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Chemistry > CH28 Amines > Flashcards

CH28 Amines Flashcards

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1
Q

Naming amines

A

-amine

amino-

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2
Q

Why are amines so reactive

A

Lone pair of electrons on N

Polar N-H bond

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3
Q

Shape and bond angle of amines

A

Trigonal pyramidal

107 degrees due to lone pair on N

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4
Q

What intermolecular forces - why

A

H bonding - polar N-H and lone pair on N

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5
Q

Stronger or weaker intermolecular forces than alcohols - why

A

Weaker - N has lower electronegativity than O, weaker H bonding

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6
Q

What state are amines at 298K

A

Short chains - gases

Longer chains - volatile liquids

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7
Q

What do they smell of - why

A

Fishy smell - rotting fish release di / tri amines

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8
Q

Which primary amines are soluble in water / alcohols

A

Up to 4 carbon atoms - H bond to water

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9
Q

What kind of solvents are most other amines soluble in

A

Less or non-polar solvents

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10
Q

Solubility of phenylamine

A

Not very - non-polarity of benzene ring - no H bonds

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11
Q

When do amines act as bases

A

When they bond with a H+ ion

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12
Q

When do amines act as nucleophiles

A

When they bond with an electron deficient C atom

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13
Q

Product from basic action of an amine with water

A

RNH3 +

Ammonium ion which forms a salt with an anion

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14
Q

Is ammonium ion soluble in water - why

A

Yes - ionic so attracted to polar bonds in water

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15
Q

How could you regenerate soluble amine from ammonium salt

A

Add strong base (NaOH) –> removes H+ ions from ammonium ion

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16
Q

In order to be the strongest base what must a particular amine have

A

Greatest electron density around N atom making it a better electron pair donor

17
Q

What is the positive inductive effect

A

Donates electrons - increase density around N

18
Q

What is negative inductive effect

A

Removes electrons - decrease density around N

19
Q

What effect do alkyl groups have

A

Positive inductive effect
Increase electron density
Stronger base

20
Q

What effect do aryl groups have

A

Negative inductive effect
Decrease density around N
Weaker base

21
Q

Why are tertiary amines never good bases

A

Insoluble in water

22
Q

Order the base strength of:

ammonia, primary amine, secondary amine, phenylamine

A

secondary amine > primary amine > ammonia > phenylamine

23
Q

How can primary amines form other amines

A

Multiple nucleophilic substitutions

24
Q

Problems with this method

A

Not efficient as low yield of primary amine due to multiple substitutions

25
Q

How would you maximise yield of primary amine

A

Use excess ammonia

26
Q

What mechanism is the reaction of a halogenoalkane and a cyanide ion

A

Nucleophilic substitution

27
Q

Conditions and product for that reaction

A

Ethanol solvent

Nitrile formed

28
Q

How do you get from a nitrile to a primary amine

A

Reduction using Nickel / Hydrogen catalyst

29
Q

Why is this a purer method of synthesising amines

A

Only primary amine formed

30
Q

Conditions needed to form nitrobenzene from benzene

A

Conc H2SO4 and HNO3 to form NO2 +

31
Q

How do you form an ammonium chloride salt from nitrobenzene

A

Reduce nitrile using Tin / HCl –> forms ammonium salt with Cl- ions
RT

32
Q

Equation for reaction of nitrobenzene to phenylamine

A

C6H5NO2 + 6[H] –> C6H5NH2 + 2H2O

33
Q

Mechanism used for forming amides from acyl chlorides and amines

A

Nucleophilic addition / elimination

34
Q

Which industries use amines

A

Dyes
Nylon
Drugs
Synthesis of new molecules

35
Q

What are cationic surfactants

A

Quaternary ammonium salts with a cation that is charged at 1 end and non-polar at the other

36
Q

How do cationic surfactants work in hair conditioner

A

-ve charges on surface of hair attract cation
Removing them from surface
Prevents build-up of static electricity keeping kair flat

Chemistry (18 decks)

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