Amines Flashcards

1
Q

How do you prepare amines?

A

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

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2
Q

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

A

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

RCH2NH2 + HX –> RCH2NH3+X-

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3
Q

Do amines dissolve in hydrochloric acid? Explain

A

Yes amines dissolve in HCl because a soluble salt is formed

CH3CH2NH2 + HCl –> CH3CH2NH3+Cl-

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4
Q

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

A

Treat salt with NaOH - AN ALKALI to produce it

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

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5
Q

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

A

Phenylamine

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6
Q

How do you prepare phenylamine ?

A

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

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7
Q

How would you separate phenylamine from nitrobenzene ?

A

Steam distillation

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8
Q

Reagents and conditions to prepare phenylamine

A

1-Sn and HCl (heat)

2-NaOH(aq)

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9
Q

What is the basic nature of amines

A

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

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10
Q

Observation of amines with universal indicator

A

It turns blue purple

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11
Q

Observation of amines with red litmus

A

It turns blue

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12
Q

What is the basic strength of aliphatic and aromatic amines?

A

Aliphatic: stronger bases than ammonia NH3

Aromatic: weaker bases than ammonia NH3

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13
Q

Describe the basic strength of phenylamine (an aromatic amine)

A

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

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14
Q

Describe the basic strength of ethyl amine (aliphatic amine)

A

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

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15
Q

What bonding occurs between amine molecules?

A

Hydrogen!

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

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16
Q

Compare bonding in amines and alcohols..

A

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

17
Q

What do amines contain?

A

A permanent dipole

18
Q

General formula of an amine

A

RNH2

19
Q

Conditions for reactions of amines with ethanoyl chloride

A

Dry conditions

Fume cupboard as hydrogen chloride produced

Ethanoyl chloride

20
Q

What do reactions of amines wth ethanoyl chloride produce?

A

N-substituted products

Ending always ethanamide is CH3COCl used

21
Q

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

A

NUCLEOPHILIC substitution or ethanoylation

22
Q

If methylamine reacts with CH3COCl what is the products?

A

N-methylethanamide + HCl

23
Q

If phenylamine is reacted with CH3COCl what is the products?

A

N-phenylethanamide + HCl

24
Q

General equation for the reaction of amines with ethanoyl chloride

A

CH3COCl+ H2NR —> CH3CONHR + HCl

25
Q

Formula of an amine

A

RNH2