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Chemistry > 17.5 > Flashcards

17.5 Flashcards

1
Q

what are amines

A

nitrogen containing compounds

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2
Q

explain the structure of an amine

A

3 bonding pairs with at least one alkyl group
1 lone pair
trigonal pyramidal shape

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3
Q

what is a primary amine

A

nitrogen is attached to 1 alkyl group

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4
Q

what is a secondary amine

A

nitrogen is attached to 2 alkyl groups

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5
Q

what is a tertiary amine

A

nitrogen is attached to 3 alkyl groups

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6
Q

whats the name of the compound C6H5NH2

A

phenylamine

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7
Q

what is the equation for the preparation of a primary amine from a halogenoalkane

A

CH3Cl + NH3 -> CH3NH2 + HCl

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8
Q

what is the equation for the preparation of a secondary amine from a halogenoalkane

A

CH3Cl + CH3NH2 -> (CH3)2NH + HCl

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9
Q

what are the 2 ways of forming amines from halogenoalkanes

A

heating with ammonia under pressure in a sealed container
or mix with aqueous ammonia

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10
Q

how does the formation of amines from halogenoalkanes involve and nucleophilic attack

A

lone pair on ammonia act as nucleophile and attack the electron deficient carbon, the amine formed then acts as a nucleophile and attacks another electron deficient carbon to form a secondary amine

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11
Q

how can the number of secondary amines being formed from the products of halogenoalkanes and ammonia be reduced

A

ammonia is used to excess so that it outnumbers the molecules of primary amines formed and some of the excess ammonia reacts with the HCl to form NH4Cl

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12
Q

what is the equation for the reduction of ethanenitrile

A

CH3CN + 4[H] -> CH3CH2NH2

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13
Q

what are the conditions and the reagent for the reduction of nitriles to primary amines

A

reducing agent - lithiumtetrahydridoaluminate
mixed in dry ether

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14
Q

why must the reduction of nitriles to primary amines be in dry ether

A

so that no water can affect the reaction

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15
Q

whats the equation for the reduction of nitrobenzene

A

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

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16
Q

what are the reagents and conditions for reduction of nitrobenzene to phenylamine

A

reducing agent (tin) and concentrated hydrochloric acid
heated under reflux

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17
Q

how does phenylamine react with acids

A

forms phenyl ammonium ion (C6H5NH3+)

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18
Q

how can phenyl ammonium ion be converted back to phenylamine

A

added alkali (sodium hydroxide)
C6H5NH3+ + OH- -> C6H5NH2 + H2O

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19
Q

what are phenylamines commonly used for

A

dying blue jeans
manufacturing polymers
pharmaceuticals

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20
Q

what is the trend in solubility of primary aliphatic amines as hydrocarbon chain decreases

A

as hydrocarbon chain increases solubility decreases

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21
Q

why are amines soluble in water

A

their lone pair on the nitrogen allows them to form hydrogen bonds with the water molecules

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22
Q

how can amines act as a base when mixed with water

A

the nitrogen uses its lone pair to form a dative bond with the hydrogen on the water molecule
CH3NH2 + H2O <=> CH3NH3+ + OH-

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23
Q

how does ammonia act as a base when mixed with water

A

the nitrogen uses its lone pair to form a dative bond with the hydrogen on the water molecule
NH3 + H2O <=> NH4+ + OH-

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24
Q

what is basicity

A

the extent to which a base can donate a lone pair of electrons to the hydrogen atom of a water molecule

25
Q

what is the trend is basicity of amines as the hydrocarbon chain length increases and why

A

basicity strength increases as chain length increases because the alkyl groups are electron-releasing so increase the density of the nitrogen and make it more open to donate its lone pair

26
Q

is ammonia a stronger or weaker base than alkylamines

27
Q

is phenyl amine a strong or weak base and why

A

weak base because the lone pair on the nitrogen are attracted to the delocalized pi bond making the nitrogen less electron rich and making the lone pair less available for donating

28
Q

how do amines react with acids

A

they all react with strong acids to form ionic salts

29
Q

what is the equation for the reaction between methylamine and nitric acid

A

CH3NH2 + HNO3 -> CH3NH3+ + NO3-

30
Q

what is the equation for the reaction between butylamine and hydrochloric acid

A

CH3CH2CH2CH2NH2 + HCl -> CH2CH2CH2CH2NH3+ + Cl-

31
Q

what is an addition-elimination reaction

A

occurs when 2 molecules join together, followed by the loss of a small molecule

32
Q

what is an amide

A

carbonyl group next to a NH group

33
Q

why do amines react with halogenoalkanes and what is produced

A

the electron deficient carbon reacts with the electron rich nitrogen to form a secondary amine a hydrogen halide

34
Q

what is the equation for the reaction between butylamine and chloroethane

A

CH3CH2CH2CH2NH2 + CH3CH2Cl -> CH3CH2CH2CH2NHCH2CH3 + HCl

35
Q

what happens if the products of the reaction between a halogenoalkane and alkylamine react further

A

the secondary amine will react with the halogenoalkane and form a tertiary amine and a halogen ion

36
Q

what is a quaternary ammonium salt

A

an ammonium ion in which all of the hydrogens have been replaced by alkyl groups

37
Q

why is reacting amines with halogenoalkanes not a good way of preparing primary/secondary/ tertiary amines

A

because the product gives a mixture of similar products

38
Q

give a use on quaternary ammonium salts

A

fabric softener

39
Q

what is the equation for the reaction of ammonia with hexaaquacopper(II)

A

[Cu(H2O)6]2+ + 4NH3 -> [Cu(NH3)4(H2O)2]2+ + 4H2O

40
Q

what will be observed when an amine reacts with hexaaquacopper(II)

A

first a blue precipitate will form then as the amine is added in excess it will dissolve and a deep blue solution will form

41
Q

what is the functional group of an amide

A

carbonyl group joined to an amino group
CONH2

42
Q

what are the properties of amides

A

solids
lower aliphatic amides are soluble
low mp & bp

43
Q

why are lower aliphatic amides soluble

A

because the central carbon atom is attached to an oxygen and a nitrogen which are very electronegative so the bonds are polar and have lone pairs which help to form hydrogen bonds with water

44
Q

what two molecules form a polyamide

A

a dicarboxylic acid and a diamine

45
Q

draw the structure of an amino acid

46
Q

what is the isoelectric point

A

the pH of an aqueous solution in which it is neutral

47
Q

what is a zwitterion

A

a molecule containing positive and negative charges but which have no overall charge

48
Q

are amino acids soluble

49
Q

what is the equation for an amino acid acting as a base

A

H2NCHRCOOH + H2O <=> H3N+CHRCOOH + OH-

50
Q

what is the equation for an amino acid acting as an acid

A

H2NCHRCOOH + H2O <=> H2NCHRCOO- + H3O+

51
Q

what does the isoelectric point tell you about the acidity or alkalinity of a zwitterion

A

low isoelectric point = predominantly acidic
high isoelectric point = predominantly basic

52
Q

are amino acids optically active

A

yes except glycine

53
Q

what is a peptide bond

A

the bond formed by a condensation reaction between the carbonyl group of one amino acid and the amino group of another amino acid

54
Q

what type of reaction occurs when two amino acids react together

A

acid-base reaction

55
Q

what is the difference between a long-chain polypeptide and a protein

A

proteins have more complex 3D structures, primary. secondary, tertiary, quaternary

56
Q

how can a protein be broken down into their individual amino acids

A

heat with concentrated HCl to break peptide bond

57
Q

how can chromatography be carried out on proteins to identify amino acids

A

hydrolyse a protein so a mixture of amino acids is produced, spot the protein on chromatography paper and using a suitable solvent the individual amino acids will rise to different heights however amino acids are colourless so the chromatogram must be prayed with a developing agent (ninhydrin) so that the position of the amino acids can be seen

58
Q

what developing agent is used for the chromatography of amino acids

59
Q

why is ninhydrin not used often

A

it is toxin

Chemistry (46 decks)

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