New Stuff 4

Aldehyde suffix?

-anal

Ketone suffix?

-One

How can aldehyde be synthesized?

Primary alcohol, PCC

How can ketones be synthesized?

Secondary alcohol, PCC or CrO3, H3O+

If there is an oxygen with a positive charge…

The neighbouring carbon(s) are a fantastic target.

Hemiacetal

Carbon bonded to one ether and one OH.

Acetal

Carbon bonded to 2 ethers

How can you go from a ketone/aldehyde to a hemiacetal?

MeOH, H+

How do you go from a hemiacetal to an acetal?

MeOH, H+.

Diol

Carbon attached to two alcohols

What do not form acetals/hemiacetals?

Esters, carboxylic acids, and amides

Sodium borohydride only reduces..

Aldehydes and ketones.

LiAlH4 can reduce..

Esters, aldehydes, and ketones.

Acetals are not reduced by..

LiAlH4

How can an ester be reduced without harming the ketone?

Protect the ketone as an acetal.

Protecting group chemistry steps.

1. Protect the ketone as an acetal.

2. Reduce the ester with LiAlH4.

3. Convert the acetal back to a ketone.

How to go from an acetal to a hemiacetal? A hemiacetal to a ketone/aldehyde? (Or, reversal.)

H3O+.

Amines form…

Imines and enamines.

Imine

Double bonded nitrogen formed from primary amines.

Enamine

Alkene + single bonded nitrogen; formed from secondary amines.

How are imines / enamines formed?

The aldehyde/ketone is reacted with the primary (imine) or secondary (enamine) amide and catalytic acid [H+].

How are carboxylic acids created?

Oxidation of primary alcohol with CrO3, H3O;

Grignard (1. MgBr 2. H3O)

What is the order of reactivity for carboxylic acid derivatives? (Most to least).

Acid chloride > Acid anhydride > Carboxylic acid > ester > amide

The reactivity of a carboxylic acid derivative is defined by…

The stability of the leaving group.

Formation of acid chloride

Carboxylic acid + SOCl2 (thionyl chloride)

Formation of symmetric acid anhydrides

Two carboxylic acids, high temperature and pressure.

What will acid chlorides and acid anhydrides react with?

Ethers, negative charges, or neutral nucleophiles.

What do carboxylic acids, ethers, and acids need to help neutral nucleophiles react?

Acid catalysts.

How to name esters?

Substituent chain + (parent chain carbons)(-anoate).

Fischer Esterification

Carboxylic acids to esters using alcohol and an acid catalyst.

What is saponification?

The hydrolysis of esters; the synthesis of soaps.

What does saponification require?

An Ester + Na^{+ -}OH , H2O

Alpha carbons

Carbons next to carbonyls.

Enolate

Deprotonated carbonyl compounds.

What can be used to form an enolate?

LDA

Enol

Alkene + Alcohol

Enols are formed under…

Acidic conditions.

Alpha-halogenation

Add a halogen to an alpha carbon.

Alpha halogenation general scheme

Carbonyl + Br2 (or Cl2), -OH or H+.

In alpha hydrogenation, H+ is for..

Enols

In alpha halogenation, -OH is for..

Enolates.

Haloform

Halogenating as many times as possible.

Haloform general steps

1. Cl2 OH

2. H3O+

Haloform mechanism

1. Form an enolate 3 times with the Cl2 OH. (Clears out the hydrogens on the CH3)

2. The -OH attacks the carbonyl and forms a tetrahedral intermediate, with the alpha carbon leaving as a leaving group.

Aldol

Aldehyde + Alcohol

Aldol formation steps

1. Form the enolate.

2. The enolate attacks the delta positive carbon.

3. Neutralize the alkoxide to form an alcohol.

4. (Optional, consider a dehydration between the delta minus carbon and the delta plus carbon.)

What does aldol formation require?

1. LDA

2. H3O+.

3 cases for dehydration of an aldol?

1. We can force a dehydration by adding concentrated sulfuric acid.

2. Intramolecular aldols (closes a ring) will dehydrate spontaneously, requiring no H+/heat.

3. If 2 aromatic rings are connected, dehydration will occur easily and quickly.

Amine traits

• Smelly

• Liquid, wax, or semi-solid

• Volatile

Amines are more stable as…

Ammonium chloride salts.

Ammonium ions are…

weak acids (Pka = 9)

Synthesis of an amine.

1. Halogenated chain + NaN3 (sodium azide).

2. H2 pd/c or 1. LiAlH4 2. H3O+