O. Chem - Ch. 17 Summary

Front 1

Functional Group Nomenclature

Back 1

Front 2

MECHANISM FOR THE REACTION OF AN ALDEHYDE OR A KETONE WITH A GRIGNARD REAGENT

Back 2

Front 3

What type of reaction occurs between an aldehyde/ketone and a Gringard reagent?

Back 3

Aldehydes and ketones undergo nucleophilic addition reactions with Grignard reagents

Front 4

What is a Gringard Reagent?

Back 4

Gringard reactions with aldehydes/ketones often incur the formation of C-C and O-H bonds, and the breaking of a C-O bond.

Mg + Et20

Front 5

Examples of aldehyde/ketone reactions with Gringard Reagent

Back 5

Front 6

MECHANISM FOR THE REACTION OF AN ESTER WITH A GRIGNARD REAGENT

Back 6

Front 7

Why doesn’t a Grignard reagent add to the carbonyl carbon of a carboxylic acid?

Back 7

We know that Grignard reagents add to carbonyl carbons, so if we find that a Grignard reagent does not add to the carbonyl carbon, we can conclude that it must react more rapidly with another part of the molecule. A carboxylic acid has an acidic proton that reacts rapidly with the Grignard reagent, converting it to an alkane.

Front 8

What is a Cyanohydrin?

Back 8

Cyanide ion is another carbon nucleophile that can add to an aldehyde or a ketone. The product of the reaction is a cyanohydrin .

Front 9

MECHANISM FOR THE REACTION OF AN ALDEHYDE OR KETONE WITH HYDROGEN CYANIDE

Back 9

Front 10

MECHANISM FOR THE REACTION OF AN ALDEHYDE OR A KETONE WITH HYDRIDE ION

Back 10

Front 11

MECHANISM FOR THE REACTION OF AN ACYL CHLORIDE WITH HYDRIDE ION

Back 11

Front 12

MECHANISM FOR THE REACTION OF AN ESTER WITH HYDRIDE ION

Back 12

Front 13

MECHANISM FOR THE REACTION OF A CARBOXYLIC ACID WITH HYDRIDE ION

Back 13

Front 14

MECHANISM FOR THE REACTION OF AN N -SUBSTITUTED AMIDE WITH HYDRIDE ION

Back 14

Front 15

components of H:H

Back 15

Front 16

Reduction by Addition of a Hydride Ion and a Proton

Back 16

When aldehydes and ketones are reduced to alcohols by NaBH 4 , we have seen that the reduction occurs as a result of the addition of a hydride ion followed by the addition of a proton.

Front 17

Reduction by Addition of Two Hydrogen Atoms

Back 17

catalytic hydrogenations, the H-H bond breaks homolytically, so reduction results from the addition of two hydrogen atoms to the reactant.

Front 18

catalytic hydrogenations - carbon–nitrogen double and triple bonds

Back 18

Front 19

catalytic hydrogenations - C=O

Back 19

Front 20

Back 20

Front 21

Back 21

Front 22

Back 22

Front 23

relative reactivities of carbonyl compounds

Back 23

Front 24

HOW ALDEHYDES AND KETONES REACT

Back 24

nucleophilic addition–eliminationreactions

- Carboxylic acid derivatives undergo nucleophilic addition–elimination reactions with nucleophiles.

the nucleophile adds to the carbonyl carbon and a group is eliminated from the tetrahedral intermediate. Overall, it is a substitution reaction in which Z − substitutes for Y − .

Front 25

MECHANISM FOR THE REACTION OF AN ALDEHYDE OR A KETONE WITH A GRIGNARD REAGENT

- Formaldehyde

Back 25

When a Grignard reagent reacts with formaldehyde, the product of the nucleophilic addition reaction is a primary alcohol.

Front 26

MECHANISM FOR THE REACTION OF AN ALDEHYDE OR A KETONE WITH A GRIGNARD REAGENT

- Aldehyde

Back 26

When a Grignard reagent reacts with an aldehyde other than formaldehyde, the product of the nucleophilic addition reaction is a secondary alcohol .

Front 27

MECHANISM FOR THE REACTION OF AN ALDEHYDE OR A KETONE WITH A GRIGNARD REAGENT

- Ketone

Back 27

When a Grignard reagent reacts with a ketone, the product of the nucleophilic addition reaction is a tertiary alcohol .

Front 28

MECHANISM FOR THE REACTION OF AN ALDEHYDE OR A KETONE WITH A GRIGNARD REAGENT

- Carbon Dioxide

Back 28

A Grignard reagent can also react with carbon dioxide. The product of the reaction is a carboxylic acid that has one more carbon than the Grignard reagent.

Front 29

What is an Acetylide Ion

Back 29

We have seen that a terminal alkyne can be converted into an acetylide ion by a strong base.

Front 30

THE REACTIONS OF CARBONYL COMPOUNDS WITH ACETYLIDE IONS

Back 30

An acetylide ion is another example of a carbon nucleophile that reacts with an aldehyde or a ketone to form a nucleophilic addition product. When the reaction is over, a weak acid (one that will not react with the triple bond, such as the pyridinium ion shown here) is added to the reaction mixture to protonate the alkoxide ion.

Front 31

Cyanohydrin in basic solution

Back 31

Cyanohydrins, however, are stable. The OH group will not eliminate the cyano group because the transition state for the elimination reaction would have a partial positivecharge on the oxygen, thereby making it relatively unstable. If, however, the OH group loses its proton, then the cyano group will be eliminated because the oxygen atom would then have a partial negative charge in the transition state. Therefore, in basic solutions, a cyanohydrin is converted back to the carbonyl compound.

Front 32

Usefulness of Cyanohydrins

Back 32

The addition of hydrogen cyanide to aldehydes and ketones is a synthetically useful reaction because of the subsequent reactions that can be carried out on the cyanohydrin. For example, the acid-catalyzed hydrolysis of a cyanohydrin forms an a-hydroxycarbox-ylic acid