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Organic chemistry and synthesis A2 > Amines > Flashcards

Flashcards in Amines Deck (25):
1

How do you prepare amines?

Halogenoalkane is heated with an excess of ammonia dissolved in ethanol

This is carried out in a Sealed tube immersed in water: it's a NUCLEOPHILIC substitution reaction

2

In preparing amines, what else happens as a result of the amine being basic?

A soluble anime salt is formed as the basic anime accepts H+ from HX (Eg HCl)

RCH2NH2 + HX --> RCH2NH3+X-

3

Do amines dissolve in hydrochloric acid? Explain

Yes amines dissolve in HCl because a soluble salt is formed

CH3CH2NH2 + HCl --> CH3CH2NH3+Cl-

4

In order to make an amine from a amine salt what would you do?

Treat salt with NaOH - AN ALKALI to produce it


CH3CH2NH3+Cl- + NaOH --> CH3CH2NH2 + NaCl + H2O

5

What other compound can follow the path of the salt dissolving in HCl and being treated with NaOH?

Phenylamine

6

How do you prepare phenylamine ?

1-nitrobenzene is reduced with Tin and HCl
2- mixture is heated and a salt is formed which is soluble in water
3-NaOH (aq) is added to produce phenylamine

Steam distillation separates phenylamine and nitrobenzene

7

How would you separate phenylamine from nitrobenzene ?

Steam distillation

8

Reagents and conditions to prepare phenylamine

1-Sn and HCl (heat)

2-NaOH(aq)

9

What is the basic nature of amines

They are all basic because the nitrogen atom has a lone pair of electrons which accept a proton.

The nitrogen atom forms a coordinate a dative covalent bond with the proton H+ - it donates an electron pair

10

Observation of amines with universal indicator

It turns blue purple

11

Observation of amines with red litmus

It turns blue

12

What is the basic strength of aliphatic and aromatic amines?

Aliphatic: stronger bases than ammonia NH3

Aromatic: weaker bases than ammonia NH3

13

Describe the basic strength of phenylamine (an aromatic amine)

The electron density on the LP of the nitrogen is decreased due to the inductive effect of the aromatic ring. The ring is electron withdrawing so the Nitrogen accents H+ less readily. The lone pair is delocalised onto the ring

14

Describe the basic strength of ethyl amine (aliphatic amine)

Electron density on the LP of nitrogen is increased due to the inductive effect of the ethyl group. The alkyl group is electron donating so the N accepts H+ more readily: it's a strong base

15

What bonding occurs between amine molecules?

Hydrogen!
It is a strong intermolecular force so the MPs and BPs are higher than expected: lots of energy needed to overcome these

16

Compare bonding in amines and alcohols..

H bonding in amines is weaker than in alcohols as the Nitrogen is less EN than the O, so alcohols have higher BPS

17

What do amines contain?

A permanent dipole

18

General formula of an amine

RNH2

19

Conditions for reactions of amines with ethanoyl chloride

Dry conditions

Fume cupboard as hydrogen chloride produced

Ethanoyl chloride

20

What do reactions of amines wth ethanoyl chloride produce?

N-substituted products

Ending always ethanamide is CH3COCl used

21

What type of reaction is the one between amines and ethanoyl chloride?

NUCLEOPHILIC substitution or ethanoylation

22

If methylamine reacts with CH3COCl what is the products?

N-methylethanamide + HCl

23

If phenylamine is reacted with CH3COCl what is the products?

N-phenylethanamide + HCl

24

General equation for the reaction of amines with ethanoyl chloride

CH3COCl+ H2NR ---> CH3CONHR + HCl

25

Formula of an amine

RNH2