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chemistry > amines > Flashcards

amines Flashcards

1
Q

how many carbons does a primary amine have

A

1

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2
Q

how many carbons does a secondary amine have

A

2

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3
Q

how many carbons does a tertiary amine have

A

3

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4
Q

how many carbons does a quaternary amine have

A

4

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5
Q

how do you name amines?

A

-amine
or
amino-

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6
Q

explain the reactivity of amines

A
  • amines are highly reactive
  • because the lone pair of electrons on the nitrogen
  • due to polar N-H bond
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7
Q

explain what shape are amines around the nitrogen? bond angle?

A
  • trigonal pyramidal
  • 107
  • due to lone pair on N
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8
Q

what kind of intermolecular forces do amines have? why?

A
  • hydrogen bonding due to polar N-H bond and lone pair of electrons on nitrogen atom
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9
Q

do amines have intermolecular forces which are stronger or weaker than alcohols? why?

A
  • weaker
  • as nitrogen has a lower electronegativity than oxygen
  • forms weaker hydrogen bonds
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10
Q

how can/when do amines act as weak bases

A

the lone pair on the nitrogen accepts a proton

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11
Q

how can/when do amines act as nucleophiles

A

when they bond with an electron-deficient carbon atom and donate a lone pair from nitrogen

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12
Q

what is the product from the basic action of an amine with water?

A

RNH3+ (an ammonium ion which forms a salt with an anion)

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13
Q

write an equation for methylamine reacting with HCl

A

CH3NH2 + HCl → CH3NH3 + Cl−

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14
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 nitrogen atom
  • making it a better electron-pair donor
  • so it attracts protons more
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15
Q

what effect do alkyl groups have on electron density and base strength of amines

A
  • positive inductive effect
  • increase electron density around nitrogen
  • stronger base
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16
Q

place the following in order of base strength:
ammonia, primary amine, secondary amine, phenylamine

A

strongest to weakest

  1. secondary amine
  2. primary amine
  3. ammonia
  4. phenylamine (the lone pair on the nitrogen atom is less available)
17
Q

how do you form a secondary/tertiary amine

A

react a primary amine with a halogenalkane
then react the salt formed with NaOH

18
Q

how would you maximise the yield of the primary amine?

A

use excess ammonia because it reduces further substitutions of the amine groups into secondary/tertiary amines

19
Q

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

A

nucleophilic substitution

20
Q

what conditions does the formation of aliphatic amines require?

A
  • ammonia in excess
  • ethanol as a solvent
21
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
22
Q

why is the use of nitriles a purer method of synthesising amines?

A

only the primary amine can be formed

23
Q

what are the disadvantages of making aliphatic amines?

A
  1. produces impure products because secondary, tertiary amines are also made due to the fact that primary amines have a lone pair of electrons on the nitrogen so it acs as a nucleophile
24
Q

describe a method of making aromatic amines

A
  • reflux nitrobenzene with concentrated HCl and tin to form a salt
  • react the salt with NaOH to produce aromatic amine
25
Q

what conditions are needed for the formation of nitrobenzene from benzene

A
  • concentrated H2SO4
  • HNO3 to form NO2+ ion for electrophilic attack
26
Q

how do you form an ammonium chloride salt from nitrobenzene? what conditions are needed

A
  • reduce the nitrile using Tin/HCl to form an ammonium salt with Cl- ions
  • conduct at room temperature
27
Q

equation for the reaction of
nitrobenzene -> phenylamine

A

C6H5NO2 + 6[H] -> C6H5NH2 + 2H2O

28
Q

What mechanism is used for forming amides from acyl chlorides and amines

A

nucleophilic addition

29
Q

how to prepare aliphatic primary amines?

A
  • substitution of haloalkanes with excess ethanolic ammonia under reflux
  • react with NaOH afterwards
30
Q

mechanism in words for preparation of primary amines

A
  • lone pair of electrons in ammonia attracted to partially positive carbon in haloalkane
  • carbon halogen bond breaks
  • carbon forms bond with nitrogen in ammonia
  • nitrogen is positively charged
  • halogen donates lone pair of electrons to hydrogen attached to nitrogen
  • one nitrogen hydrogen bond breaks

chemistry (37 decks)

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