Organic Synthesis (Chapter 16.2, Chapter 28.1, 28.3) Flashcards Preview

Chemistry A-Level > Organic Synthesis (Chapter 16.2, Chapter 28.1, 28.3) > Flashcards

Flashcards in Organic Synthesis (Chapter 16.2, Chapter 28.1, 28.3) Deck (16)
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1
Q

What are the two steps for the synthesis of an organic molecule with several functional group?

A

1) draw out the structure of molecule and identify all the functional groups
2) predict the properties and reactions of the molecule by examining the functional groups

2
Q

What is a target molecule?

A

The compound that the chemist is attempting to prepare by organic synthesis

3
Q

What are the three steps in a two stage synthesis to covert a starting molecule into the target molecule?

A

1) identify the functional groups in the starting and target molecules
2) identify the intermediate that links the starting and target molecules
3) state the reagents and conditions for each step

4
Q

Why do reactions that form C-C bonds have a central importance to organic chemistry?

A

They allow the synthesis of new compounds containing more carbon atoms

5
Q

What are three ways that C-C bonds can be formed?

A

1) by lengthening a carbon chain
2) adding a side chain to benzene ring
3) introducing new functional groups which can then be reacted further

6
Q

What are the two ways that nitriles (-CN) can be formed?

A

1) from haloalkanes and KCN/NaCN

2) from aldehydes/ketones and HCN (NaCN and H2SO4)

7
Q

Describe the formation of nitriles from haloalkanes

A
  • Nitriles can be formed by reacting haloalkanes with sodium or potassium cyanide in ethanol via a nucleophilic substitution mechanism, increasing the length of the carbon chain
  • e.g. chloropropane + KCN => propanenitrile + KCl
8
Q

Describe the formation of hydroxynitriles from aldehydes/ketones

A
  • Aldehydes and ketones react with HCN in nucleophilic addition reaction, forming a C-C bond ∴ increasing the number of carbon atoms in the molecule
  • HCN is too poisonous to use and an increased reaction rate can be obtained in the presence of CN- ∴ a mixture of NaCN and H2SO4 is used to improve safety and increase reaction rate
  • e.g. CH3COCH3 + HCN => CH3C(OH)(CN)CH3
  • or CH3COCH3 + KCN + H2O + H2SO4 => CH3C(OH)(CN)CH3 + KOH
9
Q

When are nitriles useful intermediates?

A

In the synthesis of other organic compounds e.g. amines and carboxylic acids

10
Q

What can nitriles be reduced to?

A

Amines

11
Q

Describe the reduction of nitriles to amines

A
  • Nitriles can be reduced to amines by reacting with hydrogen in the presence of a nickel catalyst
  • e.g. CH3CH2CN + 2H2 => CH3CH2CH2NH2
12
Q

Describe the hydrolysis of nitriles

A
  • Nitriles undergo hydrolysis to form carboxylic acids by heating with dilute aqueous acid e.g. HCl
  • e.g. CH3CN + 2H2O + HCl => CH3COOH + NH4Cl
13
Q

What two reactions form carbon-carbon bonds to benzene rings?

A

1) acylation

2) alkylation

14
Q

What kind of reaction mechanisms does acylation and alkylation take place by?

A

Electrophilic substitution

15
Q

What is alkylation?

A
  • A reaction that transfers an alkyl group from a haloalkane to a benzene ring in the presence of a Friedal-Crafts catalyst (halogen carrier)
  • e.g. benzene + chloroethane => ethylbenzene + HCl
16
Q

What is acylation?

A
  • Formation of a ketone when benzene reacts with an acyl chloride in the presence of AlCl3 catalyst
  • e.g. benzene + ethyl chloride => phenyl chloride + HCl