amines

Question 1

prefix for amine

Answer 1

amino-

Question 2

suffix for amine

Answer 2

-amine

Question 3

why are amines so reactive

Answer 3

lone pair of electrons on nitrogen due to N-H bond

Question 4

what shape and bond angle around N

Answer 4

trigonal pyramidal
107 degrees due to lone pair on N

Question 5

what kind of intermolecular forces do they have

Answer 5

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

Question 6

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

Answer 6

weaker as N has a lower electronegativity than O –> weaker hydrogen bonding

Question 7

what state are amines at 298 K

Answer 7

short chains are gases, longer chains are volatile liquids

Question 8

what do amines smell of and why

Answer 8

fishy smell
rotting fish and flesh releases di- and triamines

Question 9

which primary amines are soluble in water/alcohols

Answer 9

up to 4 carbon atoms, as they can hydrogen bond to water molecules. after this, non-polarity of hydrocarbon chains makes them insoluble

Question 10

what kind of solvents are most other amines soluble in

Answer 10

less or non-polar solvents

Question 11

solubility of phenylamine

Answer 11

not very soluble, due to the non-polarity of the benzene ring - C6H5 cannot form hydrogen bonds

Question 12

how can/when do amines act as bases

Answer 12

when they bond with a H+ ion

Question 13

how can/when do amines act as nucleophiles

Answer 13

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

Question 14

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

Answer 14

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

Question 15

is the product (ammonium ion) soluble in water

Answer 15

yes, as it is ionic so is attracted to the polar bonds in H2O

Question 16

how could you regenerate the soluble amine from the ammonium salt

Answer 16

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

Question 17

how could you regenerate the soluble amine from the ammonium salt

Answer 17

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

Question 18

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

Answer 18

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

Question 19

what does positive/negative inductive effect mean

Answer 19

positive inductive effect = donate electrons increase density around N
negative = remove electrons, decrease density around N

Question 20

what effect do alkyl groups have

Answer 20

positive inductive effect - increase electron density around N –> stronger base

Question 21

what effect do alkyl groups have

Answer 21

positive inductive effect - increase electron density around N –> stronger base

Question 22

what effect do aryl groups have

Answer 22

negative inductive effect - decrease electron density around N –> weaker base

Question 23

why are tertiary amines never good bases

Answer 23

they are insoluble in water

Question 24

place these in order of base strength NH3, primary, secondary and phenylamine

Answer 24

secondary > primary > NH3 > phenylamine

Question 25

how can primary amines then form secondary, tertiary amines and quaternary ammonium ions

Answer 25

multiple substitutions
primary amine is a nucleophile that attacks the original haloalkane

Question 26

problems with using NH3 as nucleophile to haloalkane

Answer 26

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

Question 27

how would you maximise the yield of the primary amine

Answer 27

use excess ammonia

Question 28

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

Answer 28

nucleophile substitution

Question 29

what conditions does this reaction require and what product is formed

Answer 29

ethanol as a solvent

a nitrile is formed

Question 30

how do you get from a nitrile to a primary amine

Answer 30

reduction using nickel / hydrogen catalyst

Question 31

why is this a purer method of synthesising amines

Answer 31

only the primary amine can be formed

Question 32

what conditions are needed to form nitrobenzene from benzene

Answer 32

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

Question 33

what conditions are needed to form nitrobenzene from benzene

Answer 33

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

Question 34

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

Answer 34

reduce the nitrile using Sn / HCl –> forms an ammonium salt with Cl- ions

room temperature

Question 35

nitrobenzene –> phenylamine

Answer 35

C6H5NO2 + 6[H] –> C6H5NH2 + 2H2O

Question 36

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

Answer 36

nucleophilic addition/elimination

Question 37

in which industries/products are amines used

Answer 37

dyes / nylon / drugs / synthesis of new molecules

Question 38

what are catatonic surfactants and where are they used

Answer 38

quaternary ammonium salts, with a cation that is charged at one end (N+) and non-polar at the other

used in fabric/hair conditioner

Question 39

how do catatonic surfactants work in fabric/hair conditioners

Answer 39

negative charges on the surface of the fabric/hair are attracted to the cation, removing them from the surface; prevents build up of static electricity and keeps hair flat and fabric smooth