Chemistry of Carbonyls Unit 10

Question 1

Ketones and Aldehydes both possess the ______ ______.

Answer 1

Carbonyl Group.

Question 2

Simplest aldehyde.

Simplest Ketone.

Answer 2

Used as a presevative.

Used mainly as a solvent.

Question 3

Preparing Aldehydes/Ketones: what reagents can be used.

Answer 3

Oxidation.

PCC, CH2CL2

Or

1) DMSO, (COCl)2
2) ET3N

Na2Cr2O7
H2SO4H2O

Question 4

Ozonolysis of Alkenes

Answer 4

O3 and DMS is used to create ketones

Question 5

Friedel-Crafts Acylation

Answer 5

Aromatic ring can be rected with an acyl group and AlCl3 (turns acyl group inton a good nucleophile)

Question 6

Nucleophilic Addition Reactions

Answer 6

• Carbonyl carbon is electrophilic.
• it is attacked by nucleophiles forming a new sigma bond forming a tetrahedral center.
• Nucleophile can attack from the top or the bottom because the carbonyl carbon is planar and sp2 hybridized.
• The only thing that is changing is what the nucleophile is and what the conditions are.

Question 7

Some nucleophiles require ______ conditions, others require _______ conditions.

Answer 7

Acidic

Basic

Question 8

Relative Rate of Nucleophilic Addition: Aldehydes are generally more towards nucleophiles than ketones due to?

Answer 8

• Steric Effects: Aldehydes are less sterically hindered
• Electronic effects: Aldehyde had a larger delta positive on the carbonyl carbon.
• a ketone has two electron-donating alkyl groups that stabilize the partial positive charge

Question 9

Nucleophilic Addition: Basic Conditions.

Answer 9

• under basic conditions, all nucleophiles react with carbonyl by the same general mechanism
• Nucleophile attacks, forming a negatively charged intermediate, which is protonated upon acidic workup.

-Grignard Reaction
-Generally, a strong nucleophile means the reaction is under
basic conditions

Question 10

Nucleophilic Addition: Acidic Conditions

Answer 10

• Acidic conditions are required in order for a weak nucleophile to attack a carbonyl carbon
• protonation of the carbonyl makes it a better electrophile
• the nucleophile may not be strong enough to attack the carbonyl carbon.

Question 11

If the nucleophile is a good leaving group ther is an _______ that can be formed.

Answer 11

Equilibrium

Question 12

Hydrogen Nucleophiles; Basic Conditions

Answer 12

Aldehydes/ketones reduced to alcohols with a hydride.

• 1)LiAlH;2)H2O
• NaBH4, MeOH

Question 13

Reduction of an unsymmetrical ketone forms a ______ ______ _______

Answer 13

A new chiral center.

Sp2 hybridized trigonal planar the H can attack from either side, we make a racemic mixture.

Question 14

_______ ______ attack ketones/aldehydes to make an alcohol with a new C-C bond. Under what conditions?

Answer 14

Grignard Reagents.

either face of the carbonyl is attacked by the nucleophiles, and a new chiral center may result.

Basic Condition.

Question 15

In the presence of _____, a ketone/aldehyde is in equibirum with its _____.

Answer 15

• Water
• Hydrate
• We can have a strong oxygen nucleophiles (basic conditions)
• Neutral weak nucleophiles (acidic conditions)

Question 16

_______ generally does not favor the formation of the hydrate (except for very simple aldehydes)

Answer 16

• Equilibrium
• The rate of reaction is slow unless acidic or basic conditions are used.
• Under the acidic conditions the carbonyl oxygen is protonated making the carbonyl carbon a better nucleophile much easier to attack by a weak water nucleophile.
• Under basic conditions we generate hydroxide which is a much better nucleophile.