6.2.1: Amines Flashcards

1
Q

How do you name amines?

A

-amine or amino

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2
Q

Why are amines so reactive?

A

The lone pair of electrons on the Nitrogen - due to polar N-H bond

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3
Q

What shape are amines around the N? Bond angle?

A

Trigonal pyramidal, 107 degrees due to lone pair on N

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4
Q

What kind of intermolecular forces do they have?

Why?

A

Hydrogen bonding due to polar N-H bond and lone pair of electrons on N atom.

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5
Q

Do amines have intermolecular forces which are

stronger than or weaker than alcohols? Why?

A

Weaker, as N has a lower electronegativity than O → weaker hydrogen bonding

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6
Q

How can/when do amines act as bases?

A

The lone pair on the nitrogen atom accepts a

proton

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7
Q

How can/when do amines act as nucleophiles?

A

When they bond with an electron-deficient C atom (donate lone pair from N)

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8
Q

What is the product from the basic action of an

amine with water?

A

RNH3+ - ammonium ion, which forms a salt with an anion

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9
Q

In order to be the strongest base, what must a particular amine have (out of a set of amines)?

A

Greatest electron density around the N atom, making it a better electron pair donor (attracts protons more)

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10
Q

What effect do alkyl groups have (on electron density and base strength)?

A

Positive inductive effect - increase electron density around N → stronger base

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11
Q

Place the following in order of base strength (in

general): NH3, 1o amine, 2o amine, phenylamine.

A

2o amine > 1o amine > NH3 > phenylamine

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12
Q

How can primary amines then form 2o, 3o amines and 4o ammonium ions?

A

Multiple substitutions; primary amine is a nucleophile that attacks the original haloalkane etc

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13
Q

What are the problems with this method?

A

Not efficient as low yield of 1o amine due to multiple substitutions

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14
Q

How would you maximise the yield of the primary

amine?

A

Use excess ammonia

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15
Q

What type of mechanism is the reaction of a haloalkane with a cyanide ion?

A

Nucleophilic substitution

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16
Q

What conditions does this reaction require? What is

the product formed?

A

Ethanol as a solvent

A nitrile is formed

17
Q

How do you get from a nitrile to a primary amine?

name of reaction type and reagents/catalysts

A

Reduction using Nickel / Hydrogen catalyst

18
Q

Why is this a purer method of synthesising amines?

A

Only the primary amine can be formed

19
Q

What conditions are needed to form nitrobenzene

from benzene?

A

Concentrated H2SO4 and HNO3 to form the NO2+ ion for electrophilic attack.

20
Q

How do you form an ammonium chloride salt from

nitrobenzene? What conditions are needed?

A

Reduce the nitrile using Tin / HCl → forms an ammonium salt with Cl- ions
Room temperature

21
Q

Equation for the reaction of nitrobenzene →

phenylamine?

A

C6H5NO2 + 6[H] → C6H5NH2 + 2H2O

22
Q

What mechanism is used for forming amides from

acyl chlorides and amines?

A

Nucleophilic addition/elimination