Carbon to Carbon bond formations

Question 1

Why is carbon to carbon bond formation so important?

Answer 1

Compounds are synthesised in nature by C-C bond formation

Question 2

What reaction is one of the classical ways to make carbon-carbon bonds?

Answer 2

The aldol reaction

Question 3

What type of media does the aldol reaction come from?

Answer 3

Acidic or basic

Question 4

What are the reagents for an aldol reaction?

Answer 4

OH- OR H+

H2O

Then heat after the intermediate is formed

Question 5

When carbonyl compounds are treated with a base, what do they form?

Answer 5

The Enolate

Question 6

Carbonyl compounds have another form, what is this called?

Answer 6

Tautomeric form (enol)

(Tautomers are isomers of a compound which differ only in the position of the protons and electrons)

Question 7

How can the -ve charge on the carbon of the enolate be stabilised?

Answer 7

By resonance

DONT DO THIS FOR EXAM AS NEGATIVE NEEDS TO BE SHOWN

Question 8

Whats the mechanism for the base catalysed aldol reaction?

Answer 8

Question 9

What happens in the first stage of the base catalysed aldol reaction?

Answer 9

Question 10

What happens in the second stage of the base catalysed aldol reaction?

Answer 10

Question 11

What happens in the third stage of the base catalysed aldol reaction?

Answer 11

Question 12

What type of reaction is the first step of the TCA cycle?

Answer 12

Aldol reaction

Question 13

The aldol mechanism in citrate synthesis

Answer 13

Question 14

Whats the mechanism of the acid catalysed aldol reaction?

Answer 14

Question 15

What happens in each stage of the acid catalysed aldol reaction?

Answer 15

Question 16

Whats more nucleophilic, an enol or an enolate?

Why can it still be used in an acid catalysed reaction?

Answer 16

An enol is not as nucleophilic as an enolate, but is sufficiently reactive to attack a protonated carbonyl compound

Question 17

What mechanism does elimination in acid- catalysed aldol chemistry occur via?

Answer 17

E1 in acid

E1cB in base

Question 18

Draw out the Claisen ester condensation reaction between 2 esters

Answer 18

Question 19

Draw the Intramolecular Claisen ester condensation reaction

Answer 19

Question 20

Draw the mechanism of the Claisen ester condensation reaction?

And what occurs in each step

Answer 20

Question 21

Whats a retro-aldol reaction?

Answer 21

Retro-aldol reaction: A reaction in which a β-hydroxy carbonyl compound decomposes into an aldehyde or ketone, plus another carbonyl compound. … This β-hydroxy ketone can be decomposed back into acetone and acetophenone in a base-catalyzed (or acid-catalyzed) retro-aldol reaction.

Question 22

Give an example of when the enzyme aldolase is used in a reaction?

What type of reaction is this?

Answer 22

Question 23

Terpenes such as vitamin A are synthesised from what?

Answer 23

dimethylallyl pyrophosphate

Question 24

The construction of an Isoprene unit begins with what type of reaction?

Answer 24

A Claisen reaction

Question 25

How is the mechanism of a Claisen reaction different when constructing an isoprene?

Answer 25

It uses a thioester rather than a carboxylic ester

Question 26

Draw out the mechanism of the construction of an Isoprene

• include the by products
• structure of intermediates and products

Answer 26

Question 27

Whats the aldol reaction an important method for?

Answer 27

Question 28

What does the Claisen reaction occur between?

What is the mechanism similar to?

Answer 28