen becomes neutral and the nucleophile gains a positive charge

A base deprotonates the intermediate, leaving the alcohol and replenishing the acid catalyst

Question 16

How can an aldehyde/ketone be converted to an acetal and water?

Answer 16

Addition of an alcohol to an aldehyde/ketone with an acid catalyst

Question 17

How can aldehydes/ketones be protected?

Answer 17

By converting to acetals

Question 18

Acetals, like ethers, are _______ to _____, _________ ______ and various nucleophile but can cleaved with treatment with _______

Answer 18

Stable

Bases

Reducing agents

Acids

Question 19

Describe imine formation using nucleophilic addition of amines

Answer 19

Ammonia or a primary amine is added to ketones/aldehyde with an acid catalyst

Imine and water is formed

Question 20

Describe how cyanohydrin is formed?

Answer 20

Ketone/aldehyde is reacted with cyanide followed by the proton action of the intermediate and forms a cyanohydrin

Question 21

What mechanism does the hydration of ketones and aldehydes use?

Answer 21

Nucleophilic addition

Question 22

What is the wittig reaction?

Answer 22

Converts the carbonyl group into an alkene

Question 23

How is the Wittig reaction carried out?

Answer 23

Adding a phosphorus ylide to the carbonyl compound

Question 24

What is a principal advantage of using the wittig reaction over alcohol dehydration for alkene synthesis?

Answer 24

In the wittig reaction has a FIXED double bond for the carbons involved

Question 25

Describe the mechanism of the wittig reaction

Answer 25

1. Phosphorus ylide reacts with the ketone or aldehyde to form a betaine
2. The betaine then forms an oxaphosphetane(four membered ring)
3. Oxasphosphenate collapses and forms an alkene and triphenylphosphine

Question 26

Describe catalytic hydrogenation

Answer 26

Addition of hydrogen and ranked nickel

Will attack an alkene first then the carbonyl

Question 27

What are products formed from each of the tests to distinguish aldehydes from ketones?

Answer 27

Tollens test- carboxylate anion and silver mirror

Feeling/Benedict’s-Carboxylate anion and cuprous oxide

Jones oxidation- Carboxylic acids and chromium ion